QC 
 
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Cornell University Library 
 QE 264.G78A91 1869 
 
 Explanation of sheet 13.Part of the coas 
 
 3 1924 004 412 692 
 
Cornell University 
 Library 
 
 The original of tiiis book is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
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 http://www.archive.org/details/cu31 92400441 2692 
 
SCOTLAND. 
 
 EXPLANATION OF SHEET 
 
 13. 
 
 PART OF THE COAST OF AYRSHIRE. 
 
 EDINBURGH: 
 PRINTED BY MURRAY AND GIBB, 
 
 FOR HER majesty's STATIONERY OFFICE. 
 1869. 
 
 Price Threepence. 
 
to tke 
 
 GEOLOGICAL SURVEY MAP 
 
 AbUshed on tfr_e Scale ofOn£> inch to a ntzU q ^ ^ „ ^ ) 
 
 I In preparation 
 
 CJ Me'fioirs pii2>U,''?ied 
 
SCOTLAND. 
 
 EXPLANATION OF SHEET 
 
 13. 
 
 PART OF THE COAST OF AYRSHIRE. 
 
 EDINBURGH: 
 PRINTED BY MURRAY AND GIBB, 
 
 FOB HER majesty's STATIONERY OFFICE. 
 1869. 
 
PREFACE. 
 
 The Map to which this Explanation refers was geologically surveyed by 
 myself, in continuation of the ground represented in Sheet 14. The 
 formations are better shown on the latter Map, and are more fully 
 described in its Explanation, to both of which the reader is referred. 
 At the time when this area was mapped, the work was superintended 
 by Professor A. C. Ramsay, Local Director, under Sir Roderick I. 
 Murchison, the Director-General. 
 
 Akch. Geikie, Director. 
 
 Geological Bubveit Office, 
 Edimburgh, 28(A June 1869. 
 
EXPLANATION OF SHEET 13. 
 
 I. AREA EMBRACED BY THE MAP. 
 
 1. The present Sheet of the one-inch Map contains merely a narrow strip 
 of the coast-line of Ayrshire, beginning a Uttle to the north of Gii-van, 
 and extending to Maidenhead Bay, about a mile and a half beyond Turn- 
 berry Point. The area of this marginal fragment is only about four square 
 mUes. Yet in this small compass, owing to the clear sections cut by the 
 sea, there is not a little which is itself of interest, and which helps to ex- 
 plam the geology of some of the inland districts. 
 
 II. FORM OF THE GROUND. 
 
 2. Two well-marked forms of ground run along the whole length of 
 this map. A flat platform, varying from 100 to 1200 yards in breadth, 
 and from 20 to 30 feet above mean tide, borders the present shore. At the 
 inner edge of this platform, a steep bank rises to the height of 100 or 120 
 feet above it, and then slopes away into the interior. The marginal ter- 
 race is the 25 -feet raised beach, while the bluff against which it abuts marks 
 the old coast-cliff of that period. This steep bank forms the dividing line 
 between the two forms of ground by which the district is marked. Along 
 its base Ues the level upraised sea margin ; at the top is the undulating 
 surface of the interior. Three streams have cut valleys through this 
 inland cliff — the Milton Burn, the Chapelton Burn, and the Lady Burn — 
 which convey the drainage of the interior to the sea. The present shore- 
 line at Turnberry Point, and northwards to Maidenhead Bay, is the only 
 part which presents a series of low rocky cMffs to the waves. Elsewhere 
 the shore is flat, and either sandy, or marked with low ledges of sandstone. 
 To the east and south of Turnljerry Point, also, a considerable depth of 
 blown sand has accumulated, and partially obscured the platform of the 
 raised beach. 
 
 III. GEOLOGICAL FORMATIONS CONTAINED IN 
 THE DISTRICT. 
 
 ( Alluvium, Peat, Soils. 
 Recent and Post- J Blown Sand. 
 Tertiary. "^ Raised Beaches. 
 
 ( Drift Clays, Sands, Gravels, and Boulders. 
 Miocene (?) Dolerite Dykes. 
 
 Middle (?) Old Red (Porphyrites, etc. 
 
 SandSLone. (Red Sandstones and Conglomerates. 
 
 Lower Llandovery. Grits and Conglomerates. 
 
IV. GEOLOGICAL STRUCTURE OF THE DISTRICT. 
 
 Lower Llandovery. 
 
 3. At the south-east corner of this Map, a small portion of Lower 
 Llandovery rocks comes in. These consist of hard grits and conglome- 
 rates, forming part of the series which sfretches from Trochraigue north- 
 eastwards to near Dalzellolie. This district is described in the Explanation 
 
 Middle (?) Old Red Sandstone.* 
 
 4. Nearly the whole of the rocks shown on the present Map belong to 
 this formation. They consist of red or reddish grey, sometimes yellow- 
 ish, false-bedded sandstones, with occasional bands of fine conglomerates. 
 Good sections are laid bare on the beach from the Brest Rocks south- 
 ward to the Lady Burn ; also in the larger water-courses. The general 
 dip is westerly, away from the Silurian rocks on which these sandstones 
 rest unconformably. Towards Turnberry Point, however, the dip veers 
 round towards the north-west, to allow the sandstones to pass under a 
 series of contemporaneous igneous rocks, which form the headland between 
 Turnberry Bay and Maidenhead Bay. 
 
 5. The Middle Old Red Sandstone series of Ayrshu-e abounds in inter- 
 bedded rocks of volcanic origin. Of these, an admirable example occurs 
 in this Map, and has been laid open by the waves. It begins at Turn- 
 berry Point, where ledges of a compact greenish- coloured porphyrite dip 
 towards the north-west, at from 10° to 15°. Similar rocks, sometimes 
 very slaggy and amygdaloidal, succeed each other for a mile along the 
 shore. Frequent thin courses of red and green sandstone, red marl, and 
 sometimes even of cornstone, separate the porphyrites from each other. 
 But the separation is further shown by the rough scoriaceons aspect which 
 the top and bottom of the beds often assume. In many places, radiating 
 veins occur in the porphyrite, filled up with sandstone. From the manner 
 in which these sandstone veins are stratified, it is evident that they must 
 have been formed by the washing of sand into open cracks in the hardened 
 lava, before the emission of the next flow of melted rock.f 
 
 6. It has sometimes been supposed that the red sandstones of this dis- 
 trict are later than the coal measures, and that coal may yet be found 
 below them. This, however, is entirely a mistake. There is no carboni- 
 ferous rock in this Map, and no coal-bearing strata nearer than Killochan, 
 where the small coal-field of the Girvan begins. J 
 
 Miocene (?) 
 
 7. Along the coast-line, a number of small dykes of dolerite occur, 
 running in a north-westerly direction, and traversing both the red sand- 
 stones and the porphyrites. Similar dykes abound in the south and west 
 of Scotland, increasing in numbers as they are followed westward, until 
 
 * For the reasons for considering this gi'oup of strata a middle series in the Old Ked 
 Sandstone, see Explanation of Sheet 14. 
 + See Explanation of Sheet 14, par. 26. 
 t Sec Map 14 and its Explanation. 
 
they are found passing iuto and intimately associated with the great 
 miocene volcanic plateaux of the north of Ireland and the Inner Hebrides. 
 They are therefore regarded as probably of miocene age.* 
 
 Drift. 
 
 8. Boulder clay covers all the district inland, from the edge of the 
 raised beach. The bluffs of the old coast-line seem to be formed mostly 
 of this deposit ; but good sections are not found here. Stiff red boulder 
 clay may be seen on the beach opposite Dipple, crovrded with its charac- 
 teristic striated stones. But though no good exposure of the clay itself 
 occurs, the beach is in many places strewed with hundreds of boulders, 
 which have been washed out of the clay, or out of the upper parts of the 
 drift. Most of these boulders are of grey granite, brought by the old ice- 
 sheets from the high grounds at the head of the Gu-van. Similar blocks 
 are scattered over the inland tracts : one, which must weigh about ten 
 tons, lies at the side of the Milton Burn, about half a mile above its mouth. 
 
 Raised Beaches. 
 
 9. There are traces here of the 40-feot beach of the west of Scotland. 
 One of these forms the triangular terrace on which the farmhouse of Dow- 
 hill stands, near the foot of the Chapelton Burn ; and again, at the bridge 
 on the Milton Burn, there are less distinct platforms, which may mark the 
 same old sea margin. But by much the most perfect example of a raised 
 beach, is that already referred to as sMi'ting the present shore along all 
 the coast-line shown on this Map. It is the 25-feet terrace which forms 
 such a conspicuous feature along the Scottish seaboard. There is no good 
 section to indicate the arrangement of its component strata of sand and 
 shmgle. Its surface has been heightened irregularly by accumulations of 
 blown sand, now covered with cultivated soil ; but it forms, nevertheless, 
 a tolerably level platform, varying, as already said, from 20 to 30 feet 
 above mean tide-mark, and from 100 to 1200 yards in breadth. The 
 contrast between this corn-bearing level and the steep gorse-covered bank 
 that rises from its inner margin, is sometimes very striking, suggesting, as 
 it does, the junction of a flat beach with the bold bluff which marks the 
 limit of the waves. 
 
 Blown Sand, Alluvium, etc. 
 
 10. Hills of blown sand form a conspicuous feature in the north part of 
 this strip of coast-hne along the side of Turnberry Bay. Smaller areas 
 occur as grassy hummocks along the surface of the raised beach further 
 south. 
 
 11. Small strips of alluvium line the sides of the water-courses. The 
 only other portion is that which lies in the hollow at Dipple, where it has 
 been worked for brick-making. It consists of a finely laminated clay, 
 without stones. In some of the layers, numerous plant remains occur, 
 but no shells have been observed. 
 
 * See on this subject, Proc. Eoy. Soc, Edin. vol. vi. p. 71; Srit. Assoc. Rep., 
 1867, Sect. p. 53; also Explanation to Sheet 14 of the Geol. Surv. Scot., par. 63. 
 
MUEEAY AND GIEB, EDISBUEGII, 
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Jllm0irs 0f tfj^ (5^0l0giml Surfed 
 
 SCOTLAND. 
 
 EXPLANATION OF SHEET 
 
 14. 
 
 AYRS,HIRE: SOUTHERN DISTRICT. 
 
 EDINBURGH: 
 PRINTED BY MURRAY AND GIBE. 
 
 FOR HER majesty's STATIONERY OFFICE. 
 
 1869. 
 
 Price Threepence. 
 
to tie 
 
 GEOLOCiCAL SURVEY MAP 
 
 BjbUshed. on the Scale of One in/fi in n mOe, "iS 
 
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SCOTLAND. 
 
 EXPLANATION OF SHEET 
 
 14. 
 
 AYRSHIRE: SOUTHERN DISTRICT. 
 
 EDINBURGH: 
 
 PRINTED BY MURRAY AND GJBB, 
 
 roK HER majesty's stationeuy office. 
 
 18 69. 
 
PREPACE. 
 
 The Map of which the present pamphlet is an Explanation, has been 
 geologically surveyed by Mr. James Geikie, Mr. B. N. Peach, and 
 myself ; Professor A. C. Ramsay being at the time Local Director of the 
 Survey, under the Director-General, Sir Roderick Murchison. My own 
 share of the work embraces all the ground lying to the west of a line 
 drawn from Genoch'on the Girvan Water, northward by Loch Spal- 
 lander, Craigs of Kyle, Ochiltree, Catrine, and Brigland, into the 
 adjoining sheet on the north (22). The area lying to the east of that 
 line was mapped by Mr. James Geikie and Mr. B. N. Peach, the former 
 taking the ground lying west and north of a line drawn from Loch Doon 
 to Dalmellington, thence by Benbeoch, Stannery Knowe, Todhill, Far- 
 dingreoch, Coalburn, and Blackloch, to Midton, 2|- miles S.E. from 
 Cumnock. 
 
 In the following Explanation, Mr. James Geikie has furnished para- 
 graphs 5, 6, 9, 19, 20, 22, 23, 44-51, 54-56 ; Mr. B. K Peach has 
 supplied Nos. 7, 8, 21, 52, and 53 ; the rest have been written by myself. 
 
 It is only necessary to add, that the present short description is simply 
 intended, as its name denotes, to be an Explanation, as brief as possible, 
 of this sheet of the Geological Survey. A much more detailed Memoir 
 will afterwards be published on the geology of the whole of Ayrshire. 
 
 Arch. Geikik, Director. 
 
 Geological Survey Offick, 
 Edinburgh, 29<A June 1869. 
 
EXPLANATION OF SHEET 14. 
 
 I. DISTRICTS EMBRACED IN THIS MAP. 
 
 1. The present sheet of the Greological Survey Map of Scotland 
 embraces the greater part of the central tracts of Ayrshire, and contains 
 an area of about 372 square miles. It includes most of the old dis- 
 trict of Kyle, along with the northern part of Carrick. It shows the 
 coast-line of the county from Troon to Culzean, and the valleys of the 
 Ayr, Lugar, Doon, and Girvan rivers. Hence it embraces the coal-fields 
 of Ayr, Coylton, Auchinleck, Cumnock, DalmeUington, and Dailly, along 
 with the agricultural districts of which Ayr, Maybole, Cumnock, and 
 Mauchline are the centres. 
 
 II. FORM OF THE GROUND. 
 
 2. The greater part of the ground shown upon this Map is hilly. The 
 highest elevations do not reach 1 900 feet. They occur towards the south- 
 east corner of the Map, where a portion of the broad uplands or table- 
 land of the south of Scotland extends from near Dalleagles south-westward 
 to Dailly. This strip of elevated land runs along the southern margin of 
 the Map, and presents, for the most part, a steep face towards the north- 
 west. From its flank the ground undulates into hill and moorland, until 
 it sinks into the cultivated lowlands through which the Ayr, Doon, and 
 Lugar flow. Between the valleys of the Girvan and Doon there rises the 
 group of hills which find then- highest summit in the Brown Carrick 
 (940 feet) to the south of the town of Ayr. Separating the valleys of 
 the Doon and Ayr runs a tract of high moorland, which, beginning at 
 the Craigs of Kyle (800 feet), stretches south-eastward to the base of 
 the southern uplands, and rises often into more or less detached hills, 
 some of which exceed 1500 feet in height. The River Ayr winds through 
 another isolated patch of hilly ground, in which it has cut a series of deep 
 ravines, ranging from Catrine westward to Stair. On the south side of 
 the river this group of hills sweeps in a kind of semicircle from Catrine by 
 Ochiltree to Stair, while on the north side it is better marked in the 
 eliptical ridge which runs from Catrine by Mauchline and Fail to Barn- 
 well Hill, and thence by Tarbolton to Stair. A glance at the Map will 
 show the reader that this cirque of elevated ground corresponds with the 
 outcrop of a series of volcanic rocks, by which the Permian basin is 
 encircled. At the north-east corner of the Map a small portion is shown 
 of the high moorlands, which rise above Sorn, and range eastward into 
 Lanarkshire. The lowland districts of the present Map are nearly con- 
 fined to the river valleys. The largest tract lies between the lower end 
 of the Doon and the Tarbolton heights. Another area, chiefly however 
 occupied by peat-moss, covers the space between the Lugar and the Ayr. 
 
III. FORMATIONS AND GROUPS OF ROCK ENTERING 
 INTO THE STRUCTURE OF THE DISTRICT. 
 
 Aqtjeous. 
 
 Recent and Post- JBlirrSn?''*' 
 •'' (Raised Beaches. 
 I Moraine Mounds. 
 Drift Sprips ) Erratic Blocks. 
 
 J Sands, Gravels, and Stratified Clays. 
 (Boulder Clays. 
 Permian. Red Sandstones and Volcanic rocks. 
 
 ^Coal Measures. 
 Carboniferous. ■< Carboniferous Limestone Series. 
 
 (Calciferous Sandstone Series. 
 Old Red Sand- (Middle Series of sandstones, etc., and Volcanic rocks, 
 stone. (Lower Series of sandstones, etc., and Volcanic rocks, 
 
 r Lower Llandovery. 
 Lower Silurian. -^Caradoc. 
 (Llandeilo 
 
 Metamobphic. 
 
 Metamorphic Rocks in Old Red Sandstone. 
 Metamorphic Rocks in Lower Silurian. 
 
 Igneous. 
 
 Miocene (?) Dolerite dykes. 
 Post-Permian, Dolerite masses, intrusive. 
 
 Permian. Porphyrites, Tuffs, Agglomerates. 
 
 Carboniferous. Tuffs and Melaphyre veins. 
 Old Red Sand-" 
 stone (Middle 1- Porphyrites, Melaphyres, Tuffs, Pelstones. 
 
 and Lower). 
 
 Post-Lower 
 
 Silurian. 
 
 Granite and Fclstone veins in Lower Silurian. 
 
 IV. GEOLOGICAL STRUCTURE OF THE DISTRICTS 
 CONTAINED IN THE MAP. 
 
 3. On comparing the Map with what has been said (par. 2.) of the 
 general form of the ground, it will be seen that a connection exists 
 between the external contour and the nature of the rocks underneath, — a 
 connection, however, which will be better understood after a detailed 
 description of the rocks has been given. The Lower Silurian, igneous, and 
 metamorphic rocks will be found to compose the hills, while the valleys 
 and lowlands lie almost whoUy on the softer sandstones, shales, and other 
 members of the Carboniferous formation. 
 
 For the sake of clearness in description, the rocks will be described in 
 geological order, beginning with the lowest ; and those of each formation 
 will be grouped under well-marked districts, for convenience of local 
 reference. 
 
 Lower Silurian. 
 
 4. The rocks of Lower Silurian age occurring within the present Map 
 are found in three separated districts. Of these the largest occupies the 
 
south-east corner of the Map ; the second is found flanking the great 
 table-land to the south-west of the village of Straiton ; while the third 
 forms the now well-known hills of Craighead, Drummuck, and MuUoch, 
 on the north side of the Glrvan, near Dailly. Each of these districts falls 
 to be described separately. 
 
 a. District of Looh Doon and Water of Deugh. 
 
 5. In this area the Lower Silurian rocks are bounded on the north- 
 west by a large fault, which brings down against them rocks of Lower 
 Old Red Sandstone and, in one place, of Carboniferous age. Throughout 
 the district the Silurian formation is made up of beds of hard grey and 
 blue greywacke, with occasional bands of dark blue and grey shales. 
 The greywacke becomes in places gritty and conglomeratic. In such 
 conglomeratic areas the pebbles are commonly well rounded fragments 
 of quartz, greywacke, and grit, sometimes with angular fragments of 
 hardened shale, from which a kind of brecciated aspect is given to the 
 rock. The most conspicuous bed of conglomerate is found running along 
 the northern flank of Benbrack Hill, about three miles to the east of Dal- 
 mellington. The pebbles are very large, sometimes four feet in diameter, 
 and consist of grey granite, hornblende rock, Lydian stone, etc. Certain 
 obscure worm-tracks (?), noticed in some of the shales in the neighbour- 
 hood of Loch Doon, are the only traces of organic life which have been 
 detected. 
 
 6. The general strike of the beds is north-east and south-west, and the 
 strata usually dip at high angles — the prevailing dip being to the south- 
 east. This constant dip, however, does not give us any means for 
 calculating the thickness of the strata, for the same beds apparently come 
 again and again to the surface, being repeated by several folds or undu- 
 lations of the strata, by which the beds are bent back upon each other. 
 Subsequent denudation having removed the tops of the arches or curves 
 of the strata, we have now the deceptive appearance of a great succession 
 of beds, dipping pretty constantly in the same direction. 
 
 7. The Silurian series of this district is traversed by numerous veins or 
 intrusive beds of pink felstone, similar to the intrusive rocks which occur 
 elsewhere in the same strata throughout the southern uplands. These 
 run along the strike, or from south-west to north-east. At the south- 
 east corner of the Map a small portion of granite is shown. It forms 
 part of the large mass of which the Cairnsmore of Carsphairn (2612 feet) 
 consists. The granite is grey and fine grained, and sends veins into the 
 surrounding greywacke and shale. These are much altered for some 
 distance, assuming a crystalhne or schistose character. 
 
 8. Two veins of galena were once worked at Dalleagles. They occur 
 in the Silurian rocks, and run in a north-west and south-east direction 
 across the strilie of the beds, until they are cut off by the large fault 
 bounding the Silurian uplands. A hematite vein has been opened along 
 the surface, in the bed of the Muck "Water. It is thin and unequal, and 
 has never been worked. It runs across the strike of the Silurian rocks, 
 but does not appear to enter the Old Red Sandstone. 
 
 b. District of Straiton and Glenalla. 
 
 9. A long band of conglomerate occurs between the Water of Girvan 
 at Genoch and the head of the Dalcairney Burn. It is bounded on the 
 north-west by a fault which lets down strata of Middle (?) Old Red Sand- 
 stone age, and on the south by another fault, bringing in igneous rocks 
 belonging to the Lower Old Red Sandstone. This is a well-marked and 
 characteristic conglomerate. It has the greenish colour so conspicuous 
 
in the Silurian conglomerates to the south-west, and contains pebbles of 
 altered rocks. The greenish matrix is sometimes hardened, but commonly 
 is soft, pulverulent, and earthy. In some places indeed the rock is quite 
 an uncompacted gravel. Courses of pebbly grit occasionally traverse 
 the conglomerate, and sometimes it consists of alternations of green grit 
 with hues of stones. Occasionally the conglomerate is a mere pell-mell 
 assemblage of stones, with very confused or no stratification. All the 
 stones are well rounded and water- worn.* 
 
 10. From the village of Straiton, as far as the hills overlooking K.il- 
 kerran, there runs along the northern flank of the upland country an 
 irregular strip of Silurian strata. The exact subdivision of the Silurian 
 series to which these strata belong has not yet been fixed. They have a 
 much less ancient aspect than the strata just described. Fossils have 
 indeed been obtained from them, but not yet sufficiently well marked to 
 indicate'how far the strata on this side of the Girvan correspond with 
 those on the north side. The best sections are to be seen -in the streams 
 to the south-west of Straiton, on the roadside near Kirkbride, in the 
 Shiel Burn, at and below Drurayork, and between that stream and the 
 farmhouse of Blair. From these sections the strata are seen to consist 
 of green, grey, yellow, and sometimes red shales, with bands of greyWacke, 
 which increase in number and dimensions towards the east, where they 
 become coarse gritty flagstones, sometimes conglomeratic. The strike 
 remains persistently in a north-easterly line, the beds being inchned at 
 high angles usually to the south-east, sometimes to the north-west, but 
 often quite vertical. Some confusion occurs in the Shiel Burn, above 
 Drumyork, at the junction of this shale and greywacke series with the 
 grits and flagstones of the Old Red Sandstone ; and further east a similar 
 difficulty occurs in drawing a line between the two formations. This 
 appears to be due partly to faulting and partly to a metamorphism 
 which, affecting both the Silurian and Old Red Sandstone, has given rise 
 to a further resemblance between strata probably to some extent originally 
 similar, and has produced crystalline masses in each of the formations. 
 (See pars. 14 and 32.) 
 
 c. District of Craighead, Drummuck, and Threave. 
 
 11. It will be observed from the Map that a band of Lower Silurian 
 rocks extends along the north bank of the Girvan from Craighead to 
 Dalzellolie. The abundantly fossiliferous nature of this band, first made 
 known by Sir Roderick Murchison,t has furnished a means of subdividing 
 the rocks according to the received Lower Silurian classification. The 
 subjoined table shows the succession in downward order. 
 
 3. Yellow and reddish brown, highly fossiliferous 
 sandstones and grits, yellow, blue, and grey 
 shales and grits. 
 2. Bands of conglomerate, sometimes very coarse. 
 ( 1. Grey and brown mudstones, hard grey grits, 
 Caradoc. ■< shales, a thick bed of limestone, with con- 
 
 ( glomerate and shale. 
 
 12. These strata are disposed in an anticlinal form. On the north- 
 west side they are uncomformably overlaid with the Middle (?) Old Red 
 Sandstone. On the south-east they are cut off by a fault which brings 
 down against them the Carboniferous rocks of the Girvan valley ; but the 
 
 * TMs conglomerate is a north-eastern prolongation of tlie massive green conglo- 
 merates whicE are associated with the Caradoc limestones of the Stinchar and Assel 
 valleys, to he described in a future memoir. — A. G. 
 
 + Quart. Joiirn. Geol. Soc, vol. vii. p. 153. 
 
 Lower Llandovery. 
 
axis of the arch is well seen on the flanks of the Quarrel Hill above 
 Dalquharran. 
 
 13. Caradoc. — Owing to the depth of drift and other causes, it has not 
 been possible properly to subdivide this group. The lunestone occurs in 
 several lenticular patches along the southern margin of the Caradoc area; 
 and as that area is formed of an anticlinal axis, the limestone might be 
 supposed to lie rather high in the series. This may indeed be its posi- 
 tion, though at present no conclusive evidence has been obtained on the 
 subject. The largest mass of limestone has long been worked at the 
 well-known little quarry of Craighead. It is a white or greyish compact 
 rock, sometimes green from diffused serpentine. At one place it contains 
 some green shale dipping towards the east, and thus indicating the bedding 
 of the limestone, which is otherwise an amorphous fractured mass. On 
 the west side of the quarry a coarse serpentinous conglomerate appears, 
 while beyond this a dirty green serpentinous rock of metamorphic origin 
 occupies the rest of Craighead Hill. A small patch of the limestone, 
 enclosed on all sides save the south by this metamorphic rock, lies in the 
 wood in the steep slope to the south-west of the quarry. Again, a similar 
 limestone, but in a much thinner bed, stretches from a cot called Thunderton 
 Hall, eastwards to the farmhouse of Glenlochrie. It is associated with a 
 metamorphic rock similar to that of Craighead Hill, and at the quarry 
 near Glenlochrie it is seen to be bedded in vertical conglomerates. 
 
 14. The rock of which Craighead Hill is formed, changes its aspect so 
 rapidly as it is followed over the ground, that it cannot easily be classed 
 under one name. In some places, as near Eallochan, it is a serpentine ; in 
 other places it resembles a fine-grained decomposing diabase. Its more 
 prevalent character is that of a dull, dirty-green, shattery rock, of which 
 a fresh fracture can scarcely be obtained, full of diffused serpentinous 
 matter, often veined with carbonate of lime, having sometimes quite the 
 aspect of a decayed greywacke, and always more or less decomposed. It 
 appears to represent a portion of the Caradoc strata which has undergone 
 metamorphism. It resembles rocks which occur in a similar way among 
 the greywacke and limestone to the south of the Girvan district. Another 
 small patch of the same kind of rock has been referred to above as occurring 
 to the east of Craighead quarry. 
 
 Characteristic Fossils from the Craighead Limestone* 
 
 Petraia elongata. Leptsena transversalis. 
 
 Palaeopora favosa. Orthis biforata. 
 Stenopora fibrosa. „ calligramma. 
 
 Favosites aspera. „ vespertilio. 
 
 Crinoid stems (fragments). Maclurea Logani ? 
 
 Encriminis punctatus. Raphistoma lenticularis. 
 
 15. The best sections of the mudstones of the Caradoc series are those 
 laid open in the channel of the Lady Burn (or Drummuck Burn), above 
 the farmhouse of Drummuck. Good sections are also exposed in the 
 streams which descend from the east and south sides of Quarrel Hill. The 
 Lady Burn sections are the chief repositories of fossils. 
 
 Characteristic Fossils from the Lady Bum {Drummuch) Section. 
 
 Ampyx rostratus. Theca triangularis. 
 
 Calymene Blumenbachii. Bellerophon acutus. 
 
 Trinucleus seticornis. ,, carinatus. 
 
 * In this and the succeeding fossil-lists (furnished by Mr. Etheridge, Palajontologist 
 of the Geological Survey), only some of the more characteristic forms are given. The 
 full lists will be given in the subsequent extended Memoir. 
 
10 
 
 16. Lower Lkmdovei-y. — I^fo unconformability has satisfactorily been 
 traced between the Caradoc rocks just described and the overlying strata 
 which are now to be noticed. But the occurrence of a massive conglo- 
 merate between the two series may possibly indicate a break in the suc- 
 cession of deposits. This conglomerate may be followed as a continuous 
 band of variable thickness along the base of the Llandovery group, forming 
 often a marked ridge or succession of ridges, owing to its great compact- 
 ness. It is thickest towards the south-west, where it covers a considerable 
 space at Trochraigue. At the north-eastern end it is seen to bend round 
 the antichnal axis, and to thin away southwards. Beds of grit and sand- 
 stone are interstratified with the conglomerate. This is particularly well 
 shown on the north side of the Quarrel Hill, where the conglomerate, by 
 a series of intercalations of flagstones, passes conformably up into the 
 Llandovery rocks of the Kirk Hill. 
 
 17. The strata into which the conglomerate thus graduates upwards 
 are reddish brown or yellow flagstones, sandstones, and grits, which pass 
 upward into blue grits, and blue, grey, and yellow shales, sometimes with 
 conglomerate bands. The lower parts of this series are best shown in 
 the numerous openings which have been made along the road between 
 Quarrel and Kirk Hills, to the north of the farm of High Mains or 
 Mullock, and in the quarry near Rough Neuk. The higher parts seen in 
 this area are exposed in the courses of the brooks to the north and east of 
 Rough Neuk. 
 
 Characteristic Fossils from the Lower Llandoveiy Rochs of Kirk Hill. 
 
 Petraia elongata. OrtMs calligramma. 
 
 Heliolites interstiiictus. Orthisina Scotica. 
 
 Nidulites favus. Macrocheiliis elongatus. 
 
 Hemithyris hemisphajrioa. Murchisonia cancellata. 
 
 Old Red Sandstone. 
 
 1 8. Between the Silurian rocks and the lowest members of the Carboni- 
 ferous system, there occurs in Ayrshire a great series of sandstones, flag- 
 stones, and conglomerates, with masses of interbedded rocks of volcanic 
 origin. These belong to two distinct groups. Of the one, the chief area on 
 the present Map ranges along the north-west side of the SUnrian uplands. 
 It lies on the same line of strike as the rocks of Corsincone, which, ranging 
 north-eastward into Lanarkshire, are undoubtedly of Lower Old Red Sand- 
 stone age, and which the Ayrshire series closely resembles. It has been 
 judged advisable, therefore, to class that Ayrshire series provisionally with 
 the Lower Old Red Sandstone. The second group lies unconformably on 
 the first, as well as on the Llandovery rocks, and is covered unconformably 
 by the lowest member of the Carboniferous series. It is classed, in the 
 meantime, as a Middle (?) Old Red Sandstone, though we have no means at 
 present of determining how far it represents the true Middle Old Red 
 Sandstone of the north of Scotland. Possibly it may prove, in the end, 
 to be merely an unconformable upper part of the great lower division of 
 that formation. Each of these groups contains an abundant suite of con- 
 temporaneous volcanic rocks ; and in each of them, but more particularly 
 in the lower group, there are proofs of considerable metamorphism. 
 
 1. LOWEK. 
 
 a. Dalmellington District. 
 
 19. The Lower Old Red Sandstone is represented in this district by a 
 long narrow strip of igneous and aqueous rocks running along the flanks 
 
11 
 
 ot the great Silui-ian uplands. This narrow band is bonnded on all sides 
 by faults — the great north-east and south-west fault separating it from 
 the hilly region to the south, while various faults on the north and north- 
 west bring it successively in contact with coal measures and Carboniferous 
 limestone, and with rocks of Caradoc age. The rocks of this district con- 
 sist of conglomerates, shales, and hardened mudstones, which are associ- 
 ated and iuterbedded with various porphyrites. Intrusive felstones and 
 , mica-traps cut through these rocks in all directions ; while, as just men- 
 tioned, certain portions of the aqueous strata have undergone some degree 
 of metamorphism. The strike of the beds is north-east a-^d south-west. 
 To the south-west of Dalmellington the dip is either vertical, or nearly 
 so, while between that village and Dalleagles the beds are commonly 
 inclined at high angles towards the south-east. 
 
 20. The conglomerates are made up chiefly of well-rounded fragments 
 of grit, greywacke, felspathic sandstone, compact crystalline felspathic 
 rocks, Lydian stone, quartz, etc. They are usually rudely stratified. The 
 other rocks of aqueous origin are shales and felspathic mudstones. These 
 are generally much jointed and shattery, and have often become highly 
 indurated. In the neighbourhood of Kuockdon the conglomerates begin 
 to show traces of metamorphic action, which is better exemplified, how- 
 ever, in the rocks south of the Water of Gu-van ; but as these are not 
 embraced in this Map, they fall to be described in the Explanation 
 to accompany Sheet 8. At Knockdon, however, it may be mentioned 
 that the conglomerates are highly altered, the matrix frequently assuming 
 a crystalline aspect even in places where the pebbles are not obliterated. 
 Near Knockdon, copper is said to have been once partially worked. 
 
 21. In the district between DalmelUngton and Dalleagles, as just men- 
 tioned, the Old Red Sandstone series is steeply inclined towards the south- 
 east : hence the highest visible beds are those next the Silurian uplands, 
 while the lowest lie next to the coal-field. This grouping is prolonged 
 towards the north-east into Lanarkshire, where a much more complete 
 development of the formation, both of its aqueous and igneous rocks, is to 
 be found. 
 
 22. The contemporaneous igneous rocks consist of various porphyrites. 
 These are either dark purplish, dull, fine-grained, .amygdaloidal, por- 
 phyritic rocks, or they are of a lighter bluish colour, less earthy, and 
 more crystalline texture, and not so conspicuously amygdaloidal, nor so 
 coarsely porphyritic, as the darker purphsh porphyrites sometimes become. 
 Between these varieties, however, there are many gradations, some of the 
 finer-grained, dull, brown rocks being with difficulty distinguished from 
 indurated felspathic mudstones. The intrusive rocks present many features 
 of interest. The most common variety is a pale or dark pink felstone, 
 which often becomes highly micaceous. When the intrusive mass comes 
 in contact with conglomerate, the latter is often highly altered, and the 
 junction between the two rocks is frequently much confused, the conglome- 
 rate being caught up and enclosed in the felstone. These phenomena may 
 be well studied on the hills looking down upon Wee Berbeth Loch, about 
 half a mile from the River Doon. 
 
 None of the streams in this neighbourhood afiord good sections ; but 
 the beds are often well exposed along the bare, rocky hill sides, which are 
 singularly free from drift. 
 
 b. Som District. 
 
 23. The Old Red Sandstone of this district forms the somewhat con- 
 spicuous hill of Blacksidend, which sweeps up from the valley of the 
 River Ayr at Sorn. Only a small portion of this area of Old Red Sand- 
 
12 
 
 stone comes into the present Map, and the rocks will therefore be more 
 particularly referred to in the Explanations accompanying Sheets 22 
 and 23. The strata here are bounded on the west and south by faults, 
 which bring down against them rocks of Carboniferous age. In Auchin- 
 longford Burn they appear to be covered nnconformably by the Calciferous 
 Sandstone series. The strata consist chiefly of grey and pinkish grey 
 felspathic sandstones and flagstones, which at Lanfine (Sheet 22) have 
 yielded remains of Cephalaspis Lyellii. They exhibit considerable meta- 
 morphism m some places, the rocks becoming quite crystalline. This 
 may be seen at Tincorn Hill. Farther north (Sheet 22), however, the 
 metamorphism becomes more intense, the strata passing into minette, 
 granite, etc. 
 
 2. Middle (?) 
 
 24. This group occupies two separated districts on the present Map. 
 One of these lies between the lower course of the Doon and the Girvan 
 Water, and may be called the Kirkoswald, Maybole, and Brown Carrick 
 district ; the other stretches as a band of hilly ground from near Dahnel- 
 lington to the south-west of Straiten, and may be named the Straiten and 
 Dahnellington district. The group contains the following rocks in de- 
 scending order : — 
 
 6. Reddish micaceous sandstones, with Ptericthys major. 
 
 4. Beds of porphyrite, with thin layers of tuff, and lenticular seams 
 of sandstone and conglomerate. 
 
 3. A very thick series of purple, reddish or greenish sandstones and 
 flagstones, with beds of porphyrite, tuff, and conglomerate 
 intercalated at different horizons. These volcanic rocks in- 
 crease in importance, when followed in descending section, 
 until they become 
 
 2. A group of porphyrites locally developed to a great thickness, 
 and resting upon 
 
 1. Reddish and greenish sandstones and conglomerates. 
 
 a. Kirkoswald, Maybole, and Brown Carrick District. 
 
 25. This area extends along the coast-line of Ayrshire-from the mouth 
 of the Girvan Water to the Heads of Ayr, and inland a little beyond 
 Kirkmichael, thus occupying pretty nearly the angle formed by the Girvan 
 and the Doon. It contains the best development of the Middle (?) Old Red 
 Sandstone to be found in the county. Beginning at the south, at the 
 margin of the Llandovery area abeady described, we find the members of 
 this middle group dipping towards the north or north north-west, at 
 angles ranging from 6° to 25° or more. The same dip continues, with 
 hardly any interruption, to the Heads of Ayr — a distance of eight miles. 
 If we allow an average angle of only 8°, and lay aside the effect of any 
 concealed faulting, we obtain a thickness of 6000 feet for this group in 
 the district now under description. 
 
 26. Good sections of the lower sandstones and flagstones are seen in 
 the streams between Kirkoswald and the Yale of Girvan, more especially 
 in the Chapelton Burn. The volcanic rocks associated with this part of 
 the group form conspicuous hills between Maybole and Daflly. They 
 consist of yellow or pinkish porphyrites and dark compact melaphyres,. 
 forming beds interstratified with the sandstones and conglomerates. 
 Higher in the series come the sandstones of Maybole, weU seen in the 
 quarries there. These beds are succeeded towards the north-west by 
 others which contain a large admixture of felspathic material, and in- 
 deed sometimes pass into a kind of coarse sandy tuff. Of this nature is 
 the zone of rock which forms the greater part of Mochrum Hill (there 
 
13 
 
 containing also a bed of porphyrite), and which stretches thence, north- 
 eastward, by Bogside and Brockloeh. Westward, a still more copious 
 development of volcanic rocks forms the range of cliffs at Culzean. The 
 sea has there laid bare a succession of different porphyrites in beds which 
 dip at low angles towards the north, and are sometimes separated from 
 each other by thin courses of sandstone, shale, conglomerate, or even corn- 
 stone. These porphyrites are for the most part dark green or purple, 
 finely crystalline, sometimes strongly porphyritic, and often amygdaloidal. 
 Here, as well as throughout the porphyrites of this group, irregular 
 vertical veins of sandstone sometimes traverse the rock in a stellar arrange- 
 ment. The sandstone is horizontally stratified, and agrees in character with 
 the sandstone lying between the porphyrites ; whence it appears that these 
 veins are due to the sand which was washed into the irregular star-shaped 
 cracks of the cooled lava, before that lava was covered by the next stream 
 of molten matter.* 
 
 27. From the Culzean porphyrites, northwards, the coast-liae affords a 
 good section of the overlying sandstones. These agree in character with 
 those which stretch inland; they are cut into ravines by the streams between 
 Brockloeh and Auchendrane. Here and there they contain bands of con- 
 glomerate; but their common character is that of flaggy or fajlse-bedded 
 red, yellow, greenish, or purplish grey sandstones. 
 
 28. The next member in ascending order is the series of porphyrites 
 which forms the range of high grounds between the Heads of Ayr and 
 Maybole, rising to a height of 940 feet above the sea. The bedded 
 character of these rocks is well shown, even at a distance, by the succes- 
 sion of low escarpments or terraces looking towards the south south-east, 
 and of gentle slopes in the opposite direction. It is further marked by the 
 intercalation of occasional short and inconstant courses of sandstone, shale, 
 and marl between the sheets of porphyrite. The prevailing rock, as at 
 Culzean, is a dark close-grained porphyrite, varying in tint from a dull 
 purple to a dirty green, but sometimes assuming brighter shades, usually 
 finely porphyritic, and often highly amygdaloidal. The best sections are 
 of course those of the cliffs to the south of the Heads of Ayr ; but sections 
 are to be seen in almost every part of the area covered by these rocks. 
 
 29. Where the porphyrite series ends on the shore near the Heads of 
 Ayr, there is some obscurity in the order of succession, owing to a number 
 of faults and dolerite dykes. A red tuff, and some red micaceous flag- 
 stones, are seen on the beach, dipping away from the porphyrite. Here 
 specimens ol ptericthys major have been obtained. Beyond these disturbed 
 beds lie the nearly horizontal red sandstones, which lie at the base of the 
 Carboniferous series, the line of junction between the two formations being 
 probably a fault. No further trace of the Old Red Sandstone is to be 
 met with to the north ; and the beds just described form the highest parts 
 of that formation which have yet been found in Ayrshu-e. 
 
 b. Straiten and Dalmellington District. 
 
 30. From the neighbourhood of Dalmellington, for fully fifteen miles 
 to the south-west, there is a strip of hilly ground which fronts the great 
 Silurian uplands, of which indeed it may be considered as a kind of out- 
 work. It is geologically marked off, however, by being mainly occupied by 
 members of the Middle Old Red Sandstone series, though m many places 
 portions of the lower group of that formation, as well as different parts 
 of the Lower Silurian series, appear. It will be seen from the Map (which, 
 however contains only a portion of the area, the rest being embraced by 
 Sheet 8) that the structure of this district is somewhat complicated. 
 
 * See ExplaDation of Sheet 13, par. 5. 
 
14 
 
 Both the Silurian and Lower Old Red Sandstone formation had been 
 here much disturbed before the deposition of the Middle Old Red Sand- 
 stone. The latter series has been subsequently fractured, invaded by 
 masses of intrusive felstone, and in some places changed into crystalhne 
 rocks. In spite of these causes of obscurity, however, it is evident that 
 we have here an unconformable group of strata, identical in character 
 and in geological relations with those which occupy the Kirkoswald, May- 
 bole, and Brown Carrick district. 
 
 31. That portion of the series which is shown on the present Map consists 
 of a thick series of reddish, greenish, and sometimes yellowish sandstones 
 or flagstones, often gritty or pebbly, and green or reddish conglo,merates, 
 the whole passing under a massive group of porphyrites, like those of the 
 Brown Carrick HiEs. The sandstones and conglomerates are seen in 
 greatest thickness in the streams which fall into the Girvan a few miles to 
 the south of Straiton, — particularly the Balbeg Burn, the Palmullan Burn 
 and its tributaries, and the Genoch Burn. But in this district the hill 
 sides are for the most part so bare of drift, that sections of the rocks are 
 everywhere abundant along the slopes. A marked stratum at the top of 
 the series is a coarse red, green, or yellowish conglomerate, which has 
 been traced for several miles along the foot of the porphyrite escarpment. 
 No fossils have yet been found among any of these rocks. 
 
 32. The most marked example of metamorphism met with in this group 
 occurs in the Black Hill of Knockgardner, about two mUes to the south- 
 west of Straiton, where the felspathic sandstones pass into crystalline 
 porphyritic rocks, which in places become diorites. Three separate 
 areas of metamorphism occur here : two in the Middle Old Red Sand- 
 stone series, and one among the Silurian rocks. The latter forms the 
 Green Hill of Knockgardner, whore a pinkish grey compact rock passes 
 into a quartziferous porphyry, while the shales in the neighbourhood are 
 much altered. Large masses of a pink or yellow intrusive porphyritic 
 felstone traverse the Middle Old Red Sandstone series of this district. 
 Of these, the largest lies to the south-west of Straiton, and includes the 
 conspicuous lull of Glenalla (1406 feet) while other masses occur near 
 Dalmellington. 
 
 33. The porphyrites which overHe the sandstone series form a marked 
 group of hills to the south and south-east of Straiton. Where their 
 lower limit is exposed vrithout faulting, they form an escarpment which 
 runs as a bold feature along the summit of the sandstone slopes. Their 
 bedded character is hkewlse indicated by the terraced outline of the hills, 
 as in the case of the Brown Carrick Hills already noticed. These por- 
 phyrites agree in petrological character with those of the other Middle (?) 
 Old Red Sandstone district of this county. They are usually fine-grained, 
 and dark in colour, the tint ranging from a bluish grey, through various 
 shades of purple and red, to a du-ty brown. Usually they are more or 
 less porphyritic — sometimes strongly so — while the upper and under 
 portions of the beds tend to assume an amygdaloidal character. The 
 same veinings of sandstone, and thin intercalations of conglomerates, sand- 
 stones, etc. occur which were referred to in pars. 26, 28. No strata are 
 found resting on these volcanic rocks, which form the highest members of 
 the group visible in this district. A reference to the Map will show how 
 much the group has here suffered from the effects of faults, especially 
 towards the eastern end of the area. 
 
 Carboniferous. 
 
 34. This great formation covers by much the largest part of the county 
 of Ayr. There being no Upper Old Red Sandstone here into which it 
 
15 
 
 might graduate downward, it rests unconformably upon all the older 
 formations. Its upper member is overlaid unconformably with the 
 Permian rocks. In this way neither the true base nor summit of the 
 Carboniferous series of Ayrshire can now be seen. The formation con- 
 sists of the following groups, in descending order : — 
 
 Sign on Map. Groups of Strata. Localities. 
 
 d 5. Coal Measures, consisting of — 
 
 b. Red sandstones, fireclays and Monkton, Aucheneruive, Ann- 
 marls, with carboniferous plants, bank ; Coylton Water below Coyl- 
 aud a seam of limestone containing ton ; from Craigs of Kyle to Auclien- 
 spiroriis carbonarius. 'So work- leek ; ravines of Lugar near Ochil- 
 able coal-seams in this group. tree, and of the Ayr at Catrine ; 
 
 a. A thick group of white and coal-fields of Ayr, Coylton, Dal- 
 grey sandstones, dark shales, fire- mellington, Cumnock, Auchen- 
 clays, ironstones, and coal-seams, leek, Lugar, and Sorn. 
 
 d 2. Carboniferous Limestone Series. 
 
 A suite of sandstones, shales, Grirvan coal-field, Craigs of Kyle, 
 
 and limestones, with seams of Patna, Keirs ; road from Dalmel- 
 
 coal. lington to Cumnock, near Old Cum- 
 nock, Sorn. 
 d 1. Calciferous Sandstone Series, 
 consisting of— 
 
 b. A variable group of white Dailly ; coast between mouth of 
 sandstones, cement -stones, and Doon and Brackenbrae ; between 
 marls, below which lies Ayr and Martnaham Loch ; neigh- 
 
 a. A group of red sandstones, bourhood of Sorn ; Kilkerran ; 
 marls, and cornstones. Girvan "Water below Straiten ; 
 
 moors north of Straiten ; Eiver 
 Doon from Patna to the sea. 
 
 It will be at present most convenient to divide the carboniferous area 
 into districts, and to describe the different members of the formation 
 which these districts contain. 
 
 a. District of the Vale of Girvan. 
 
 35. In this district are included all the carboniferous rocks which 
 extend from Dailly to the limestones of Patna and Keirs. The lowest 
 group of strata consists of red and reddish or purplish grey sandstones, 
 marls, with bands of cornstone and coarse sandy limestone, forming the 
 lower division of the Calciferous Sandstone series. These strata are 
 well seen in the Lady Glen of Kilkerran, where their base rests uncon- 
 formably upon the Silurian rocks. Good sections are likewise exposed in 
 the other streams which descend from the hills, on the south side of the 
 Girvan valley, as well as in the course of the Girvan Water itself, between 
 Kirkmichael and Straiton, and in the water-courses between this part of 
 that stream and the valley of the Doon. The limestones are laid open 
 in quarries at Lannielane, Kirkbride, Todglen, Balgreggan, and to the 
 east of Kirkmichael. Fossils are scarce throughout this group of strata. 
 Plant remains occasionally occur ; also worm-burrows and surfaces show- 
 ing ripple-marks. 
 
 36. This red sandstone group, as indicated on the Map, has been in 
 great measure cut off along the north side of the Girvan valley by a large 
 fault. On the south side, however, it is largely developed, and it spreads 
 eastward over the moorlands up to the valley of the Doon. It there 
 passes under the carboniferous limestone series, though in some locali- 
 ties, as at the Meiklehohn Burn, there are mdieations of the intermediate 
 cement-stone group, which elsewhere separates the red sandstones from 
 the carboniferous limestone. 
 
 37. Above the red sandstones comes a group of white or grey sand- 
 stones, blue or grey marls, shales, and cement-stones. It is seen m the 
 
16 
 
 lower portions of the streams near Dailly, but is not so well developed 
 here as in the district of the Doon. It is liable to great changes in its 
 extension over the county, being in some places several hundred feet 
 thick, while in others, and at a short distance, it is entirely absent. 
 
 38. Girvan Coal-field. — Overlying the cement-stone group, comes the 
 Carboniferous Limestone series, stretching along the north-west side of 
 the Girvan valley from near Craighead to beyond Dalzellolie. The 
 following table shows the succession of the chief strata in descending 
 order : — 
 
 Sandstones, shales, and fireclays, with thin coals 
 and limestones {not yet wholly proved); 
 thickness probably from . 450 to 500 feet. 
 
 6 inches. 
 
 Dalquharran Limestone, 
 
 Strata, chiefly Yellow Sandstone, 
 
 2 
 102 
 
 Main Coal, .... 
 
 7 
 
 Fireclay, 
 Ground Coal, 
 
 
 
 2 
 3 
 
 Strata, . 
 
 
 
 3 
 
 Little Coal, . 
 
 
 , 
 
 4 
 
 Strata, . 
 
 
 
 12 
 
 Parrot Coal, 
 
 
 
 6 
 
 Strata, . 
 Coral Coal, . 
 
 
 
 10 
 5 
 
 Strata, . 
 
 
 
 18 
 
 Craigie Coal, 
 Strata, 
 
 
 • 
 
 8 
 30 
 
 Rotten Coal, 
 
 
 
 6 
 
 Strata, . 
 
 
 about 60 or 70 
 
 Captain's Bridge Lin 
 
 aestone, 
 
 
 27 
 
 Sandstones, Shales, Fireclays, etc. 
 
 In this small coal-field there are in all fully forty feet of workable coal. 
 The strata overlying the Dalquharran hmestone are at present being sunk 
 through, with the view of reaching the Main coal in the centre of the field. 
 When the new pit is completed, a section will be obtained of the whole 
 of the strata contained in this coal-field. As shown on the Map, there is 
 here a basin-shaped arrangement of the rocks ; the coals and limestones 
 dip into a long trough from the south-east side, and rise again to the 
 surface on the north-west side. 
 
 Detailed Map of this Coalfield. — The effects of the faults by which the 
 field is traversed, as well as the detailed outcrops of the different seams, 
 are given on Sheet No. 50 of the 6-inch Geological Survey Map of 
 Ayrshire. 
 
 b. Lower District of the Doon. 
 
 39. In this district is embraced the Calciferous Sandstone group, which 
 is developed between the limestones and coals of Patna and the shores of 
 the Firth of Clyde at and south of the mouth of the Doon. The lower 
 or red sandstone series is copiously displayed here, particularly along the 
 course of the River Doon, from Cambusdoon to near Auchendrane. It is also 
 well shown in some of the ravines of the same river above Dabymple, and 
 in the shore-cliffs immediately south of the Heads of Ayr. In a quarry 
 near Kersepark, south of the Craigs of Kyle, the red sandstones contain 
 well-preserved remains of Iqndodendron, and other carboniferous plants. 
 But fossils are remarkably scarce. This group of strata rests unconfor- 
 
17 
 
 mably upon the Middle (?) Old Red Sandstone, the beds of which have 
 their edges overlapped by it as far south as Barnshean Loch, where it is 
 thrown down against the older formation by the great Girvan fault already 
 referred to. It passes upward into the cement-stone group. The latter 
 group of strata reaches a considerable thickness in this district. The best 
 sections are those on the beach between the mouth of the Doon and the 
 Heads of Ayr. But inland the exposures are few, owing to the depth of 
 drift with which the district is covered. The position and thickness of the 
 series, however, is shown by a number of borings (one of which, near 
 Macnairston, passed down through 330 feet without reaching the bottom), 
 and also by numerous old fiUed-up quarry-holes and ruinous limekilns, which 
 mark where the more calcareous beds were formerly burnt for lime. As 
 exposed on the shore section, the series consists of numerous alternations 
 of grey, green, and blue shales or argillaceous marls, white or grey sand- 
 stones, and ferruginous hmestones or cement-stones. Some of these strata 
 abound in organic remains, as cypridcases, fish-scales, and plants. At 
 Greenan Castle, and at the Heads of Ayr, dolerite-tufif occurs. At the 
 former locaUty, the tuff is seen on the beach to be both distinctly inter- 
 bedded with the cement-stone group, and to break through it intrusively. 
 We have there probably a part of the neck or orifice of ejection, as well 
 as a portion of the ash which was thrown out and stratiiied among the 
 sandstones and shales. At the Heads of Ayr the tuff is either coarse and 
 unstratified, or its bedding is confused or pitched at high angles, while the 
 stratified rocks which adjoin it dip into it, and are much broken, or have 
 the edges of their beds truncated sharply by the tuff. These appearances 
 are similar to these presented by the tuffs of Dunbar and the Fife coast. 
 They serve to mark what was probably a focus of eruption. The Heads 
 of Ayr would therefore represent the ' neck ' or vent of a volcano which 
 was active during the period of the calciferous sandstones. The coast sec- 
 tion likewise furnishes some excellent examples of dolerite dykes ; but these 
 belong to a much later period (see par. 63). 
 
 c. The Ayr Coal-field. 
 
 40. Under this title is here included the district which extends along 
 the coast from Ayr to Troon, and stretches inland to the foot of the Tar- 
 bolton HiUs, Stair, Drongan, and the southern extremity of the Craigs of 
 Kyle. There is here a great development of carboniferous rocks, extend- 
 iug from the Carboniferous Limestone series up to the Permian formation. 
 The limestone series is, however, but ill represented. It may be seen on 
 the south-west side of the Craigs of Kyle, where one of the limestones has 
 been quarried. It has likewise been met with in bores to the north-west 
 of these Craigs ; but from that point onward to the sea no exposure of 
 limestone can be seen at the surface. Indeed no evidence has been 
 obtained as to whether the limestone series really exists between- Loch 
 Martnaham and the sea. If it does, it must be exceedingly thm. In 
 default of any proof of the presence of this series here, a dotted Kne has 
 been drawn on the Map along the doubtful ground, and the coal measures 
 have been shaded into the calciferous sandstones. 
 
 41. Numerous natural sections of the Coal Measures are furnished by 
 the different water-courses of the district. The lower parts of the series 
 are well seen in the Coylton Water, at and below Sundrum. The same 
 stream, between Sundrum and Garrochhead, flows over all the coals, and 
 a part of the overlying barren red measures. Good sections are likewise 
 laid open along the course of the River Ayr at Cameronsholm and above 
 Auchencruive. The foUowmg table shows the position and average 
 thicknesses of the principal coals in the district : — 
 
18 
 
 Red Sandstone Series. 
 
 
 
 Light Sandstones, Shales, Fireclays, and thin Coat, 
 
 60 to 70 feet. 
 
 Ell Coal, 
 
 3 feet 4 inches 
 
 Strata, .... 
 
 
 78 feet 
 
 Crawfordston Coal, 
 
 
 8 „ 
 
 Strata, .... 
 
 
 30 to 60 „ 
 
 Ayr Soft, or Five-feet, or Three-dirt Coal, 
 
 
 5 to 7 „ 
 
 Strata, .... 
 
 
 . 150 „ 
 
 Ayr Hard or Splint Coal, 
 
 
 4 „ 
 
 Strata, .... 
 
 
 . 300 „ 
 
 Black-band Ironstone, . 
 
 
 1 „ 
 
 Strata, .... 
 
 
 • 120 „ 
 
 Uppermost Limestone. 
 
 
 
 The black-band ironstone in this table is the same as the Burnfoot 
 seam of Dahnellington, but it is not well seen in the Ayr and Coylton 
 district. Its position has been found in borings to the south-west of 
 Coylton, but the seam is not worked there. The best of the coal seams 
 is the Ayr Hard Coal, long worked at Ayr and the neighbourhood, but 
 now exhausted in that part of the field. The higher seams are found in 
 the eastern half of the district ; but as they are traced seawards, their posi- 
 tion becomes uncertain, owing to the want of natural sections, and to the 
 number of faults and igneous rocks by which the results obtained from 
 borings are much obscured. It is quite possible, however, that a large 
 area of workable coal may yet be found to exist to the north and north- 
 east of Ayr. The upper barren red measures do not lie quite comf ormably 
 upon the coal-bearing series ; and a more systematic series of deeper 
 bores might reveal the existence of a new coal-field between Ayr and the 
 Dundonald Hills. There can at least be no doubt that the true coal- 
 bearing series underlies the red sandstones throughout that district. 
 Whether or not the coal seams would be found in such a state as to form 
 a profitable working, could only be learnt by proper borings. 
 
 42. The upper red sandstone group, to which reference has just been 
 made, forms the highest group of carboniferous strata in Ayrshire. The 
 Map shows how these rocks occupy the central part of the county, and 
 are overlaid with the Permian basin. They consist of red, and reddish 
 or purplish grey sandstones, red, purple, or lilac clays and shales, and an 
 occasional but inconstant thin band of fine white limestone. Coal-measure 
 plants occur in some of the argillaceous beds, and the mici-oconchus car- 
 bonarius occurs in the limestone. A section of a portion of the series has 
 been cut by the Coylton Water below Coylton, but the best sections are 
 those of the River Ayr, between Sorn and Ballochmyle, where the alter- 
 nating red sandstones, clays, and shales, with plants, are well seen, and 
 where the limestone is better developed than at any other place in the 
 county. This group of rocks, when mapped out in detail, is found not to 
 rest always on the same horizon of the coal-bearing measures below, but 
 to steal across or overlap them. This is particularly observable to the 
 east of the Permian basin, where the upper red sandstones come to lie 
 directly upon the carboniferous limestone. 
 
 43. The Ayr and Coylton coal-field, Uke the other coal-fields of Ayr- 
 shire, is traversed by numerous faults, and by masses of igneous rock, 
 whereby the coal seams are more or less destroyed. The prevailing 
 direction of the faults is from W.N.W. to E.S.E. None of them have a 
 great throw, few exceed 20 or 25 fathoms, and the majority are only a 
 few feet. There is a belief in the district that a 60-fathom fault runs in 
 the usual direction from Auchencruive to the shore at Kincase, near Prest- 
 wick, and that no workable coal exists to the north of it. There does 
 
19 
 
 not appear, however, to be any good foundation for this supposition. A 
 coal, believed to be the Splint or Hard Coal of Ayr, has been found in 
 several bores between Prestwick and Kincase, at depths varying from 28 
 to 45 fathoms. If there be any fault along the line just mentioned, it 
 does not throw out the coals, nor sink them to a great depth on the north 
 side. The practicability of working the coals does not depend upon the 
 existence of this fault, but on the quality and extent of the seams them- 
 selves ; and for this information, further borings are necessary. 
 
 44. The igneous rocks occur in the form of dykes and intruded masses of 
 dolerite. These are of at least two ages. The older series consists of sheets 
 of dolerite overlying or injected between the strata of the coal-field. The 
 largest mass of this kind in the district forms the conspicuous eminence of 
 the Craigs of Kyle. Another considerable area of dolerite overlies the 
 coals at Auchencruive, and other patches are seen higher up the Ayr, 
 south of Enterkine and Stair, where a thick series of pale grey shales has 
 apparently been hardened by the heated masses, so as to form the well- 
 known whetstones or Water-of-Ayr stones. The dolerite dykes belong as 
 a whole to a much later period. In the Ayr, at Auchencruive, one of 
 them may be seen cutting the older dolerite. They form part of a series 
 which spreads over the whole of the west of Scotland, and which is further 
 described in par. 63. 
 
 Detailed Maps of this Coal-field. — The detailed structure of this coal-field 
 is shown upon the published Maps of the Geological Survey, on the scale 
 of six inches to a mile — viz. Sheets 27, 33, 34, and 40 of the 6-inch 
 Map of Ayrshire. 
 
 d. The Dalmellington Coal-field. 
 
 45. The Dalmellington coal-field is bounded on the north-west by the 
 Calciferous Sandstone series, and on the south-east by rocks of Lower 
 Old Red Sandstone age, against which it is thrown by several powerful 
 faults. On the south-west it reposes conformably on the calciferous sand- 
 stones, and stretches away to the north-east until it verges with the coal- 
 fields of New Cumnock and Cumnock. The bottom beds of this coal-field 
 beloug to the Carboniferous Limestone series, which is here of inconsider- 
 able thickness. Upon the top of the limestone series come the true coal 
 measures, which again are covered unconformably by the upper barren 
 red measures already described. The millstone grit is thus unrepresented, 
 unless it be by some sandstones lying at the base of the coal measures. 
 
 46. The lowest bed of limestone in the Carboniferous Limestone series 
 is that worked at Patna. It contains productus giganteus, and other charac- 
 teristic fossils. About 50 fathoms higher in the series occur three and 
 sometimes four limestones, separated from each other by a few fathoms of 
 intervening sandstones and shales. They are seen at Keirs and Drum- 
 grange near Waterside, and at Coalston near Patna. In Grimmet Burn 
 and Glenhead Burn thin impure limestones also appear. The whole thick- 
 ness of the limestone series in this district does not exceed 360 feet. But 
 no good continuous section of the series is exposed, and the little that can 
 be seen is much confused by the numerous dislocations which traverse the 
 district. Only one coal is worked in this series — viz. the Patna coal. In 
 some pits this coal is split up by mtervening strata into two, and even as 
 many as four seams. When all these come together so as to form one 
 seam, the coal is as much as 14 feet in thickness. 
 
 47. In the overlying Coal Measures three coal seams have been worked: 
 the Minnivey, the Chalmerston, and Sillyhole coal seams. But the prin- 
 cipal mineral of the district is the Burnfoot black-band ironstone. This 
 valuable seam is 2 feet 3 inches thick in the Waterside workings ; but as 
 
20 
 
 Fms. 
 
 ft. 
 
 in. 
 
 
 
 
 
 10 
 
 47 
 
 
 
 
 
 
 
 5 
 
 6 
 
 50 
 
 
 
 
 
 
 
 4 
 
 
 
 10 
 
 
 
 
 
 
 
 3 
 
 6 
 
 109 
 
 
 
 
 
 
 
 2 
 
 3 
 
 it passes eastward it thins out, till in the New Cumnock coal-field it is often 
 not 2 inches thick. It is beheved to be the same seam as the black-band 
 of Auchinleck and Lugar. Besides this seam of ironstone, there is a 
 thinner black-band ironstone, worked for a time at Craigmark, Dalmel- 
 lington, but it was found to pass eastwards into a gas coal. 
 
 The general succession and thickness of the principal seams in the Dal- 
 mellmgton field is as follows : — 
 
 Craigmack Black-band Ironstone, 
 
 Strata^ . 
 Sillyhole Coal, . 
 
 Strata, 
 Chalmerston Coal, 
 
 Strata, 
 Minnivey Coal, . 
 
 Strata, 
 Burnfoot Black-band, 
 Besides these coal seams, there are others which may yet come to be 
 arailable. Fireclay is also worked in this district. 
 
 48. The overlying red sandstones, containing here and there a thin poor 
 coal, are brought into the Dalmelhngton district by two large faults, 
 which, coming from the north-east, converge and meet not far to the north 
 of Patna. 
 
 49. Intrusive sheets of dolerite are more numerous in this district 
 than in the Ayr coal-field. As a general rule, they lie more or less 
 closely along the planes of bedding. Owing to this circumstance, they 
 give to the hilly portions of the district a terraced outMne — the softer 
 sandstones above and below them having yielded more extensively to the 
 denuding agents. These dolerites form the hill-tops of Kilmein, Benwhat, 
 Ewehill, Benbeoch, Benbain, etc. A glance at the Map will show that 
 the doleritic masses are faulted and shifted by the dislocations which cross 
 the coal measures. They must therefore have been intruded at a period 
 anterior to the faulting of the district. As these dislocations are partly 
 at least, if not entirely, of earlier date than the Permian rocks, it is in- 
 ferred that the intrusive masses of dolerite in the coal measures were erupted 
 before the deposition of the Permian series, and that they belong to some 
 late part of the Carboniferous period. 
 
 50. The faults in the Dahnellington coal-field are very numerous ; "those 
 of largest throw have a general north-east and south-west trend. Another 
 set of dislocations — some of which are of considerable extent — runs in a 
 direction nearly at right angles to the former. Of these dislocations, some 
 at least appear to have had their origin after the deposition of the coal 
 measures, and prior to the accumulation of the Permian rocks. With 
 intrusive rocks of the latter period, this district is abundantly studded ; 
 and vertical dykes of dolerite, beheved to be of tertiary date, also traverse 
 the coal measures. These igneous rocks are described in pars. 60, 63. 
 
 Detailed Maps of this Coal-field. — Detailed information regarding mioerals, 
 faults, etc. is given in the published Maps of the Geological Survey, on 
 the scale of six inches to a mile — viz. Sheets 40, 46, and 47 of the 6-inch 
 Map of Ayrshire. 
 
 e. The Cumnock, Lugar, and Sorn Coal-fields. 
 
 51. These coal-fields are simply continuations of the same strata as 
 are developed in the neighbourhood of Dalmellington. At the base of 
 the whole we have the Calciferous Sandstones, presenting much the 
 same character as in the district of the Doon. But whereas, near 
 Dalmellington, the upper or cement-stone division of the series is very 
 
21 
 
 meagerly represented, we find that upper member, in the district under 
 review, attaining a considerable thickness. The underlying sandstones 
 are, as usual, soft red and grey coarse-grained rocks, interbedded here 
 and there with beds of conglomerate and occasional bands of concretionary 
 eornstone. Overlying these comes the cement-stone group, consisting, 
 as in the Doon district, of a set of shales, ceraent-stones, and grey fine- 
 grained sandstones and flagstones. These cement-stones and shales have 
 yielded many entomostraca and other fossils, and the fine-grained sand- 
 stones frequently show worm-tracks, rain-pits, ripple-marks, and sun- 
 cracks. In the neighbourhood of Sorn, the calciferous sandstone series 
 seems to rest unconformably upon the Lower Old Red Sandstone. 
 
 52. Next in ascending order comes the Carboniferous Limestone series, 
 which is but poorly developed in this district. The lower limestones 
 are seen at Laigh Holehouse and BlairmuUoch, near Sorn, and in Auchin- 
 longford Burn, near Nethershields. ' The upper limestones occur in the 
 bed of the Ayr at Sorn, near Upper Heilar, and other places. Farther 
 south, in the Cumnock district, the upper limestone is worked at Ben- 
 ston. A coal lying about 7 fathoms below the Pottery Wood limestone 
 was formerly worked at Sorn; near BlairmuUoch coal has also been 
 got. At present, the only coal (belougiog to the limestone series) 
 which is being raised, is a gas coal at Laigh Brocklar, near Sorn. The 
 strata are much disturbed and dislocated, and the succession of the beds 
 is exceedingly confused, so that it is impossible to give any estimate 
 of the probable thickness of the carboniferous limestone series in this 
 neighbourhood. 
 
 53. Between Dalmellington and New Cumnock the upper limestones 
 are seen rising from under the coal measures. In this locality, beds of 
 grit and conglomerate occur a little below the limestones. Coarse con- 
 glomerate is likewise associated with the lower limestone series to the 
 south of DalmeUington. These pebbly strata may indicate an original 
 overlap of the Limestone series upon the Old Red Sandstone ; a supposi- 
 tion which is farther supported by the fact that the thick calciferous 
 sandstone and carboniferous hmestone series of Dalmellington die out 
 towards the south-east, until, in the Sanquhar basin, the coal measures 
 rest directly upon Silurian rocks. 
 
 54. Above the limestones comes the Coal-measure series. Around New 
 Cumnock the succession of beds agrees with that at Dalmellington. The 
 eastern extension of the black-band ironstone has already been referred 
 to. It may be added that the two uppermost coal seams of Dalmelling- 
 ton — ^the Sillyhole and Chalmerston — are represented at New Cumnock 
 by the Lanemark and Boig gas coals. 
 
 65. In the Lugar district the principal mineral is the black-band iron- 
 stone, which appears to occupy somewhat the same position as the black- 
 band at Dalmellington. 
 
 The general succession of the bods is as follows : — 
 
 Ell Coal, 
 
 Strata, 
 Main Coal, 
 
 Strata, 
 Claud Coal, 
 
 Strata, 
 Maid Coal, 
 
 Strata, 
 Low Maid, 
 
 Strata, 
 Black-band Ironstone, 
 
 Fms. 
 
 ft. 
 
 in. 
 
 
 
 4 
 
 
 
 7 
 
 
 
 
 
 
 
 4 
 
 
 
 45 
 
 
 
 
 
 
 
 2 
 
 
 
 7 
 
 
 
 
 
 
 
 4 
 
 
 
 2 
 
 
 
 
 
 
 
 2 
 
 7 
 
 70 
 
 
 
 
 
 
 
 1 
 
 7 
 
22 
 
 56. The coal-bearing strata are here overlaid unconformably by the 
 usual red sandstones ; but the unconformity is so gentle as to be readily 
 overlooked in many places. To the west of Sorn, however, the red beds 
 steal over the coal-bearing strata, until they overlap upon the carbonifer- 
 ous limestone series. There is reason to believe that both the limestone 
 series and the overlying coal-beds are thinning out to north-west below 
 the red sandstones. But this question will be more properly discussed in 
 the extended Memoir. 
 
 57. In this, as in the other coal-fields, the strata are invaded by intru- 
 sive sheets of dolerite. A fine example of the effect produced upon a 
 coal seam by intruded trap, is seen in the railway cutting near Auchin- 
 leck, where the Claud coal is converted into a kind of coke, while the 
 igneous rock itself is altered, and takes the form of what is known as 
 ' white trap.' The intrusive sheets of dolerite are not so abundant, how- 
 ever, as in the neighbourhood of Dalmellington. The Lugar district is 
 much broken by faults, some of which are of great extent. Vertical 
 dykes of dolerite also traverse the strata in some places. 
 
 Detailed Maps of this Coal-field, on the scale of six inches to a mile, have 
 been prepared by the Geological Survey. They form Sheets 29, 35, 41, 
 and 47 of the 6-inch map of Ayrshire. 
 
 Permian. 
 
 bS. In the centre of the great coal basin of Ayrshire lies a pear-shaped 
 area, occupied by igneous rocks and red sandstones, believed to be of 
 Permian age. Nearly the whole of this area is contained on the present 
 Map. Its structure is exceedingly simple. The rocks of which it is 
 composed are arranged in the form of an oval basin, the long axis bemg 
 directed from north-west to south-east. At the bottom of the series lies 
 a group of porphyrites, melaphyres, and tuffs — the products of volcanic 
 vents, which were here active during the earlier part of the Permian 
 period. These igneous sheets form the rim of the basin, round which 
 they run as a continuous band. Inside of the rim, and lying above the 
 volcanic masses, is a set of brick-red sandstones, very distinct in colour 
 and structure from any of the red sandstones in the carboniferous forma- 
 tion underneath. 
 
 59. The lower or igt.eous zone consists of a succession of beds of 
 poi-phyrite and melaphyre, marking different eruptions of volcanic 
 material. It is admirably seen in the course of the River Ayr at Balloch- 
 myle, and again above Stair. Good sections are likewise laid bare in 
 numerous artificial openings along the greater part of its course. The 
 prevailing character of the rocks is that of a dull, reddish brown, amyg- 
 daloidal porphyrite, the kernels often full of steatite, and the matrix of 
 the rock usually ferruginous, and more or less decomposed. That this 
 volcanic series really belongs to the Permian system, and not to the 
 underlying coal measures, is showu by its included beds of the charac- 
 teristic brick-red sandstones, and by the way in which its upper tuffs 
 pass up by frequent intercalations into the overlying Permian sand- 
 stones.* 
 
 60. But besides these interbedded volcanic masses, this county 
 furnishes other evidence of the number and activity of the Permian 
 volcanos. Outside the Permian basin the coal measures are pierced by 
 numerous more or less circular masses of a coarse unstratified agglome- 
 rate. These come up as huge columns or pipes through the coal 
 measures, and appear at the surface usually as small rounded hillocks or 
 
 * See Geol. Mag. for June 1865. 
 
23 
 
 hills. The coal seams have been worked round and up to them, and 
 have sometimes been found to show the alteration which is usually visible 
 near igneous rocks. TJsually these pipes consist of a coarse, irregular, 
 reddish agglomerate, chiefly of different volcanic rocks, but porphyrite or 
 other lava-form rock sometimes occurs. In each case the material closely 
 resembles the Permian igneous masses. There can be little doubt that in 
 these columns or ' necks ' we see part of the vents through which volcanic 
 material was ejected in Permian times. Each of these green hills is thus the 
 stump, as it were, of an old Permian volcano. The most numerous ' necks ' 
 are those in the Dalmellington coal-field. They are found south-eastwards 
 near New Cumnock, and even in the Sanquhar coal-field. Good examples 
 occur in Raith Hill near Coylton, and in Sorn Hill near Catrine. Other 
 illustrations occur to the north, beyond the limits of the present Map. 
 The details of this interesting subject will be given in the larger Memoir. 
 
 61. The overlying red sandstone group is distinguished by the pecuUar 
 bright brick-red colour of its strata. It has been cut by the River Ayr 
 into a series of deep and picturesque ravines, along which the character- 
 istics of the strata are well exposed. Similar sections have been exca- 
 vated by the Lugar Water. The quarries at Mauchline likewise show 
 the quality which some of the strata possess as building stones. 
 
 62. The Permian basin, like the coal measures, is traversed by intrusive 
 dolerite. One irregular intrusive mass occurs at Ballochmyle ; the other 
 portions are dykes belonging to the north-west or late series. 
 
 Igneous Rocks of Miocene (?) Age. 
 
 63. In the foregoing paragraphs reference has several times been made 
 to a series of dolerite dykes of later age than any of the other igneous 
 rocks, and running in a north-west and south-east, or somewhat east and 
 west direction. The position of these dykes is indicated on the Map by 
 the narrow strips of dark crimson. At Craighead Hill one of them is seen 
 to cut through altered Lower Silurian rocks; along the shore from Culzean 
 to near the Heads of Ayr, they are found traversing the Old Red Sand- 
 stone and its porphyrites ; they cut through all parts of the Carboniferous 
 series from base to top, and near the junction of the Lugar and Ayr they 
 are found rising through the Permian sandstones. They vary in thick- 
 ness from only a foot or two up to 15 or 20 yards. As a rule, they do not 
 run along lines of fault. They preserve their course with singular per- 
 sistence, irrespective of the changes of dip and strike, or of the varying 
 nature of the rocks. They even cut across large faults without any 
 sensible deviation. It has been inferred that these dykes are connected 
 with the doleritic plateaux of Antrim and the Western Islands, and that 
 they are probably of miocene age.* Probably the best example of them 
 in the district is that (referred to in par. 44) which crosses the Ayr 
 above Auchencruive, whence it runs south-eastward for more than two 
 miles across the coal-field. The coast section to the south of the Doon 
 likewise lays bare some good exposures of these rocks, and of the manner 
 in which they alter the walls of the fissure up which the melted rock has 
 risen. 
 
 Faults. 
 
 64. Reference has already been made to some of the faults which 
 traverse the districts embraced on the present Map. It will be seen that 
 all the great dislocations run in a north-east and south-west direction, 
 
 * See Proc. Roy. Soc, Edin. vol. vi. p. 71 ; Brit. Ass. Report, 1867, Sect. p. 53, 
 
24 
 
 agreeing in this respect with the prevailing trend of the great faults in 
 the central valley of Scotland. One of these defines the boundary of the 
 Lower Silurian and Lower Old Red Sandstone rocks,' forming a long 
 straight line between them, and throwing out a vast thickness of strata on 
 the north side. Another runs along the north side of the Girvan valley, 
 and stretches thence north-eastward until it dies away into the coal-field. 
 It depresses all the rocks on its south-east side, bringing down at one 
 place the carboniferous limestone against the lower Llandovery rocks. 
 A third fault is seen on the south side of the same valley, letting down 
 the rocks on its north side. In the coal-fields the prevailing direction is 
 north-west and south-east, or west by north to east by south, and the 
 amount of displacement by these faults is much less than in the great 
 north-east and south-west series. 
 
 Drift. 
 
 65. Over a large part of the ground which this Map represents, the 
 rocks are concealed under a thick deposit of Drift. Beneath the drift, 
 or on hard rocks from which it has been removed, the surface of the rock 
 is grooved and striated with the characteristic ice-markings of the glacial 
 period. From the trend of these flutings and striae, as well as from the 
 composition of the drift itself, it appears that the centre of Ayrshire was 
 the meeting-place of the masses of ice which were moving southward 
 from the Highlands, and northward from the uplands of Galloway. 
 Throughout the hilly district of the southern portion of the Map, the ice- 
 striae point towards the N.W. or N.N.W., but bending round more to 
 the westward, as they recede from the high grounds and approach the 
 Clyde. On the northern side, again, the strise point towards S.W., as 
 shown on the Lady Isle, and near Prestwick. 
 
 66. The drift deposits consist of — 
 
 c. Loose earthy debris = moraine stuff. 
 b. Sands and gravels, and stratified clays. 
 a. Upper and lower boulder clay. 
 
 The boulder clay varies in colour and composition, according to the 
 districts in which it occurs. Among the Silurian rocks it is of a pale 
 grey ; on Old Red Sandstone it is red ; on the coal-fields it is usually 
 dark grey, blue, or brown. The stones it contains are for the most part 
 well striated and local in character. As we advance northward, however, 
 and come within what was probably the area of the ice that drained from 
 the Highlands, we meet with occasional fragments of gneiss or mica- 
 schist, which must have come from the Highlands. These are found in 
 the valley of the Lugar, and westward to the northern slopes of the Brown 
 Carrick range. To the west of Stair, gravel and a bed of peat are found 
 below the boulder clay. Stratified sands, gravels, and clays occur in the 
 boulder clay itself, particularly along the chief valley lines. It has not 
 been found possible, however, to map but these intercalations, or to sub- 
 divide the boulder clay into well defined zones. No fossils have yet been 
 found in the boulder clay in any part of these districts. 
 
 67. There are many indications that the drift has been laid down with 
 a very irregular surface. Some of the most striking are to be found in 
 the numerous hollows, either now or formerly filled with water. Such 
 hollows must be due to original irregularities of the drift deposits, as no 
 surface action could have produced them. In the district between Ayr 
 and the Girvan valley, they may be counted in dozens. Although com- 
 paratively few are , still covered with sheets of water, they have all 
 
25 
 
 evidently been bo at no very distant date ; and in some of them may be 
 seen the process of silting up, by which the lake is gradually converted 
 into the meadow. 
 
 68. The overlying sand and gravel group is only scantily developed in 
 Ayrshire. It forms some well-marked ridges or kames, about a mile and 
 a half to the north-west of Ochiltree. It may be seen also in a line of 
 kames which stretches up the valley of the Nith by Sanquhar and New 
 Cumnock, and extends for some way in the line of the railway. Between 
 Old and ISTew Cumnock some of these sand and gravel mounds enclose a 
 few small lochs. Another line of kames, about 1000 feet above the sea, 
 runs along the hollow between Benbrack and Clawfin, to the east of Dal- 
 mellington. In the neighbourhood of Maybole also, there is a series of 
 gravel and sand ridges, rising in places into well-marked kames. Similar 
 mounds occur on the south side of New Dailly. Near the sea there is 
 sometimes a considerable covering of sandy and gravelly deposits not 
 ridged up into definite kames. 
 
 69. Fine clays without stones occur in many parts of the area embraced 
 in this Map, usually in hollows, and therefore referable possibly to the 
 accumulation of silt washed by rains and rills off the slopes of boulder 
 clay. Some of these clays, however, may belong to the Glacial series, 
 though the absence of fossils and the want of continuous sections make 
 their true relations somewhat obscure. In only one instance have organic 
 remains been detected in these deposits. This was in a bed of fine clay, 
 cut open by the Pow Burn, about a mile to the east of Monkton. Here 
 shells of Arctic species occur ; among them astarte compressa and natica 
 clausa. 
 
 70. Erratic blocks are abundant throughout the southern half of Ayr- 
 shire. Like the strise on the rocks, and the stones in the boulder clay, 
 they point to the former existence of large masses of ice on the southern 
 hills. They consist in great part of grey granite, derived from the granite 
 hills, which rise among the Silurian rocks from near New Cumnock, south- 
 westwards by Cairnsmore of Carsphairn and Loch Doon, to the sources of 
 the Girvan and Stinchar. These blocks are found at least as far north as 
 the hUls overlooking the lower reaches of the River Doon. They are some- 
 times of large size, one of the largest — the Baron's Stone of Killochan — 
 measuring about 480 cubic feet. They lie by thousands in the valley of 
 the Girvan, and over the sides and summits of the adjoinmg hills. Farther 
 east they are found even as high as 1865 feet above the sea, on the top 
 of Enoch HiU, which is separated from the granitic mass of Cairnsmore by 
 four miles of intervening hill and valley. 
 
 Raised Beaches. 
 
 71. Along the coast-line, at varying distances from the present sea 
 margin, there are indications of former sea-levels in the form of more or 
 less perfectly preserved terraces. To the north-west of Kirkoswald, 
 below the farm of Jameston, there is one of those terraces at a height of 
 between 60 and 70 feet above mean tide-mark. Traces of another at a 
 somewhat lower level occur between Monkton and the old church of 
 Crosbie. To the east of the Ayr racecourse there is the remnant of a 
 third terrace, at a height of between 45 and 50 feet above half-tide, cor- 
 responding probably with the vrell-marked 40-feet beach of the west of 
 Scotland. The same terrace is seen in fragments at intervals along the 
 coast-line to the south. But the most persistent and best marked of the 
 terraces is the lowest and most recent, occurring at an average height of 
 about 25 feet. It forms along the present coast-line a strip of fiat land 
 
26 
 
 stretching northwards for many miles from the mouth of the Doon. On 
 this terrace all the coast towns of the district are built. It consists of 
 layers of sand and gravel identical in character with those forming on the 
 present beach. Throughout a great part of its course, however, its surface 
 has been much heightened and made uneven by inroads of blown sand 
 driven landwards from the beach. Cultivation has done much to smooth 
 the inequalities thus produced ; but the influence of the drifted sand in 
 altering the aspect of the raised beach may still be well seen in progress 
 at Prestwick. 
 
 Blown Sand. 
 
 72. From New Prestwick northwards for many miles, the coast-line is 
 marked with ridges of sand hills driven up by the wind from the present 
 beach. Where vegetation has been able to get a firm footing, the shape 
 of the mounds may remain for a long time unchanged ; but where the sand 
 lies exposed to the wind, the mounds undergo modifications during every 
 gale. As mentioned in the foregoing paragraph, the inequalities of surface 
 which mark the lowest of the raised beaches are in great measures due 
 to the former drifting of blown sand, although the ground has now been 
 cultivated for many centuries. The town of Ayr was formerly much 
 exposed to inroads of sand. 
 
 Alluvium, Peat, Soils. 
 
 73. Under the term allwinum are comprised all the deposits of clay, 
 sand, silt, loam, or gravel deposited by streams or by rain. The Map 
 shows the disposition of this alluvium along the water-courses, and the 
 manner in which the streams wind across it from side to side. In many 
 cases the alluvium of a river valley consists of several terraces rising 
 over each other, that of the present stream being the lowest. Good 
 examples of such terraces are found along the course of the Ayr between 
 Stair and its mouth. In addition to the stream alluvia, there are many 
 small isolated patches marking the sites of ancient bogs or lakes. These 
 are particularly numerous between Ayr and the valley of the Girvan (see 
 par. 67). They are now for the most part occupied by flat meadows or 
 cultivated fields ; some are stiU marshy ; a few yet show a dimiiiished 
 representative of the lake which once filled the hollow, — while here and 
 there, where the slopes of the hollow have been steeper and its bottom 
 
 •deeper, or where the inflow of sediment has been small, the lake still con- 
 tinues to cover most of its original area. Some of the lakes have been 
 drained artificially and converted into arable land. Others, as Tarbolton 
 Loch, are sometimes meadows and sometimes sheets of water, according 
 to the wetness or dryness of the season. 
 
 74. Much of the south of Ayrshire was formerly covered with peat and 
 heather, which is now cultivated. But there still remain many peat- 
 mosses, some of them of considerable size. They lie both on the low 
 grounds and among the hiUs, sometimes in small hpUows, sometimes in 
 broad, open valleys. One of the most considerable is Aird's Moss, between 
 the Lugar Water and the River Ayr. Other large areas of peat cover 
 the hilly grounds to the east and south-east of Dalmellington. Many of 
 the small alluvial' hollows referred to in the preceding paragraph contain 
 deposits of peat. A great deal of the peat now no longer continues to 
 grow. On hilly grounds it often cracks up and is blown away as dust 
 by the wind, or is washed off by rain, so as to present a brown verdureless 
 surface, roughened with stumps of heather, or projecting trunks and roots 
 
27 
 
 of ancient trees. On low lands or in hollows, the dead peat gets covered 
 with heath or with coarse grass. 
 
 75. The distribution of soils in Ayrshire follows approximately that of 
 the geological formations beneath the surface. On the hilly tracts the 
 covering of soil is usually thin and stony, but light and dry ; and when its 
 heather is burnt off, it affords good pasturage. Where the boulder clay 
 spreads over the vaJleys and lowlands, it usually' gives rise to a stiff, re- 
 tentive soil. This is the character of much of the eastern and north- 
 eastern districts. The sandy and gravelly parts of the Drift series are 
 covered with a good free soil ; but the richest soils are, as a rule, those 
 which lie along the alluvial plains, as in the lower parts of the valleys of 
 the Ayr, Doon, and Girvan. 
 
MUBRAr AND GIBB, EDINBURGH, 
 PRINTERS TO HER MAJESTY'S STATIONERY OFFICE. 
 
LIST OF PUBLICATIONS 
 
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 A Detailed Catalogue may be had gratis, on appUcaiion to the Geological Survey 
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 Agents appointed for the Sale of the Publications of the Geological Survey. 
 
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SCOTLAND. 
 
 EXPLANATION OF SHEET 
 15. 
 
 DTTMFRIESSHIRE (lorti-West Part) ; LANARKSHIRE (South 
 Part) ; AYRSHIRE (South-East Part). 
 
 EDINBURGH: 
 PRINTED BY MUERAY AND GIBB, 
 
 FOR HER majesty's STATIONERr OrFICE. 
 
 1871. 
 
 Price Threepence. 
 
to th.e 
 
 GEOLOGICAL SURVEY MAP 
 
 SC®TLAH 
 
 PubUsJied on the Scale of One inch to a mile 
 
 FuJylijlied 
 
 'MM i' 
 
 mm Ty fiqra vui/f 
 
 \J Memoirs ptjJ)lzs7ted 
 
Jll^m0trs 0f tfj^ (geological Sur&C2, 
 
 SCOTLAND. 
 
 EXPLANATION OF SHEET 
 
 15. 
 
 LTJMFEIESSHIRE (I[ortli-¥est Part) ; LAIARKSIIRE (Soutli 
 Part) ; ATRSHIEE (South-East Part). 
 
 EDINBURGH: 
 PRINTED BY MUERAY AND GTBB, 
 
 VOK lIEli majesty's STATIONERY Ol'FlCJE. 
 
 187 1. 
 
PREFACE. 
 
 The Map of which the present pamphlet is an Explanation has been 
 surveyed under my direction, and with the approval of the Director- 
 General, Sir Roderick Murchison. All the ground lying to the north- 
 west of the great fault bounding the Silurian uplands has been mapped 
 by Mr. B. N. Peach, as well as a strip of ground on the south-east side 
 of that fault stretching from the Clyde by Crawfordjohn, Upper White- 
 cleugh, Spango Water, Ku'kland Hill, and from Upper Cairn along the 
 southern hmits of Ayrshire to the south-west corner of the map, including 
 the Sanquhar coalfield. South of that strip the Silurian tracts have 
 been mapped by Mr. R. L. Jack as far south as a line drawn from the 
 head of the Buchan Water along the watershed between that stream 
 and the Scar Water to the Nith at Dalpedder Hill, thence along the 
 crest of the Lowther range to Leadburn Rig, and as far east as a line 
 striking from the last-named locality north-westward by Glendowran 
 Burn to the Duneaton Water. East of Mr. Jack's area the survey was 
 carried on by Mr. Harriman Skae into the adjoining sheet (16), and 
 southwards from the Lowther range by Durisdeer through the Silurian 
 hills into the next map on that side (sheet 9). South of Mr. Jack's 
 ground, the remainder of the Silurian tract was surveyed by Mr. John 
 Home from the head of the Afton Water eastwards to the Enterkine 
 Burn and the Nith. The Permian and Carboniferous basin of the Carron 
 Wa ter and Thorn hill was surveyed by myself. 
 
 ERRATUM. 
 
 Br a typographical error, the numbers referred to in the second para- 
 graph of the Preface have been deranged. The reader is requested to 
 insert the subjoined corrected paragraph in its place. 
 
 Of the following Explanation, Mr. Peach has supplied paragraphs 18 
 24, 38-40, 45-53, 56-76, 88-90, 93-98, 106, 107, 109 and 110 ; Mr! 
 Jack, paragraphs 7, 13, 19, 20, 23, 25, 28-31, 36, 102, 108, and 111 ; 
 Mr. Skae, paragraphs 14-17, 21, 22, 26, 27, and 37; Mr. Home, the 
 account of the glaciers given in paragraphs 100 and 101. Paragraphs 
 1-6, 8-12, 33-35, 41-44, 54, 55, 77-87, 91, 92, 99, 103, 105, and 112, 
 have been written by myself ; and I have, as usual, arranged and edited 
 the whole. 
 
EXPLANATION OF SHEET 15. 
 
 I. DISTRICTS EMBRACED IN THIS MAP. 
 
 1. In the present Map are represented 432 square miles of the high- 
 lying ground between the sources of the Nith and the Clyde, stretching 
 from Aird's Moss eastwards by Cairn Table and the Douglas coalfield 
 to beyond Abington, and southwards by New Cumnock, Sanquhar, and 
 the Leadhills, to Cairnsmore, Drumlanrig, and the hills about Queens- 
 berry. The Map thus includes the coalfields of Keniiox, Muirkirk, 
 Lugar, New Cumnock, and Sanquhar, as well as the mineral tracts of 
 Wanlockhead and Leadhills. Most of its area lies within the broad 
 tract of Silurian uplands of the southern counties of Scotland, while its 
 north-western portions come into the Carboniferous and Old Red Sand- 
 stone tracts of the great Midland Valley. About three-fifths of the Map 
 lie, half in Dumfriesshire, half in Lanarkshire ; the remainder lies in Ayr- 
 shire, except a small fraction at the south-west corner, which comes into 
 Kirkcudbright. 
 
 II. FORM or THE GROUND. 
 
 2. Occupying, as it does, part of the watershed between the Solway 
 and the Firth of Clyde, the area embraced in this Map is almost wholly 
 hilly ground. It may be divided into two regions, separated from each 
 other by the long straight N.E.-S.W. fault, which cuts off the Silurian 
 uplands from the uneven ground to the north-west. 
 
 3. The Silurian Area. — Of these two regions, that which lies to the 
 south-east, and forms the greater part of the Map, belongs to the great 
 Silurian table-land of the south of Scotland, and exhibits the well-known 
 characteristic surface-features of that tract of country. Although every- 
 where hilly, it contains no definite ranges or systems of hills. It must 
 rather be regarded as an undulating area of high ground, cut into wind- 
 ing valleys, between which the ground rises into irregular ridges. Its 
 surface is almost everywhere smooth, flowing, and covered with turf 
 or heath ; and only here and there, where the valleys narrow, or where 
 some harder bed of rock protrudes from a hill side, do we meet with cliffs 
 and rocky scars. It is traversed by two main valleys, that of the Nith 
 and that of the Clyde, the waters of which flow in opposite directions 
 across the Silurian uplands. Both the Nith and the Clyde flow obliquely 
 across the strike of the Silurian strata, although, on the whole, they may 
 be regarded as occupying transverse valleys. Their tributaries ought to 
 be looked upon as lying in longitudinal valleys, but they do so only in a 
 very general sense, since they wind and curve across the general trend 
 of the rocks with as much independence as their principals. Hence the 
 
intervening ridges of the old table-land are not regular and parallel hill- 
 ranges, but irregular masses which have been left standing, during tlie 
 general erosion of the valleys, between them. It is the excavation of 
 the valleys which has determhied the form of the hills. Nevertheless, the 
 influence of the geological structure of the rocks, iu guiding the gradual 
 sculpture of the hills formed out of them, can still be traced, in the gene- 
 ral trend of the ridges in a north-easterly and south-westerly direction, 
 that is, along the strike of the rocks. The long bank of the Lowthers, 
 for example, runs for five or six miles in the same line as the strike of 
 the Silurian strata of which it is composed. This is the best and indeed 
 almost the only noticeable example of the coincidence of the line of ridge 
 with the line of strike of the rocks. But even where the coincidence 
 is more faintly marked, we see everywhere a kind of striving after 
 a north-easterly trend, as if geological structure could only exercise a 
 pervading but not very potent influence upon the process of denudation. 
 The Silurian strata of this area are highly inclined and folded, but the 
 anticlinal arches do not form ridges, nor the synclinal troughs hills ; on 
 the contrary, the Lowther ridge runs along a synclinal fold. 
 
 4. The form of the surface in the Silurian area is partly of very ancient 
 date. There can be no doubt that the Silurian rocks were curved and 
 then denuded before the time of the Lower Old Red Sandstone, and that 
 they were here overspread by some 10,000 or 12,000 feet of that forma- 
 tion. What was the form of the Silurian ground at that ancient date 
 we have now no means of ascertaining, for that great depth of overlying 
 Old Red Sandstone has been since so entirely removed, that no trace 
 of any portion of it now remains. We know, however, that this vast 
 denudation took place previous to the time of the Carboniferous Lime- 
 stone, for that formation occurs in different parts of the Map, resting 
 directly on the Silurian rocks, without the intervention of any Old Red 
 Sandstone whatever. The Silurian region, bared of its Old Red Sand- 
 stone, had been cut out into valleys, in which the Carboniferous Limestone 
 was laid down ; and these valleys are valleys still, since the Carboniferous 
 and Permian strata, under which they were eventually buried, have since 
 been in great measure removed. 
 
 5. Thus only after a vastly prolonged denudation has the Silurian area 
 been brought into its present form of sui-face. The largest and highest 
 fragments which remain of the original table-land out of which the existing 
 valleys have been carved, form the group of the Wanlockhead, Leadhills, 
 and Lowther Hills, between the Nith and Clyde, and the high grounds 
 about the sources of the Afton, Euchan, Snar, and Ken waters. In the 
 Lowthers the highest point is 2403 feet above the sea, and a space of 
 about two and a half square miles exceeds an elevation of 2000 feet ; while 
 on the south-west side of the Nith the area above 2000 feet amounts 
 to rather more than a square mile, its highest point being the Black 
 Craig of Afton, which has an elevation of 2298 feet. The only cliff of 
 any size in the district is Glenwhorgan Craig, in the valley of the Scar 
 water, which has a height of upwards of 400 feet. It is on the north- 
 east side of the Nith, however, that the valleys are deepest and narrowest. 
 This is particularly to be observed on the south side of the Lowther Hills, 
 in such valleys as that of the Enterkin, or of Dalveen, and in their tribu- 
 taries. Yet though the slopes are steep, they are almost always grassy 
 or heathy ; and where rock does roughen them, it is for the most part 
 only in detached little crags and hummocks. The steep green declivities 
 of the Pass of Dalveen, and of the minor valleys which enter into it, form 
 a singular feature in the scenery of this region. 
 
 6. In this, as in other parts of the Silurian uplands of the south of 
 Scotland, there occur examples of dry ravines or hollows running along 
 
hill-sides, but truncated at either end, and not now occupied by running 
 water. One of these curious hollows occurs at Dnnmoss, near Elvanfoot ; 
 and a more remarkable instance occurs on the south-east end of Crucreacb. 
 Hill. Such fragments of older systems of drainage help us to realize the 
 long series of denudations which these uplands have undergone. 
 
 7. There is only one natural sheet of water in the Silurian region — 
 Polvaird Loch — which measures 700 feet long by 200 feet broad, and lies 
 at a height of 1760 feet above the sea, on a col of the great ridge 
 between the Scar and Euchan waters. It is surrounded and retained by 
 peat, and appears to have originated in the gradual decay and removal of 
 the central part of the peat moss of this col. During dry weather the peat 
 cracks and crumbles avray into dust, vyhich is blown off by the wind ; and 
 hence a hollow might have been worn in the middle of the moss capable 
 of holding water, and of being increased in size by the same process. 
 
 8. Tract to the N. W. of the Great Fault. — ^The Silurian area is flanked 
 on the north-west by an irregular series of widely-parallel ridges and 
 valleys, which, running from S.W. to N.E., correspond in direction with the 
 general strike of the Old Red Sandstone, conglomerate, and igneous rocks 
 of which they are chiefly composed. In this district, as in that already 
 described, there is a twofold valley-system, one series transverse to the 
 strike of the rocks and trend of the ridges, the other more or less parallel 
 with the strike. The former are most marked, and descend for the most 
 part to the north-west, towards the valley of the Ayr, which is here itself 
 a longitudinal valley. One important stream, the Duaeaton water, how- 
 ever, flows in the opposite direction, and actually crosses into the Silurian 
 region, where it flows along a longitudinal valley, until its waters are 
 caught and carried back again out of the Silurian tract by the transverse 
 valley of the Clyde. 
 
 9. The highest part of this district is Cairn Table (1944 feet), which 
 forms a central dome of high ground, whence the Garpel, Duneaton, and 
 Parishholm waters diverge. This dome, however, is merely the highest 
 portion of one of the long N.E. and S.W. parallel ridges which have been 
 referred to as characteristic of this part of the country embraced in the 
 present Map. Another of these ridges, formed mainly of a great con- 
 glomerate band, runs from the Duneaton water south-westwards until it 
 ends in the bold eminence of Corsincone, which, rising to a height of 1547 
 feet, forms a conspicuous landmark in Nithsdale. 
 
 10. Form of the Ground- little affected hy Faults. — In the present Map the 
 comparatively trifling influence exerted upon the form of the surface by 
 even large faults is well shown. The great boundary fault along the north- 
 western margin of the Silurian region, must be a dislocation of at least 
 10,000 or 12,000 feet, as will be shown on a subsequent page. Yet this 
 great fracture has not given rise to any long depression, valley, or gorge. 
 Sometimes it runs along a valley, sometimes over a hill, somethneS' along 
 a ridge. But what is still more noticeable, it is crossed by a long series 
 of transverse valleys, and in more than one instance it is traversed twice 
 by the same stream. The large valleys of the Clyde and Nith have been 
 excavated across this dislocation, as well as the minor depressions, in 
 which flow the Afton, Duneaton, Black Burn, and Mill Burn, besides still 
 smaller streams. The Nith rises m the Silurian region, and after flowing 
 across the large fault (see Sheet No. 14 of the Geological Survey Map of 
 Scotland) into the CarlDoniferons district, it turns round at New Cumnock, 
 and again crossing the fault, flows completely across the Silurian uplands 
 into the Solway. The Duneaton water and its tributaries from the 
 north-west in like manner cross the great fault, and again repass it when 
 their waters are carried off to the north in the Clyde. 
 
8 
 
 HI. FORMATIONS AND GROUPS OF ROCK ENTERING INTO 
 THE GEOLOGICAL STRUCTURE OF THE REGION 
 EMBRACED IN THE MAP. 
 
 Aqueous. 
 
 Sign on Map. 
 
 Recent and Post-Ter-) ^^^^i P^^^^ 
 tiary. j ' 
 
 /" Moraine mounds. 
 Y\ tj. a • ) Sands and Gravels. 
 
 Dnft Senas. ^. Erratic blocks. 
 
 V. Boulder-clays. 
 
 Permian. Red Sandstones and Volcanic rocks, e 
 
 /" Coal-measures, .... d' 
 
 rnrhnnifprniiq ) Millstone grit, .... d* 
 
 oarDOnuerous. < Carboniferous Limestone series, . d^ 
 
 \ Calciferous Sandstone series, . dl and d" 
 
 Lower Old Red Sand- jRed Sandstones, Conglomerates, and) , 
 
 stone. ( associated Volcanic rocks, . ) 
 
 Upper Silurian. Ludlow and Wenlock rocks, . b° 
 
 _ ci-i • (Caradoc beds, .... b» 
 
 Lower Silunan. JLlandeilo beds, .... b^' 
 
 Metamokphic. 
 
 Altered Lower Silarian strata, /3' 
 
 Dioritic rocks, etc., in Lower Silurian series, . . . . " Di? 
 
 Igneous. 
 
 L Interhedded or Contemporaneous. 
 
 In Permian. Porphyrite, Tuffs, etc., . . . Fe 
 
 „ Carboniferous. Basalt-rocks and tuffs, . . . Fd 
 
 „ Lower Old Red| Porphyrites, Melaphvres, and Tuffs, Fc 
 Sandstone. J f ^ ' f . -, 
 
 2. Inti'usive or Svhsrquent. 
 
 Of Miocene (?) age. Dolerite dykes, . . • . . Gn 
 
 „ Permian age. Necks of Agglomerate, . . . Ne 
 
 „ Post-Carboniferouslgj^^g^^^fB^3^H.^^^]^ ^^^ 
 
 age. > 
 
 „ Lower Old Redl ^ j ^ 
 
 Sandstone age. ) ' 
 
 „ Post-Llandeilo age. Felstones in Lower Silurian serie.'?, F 
 
 Diorite dykes, .... Di 
 
 Granite, G 
 
 IV. GEOLOGICAL STRUCTURE OF THE DISTRICTS 
 CONTAINED IN THE MAP. 
 
 11. In the followinpc descriptions each geological formation which 
 occurs in the Map is described in stratigraphical order, beginning with 
 the oldest. Where the area covered by a formation is scattered, or is 
 more conveniently treated under topographical subdivisions, it is divided 
 and described in separate districts. 
 
Lower Silurian. 
 
 12. By the valley of the River Nith the Lower Silurian area of this 
 Map is divided into two parts, which present sufBcient topographical and 
 geological differences to merit separate description. The district to the 
 north-east of the Nith will be termed the Leadhills District, and described 
 first, as containing the clearest section of the order of successioii among 
 the rocks of this part of the country. The area to the south-east of the 
 Nith will, for convenience of reference, be called in the following pages 
 the Sanquhar District. 
 
 a. Leadhills District. 
 
 1. Llandbilo Beds. 
 
 13. The geological structure of this district is best seen by taking a 
 section from near Crawfordjohn across the Snar water, Leadhills, and 
 the Green Lowther, to the valley of the Potrail water. In this section the 
 Lower Silurian rocks traversed may be regarded as forming one great 
 synclinal trough, since the lowest strata, which are seen to the north- 
 west along the great boundary fault, rise again to the surface on the 
 south-east side along the valley of the Potrail water. In reality, how- 
 ever, this synclinal trough is folded into several minor synclinal and 
 anticKnal curves, so that the same series of beds is repeated more than 
 once along the line of section. Two divisions of the Lower Silurian 
 system are here represented — the Llandeilo and the Caradoc beds. The 
 Llandeilo series consists of seven well-marked local groups of strata, 
 which, for the sake of clearness, will be described separately in ascending 
 order. They consist of the following divisions : — 
 
 H. Caeadoc or Bala Beds. 
 
 ( G. Black Shale Group. — Grey shales, with bands of fine-grained blue 
 greywacke and flinty mudstones, the most eharacteristic feature 
 being the intei-polation of numerous bands of dark anthracitic 
 shales with graptolites — Estimated thickness . . . 3400 ft. 
 
 F. Lowther Group. — Fine grey shales, and finely laminated felspathic 
 
 greywackes, with occasional giit beds — Estimated thickness . 5000 ft. 
 
 E. Haggis Bock Group, — consisting of coarse and fine grits and grey- 
 wackes, with associated bands of red and green flinty mudstone, 
 conglomerate, and occasionally breccia. The most marked feature 
 of the group is the occurence of a persistent band of conglomerate 
 containing pebbles of quartz rock, Lydian stone, and jasper, 
 locally known as the ' Haggis Rock ' — Estimated tliickness . 1800 ft. 
 
 D. Dalveen Group. — A series of fine blue and gi-ey greywackes and 
 shales, having no marked characteristic to distinguish them from 
 the other members of the Llandeilo series — Estimated thickness 2900 ft. 
 
 0. Daer Group. — A series of hard blue and purplish greywackes and 
 grey shales — Thickness not ascertained. 
 
 B. Hartfell Shale Group. — Black and grey shales with graptolites — 
 Thickness not ascertained. 
 
 A. Queensberry Grit Group. — Grey and purple giitty greywacke, with 
 occasional bands of pebbly grit — Thickness not ascertained. 
 
 14. A. Queensberry Grit Group. — This group of strata only comes 
 into the extreme south-east corner of the Map. It forms Queensberry Hill 
 (Sheet 1 6), and stretches north-eastward by the north of Moffat, forming 
 a band of rough craggy hills. This mass of rocks, as well as group B, 
 fall to be described more appropriately in the Explanation to accompany 
 Sheet 16. 
 
 15. B. Hartfell Shale Group. — One of the characteristic black 
 shales of this group comes into the south-east corner of the Map, and is 
 seen on the crags at the head of the Capel burn. It contains a few, grap- 
 tolites, but these will be described in the Explanation to Slieet 16. 
 
10 
 
 16. C. Daer Group. — This mass of strata occupies in the south-east 
 corner of the Map the basin drained by the Daer water and its tributaries 
 north-westwards to a line drawn from Durisdeer by Well Hill, Coom Rig 
 to Tomont Hill. It consists of hard blue and purplish gritty greywacke, 
 accompanied by, and interbedded with, grey shales and shaly greywacke. 
 The greywacke generally occurs in bands of a foot or so in thickness, 
 separated by hard thin shaly courses. Sometimes, however, it is met with 
 in great thick masses which present no trace of bedding. It often eon- 
 tains much diffused iron, which oxidizes, and causes it to assume a dull 
 red colour in the midst of beds of the usual grey or purplish tints. This 
 is more observable in the neighbourhood of dykes, and where the rock is 
 much broken up by joints. In some places it has a coarsely schistose 
 structure, breaking under the hammer with a shivery fracture. The 
 shales frequently become very sandy and micaceous, decomposing with 
 an oMve-green colour to a considerable depth. The prevailing strike is a 
 north-easterly one, the beds dipping at high angles to the north-west, or 
 in many cases being vertical. Although it is not easy to detect in this 
 area actual foldings of the beds, it is highly probable that many such do 
 occur, and that the same strata are repeated again and again, though, 
 owing to the reversal of the dips, the whole seem to slope towards the 
 north-west. Under these circumstances, no reUable estimate can be 
 formed of the thickness of this group in the present district. 
 
 17. D. Dalveen Group. — North of the line which has been indicated 
 as hmiting the Daer group, lies a considerable thickness of hard grey flaggy 
 shales, with bands of dark gritty greywacke. Their strike is the same as 
 that of the last group, and, although nearly vertical, they show on the 
 whole an inchnation towards the north-west. They are well exposed in 
 the Dalveen Pass. Their bedding is sometimes much jointed, contorted, 
 slickensided, and veiued with quartz. Other evidence of the extent to 
 which these strata have suffered metamorphism is shown by the fre- 
 quent corrugated texture of their laminse, and also by the occasional 
 appearance of a distinct set of cleavage planes, which, on the slope of 
 the Laght Hill, are inclined at a high angle in a direction opposite to that 
 of the planes of stratification. This group of beds in the Dinabid Linn 
 passes under a bed of coarse pebbly conglomerate, which is regarded as 
 the equivalent of the ' Haggis Rock ' to be immediately described. 
 
 18. On the north-west side of the Silurian area, abutting against the 
 great boundary fault, there comes a group of beds which are probably 
 the uppermost part of the Dalveen group. They consist of a series of 
 dark blue flaggy shales, with bands of dark greywacke, very much jointed 
 and shattered, in some cases so much so, that, as the fragments have been 
 re-cemented, a brecciform rock has been produced, which has in turn been 
 cut up by a new series of joints. The rocks in this area are highly 
 inclined, almost vertical, but dip steadily away from the large fault, and 
 plunge under the Haggis Rock series. The estimated thickness of the 
 Dalveen group is 2900 feet. 
 
 19. E. Haggis Rock Group. — This series of beds is seen along the 
 north-west margin of the Silurian area, from the Clyde at Mote, by Craw- 
 fordjohn, Pingland, and Kirkland Hill, to the edge of the Sanquhar coalfield, 
 on the other side of which it is again seen striking across the Afton into 
 Sheet 14. Throughout this tract its general dip is south-easterly, at an 
 average angle of about 65°. It consists of thin bedded shaly greywackes, 
 hard red mudstones, and fine conglomerates. The bottom bed in the 
 neighbourhood of Mountherrick is taken to be a band of breccia made up 
 of fragments of shale. This is succeeded by flinty red mudstones, in which 
 occurs the bed of conglomerate, locally known as 'Haggis Rock,' from 
 which this group has been named. The pebbles of this conglomerate are 
 
11 
 
 chiefly of quartz, jasper, aud Lydian stone, varying in size from that of a 
 pea to that of a large walnut. From its hardness and its characteristic 
 texture, this band of conglomerate forms a marked feature along the 
 north-western margin of the Silurian area ; and its fragments, whether 
 lying loose on the surface, or imbedded in the drifts, can be recognised all 
 over the lower grounds for a number of miles to the north and north-west. 
 The Haggis Rock is succeeded by a series of fine hard greywackes, with 
 occasional bands of grit and shale, the uppermost bed being one of fine 
 conglomerate. The thickness of the whole group between this upper 
 conglomerate and the bottom breccia is estimated in the Mountherrick 
 district to be about 1800 feet. 
 
 20. By a great syncHnal fold of the Llandeilo rocks, the Haggis Rock 
 group, after plunging underneath a vast thickness of overlying strata, 
 rises again to the surface along the north-west flank of the Lowther 
 ridge. It is there exposed underlying the Lowther beds in the Glen 
 Pranka burn, where it exhibits a conglomerate containing small pebbles 
 of quartz and angular fragments of hardened shale, which may be the 
 equivalent of the uppermost conglomerate bed of the Haggis Rock group 
 above referred to. Where seen, these beds liave a north-west dip ; but 
 they probably curve over immediately in the opposite direction, thus 
 forming the crest of an anticlinal axis, since they are succeeded a httle to 
 the south-east by the great overlying mass of the Lowther beds. 
 
 21. What appear to be the same strata are found on tlie north-western 
 slope of Lousie Wood Law, whence they may be followed as a continuous 
 band of considerable thickness, which, forming often a marked feature 
 along the hill-sides, is prolonged beyond the other side of the Clyde across 
 the Cakelaw and Glespin Burn. As it is traced to the north-east, this 
 conglomeratic band becomes much finer in grain, until it passes into a 
 gritty greywacke. Where its conglomeratic texture is best seen, it is 
 made up of well-rounded pebbles of quartz, grit, greywacke, and Lydian 
 stone, with angular fragments of hardened shale in a matrix of greenish- 
 grey quartzose grit. In some places, where the matrix is scanty, or even 
 almost wholly absent, the stones may be observed broken aud squeezed 
 into one another. As exposed in the Glespin Burn, the grey micaceous 
 shales, associated with the conglomerate, are either vertical, or dip at a 
 high angle to the south-east. 
 
 22. The south-easterly dip with which the Haggis Rock group plunges 
 under the Lowther Hills is succeeded by a dip to north-west, so that 
 the ridge of the Lowthers lies in a syncUnal trough, and the Haggis Rock 
 group is brought up again along its south-eastern flank. In the Dinabid 
 Linn, which descends into Dalveen Pass, a bed of coarse pebbly con- 
 glomerate is found associated with courses of greywacke and dark crumb- 
 ling shale. In composition and texture, this conglomerate agrees with 
 the corresponding bed to the north-west. It has here a north-easterly 
 dip, which, however, may be merely local, indicative perhaps of another 
 minor fold ; for a little to the north-east, in the two streams flowing east, 
 from the Lowther Hill, two bands of similar conglomerate are found 
 with a north-westerly dip, passing under the ridge of the Lowthers. 
 The conglomerate has not been recognised in any of the other streams 
 descending from the east side of that ridge ; but still further to the north- 
 east, on the side of the road to the south-east of Watchman Hill, and 
 again in the small stream which flows south from Lady Cairn to jom the 
 Clyde, alternations of coarse brecciated conglomerate and pebbly grit 
 occur. 
 
 23. P. Lowther Group — Overlying the group of which the Haggis 
 Bock is the prominent feature, comes a great thickness of finely-lami- 
 nated and flaggy blue felspathic greywackes and thin-bedded shales. 
 
12 
 
 with occasional beds of grit. This group of strata is well seen in all the 
 streams descending from the crest of the Lowther ridge, which is formed 
 of them, and from which their local name has been taken. As already 
 mentioned, they lie here in a synclinal trough, the centre of which corre- 
 sponds in a general sense with the trend of the ridge of the Lowthers. 
 The top of the group is not reached in this synclinal fold. To the 
 north-west, however, the wliole thickness of the group is met with along 
 the ridge which, between Leadhills and Crawford, separates the valleys of 
 the Elvan and Glengonnar waters. The best section of these strata, in 
 the present district, occurs in the cutting of the Caledonian Railway at 
 Crawford. It is in this group of strata, as developed along the Leadhills 
 line of outcrop, that the mineral veins of Leadhills and Wanlockhead 
 chiefly occur.* 
 
 24. By the great synclinal fold in which the Caradoc trough lies, the 
 Lowther beds are again brought up with a south-easterly dip, ranging 
 from the margin of the Sanquhar coal-field north-eastwards by the 
 valley of the Duneaton water to the Clyde. They are much altered, as 
 will afterwards be described, round the granite of the Spango water, 
 but in the streams descending into the Duneaton water their character- 
 istic features are well displayed. The estimated thickness of the strata 
 which form this group is 5000 feet. 
 
 25. G. Black Shale Group. — The main mass of the beds entering 
 into the composition of this group does not essentially differ in lithological 
 character from the group last described. It is, however, distinguishable 
 from it by the occurrence of bands of red and green flinty mudstone, and 
 of black anthracitic, pyritous, occasionally gnarled shales, containing 
 graptolites. This group is curved into a great synclinal trough, which, 
 flanked on either side by the underlying Lowther beds, has its centre 
 occupied by the Caradoc group (H), of Duntercleuch and Glendowran. 
 The black shale bands are numerous, and the group containmg them 
 may be traced by their means along the southern side of the basin in a 
 zone of over a mile in breadth, from Cogshead, by the smelting mills at 
 Wanlockhead and Leadhills, to Laggen Gill near Abington. Good sec- 
 tions of the graptohtic shales may be seen in Cog Burn, Wanlock Water 
 near Raecleuch Hill, Sowen Burn behind the Wanlockhead Smelting- 
 mill, and Glengonnar Burn (east of Black Hill). The lowest beds of this 
 series may be seen resting on the Lowther beds in the burn south of the 
 Wool Law, Leadhills, while the uppermost beds dip under the Caradoc 
 group at a high angle in Back Burn, Wanlockhead, and Glenkip Burn, 
 Leadhills. In Snar Water, south of Hunt Law, and at the head of the 
 Glenkip Burn, beds of this group may be observed much crumpled and 
 folded. The estimated thickness of the Black Shale group is 3400 feet. 
 
 26. In contmuation of the zone from Cogshead to Laggen Gill, a band 
 of black pyritous shales is exposed on the eastern base of Craig Dod, 
 near Abington, and also in the Glencaple Burn. The same shales are 
 seen in the railway cutting under the bridge opposite to Kirkton, and, 
 skirting the southern slopes of Southwood Big and TewsgUl Hill, are 
 prolonged by the head of Ringwood Gill into the adjoining Map (Sheet 
 16). Another bed runs from Glengonnar Mill to the north-east, by the 
 head of the Raggen Gill and Coldchapel Burn, to Rein Gill near Birnock. 
 The shales are dark grey or black ; usually soft, crumbly, and glossy. 
 In most instances they are profusely veined with white quartz, jointed 
 and slickensided. Sometimes they are interstratified with dark grey 
 siliceous courses. Although retaining well-marked bedding, they have 
 undergone much contortion and metamorphism. 
 
 * The general trend of the mineral veins is shown upon the Map, and a description 
 of theii- general character is given in par. 112. 
 
13 
 
 27. The flinty mudstoues, already referred to as characteristic of this 
 group, here consist of indurated green, red, or chocolate-coloured mud- 
 stones or shales, with thin courses of dark flinty slate or Lydian stone. 
 The latter are shattery, and much veined with quartz. These rocks ex- 
 tend, with an average breadth of one mile, from Craig Dod to the north- 
 east, by Southwood Rig, Tewsgill Hill, Rome Hill, and thence into the 
 adjoining sheet. M ore metamorphosed portions, to be presently described, 
 occur sporadically on both sides of the Clyde, between Abington and 
 Crawford. On Harkwood Rig, a vertical bed of coarse serpentinous 
 conglomerate appears, and seems to form a lenticular patch in the red 
 indurated shales. It consists of well-rounded stones of different flinty 
 altered rocks, in a dirty green, sandy decomposed matrix, veined with car- 
 bonate of lime. In some places it is a mere uncompacted assemblage of 
 stones, without any visible trace of stratification. 
 
 28l On the north-west side of the Caradoc trough (H), the black 
 shale series reappears, where its characteristic beds may be traced dip- 
 ping persistently to the south-east, from the edge of the Sanquhar coal- 
 fields, near Towerhill, north-eastward to Whiteside Hill, near the head of 
 the Crawick water. For about three miles further on in the line of 
 strike, the black shales of this group are concealed partly by the grassy 
 surface of the ridge of the Windy Dod, and partly by the Permian out- 
 Uer of Glendowran Burn. On the north-east side of this outlier, however, 
 a black shale containing graptolites occurs between Clench and Glen- 
 tewing, whence it may be inferred that, although not seen, the black shales 
 are nevertheless continuous. The Caradoc group, which occupies the 
 centre of a great synclinal fold of the Black Shale series, ' noses out '* to the 
 south-west about Wedder Dod, from which point, south-westward, the 
 trough is formed of the Black Shale group. 
 
 29. Fossils of this Group.-] — The following hst proves that the Black 
 Shale group belongs to the upper portion of the Llandeilo series :— 
 
 //iy(iro2oa Graptolithus Hisingeri. — Carr. Hydrozoa Dicellogi-apsus Moffatensis. 
 
 Nilssoni. — Barr. Garr, sp. 
 
 ' tennis. — Portl. Dicranograptus formosua. — 
 
 sp. nov. (?attenuatus). — Hopk. Hopk. 
 
 Sagittarius. — Linn. Nicholsoni. — Hopk. 
 
 Diplograpsus angiistifolius. — Hall. ramosus. — Hall. 
 
 mucronatus. — Hall. sextans. — Hall. 
 
 pristis. — His. Clingani. — Carr. 
 
 quadri-mucronatus. — Hall. Climacograptas bicornis. — 
 
 tamariscus. — Nich. Hall. 
 
 tricornis. — Carr. minutus. — Carr. 
 
 Whitfieldi. — Hall. • teretiusoulus. — His. 
 
 sp. nov. (? Etheridgei). — Hopk. Corynoides calicularis. — 
 Didymograpsus elegans. — Garr, Nich. 
 ISTemagrapsus linearis ? Brachiopoda Discina sp. 
 Dicellograpsus elegans. — Carr, sp. Siphonotreta micula. — 
 Forchhammeri. — Ocin, sp. M'Coy. 
 
 2. Caradoc Beds. 
 
 30. H. Caradoc Gfi-oup of Duntercleuch and Glendowran. — The great 
 synclinal curve of Llandeilo rocks in the Leadhills district is occupied 
 by a central group of beds, which, from the fossils found in them, have 
 been ascertained to belong to the Caradoc or Bala series. A reference 
 to the Map will show that this Caradoc trough extends from the neigh- 
 bourhood of Wedder Dod, in a north-easterly direction, at least as far as 
 
 * TMs phrase, which has heen used for some time by the Irish Geological Survey, 
 implies that strata folded into a. synclinal trough approach the surface at either end 
 of the trough, and finally crop out in the line of axis, their place being taken by 
 lower strata. 
 
 + These and the other fossil lists have been deterniiued by Mr. Etheridge. 
 
14 
 
 the hills on the right bank of the Clyde below Abington. Beyond that 
 locality, it has not yet been satisfactorily traced. The strata found in 
 this well-marked trough consist of greywacke, passing, on the one hand, 
 into crumbling sandstone, and, on the other hand, into pebbly grits, with 
 partings of shale resembling that of the Lowther series, and with beds of 
 conglomerate, which are chiefly found at the base of the group. In mapping 
 the district, the basement beds of the Caradoc series were taken to be two 
 bands of conglomerate, in which the pebbles, chiefly of quartz, vary in size, 
 from that of a small pea to that of a hen's egg. Not far from the bottom 
 of the trough, in a streamlet coming southward into Glendowran Burn, 
 a little concretionary limestone is seen, — ^the only example of limestone 
 met with in the Lower Silurian rocks of this Map. No fossils could be 
 found in it ; but the conglomerates, and a few of the gritty or pebbly beds 
 higher up, were found, in the course of the Survey, to be abundantly 
 fossiliferous, — the fossils indicating a Caradoc or Bala horizon. The 
 total thickness of strata in this group amounts to about 1700 feet; but 
 the top of the series has been removed by denudation, while the base may 
 possibly be an irregular and unconformable one upon the underlying 
 Llandeilo rocks. It has not been possible, however, accurately to ascer- 
 tain whether there is an unconformity here between the Llandeilo and 
 Caradoc rocks, although such a kind of junction may possibly be indi- 
 cated by the occurrence of the conglomerates, and by the way in which 
 the upper group seems gradually to overlap the lower, from south-west 
 to north-east, on the north-west side of the trough. 
 
 31. The Caradoc group appears to nose out between Arbory Hill and 
 the head of Coldchapel Burn, as the latter exposes a section in which the 
 beds of the graptolite zone dip to the south-east, and again rise up with- 
 out bringing on any higher beds. At Wallace's Cast, on Waudel Burn, 
 a conglomerate is seen, which, from its general appearance and fossil 
 contents, can be pronounced without hesitation to be identical with the 
 conglomerates of Snar water and Kilbucho.* Owing to the want of con- 
 tinuous sections here, the exact relation of this bed to the graptohte zone 
 cannot be made out ; but it is presumable that, as in Wandel Burn, oppo- 
 site Birnock (in the hne'of strike of the Caradoc zone of Arbory HUl), 
 the beds seen are of the graptolite zone, and nearly vertical. The syn- 
 clinal axis has there become a mere doubling of the beds together, 
 the graptolite zone being again folded over with a slight dip to the 
 N.W., opposite Rob's Bog, which carries it under the Caradoc con- 
 glomerate at Wallace's Cast. Beds containing graptolites are seen above 
 Old Wandel Mill, dipping to the S.E., and this dip continues as far as 
 the foot of Shiel Bum. An unfortunate gap in the section hides the 
 place where the conglomerate is supposed to crop out in this direction. 
 
 32. The following fossils have been obtained from the Caradoc rocks 
 of the Leadhills, in the course of the Geological Survey of the district: — 
 
 Amorphozoa . Nidulites favus. — Salter. Polyzoa Fenestella sp. 
 
 Ccdenteraia , Favosites fibrosa. — Gold/. Ptilodictya diehotoma. — Portl. 
 
 aspera. — D'Orh. Crustacea Homalonotus (part of axis). 
 
 Petraia bina. — Lons. Trinucleua fimbriatua (portion 
 
 uniserialis. — M'Coy. of shield). — Murch. 
 
 elongata. — Phill. Phacops caudatus. — Brwn. 
 
 MonticiJiporaleiis. — M'Coy. Cheirurus (fragment). 
 
 Echinodermata Glyptocrinns basalis. — M'Coy. Calymene (eye only). 
 
 * Kilbucho is in Sheet 24 of the Geological Survey Map (see the Explanation to 
 that sheet, par. 9). From the collections of fossils which have been made by the 
 Survey from that locality, and from the Wrae Umestone, there can be no doubt that 
 these Peeblesshire fossiliferous bands are prolongations of those of Leadhills — that 
 is, of Caradoc or Bala age. ' 
 
15 
 
 Cni.-lcKea . Ogygia. 
 
 Brachiopoda Leptsena sericea. — Sov). 
 
 tenuicincta. — M't'oy. 
 
 transversalis. — Dalm. 
 
 Ortliis calligramma. — Dalm. 
 
 var. Wallsalliensis. — 
 
 Dav. 
 
 vai'. Boucliardii. 
 
 elfgantula. — Dalm. 
 
 protensa. — Sow. 
 
 Actonife. — Sow. 
 
 Strophomena corrugata. — 
 Portl. 
 
 pecten. — X/inu. 
 
 grandis. — Sow. 
 
 rhomboidalis. — Wil k. 
 
 Atrypa marginalis. — Dalm. 
 
 hemispiiaerica. — Sow. 
 
 Sprifera plicatella. — Linn. 
 
 Brachiopoda . . Meristella angusti- 
 frons. — M'Coy. 
 Rhynchonella. 
 Pentameriis oblongus ? 
 — Sow. 
 Lamellibranchiata Gtenodonta (cast). 
 Modiolopsis (cast). 
 Gasteropoda . . Raijhistoma lenticu- 
 laris. — Sow. 
 
 elliptica. — His. 
 
 Eiiomphalus. 
 Miirchisonia. 
 Cyclonema sp. 
 Turbo. 
 Holopella. , 
 Bellerophon acutus.^- 
 Sow. 
 
 tiilobatus.->So«;. 
 
 Ceplialopoda Orthoceras. 
 
 b. Sanquhar District. 
 
 33. In that portion of the Silurian area which lies to the south-west of 
 the Nith, the geological structure is less easily traceable than in the Lead- 
 hills district. Regarded in a general view, the district now to be de- 
 scribed may be taken as occupying a broad synclinal fold, which is a 
 continuation of the great trough of the Leadhills. This fold is interrupted 
 by a minor anticlinal axis in the high ground at the head of the Afton, 
 somewhat in the same way as the Leadhills trough is varied by the 
 occurrence of the arch along the north-west flank of the Lowthers. These 
 two anticlinal folds, however, are not continued into each other, each 
 dying out in an opposite direction, so as partly to overlap the other. In 
 the Sanquhar district also there appear to be other folds, and there is 
 reason to believe that in some cases these folds are actually inverted, so 
 that a series of strata which dip persistently in one direction may be made 
 up of several arches and troughs bent into one uniform inclination, and 
 subsequently much denuded. 
 
 34. Beginning at the south-east corner of the district, we encounter 
 the Daer and Dalveen groups in the ravine of the Nith, having a general 
 north-westerly dip. The Haggis Rock group, from the failure of its 
 characteristic conglomerate, is not recognisable there. At Chaulockfoot, 
 on the Scar, some massive conglomerates occur, and a similar rock is 
 seen in the ravine of the Nith at Burnmouth : these appear to be lenti- 
 cular beds, for they are not traceable for any distance. The group which 
 is most easily followed, and from the convolutions of which the com- 
 plicated geological structure of the district can best be seen, is that of 
 the Black Shales. As shown on the map, a continuous band of the cha- 
 racteristic anthracitic shale with graptolites can be traced from the Nith, 
 at Burnmouth, for a distance of more than seven miles in a south-westerly 
 direction to the valley of the Shinnel. Wherever these shales occur, they 
 are much crumpled and shattery, and they usually contain bands of very 
 siliceous greywacke. This group of beds, much seamed with veins of 
 felstone, diorite, etc., stretches across the Map from the high ground south 
 of Windy Standard, north-eastward along the right bank of the valley of 
 the Ken, and the hills on the left bank of the Scar Water, striking thence 
 obliquely along the ridge between the Scar and the Euchan to the southern 
 border of the Sanquhar coal-field. On the north-west side of this belt, 
 and rising from underneath it, the Lowther beds appear, and cover nearly 
 the whole of the remaining part of the Silurian area up to the edge of 
 the ^ew Cumnock coal-field. In this tract they are thrown into two 
 folds — one anticlinal, the other synclinal. The former, coming up from 
 
16 
 
 the south-west, strikes through the high grounds near the head of the 
 Afton Water. Its effect has been to bring up a portion of the Haggis 
 Rock group, which is seen forming the crest of the arch along the western 
 slope of Oraigbraneoch Rig. As already mentioned, this arch gradually 
 dies out towards the north-east, and the Lowther beds roll over it into 
 the second or synclinal fold just referred to. In the centre of this trough 
 a portion of the Black Shale group is met with, stretching from Auchin- 
 cally Burn, on the south-west, to the edge of the Sanquhar coal-field at 
 Polmorlach Burn. Between the outcrop of these shales and the great 
 bounding fault, the north-west side of the trough is formed by the Low- 
 ther and Haggis Rock groups, which are here best seen in the March 
 Burn dividing the counties of Ayr and Dumfries. It will be observed 
 from the Map that the strike of the Silurian rocks here undergoes a con- 
 siderable deflection. The Haggis Rock abuts against the boundary fault 
 at the Afton with a N.N.E. strike ; but, three miles further on, it again 
 appears on the south side of the fault coming out of the metamorphic 
 area of the Garepool Burn, with a nearly easterly strike, whence it con- 
 tinues to run parallel to the fault for a great many miles to the north-east. 
 The characteristic red and green mudstones of the Haggis Rock group 
 are well seen at Nether Carin and in the Afton. 
 
 Metamorphic Rocks in Lower Silurian Series. 
 
 35. Throughout the Lower Silurian area embraced in this Map there 
 occur some of those patches so frequent in the Silurian uplands of the 
 south of Scotland, where the strata have undergone local but extreme 
 metamorphism. There appears to be always a close connection between 
 the nature and extent of this metamorphism and the chemical constitution 
 of the rocks in which it is manifested. It is always most developed in 
 those strata into whose composition felspar enters as a main ingredient, 
 while, on the other hand, in the more quartzose rocks little, or compara- 
 tively little, change has taken place. From St. Abb's Head to ]?ort- 
 patrick the greywackes are very commonly felspathic, sometimes so much 
 so that they ought rather to be called sandy mudstones. Such rocks 
 have afforded peculiar facilities for the development of metamorphic 
 action ; and accordingly we find that it is along their outcrop that 
 metamorphism is chiefly seen. While the whole of the Lower Silurian 
 rocks have undergone a general and comparatively slight alteration, it is 
 only in detached and limited areas that metamorphism has reached an 
 extreme. Of this feature, several characteristic examples occur in the 
 present Map. Two tolerably distinct aspects of metamorphism are here 
 represented. In one of these, the stratified rocks, probably originally 
 more quartzose, have been changed into granite ; while in the other, where 
 the strata were probably more felspathic or argillaceous, they have been 
 altered into various porphyries, diorites, etc. The former type of meta- 
 morphism is more acidic, the latter more basic ; and although the two 
 occur in sepai ate and independent areas, they yet occur together in such 
 a way that sometimes no very sharp line of demarcation can be drawn 
 between them. 
 
 36. At the Bail Hill, near Kirkconnel, on the line of outcrop of the 
 Black Shale group, their occurs a remarkable area of metamorphism, 
 covering a space of about three-fourths of a square mile. Owing to the 
 fault which lets down the Sanquhar coal-field, only a fragment of this 
 area is now visible. Round its edges the passage from ordinary grey- 
 wacke and shale into crystalline amorphous rocks may be traced, while 
 within the crystalline portion there occur beds of mudstone, baked into 
 Lydian stone, but still showing stratification. In one place, at the upper 
 part of the Cat Cleuch Burn, a narrow tongue of hardened, but other- 
 
17 
 
 wise unaltered, rocks, some of which contain graptolites, penetrates the 
 more metamorphosed area, and even in the heart of the crystalline rocks 
 there weather out knobs of comparatively unaltered greywacke or mud- 
 stone. The crystalline rocks within this metamorphic patch vary greatly 
 and rapidly in composition. Generally speaking, their matrix is a dull, 
 green, felspathic crystalUne-grauular mass, through which are dispersed 
 crystals of orthoclase and plagioclase felspar. In some places perfect 
 crystals of hornblende, and others of diallage, mica, and talc, likewise 
 occur, the mica being sometimes so abundant as to form the main mass 
 of the rock. These petrographical changes are so frequent, that it is 
 difficult to find any one name which would suffice to express the general 
 character of this crystalline mass. At different points it might be called 
 quartziferous porphyry, quartzless porphyry or porphyrite, diallage rock, 
 syenite, or even granite. The alteration of the Silurian rocks into these 
 crystalline masses is best seen in the case of the pebbly grits, conglo- 
 merates, or breccias ; for in such cases the included fragments or pebbles 
 are sometimes little altered, while the surrounding matrix has become 
 coarsely crystalline, abounding ia large crystals of hornblende, ortho- 
 clase, mica, etc. Reference may be made to Sheet 6 of the Geological 
 Survey of Dumfriesshire, in which this area is mapped in detail. South 
 of Glenmaddie Wood, Euchan Water, a Kttle knob of metamorphosed 
 greywacke is exposed on the hill-side, but is too small to be expressed 
 on the map. The rock has a dull, reddish-green felspathic matrix, with 
 scattered felspar crystals. 
 
 37. Reference has already been made (par. 27) to the general but not 
 very intense metamorphism which the shales of group G have undergone 
 along their outcrop north-eastward from Craig Dod, between Abington 
 and Crawford. These strata have there been greatly hardened, crumpled, 
 and veined with quartz. In several places, however, there occur limited 
 areas, where the metamorphism has been more pronounced. The pre- 
 vailing character of the altered rock at these points is that of a dull, 
 dirty green, somewhat decomposed mass, with much diffused serpentine, 
 and breaking up, under the influence of the weather, into small nodular 
 fragments. Here and there it becomes distinctly and sometimes even 
 coarsely crystalline, passing into what might be termed diorite. On 
 Craig Dod the rock is of a dark, purplish grey colour, and abounds in 
 small kernels or grains of quartz (possibly the original pebbles of the 
 greywacke), coated with green earth, among which hornblende crystals 
 are scattered. 
 
 38. The second, or granitic, type of metamorphism is well seen along 
 several parts of the north-western margin of the Silurian area. In ap- 
 proaching the localities where it is developed, we find the Silurian strata 
 to become gradually harder, more crystalline, and, in the case of the 
 shales, more schistose, until, after traversing a space from about 100 
 yards to fuUy half a mile, we come at last upon the granitic centre. 
 Hence each of these metamorphic areas consists of a central nucleus of 
 granite, with a varying band of altered rocks around it. The largest 
 area is that which is traversed by the Spango Water ; it lies on the line 
 of outcrop of the Haggis Rock group and the lower part of the Lowther 
 beds, having a breadth of about two miles and ' a length of about four. 
 A portion of its northern margin has been cut off by the great boundary 
 fault. Round its margin the more argillaceous shales, which elsewhere 
 are not micaceous, begin to show minute spangles of black mica, which, 
 further into the metamorphic band, increase in number, until they impart 
 a schistose texture to the rock ; the colour likewise changes from the 
 ordinary blueish grey of the unaltered districts to a purpHsh black, owing 
 to the abundance of mica. These superinduced mica-plates have been 
 
 B 
 
18 
 
 developed along the line of bedding of the shales, and the rock splits 
 most easily in that direction, the edge of the fracture, owing to the close 
 grain of the rock, being slightly translucent. Notwithstanding the folia- 
 tion of these shales, their original bedding can be distinctly traced. It is 
 generally greatly crumpled, the plications being so small as sometimes to be 
 visible on a hand specimen. The red and green mudstones, which appear 
 usually to be more siliceous than the shales, have not undergone folia- 
 tion. Where they come within the metamorphic area, though they retain 
 very much the same external character as elsewhere, breaking up with 
 their usually shattery fracture, yet they bear evidence of being greatly 
 hardened, while sometimes they have been converted into a kind of coarse 
 Lydian stone or jasper. In the case of the greywackes, pebbly grits, 
 and conglomerates, it is chiefly the matrix of these rocks which has been 
 altered, while the included grains and pebbles of quartz or siKceous rock 
 have remained comparatively unchanged. The matrix probably resembled 
 originally the shales, for it has undergone a similar metamorphism ; it 
 abounds in small spangles of mica, which give it a kind of schistose 
 texture. 
 
 39. It will be seen from the Map, that, in the case of the Spango 
 granite, as well as in those of the other granitic areas, the Silurian strata 
 strike at the granite on one side, and reappear on the other, without 
 deflection. The granite, therefore, whether we regard it as metamorphic 
 or intrusive, certainly occupies the area once filled by an equivalent mass 
 of Silurian strata. Wherever a junction of the granite and the Silurian 
 rocks is seen, there appears to be a tolerably sharp line of demarcation 
 between the two, no example of an actual passage from the foliated 
 schist into the granite having been met with in any part of the district. 
 At the same time, it is to be noted that in many places they are locked 
 into each other, as it were, by numerous veins, which proceed from the 
 granite, and run chiefly along the bedding planes of the altered rocks. 
 Fragments of the stratified rocks are met with in the mass of the granite, 
 but chiefly along its margin. These are usually angular and oblong, and 
 vary in size from mere " galls " of a finger-length, up to masses ten feet 
 long or more. 
 
 40. In the area of the Spango Water and the Garepool Burn the 
 granite is a fine grained mixture of pink orthoclase, with a little oligo- 
 clase, quartz, black mica, and hornblende. The quartz, which is second 
 in abundance, is comparatively small in quantity, and the black mica is 
 more plentiful than the hornblende. In the centre of each of these two 
 areas, the granite becomes white in colour and coarser in texture, while 
 the finest grained varieties are those which occur in veins. In each dis- 
 trict, also, the granite weathers with comparative rapidity into a rusty 
 coloured sand. The waste is greatest towards the margin of the granite, 
 where the lower general level of that rock shows how much more readily 
 it yields to disintegration than the more prominent altered rocks which 
 rise up around it. A white coarser variety of granite than that already 
 described occurs at the Knipes, the Afton Water near Montraw, and at 
 Cairnsmore, of which a small portion comes into the present Map. Round 
 each of these areas the phenomena of metamorphism above described are 
 well shown, the alteration of the mudstones being specially exhibited 
 round the Garepool granitic boss, and that of the schists round the 
 Knipes ; in the latter mass of granite a vein of antimony-glance has been 
 worked, to which reference wiU be made under the section of economic 
 minerals. It is worth while observing, that while the Spango and Gare- 
 pool granites come to the surface chiefly in the Haggis Rock group, the 
 granite in the areas now referred to is entirely surrounded by the Low- 
 ther beds and a small part of the Black Shale group. 
 
19 
 
 Intrusive Igneous Rocks associated with Lower 
 Silurian Series. 
 
 41. It will be seen from the Map that the Lower Silurian area is 
 traversed by many bands of various intrusive rocks. As in other parts 
 of the Silurian uplands of the south of Scotland, these roclss coincide 
 generally with the line of strike of the country, and therefore, though 
 they often cut across the bedding of the shales, etc., they run as dykes, 
 veins, or bands, with a north-easterly and south-westerly direction. It 
 will likewise be observed that, as elsewhere, they tend to occur in groups, 
 being here and there profusely abundant, and then absent altogether 
 for considerable distances. In this sporadic development, they closely 
 resemble the distribution of the more metamoriDhosed areas. There is 
 ground, indeed, for the conjecture, that both the metamorphism and the 
 intrusive dykes have resulted together from the working of some general 
 cause. 
 
 42. The most abundant rock of which these dykes consist is a felstone, 
 which, on a fresh fracture, is usually pale flesh-coloured, but weathers 
 into various tints of yellow or grey. It is a fine granular mixture of 
 orthoclase, with occasionally a Httle free quartz, sometimes hornblende, 
 more rarely biotite. The quartz occurs in minute granules, which are, 
 however, sometimes as large as peas, or even as almonds. Next in import- 
 ance to felstone, as a constituent of the dykes or veins, comes diorite. 
 This rock occurs frequently in the south-west part of the Map, where it 
 is seen to consist chiefly of hornblende crystals, diffused through a some- 
 what decomposed felspar base. Syenite occurs in a larger band, running 
 along the hill-tops from Scawd Law to Rodger Law, a distance of about 
 two miles and a half. It is a coarse-grained rock, consisting of a decom- 
 posed felspar, with silvery mica and a little hornblende. It weathers into 
 a pale flesh- colour, and spUts into large irregular blocks, the surfaces of 
 which are much decomposed. ' From its linear direction, this mass is pro- 
 bably an intrusive sheet or vein rising along the line of strike of the grey- 
 wacke and shale, but its relations to the surrounding strata are obscured 
 by the turf of the hill-slopes. No great alteration is produced by any of 
 these intruded masses upon the Silurian rocks. The shales are sometimes 
 hardened, and even to some extent porcelainized. 
 
 43. Among the intrusive rocks may be mentioned one or two small 
 bosses and veins of granite, which rise through a portion of the Lowther 
 group near the head of the Afton Water, but the rocks round these are 
 not so much metamorphosed as round the larger granitic masses already 
 described. 
 
 Mineral Veins in Lower Silurian Area. 
 
 44. In the high ground round the villages of Wanlockhead and Lead- 
 hills, the Lower Silurian rocks are traversed by two systems of mineral 
 veins, the one running N.W. and S.E., the other W.N.W. and E.S.E. 
 These veins contain lead and other ores. Mineral veins have been 
 observed in several other parts of the Silurian area, but not of a kind to 
 offer any prospect of being ever worked for ores. A reference to the 
 mineral veins on the present Map will be given on a subsequent page, 
 under the head of Economic Minerals. 
 
20 
 
 Upper Silurian. 
 
 45. Two small areas of this formation occur on the present map, one 
 m the valley of the Greenock Water, the other in that of the Douglas 
 Water. As these are only prolongations of the much larger and more 
 important Silurian tract of Lesmahagow (Sheet 23), their structure will 
 be better understood, by reference to the forthcoming Map and Memoir of 
 that district. 
 
 a. Greenock Water District. 
 
 46. Bands of hard flaggy shales and grey gritty greywackes are 
 seen in the Greenock Water atBurnfoot. In the same series of strata, in 
 the adjoining Map, Ceratiocaris and fragments of Ovthoceras have been 
 found. 
 
 b. Douglas Water District. 
 
 47. At Parishholm, near the source of the Douglas Water, is exposed 
 a series of highly inclined blue flaggy shales, containing Ceratiocaris, 
 Orthoceras, and Beyrichia. These strata form the continuation of an 
 anticlinal axis which runs through the Hagshaw Hills (in Sheet 23). 
 The existence of this anticline is not at fii-st easily perceived, owing to an 
 inversion of dip, and to the presence of a large fault, which cuts off the 
 Silurian rocks by bringing down against them sandstones and conglo- 
 merates of Lower Old Red Sandstone age. At the back of Parishholm 
 Steading, blue and grey shales, forming the uppermost beds of the series, 
 are seen to dip under a fine (Conglomerate, which forms the lowest member 
 of the Old Red Sandstone series. 
 
 Lower Old Red Sandstone. 
 
 48. The area in this Map, occupied by the Lower Old Red Sandstone 
 series, with its accompanying volcanic rocks, is considerable, taking up 
 nearly half of the space lying to the north of the great boundary fault, 
 and is more or less hilly. The rocks, as will be seen, are folded into a 
 series of anticlines and troughs, with a prevailing north-easterly and 
 south-westerly strike. These folds, however, do not affect the surface of 
 the ground ; but as the rocks are of very variable hardness and power of 
 resisting the weather, the whole area is denuded into a number of parallel 
 ridges, the harder beds occupying the heights, and the softer ones the 
 valleys. As a rule, the highest ground is that flanking the Silurian up- 
 lands, but the greatest elevation attained by any member of the series is 
 in Cairn Table, though the summit of that hill is capped by rocks of Car- 
 boniferous age. For convenience of description, the formation, as here 
 represented, has been divided into three zones, which are composed as 
 follows. 
 
 49. Table of the Lower Old Red Sandstone, as developed in this Map. 
 
 (12. Chocolate-coloured sandstones, with occasional beds of conglomerate to- 
 wards their base. 
 11. Conglomerate with pebbles of porphyrite, associated with lenticular beds 
 of purple porphyrite. 
 10. Grey gi-its and ferruginous yeUow sandstones. 
 Average thickness, 5000 feet. 
 
 ( 9. Grey sandstones, tuffs, and beds of shattery melaphyre. 
 Tj ; 8. Purple and greenish slaggy and amygdaloidal porphyrites, and tuffs, be- 
 ) coming split up by intercalations of chocolate-coloured sandstones to- 
 
 ( wards their base. 
 
 Average thickness, 4000 feet. 
 
21 
 
 7. Chocolate-coloured sandstones, and thin lenticular beds of conglomerate. 
 6. Conglomerate with greywacke pebbles. 
 5. Cliocolate-colom'ed sandstones. 
 
 4. Conglomerate with large pebbles of liver-coloured quartz-rock. 
 3. Green and red mudstones, with bands of grey shale and greywacke. 
 2. Eed mudstones and chocolate-coloured flaggy sandstones. 
 1. Conglomerate with small pebbles of quartz, Lydian-stone, etc., resting 
 directly upon Upper Silurian shale. 
 
 Probable total average thickness of A, B, and C, 15,000 feet. 
 
 Group A. 
 
 50. TMs lower group of the Old Red Sandstone of this district is 
 found occupying three separate areas on the present map — viz., along 
 the Douglas Water from Cairn Table to Parishholm ; along the northern 
 flanks of Wardlaw Hill ; and in the valley of the Greenock Water at the 
 north-west corner of the Map. At each of these localities the group is 
 distinguished from the middle and upper groups, by the entire absence of 
 any intercalated contemporaneous volcanic rocks. 
 
 (1.) This band of conglomerate is found resting on the Upper Silurian 
 shales along the side of the Parishholm Reservoir and in the Douglas 
 Water, whence it is continued northwards on the same horizon through- 
 out the Hagshaw Hills (Sheet 23). 
 
 (2.) This subdivision follows the line of outcrop of its underlying con- 
 glomerate. 
 
 (3.) Some of the members of this subdivision show ripple-marked, 
 sun-cracked, and rain-pitted surfaces. They are best seen on the north 
 side of the Reservoir, and in the Douglas Water above Parishholm. 
 
 (4.) This peculiar band forms a well-characterized horizon in the Lower 
 Old Red Sandstone from Little Cau'n Table northwards into the Lesma- 
 hagow district. Its pebbles often exceed eight inches in diameter, and 
 are in many cases dented into each other, indicating the amount of pres- 
 sure which the rocks of this district have undergone. This and the pre- 
 ceding three subdivisions are only found on the north side of the anti- 
 clinal axis, which, striking westwards from the Hagshaw Hills, runs up the 
 Douglas Water and passes underneath Cairn Table. That they are not 
 seen on the south side of this arch, is owing to the presence of a large 
 fault which brings down the sandstones. No. 5. The order of succession, 
 however, can be clearly ascertained from the sections at the reservoir, 
 which show that the strata on the south side of the fault are those which 
 overhe the quartz conglomerate. No. 4. 
 
 (6.) Between the quartz conglomerate and another band of conglo- 
 merate. No. 6, comes a series of chocolate-coloured sandstones. These 
 run along the south side of the Parishholm fault, and they are likevrise 
 seen on the north side of the anticlinal fold, along the slopes of Little 
 Cairn Table which rise above the Muirkirk coal-field. 
 
 (6.) This conglomerate differs from all the other conglomerates in 
 the nature of its pebbles, which consist almost wholly of greywacke. It 
 is found on both sides of the arch. The northern outcrop, broken by 
 faults, stretches from near the Blackhill to Auldhouse Burn, whence it 
 turns round the western flanks of Little Cairn Table until it unites with 
 the southern outcrop, which, as is shown in the Map, may be traced con- 
 tinuously into the Hagshaw Hills (Sheet 23). 
 
 (7.) The sandstones, which form the uppermost division of the lower 
 group, are best seen at the head of the Duneaton Water, between the 
 conglomerate No. 6 and the base of group B, near North Bottom. In 
 that section they are inclined at an angle of 60°-70° ; but westwards, in 
 the Wardlaw Hill tract, they are much less highly inclined, and cover, in 
 consequence, a much larger area. 
 
22 
 
 Group B. 
 
 51. The distinguishing characteristic of this group consists in the fact 
 that it is almost wholly made up of contemporaneous volcanic rocks. 
 These are partly lava-form, partly tuffs, and with them are associated 
 other stratified beds, largely made up of volcanic detritus. 
 
 (8.) The porphyrites occur in district beds, separated from each other 
 sometimes by intercalations of sandstones and tuffs, sometimes merely 
 by their own slaggy upper and under surfaces. They are usually of a 
 dark purplish or greenish grey colour, close grained, sometimes slightly, 
 sometimes coarsely, porphyritic. They frequently show an amygdaloidal 
 texture, the cavities being lined with green earth, and filled with calcspar, 
 and sometimes with agates. The tuffs are fine grained, weU-stratified 
 beds, resembUng in colour the porphyrites, from the volcanic detritus of 
 which they have been derived. They occasionally contain bombs of por- 
 phyrite. The sandstones interstratified in this division are thicker than 
 the tuffs. Like these, however, they occur as intercalations between the 
 sheets of porphyrite. They consist of a varying mixture of trap debris 
 and ordinary sedimentary detritus. In the Duneaton Water, near North 
 Bottom, they contain worm burrows. 
 
 (9.) In this subdivision the characteristic beds are grey sandstones and 
 brecciated conglomerates, composed entirely of trappean debris, and with 
 bands of true tuff interstratified. Among these strata he thin sheets of 
 dark, heavy, close-grained melaphyre. The latter are sometimes sUghtly 
 amygdaloidal along the surface of each bed, are much veined with calc- 
 spar, and weather into shattery fragments. They are seen at the head 
 of the Glemnore Water, in the Duneaton Water, and the head of the 
 Kennox Water, but they become much more largely developed as they 
 pass north-eastwards into the Douglas district (Sheet 23), while their 
 associated grey sandstones and conglomerates undergo a corresponding 
 diminution. 
 
 Group C. 
 
 52. In this group, the volcanic rocks, so abundant in the middle divi- 
 sion (B), gradually die out, and in its upper part the ordinary chocolate- 
 coloured sandstones, characteristic of the lower series (A), reappear. 
 Hence, in the Lower Old Red Sandstone, as developed within the area 
 of the present Map, we have evidence of the beginning and the ending of 
 a long volcanic period. 
 
 (10.) The grits and sandstones of this division have been almost en- 
 tirely derived from the waste of previously erupted porphyrites. They 
 are best seen in the course of the Duneaton Water, from the foot of 
 Bain's Burn to near the Brown Rig. From that locality, south-westwards 
 they range along the flanks of group B, bending round the anticlinal 
 fold of the latter at Black Law, and running north-eastwards, as a syn- 
 chnal trough, back as far as the Duneaton Water. As shown on the 
 Map, however, along the south-east side of this trough they are brought 
 down against the porphyrites by a fault. 
 
 (11.) This subdivision is made up of massive conglomerates, with occa- 
 sional lenticular sheets of porphyrite. The conglomerate has been entirely 
 derived from the waste of various porphyrites, its well-rounded pebbles 
 varying from the size of a hazel nut to that of a man's head. This con- 
 glomerate forms all the ridges which, flanking the great boundary fault, 
 run in a north-easterly direction from Corsoncone on the Nith to Dun- 
 gavel Hill on the Clyde ; while, on the other hand, the overlying and 
 underlying sandstones have been worn into hollows. As shown in the 
 Map, this band of conglomerate has been thrown into a long synclinal 
 
23 
 
 fold, running parallel with, but sometimes cut off by, the boundary fault. 
 It will be seen that the soutliorn outcrop runs from the northern margin 
 of the Map to the edge of the Spango granite. It is there cut out for a 
 little by tli6 fault, and, on again reappearing, sweeps on continuously to 
 the Nith. The northern outcrop of the trough has been partly concealed 
 by the southern prolongation of the Douglas coal-field. But on the south- 
 west side of that tract it reappears, stretching on to Mountstuart, where, 
 owing to the contraction of the trough, it unites with the southern out- 
 crop. West of Glengaber Hill it again diverges, so as to enclose a long 
 trough of the uppermost subdivision (12). At Corsoncone Hill the 
 southern outcrop of the conglomerate folds over in an arch, which is 
 obliquely truncated by the boundary fault. Here and there, along the 
 strike of this band of conglomerate, there occur intercalated sheets of 
 fine-graiBed purple porphyrite, exactly similar to that of which the mahi 
 mass of the stones in the conglomerate has been formed. It will be seen 
 from the Map, that these volcanic rocks occur on both sides of the syn- 
 clinal trough of conglomerate. It is on the south side, however, that 
 they are chiefly visible ; and as they thicken towards the south, we are 
 led to infer that it was from that quarter that they were emptied. No 
 trace, however, has been found of any actual volcanic neck in any part 
 of the Silurian district, unless we may speculate on the possibility of the 
 granitic bosses being in some way connected with volcanic action. 
 
 (12.) In this series of chocolate- coloured sandstone we lose all trace of 
 any intermixture of trappean detritus. In the fine conglomerates, which 
 are interspersed through the upper part, the pebbles consist not of por- 
 phyrite, but of white quartz. This series of beds is best seen in that 
 part of the trough which is cut through by the Duneaton Water, between 
 Brown Rig and Sheriffcleugh. These are the highest members of the 
 Lower Old Red Sandstone seen in this district of Scotland ; but as their 
 uppermost beds have been removed by denudation, no means are left by 
 which to ascertain what may have been here the original thickness of 
 that formation. 
 
 Intrusive Rocks in Lower Old Ked Sandstone and 
 Upper Silurian. 
 
 53. Both these formations are sparingly traversed by intrusive masses 
 of pink felstone. The largest of these is that which stretches from near 
 Muirkirk for some distance to the north-east, and of which only a small 
 portion comes into the present Map. The others are of much smaller 
 extent, being mere dykes and small bosses. The rock of which they con- 
 sist has a granular base, through which are scattered small granules of 
 free quartz, with occasional mica. Taken in connection with similar 
 intrusive masses to the north-east and south-west of the present Map, 
 these felstones may possibly represent, in some cases, necks from which the 
 porphyrite flows of the Old Red Sandstone were erupted. 
 
 Carboniferous. 
 
 54. This system of rocks is largely developed in the north-western 
 point of the Map, whence it extends in separate patches down the valley 
 of the Nith. It is here capable of division into the following groups of 
 strata, which can be now recognised over the whole of the Carboniferous 
 area of Scotland : — 
 
2-t 
 
 Sign on Map. 
 
 Groups of Strata. 
 
 Localities -where seen. 
 
 d5' 
 d5 
 
 Coal Measures,' coTiRisting of — 
 (6.) Red Sandstones and Clays. 
 
 (a.) WMte and grey Sand- 
 stones, dark Shales, 
 Coal Seam.s, and Iron- 
 stones.^ 
 
 Aird's Moss, Douglas Water, 
 Sanquhar, Kirkconnel. 
 
 New Cumnock, Lugar, Muirkirk, 
 Douglas, Sanquhar. 
 
 d4 
 
 Millstone Grit series. 
 
 Lugar, Muirkirk, Kennox Water. 
 
 d2 
 
 Carboniferous Limestone series, 
 consisting of white, grey (some- 
 times red) Sandstones, and 
 dark Shales, with Seams of 
 Coal, Ironstone, and Limestone. 
 
 New Cnninock, Glenmore Water, 
 Gass Water, Muirkirk Coal-field, 
 Kennox Water, Sanquhar, Out- 
 liers at Wildshaw, Penhreck, 
 and Whitecleugh ; Valley of 
 Carron Water and Nith at 
 Drumlanrig. 
 
 dl' 
 dl 
 
 Calciferous Sandstone series, con- 
 sisting of — 
 (b.) Cement-stone Group. 
 
 (a.) Red Standstone Group. 
 
 Greenock and Garpel Waters, 
 Water of Ajt. 
 
 Hilly Ground from Corsoncone to 
 Cairn Table, Water of Ayr at 
 Limmerhaugh, Greenock Water 
 at Netherwood, Douglas and 
 Kennox Waters. 
 
 55. For convenience of reference, the Carboniferous rocks will be 
 described here as forming six separate districts on the Map. Of these, 
 the largest, stretching from near the Afton Water northwards to Wardlaw 
 Hill, may be termed the New Cumnock and Guelt district. The area 
 occupying the valley of the Ayr may be called the Lugar and Muirkirk 
 district. Separated from these by the great ridge of Cairn Table, and 
 forming the southern lip of the Douglas basin, is the Glespia district ; 
 while detached from it are the outliers of Peabreck, Wildshaw, and 
 Whitecleugh. The coal-field of Sanquhar forms the fifth district, and 
 the sixth lies in the valley of the Carron Water. 
 
 «. District of New Cumnock and Guelt. 
 
 56. In this district are included all the Carboniferous rocks lying 
 between the great fault bounding the field to the south, and the Glenmore 
 and Guelt Waters. The lowest beds of the series are the Calciferous Sand- 
 stones, consisting of red and yellow sandstones and red marls, with con- 
 cretionary grey sandy Mmestone or cornstone. The latter rock is 
 considerably quarried at Guelt and CraigduDeart, where large mines have 
 been wrought from time immemorial, the lime being in great demand for 
 agricultural purposes. This cornstone lies near the base of the series, and 
 in some cases rests on the older rocks. It is well seen ia the Glenmore 
 and Guelt Waters, in which are exposed good sections of the whole series. 
 The upper part of the series, as seen near Dalblair, consists of very irre- 
 gularly bedded red tills or fire-clays, with lenticular beds of grey gritty 
 sandstone. These may probably represent the Upper or Cement-stone 
 group. The Carboniferous Limestone series is well developed in this area, 
 and consists of a lower group of sandstones, shales, and limestones ; a 
 middle group of sandstones, shales, and coals ; and an upper group of 
 sandstones and shale, with bands of limestone, fireclay, and thin coals. The 
 
25 
 
 ft 
 
 in 
 
 1 
 
 8 
 
 . 10 
 
 
 
 9 
 
 
 
 . 16 
 
 
 
 . 11 
 
 
 
 . 12 
 
 
 
 . 12 
 
 
 
 9 
 
 
 
 3 
 
 
 
 low limestones are seen at Dalblair and Dornal, where one seam, corre- 
 sponding to the Gass Water limestone and the ' Hawthorn limestone ' of 
 Muirkirk, has been wrought. 
 
 57. The coals of the celebrated Edgehill coal-field belong to the 
 Middle series. They he in the form of a little basin, and their position is 
 proved by the low limestones, which are seen to rise out from below them 
 to the north. The coal seams in this little area are very thick and close 
 together, as will be seen from the following section : — 
 
 Clay Gas Coal, 
 
 Strata, 
 ■ Nine-foot Coal, 
 
 Strata, 
 Eleven-foot Coal, 
 
 Strata, 
 Twelve-foot Coal, 
 
 Strata, 
 Three-foot Coal, 
 
 The strata intervening between the coals vary in thickness, and a httle to 
 the east entirely disappear, so that the different coals come together and 
 form a seam forty feet thick. This occurs in a little trough, locally 
 known as the " Ship." The quality and thickness of some of these coals 
 have induced a rigorous search for the reappearance of the seams, 
 but hitherto without success, owing to the borings having been conducted 
 too near the edge of the basin, and consequently through lower rocks. 
 A series of bores, properly conducted along a line from High Polquheys 
 to Laigh Glemnuir, would probably discover them, though the character 
 of the coals would be found to differ from their representatives at Edge- 
 hill, — as at DaUad and Gass Water, where they are known to exist, they 
 have varied considerably. On the other side, bores have been put down 
 through their position at Mansfield, but no workable seams were passed 
 through. In the streams which descend from the Silurian uplands into 
 the Carboniferous Limestone area no coal seams of any thickness are met 
 with ; nor, from the conglomeratic character of the deposits there ex- 
 posed, and the consequent evidence of shore conditions, is it hkely that 
 coal seams of any value will be found to occur there. The upper 
 limestones are seen at Mansfield, Polquheys, and at High Park, where 
 they have been long quarried. Polquheys Burn exposes the best section 
 of this series, where a few thin limestones are seen above the main work- 
 able one. 
 
 58. Overlying the Carboniferous Limestone series come the Coal-Mea- 
 sures, which form the New Cumnock c.oal-fleld. The rocks composing 
 this field consist of sandstones, grey shales, fireclays, coals, and iron- 
 stones. The succession, in descending order, is given in the following 
 table : — 
 
 Lanemark Gas Coal, 
 
 Strata, 
 Boig or Lower Gas Coal, 
 
 Strata, . 
 Eight-foot Coal, 
 
 Strata, 
 Laird's Coal, 
 
 Strata, 
 Creoch Coal, 
 
 Strata, 
 Coal, .... 
 
 Strata, . 
 Musselband, in several thin beds. 
 
 Strata, 
 
 
 fms. 
 
 ft. in 
 
 
 
 5 4 
 
 12-15 
 
 
 
 1 
 
 
 
 8 
 
 
 
 1 
 
 2 
 
 . 13 
 
 3 
 
 
 
 
 3 2 
 
 
 4 
 
 
 
 
 
 
 4 1 
 
 
 10 
 
 1 
 
 
 
 
 3 
 
 
 4 
 
 1 
 
 
 6 
 
 
 
26 
 
 fms. ft. in. 
 Musselband Coal. . . .031 
 
 Strata, .' . . . 10 
 
 Coal, . ... ..021 
 
 Strata, ..... 40 
 
 Position of the Black-band Ironstone. 
 
 The Black-band Ironstone, the position of which is above mentioned, 
 is the same as that worked at Lugar and Dalmellington, and holds tlie 
 same horizon as the Slatey-band Ironstone of Lanarkshire. At New 
 Cumnock it is represented by an impure pyritous gas-coal or shale, used 
 for making alum. 
 
 There is reason to infer the existence of a large fault stretching east 
 and west, which divides the New Cumnock coal-field, bringing down muc"h 
 higher beds on the south side of the field than those on the north ; but it 
 is nowhere seen, owing to its being covered by the alluvium of the River 
 Nith. Many minor faults are found in the coal workings, having a gene- 
 ral north-west and south-east direction. 
 
 /s. Lugar and Muirkirk District. 
 
 59. Under this title are included all the Carboniferous rocks lying 
 between Glenmore Water and the north margin of the Map. It embraces 
 the Lugar and Muirkirk coal-field. The lowest beds of the Calciferous 
 Sandstone series everywhere lie unconformably on the older rocks, and 
 consist of a group of red and white sandstones alternating with red and 
 green marly beds, and with occasional beds of grey concretionary corn- 
 stone, as in the New Cumnock area. This lower group (a) attains its 
 greatest development to the south of the Muirkii-k coal-field, and rises in 
 Cairn Table to a height of 1944 feet above the sea. On that hill the 
 red sandstones are very hard and quartzose, and, as they bleach white 
 when exposed to the weather, the resulting fragments are easily recog- 
 nisable, and hence afford an evidence as to the dispersion of boulders 
 during the glacial period. Good sections of these beds are seen in Gass 
 Water, and all the burns which flow north from the Cairn Table range. 
 The same beds are seen on the Greenock and Garpel Waters, and on the 
 water of Ayr at Limmerhaugh. At these latter places the lower or 
 red sandstone group is overlaid by the upper group of blue clays or tills, 
 with occasional bands of grey and blue impure limestone or cement-stone, 
 and grey gritty sandstones. The cement-stone bands contain Cyprides 
 and Microconchus. On this side of the field these beds everywhere inter- 
 vene between the red sandstone group and the Carboniferous Limestone 
 series, but they are not seen on the south side. 
 
 60. The Carboniferous Limestone series of Muirkirk is divisible, as at 
 New Cumnock, into three groups — 1st, A lower group of sandstones, 
 shales, and limestones ; 2d, A middle group of sandstones, shales, coals, 
 and u-onstones ; and 3d, An upper group of sandstones, shales, and lime- 
 stones. The position and thickness of the several limestones and coals, 
 with the average thickness of the strata intervening between them, are 
 shown in the section of the Muirkirk coal-field, par. 63. It is possible to 
 distinguish between the different Mmestones by means of their respective 
 fossils. The following table contains the results of the search made by 
 the Geological Survey into the fossil contents of these beds : — 
 
 Table of the Muirkirk Limestones, with their respective Fossils. 
 
 Name of Limestone. Names of FossiJs. Localities of Limestone.-). 
 
 fEhodocriiJus. Axinus sp. 1 Bluetour, Pro- 
 
 10. Bluetour J Atliyris ambigiia. — Sow. Ctnodoiita attenu- i scribe Burn, 
 
 Limestone. 1 sp. ' ata. — Flemg. [ Catchie Bui'n, 
 
 (. Eoysii. — L'Eve. I Waulkmill. 
 
27 
 
 Name of Limestone. 
 
 Names of Fnasils. 
 
 Localltiea of Liraestnnes. 
 
 'Orthia resupinatii. — 
 Mart. 
 
 10. 
 
 Bluetour 
 Limestone. 
 
 9. Thin Lime- 
 stone. 
 
 8. Tibby Pagan's 
 
 Limestone. 
 7. Limestone, 
 6. Limestone, 
 Ell Coal Lime- 
 stone, 
 
 Ctuodonta gibbosa. ") 
 — Flemg. 
 
 sp. Bellerophon Urii. 
 
 Producta semu'eticu- — Flemg. 
 
 lata. — Mart. apertus. — 
 
 sp. Sow. 
 
 Ehynchonellapuguus. — Pleurotomai-ia sp. 
 
 Mart. 
 Spirifera bisulcata. — Sow. 
 
 lineata. — Mart. 
 
 Streptorhyncns crenis- 
 
 tria. — Phill. 
 ' Cyathophyllum turbi- Fenestella plebeia. "^ 
 
 natiim. — Gold/. — M'Ooy. 
 
 Actinocrinns sp. Athyris sp. 
 
 Platycriuus sp. Producta gigantea. 
 
 Poteriocrinus crassus (?) — Mart. 
 
 — Miller. • costata. — Sow. 
 
 PliillipsiaDerbyensis(?) Ortbis resupinata. 
 — Martin. — Mart. 
 
 Axinns carbona- 
 
 rius. — Portl. 
 Belleropbon Urii. 
 — Flemg. 
 Calamites Suckowii (in shale). — Brong. 
 sp. ( „ ). 
 
 Bluetonr, Pro- 
 scribe Burn, 
 Catohie Burn, 
 Waukmill. 
 
 j- Garpel Water, 
 
 5. 
 
 4. Macdonald 
 
 Limestone, &- 
 3. Limestone. 
 
 Hawthorn 
 Limestone. 
 
 Cyathophyllum turbinatum. — Goldf. 
 
 Lithostrotion. 
 
 Actinocrinus. 
 
 Poteriocrinus crassus. — Miller. 
 
 Athyris ambigua. — Sow. 
 
 Orthis resupinata. — Mart. 
 
 Producta gigantea. — Mart. 
 
 latissima. — Sow. 
 
 longispina. — Sow. 
 
 semireticulata. — Mart. 
 
 costata. — Sow. 
 
 Spirifera bisulcata. — Sow. 
 
 striata. — Mart. 
 
 ti'igonalis. — Mart. 
 
 Axinus carbonarius. — Portl. 
 
 Bellerophon Urii. — Flemg. 
 ^ Ortboceras. 
 
 Cyatliophyllum turbinatum. — Goldf. 
 
 Lithostrotion irregulare. — Phill. 
 
 Amplexus coraUoides. — Sow. 
 
 Athyris sp. 
 
 Producta gigantea. — Mart. 
 
 latissima. — Sow. 
 
 longispina. — Sow. 
 
 semii'eticulata. — Mart. 
 
 costata. — Sow. 
 
 Orthis resupinata. — Mart. 
 
 Spirifera glabra. — Mart. 
 
 bisulcata. — Sow. 
 
 striata. — Mart. 
 
 Avicula Vemeulii. — M'Goy. 
 .Aviculopecten alternatus. — M'Coy. 
 
 J 
 
 ) Garpel Water, 
 ( Aiidhouse Burn. 
 
 Garpel Water. 
 
 Gai'pel Water. 
 ( Garpel Water, 
 I Auldhouse Bum. 
 
 Wellwood Burn, Garpol 
 Water, Bankend, Auld- 
 house Biu'n, Crossflatt, 
 Ashaw Bum, Water of 
 Ayr near Wellwood 
 Kow. 
 
 Wellwood Bum, Garpel 
 Water, Springhill, 
 
 Bankend, Auldhouse 
 Bum, Crossflatt, Ashaw 
 Burn, Darnhaunch, 
 Tordoes. 
 
 1. Wee Limestone, 
 
 (Auldhouse Burn, Ashaw 
 ( Burn, Darnhaunch. 
 
 61. The Millstone Grit which overlies the Carboniferous Limestone 
 series is well seen at Muirkirk, where it occurs as coarse white and yellow 
 friable grits and sandstones, with seams of fireclay and thin coal. It 
 
28 
 
 occurs alsoin the Lugar Water at Wallacetown, but is there much thinner 
 than at Muirkirk, and its outcrop is still further narrowed by the intrusion 
 of a large basaltic mass. 
 
 62. A very small portion of the Coal-Measures constituting the Lugar 
 coal-field comes into the present Map, as may be seen by the outcrop of 
 the black-band ironstone ; but as this field has already been described, 
 and a section of it given in par. 55 of the Memoir accompanying Map 14 
 of the Geological Survey, reference may be made to that publication. It 
 will be seen from the present Map, that a detached portion of the Coal- 
 Measures forms the western extension of the Muirkirk coal-field; and, owing 
 to the quantity and quahty of the coal seams, they have been extensively 
 worked at Nether Wellwood ColKery. The black-band ironstone has been 
 the main object of search. It is the same as that worked at Lugar and 
 DahneUington. A section of this field is exposed in the Powharnal Burn, 
 along the sides of which most of the coals have been worked open-cast. 
 The red sandstone group, which forms the uppermost part of the Coal- 
 Measures, is seen at Nether WeUwood, on the Powharnal Burn. It 
 consists of purple sandstones and shales very much crumpled, their dis- 
 turbance being probably due to their proximity to a large fault, which 
 brings them down against low members of the Carboniferous Limestone 
 series. The coals of this field are in many places destroyed by thin 
 intrusive sheets of white trap, and they are further traversed and altered 
 by a number of trap dykes and volcanic necks. 
 
 63. 
 
 Coal-Measures 
 
 Millstone Grit 
 
 Carboniferoas Limestone Series 
 
 Muirkirk Section. 
 
 
 
 
 
 fma. 
 
 feet. 
 
 in. 
 
 
 fCoal, .... 
 
 
 
 2 
 
 6 
 
 
 Strata, 
 
 2 
 
 
 
 
 
 
 Coal, .... 
 
 
 
 5 
 
 
 
 
 Strata, 
 
 11 
 
 
 
 
 
 
 Three-foot Coal (Claud), 
 
 
 
 3 
 
 3 
 
 
 Strata, : 
 
 9 
 
 
 
 
 
 
 Seven-foot Coal (Maid), 
 
 1 
 
 1 
 
 
 
 
 Strata, 
 
 
 
 3 
 
 
 
 
 Coal (Low Maid), 
 
 
 
 3 
 
 
 
 
 Strata, 
 
 18 
 
 
 
 
 
 
 Coal, .... 
 
 
 
 2 
 
 4 
 
 
 Strata, 
 
 21 
 
 
 
 
 
 
 Musselband Ironstone, 
 
 
 
 
 
 6 
 
 
 Strata, 
 
 3 
 
 
 
 
 
 
 Five-foot Coal, . 
 
 
 
 5 
 
 6 
 
 
 Strata, 
 
 3 
 
 
 
 
 
 
 Six-foot Coal, 
 
 
 
 6 
 
 6 
 
 
 Strata, 
 
 23 
 
 
 
 
 
 
 Black-band Ironstone, 
 
 
 
 1 
 
 
 
 
 Strata, . 
 
 10 
 
 
 
 
 
 
 ^Thin Black-band, 
 
 
 
 
 
 6 
 
 
 Strata consisting cHefly of S 
 
 and- 
 
 
 
 ■ 
 
 stones, Grits, Fireclays, 
 
 and 
 
 
 
 i 
 
 Thin Coals, . 
 
 140 
 
 
 
 
 
 
 " 10. Bluetour Limestone, 
 
 8 
 
 4 
 
 
 
 
 Bluetour Coal, 
 
 1 
 
 2 
 
 
 
 
 Strata, . 
 
 10 
 
 
 
 
 
 
 9. Limestone, . 
 
 
 
 2 
 
 
 
 
 Strata, . 
 
 15 
 
 
 
 
 
 
 8. Tibby Pagan's Limeston 
 
 e, 
 
 6 
 
 2 
 
 
 Strata, . 
 
 12 
 
 
 
 
 
 3S • 
 
 Cokeyard Coal, 
 
 
 
 3 
 
 6 
 
 
 Strata, , 
 
 13 
 
 
 
 
 
 
 7. Timestone, . 
 
 
 
 4 
 
 
 
 
 Strata, . 
 
 8 
 
 
 
 
 
 
 6. Limestone, . 
 
 
 
 1 
 
 3 
 
 
 Strata, . 
 
 5 
 
 
 
 
 
 
 5. ELL Coal Limestone, 
 
 
 
 2 
 
 3 
 
 
 Strata, . 
 
 6 
 
 
 
 
 
29 
 
 Carboniferous Limestone Series 
 
 Ell Coal, 
 
 Strata, . 
 Black-band Ironstone, . 
 
 Strata, . 
 Seven-foot Coal, . 
 
 Strata, . 
 Nine-foot Coal, 
 
 Strata, . 
 High-band Ironstone (Clay), 
 
 Strata, . 
 Mid-band Ironstone (Clay), 
 
 Strata, . 
 Thirty-inch Coal, . 
 
 Strata, . 
 Six-foot or Catchybun Coal, 
 
 Strata, . 
 Low-band Ironstone (Clay), 
 
 Strata, . 
 M'Donald Coal, . 
 
 Strata, . 
 M'Donald Ironstone (Clay), 
 
 Strata, . 
 4. M'Donald Limestone, . 
 
 Strata, . 
 Smith Ironstone (Clay), 
 
 Strata, . 
 3. Limestone, . 
 
 Strata, 
 Crossfiatt Ironstone (Clay), 
 
 Strata, . 
 2. Hawthorn Limestone, . 
 1. "Wee Limestone, 
 
 Calciferous Sandstone Series, 
 
 fhia. feet, in, 
 4 
 
 64. Gass Water Section. 
 
 Limestone, 
 
 Strata, 
 Limestone, 
 
 Strata, 
 Limestone, 
 
 Strata, 
 Coal, . 
 
 Strata, 
 Coal, . 
 
 Stone, 
 Coal, . 
 
 Stone, 
 Coal, . 
 
 Stone, 
 Coal, . 
 
 Strata, 
 Coal, . 
 
 Strata, 
 Coal, . 
 
 Strata, 
 Smithy Coal, . 
 
 Strata, 
 Clay Ironstone, 
 
 Strata, 
 Coal, . 
 
 Strata with Ironstone, 
 Coal, . 
 
 Strata, 
 Limestone, 
 
 4 
 10 
 
 
 5 2 
 
 
 
 1 6 
 
 1 
 
 1 
 
 
 2 6 
 
 
 
 
 
 1 
 
 5 
 
 
 
 1 2 
 
 2 
 
 
 4 
 
 
 3 
 
 2 3 
 6 
 
 
 3 6 
 
 fms. feet. in. 
 6 
 3 16 
 
 
 6 
 
 
 5 
 
 
 2 6 
 2 2 
 2 4 
 
 10 
 
 9 
 
 
 
 3 
 
 
 
 1 
 
 9 
 
 6 
 3 
 
 
 
 2 
 3 
 
 8 
 
 10 
 
 8 
 2 
 
 1 
 3 
 
 1 
 
 7- Glespin or Douglas Water District. 
 
 65. As shown on the Map, this district has a rudely triangular 
 shape : the base of the triangle is formed by the somewhat irregular and 
 
30 
 
 faulted overlap of the carboniferous rocks upon the Old Red Sandstone, 
 while the two sides are bounded each by a fault which brings these two 
 formations together. 
 
 66. The lower or red sandstone group of the Calciferous Sandstone 
 series is found in the south-western part of the district in the Kennox and 
 Carmacoup Waters. The bottom on which these strata were deposited 
 must have been remarkably irregular, for it will be observed that, in a space 
 of little more than a mile, the sandstones of the Kennox Water, which 
 maybe about 500 feet thick, die out altogether, and the Carboniferous Lime- 
 stone series rests directly on the Old Red Sandstone. Nor is this thinning 
 out confined to the Calciferous Sandstones : the lower part of the Carbon- 
 iferous Limestone series has also disappeared. In connection with this 
 point in the physical structure of the district, it is interesting to observe, 
 that where the carboniferous rocks rest upon the Old Red Sandstone, 
 their lowest beds consist of conglomerate made up from the waste of the 
 older formation, and that these conglomerates continue to fringe the car- 
 boniferous area, while the strata above them pass quite away. Hence, in 
 this continuous band of conglomerate, one portion is on the horizon of a 
 low part of the Calciferous Sandstone series, while another portion is on 
 the horizon of some of the higher members of the Carboniferous Limestone 
 series. It thus brings before us evidence of shore conditions during a 
 protracted submergence of this area in Lower Carboniferous times. 
 
 67. The Carboniferous Limestone series, where most fully developed in 
 the Kennox Water, resembles that at Muirkirk. The lower limestone 
 and clay-band ironstones, in particular, are readily recognisable. Coal 
 seams likewise occur, which, although probably the equivalents of those at 
 Muirkirk, are yet not easily determined, owing to the absence of good 
 natural sections and the want of any borings. As already remarked, the 
 Limestones series undergoes considerable modification in its passage from 
 west to east. The lower limestone group, so well developed in the Kennox 
 Water, dies out entirely in about a mile. It is the uppermost limestones 
 which are seen in Glentaggart Burn; yet, notwithstanding this rapid 
 attenuation, the basement conglomerate above described continues to be 
 seen wherever a section has been cut by a water-course. 
 
 68. The Millstone Grit is here well developed, and gives rise to a series 
 of not inconsiderable hills. It is best seen in the Kennox Water, where 
 it consists of sandstones, which in their lower part are yellow, coarse- 
 grained, and friable ; and in their upper part contain fireclays and thin 
 coals, of which latter, however, one seam is four feet thick. 
 
 69. The Coal-Measures of this district contain all the coals at present 
 wrought here : the position and thickness of the several seams are shown 
 in the subjoined section. The upper group of red sandstones is seen in 
 the bed of the Douglas Water at Mavisbank School. 
 
 Coal-Measures 
 
 Glespin Section. 
 
 
 fms. ft. in 
 
 Seven-foot Coal, 
 
 
 1 1 
 
 Strata, 
 
 
 6 
 
 Musselband Ironstone, . 
 
 
 n 
 
 Strata, 
 
 
 8 
 
 Four-foot Coal, . 
 
 , 
 
 4 2 
 
 Strata, . 
 
 
 :i 
 
 Nine-foot Coal, 
 
 
 12 6 
 
 Strata, . 
 
 
 6 
 
 Foiil Dross Coal, 
 
 
 4 
 
 Strata, . 
 
 
 10 
 
 Dross Coal, 
 
 
 2 10 
 
 Strata, . 
 
 
 40-50 
 
 Black-band (Slatey-band) 
 
 Ironstone (not 
 
 
 workable as an Ironstone here;, 
 
 
 
31 
 
 The extent to which this field is faulted will best be seen by a glance at 
 the Map. In addition to the two boundary faults already referred to, the 
 southern outcrop of the district is broken by three dislocations. Of these, 
 the most important is that which, diverging from the great boundary 
 fault, strikes northwards parallel to the line of the Glespin Water : its 
 effect has been to let down the Glespin coal-field against the Carboniferous 
 Limestone series on the east. 
 
 J- Outliers of Moss Burn, Penbreck, Wildshaw, and 
 Whitecleuch. 
 
 70. That the Carboniferous rocks once extended over a much larger 
 area than they now cover, is shown not only by the denudation so clearly 
 marked by the outcrop of the strata in the several districts, but by the 
 occurrence of small outliers, lying sometimes far away from the main 
 mass of the formation to which they belong, and of which they once 
 formed a part. Of these outliers, the largest is that which lies in the 
 Duneaton valley at Whitecleuch. At its southern end it rests uncon- 
 formably on the Lower Silurian rocks ; while on either side, and at the 
 north end, it is brought down by faults against the older rocks. The 
 bottom beds are fine conglomerates, which, as they lie below the lowest 
 Umestone, are presumed to belong to the Calciferous Sandstone series. 
 The main portion of the outlier, however, consists of a portion of the Car- 
 boniferous Limestone series. As the limestone which is seen at the north 
 end close to the boundary fault is one of the upper limestones, we may 
 infer that the whole of the Muirkirk section, except the Coal-Measures, is 
 here represented. The M'Donald coal only has been worked. 
 
 71. At Wildshaw, on the northern edge of the Map, a small outlier 
 of the Hawthorn limestone of Muirkirk rests almost directly upon the 
 Old Red Sandstone, being separated from it by only a few yards of 
 friable sandstone and conglomerate. In this instance, also, we see that 
 the whole of the Calciferous Sandstone group is wanting. The eastern 
 side of this outlier is bounded by a fault. 
 
 72. At Penbreck, a shepherd's house, near the source of the Glenmore 
 Water, a little Carboniferous basin is found, of which the margin is to a 
 large extent bounded by faults. Its lower portion contains the Haw- 
 thorn and M'Donald limestones of Muirkirk, above which he some of the 
 lower coal-seams of that field. It will be seen from the Map, that along 
 the side of the same fault, which bounds this outlier on the south, there 
 occurs a small outlier of Calciferous Sandstone close to the edge of the 
 Glespin coal-field, and that this fault is one of those by which the southern 
 margin of that field is broken. 
 
 ' The Sanquhar Coal-field. 
 
 73. With the exception of the small faulted outUer at Whitecleugh, 
 all the Carboniferous districts described in the foregoing pages lie to the 
 north of the great boundary fault, and therefore outside of the Silurian 
 region. The districts which remain to be described Me wholly within the 
 Silurian uplands. In tracing their outlines, we soon learn that the Car- 
 boniferous rocks have been deposited in ancient hollows or valleys, which, 
 worn out of the Silurian rocks in palaeozoic times, were afterwards filled 
 up with Carboniferous and Permian deposits, and in long subsequent ages 
 were re-excavated, so as now to present the form of valleys and hollows 
 once more. In the course of this protracted denudation so much of the 
 original Carboniferous and Permian covering has been removed, that only 
 fragments of it are now left ; while the Silurian floor, on which it was 
 laid down, has been everywhere, and often deeply, eroded. Enough, 
 
32 
 
 however, remains to show us, that what is now the valley of the Nith was 
 also a valley in Carboniferous times, and that somewhere about the site 
 of Kirkconnel lay the head of this valley in the form of a col, from which 
 the ground descended northward, with probably an abrupt slope, into 
 Ayrshire. In proof of this statement, we find that, in ascending the Nith 
 valley, the Carboniferous Limestone series, which is so well developed in 
 the Thornhill basin, thins out towards the north, until along the south- 
 eastern borders of the Sanquhar coal-fiield it disappears altogether, and 
 the overlying Coal-Measures come to rest directly on the Lower Silurian 
 rocks. No Carboniferous Limestone beds reappear until we reach the 
 great fault, immediately on the north side of which they come iu in force. 
 It is difficult to understand how this should have happened, unless on the 
 supposition that, at the time when the Carboniferous Limestone series was 
 in the act of deposition, the line of fault was represented at the surface 
 by a steep bank shelving to the north, which formed the limit of the 
 Limestone series on that side, but which, as the whole region continued to 
 sink, was gradually buried under the continuous sheet of Coal-Measures 
 which stretched through the Sanquhar valley northwards into Ayrshire. 
 
 74. Of the remaining fragments of the Carboniferous deposits once laid 
 down within the Silurian area, the largest and most important forms the 
 Sanquhar coal-field. As shown on the Map, this area covers a part of the 
 Nith valley, about nine miles long, and from two and a half to four miles 
 broad, with the river flowing down its centre. On the left bank of the Nith 
 the boundary of the coal-field is formed by a long and powerful fault, while 
 on the right bank the edge of the field is defined by the line of the out- 
 crop of the lowest bed of the Coal-Measures upon the Silurian rocks. At 
 the south-eastern end of the field several small outlying patches of the 
 Carboniferous Limestone series occur. They consist, at the base, of fine 
 conglomerate, covered by sandstones, shales, and thin concretionary fossil- 
 iferous limestones. At Brandleys a portion of the same rocks is seen 
 passing underneath the Coal-Measures, whence it may be inferred that 
 only the upper part of the Carboniferous Limestone series is here repre- 
 sented. 
 
 75. The Sanquhar coal-field is entirely made up of strata belonging to 
 the true Coal-Measures. Although it has not yet been possible to identify 
 many of the coal-seams of this field with those in the neighbouring dis- 
 trict of New Cumnock, yet, from the general resemblance of the other 
 strata in the two coal-fields, there can be Kttle doubt that they have at 
 one time been connected, and therefore that the Sanquhar coal-field is 
 only a prolongation of the Ayrshire Coal-Measures. 
 
 Coal-Measures 
 
 Sanquhar Section. 
 
 
 
 fms. ft. in 
 
 ' Creepie Coal, 
 
 2 7 
 
 Strata, . 
 
 7 
 
 Calmstone Coal, . 
 
 4 1 
 
 Strata, . 
 
 11 
 
 Twenty-incli Coal, 
 
 18 
 
 Strata, 
 
 40 
 
 Daugli Coal, 
 
 4 7 
 
 Strata, 
 
 50-60 
 
 Splint Coal, 
 
 5 
 
 Strata, . 
 
 16 
 
 Coal, 1 
 
 15 
 
 Strata, 
 
 3 
 
 Coal, [ Swallow-Craig Coals, 
 
 1 10 
 
 Strata, . . 
 
 6 
 
 Coal, J 
 
 12 
 
 Strata, 
 
 30 
 
 Position of (Slatey) Black-band Iron 
 
 
 stone. 
 
 
33 
 
 On the north-east side of the field lies a portion of the upper barren red 
 siindstones, which here, as in Ayrshire, overlap the older portions of the 
 C'arboniferous system. The interval between their deposition and that of 
 the highest part of the underlying Coal-Measures is further shown by the 
 faet that at one place, near Bankend, they actually spread over a fault in 
 the Coal-Measures of ninety fathoms without being themselves disturbed. 
 Yet that these red sandstones are of Carboniferous and not of later age, 
 is indicated by the occurrence in them of at least two coal seams (one of 
 which is two feet thick) and one of black-band ironstone, which are seen 
 in the stream near Kirkland. Overlying the red sandstones at the south- 
 east end of the field are three small outliers of melaphyre, which, from 
 their position and their petrographical character, must he placed on the 
 same horizon with the Permian volcanic rocks of the Carron Water, to 
 be afterwards described, and with the corresponding Permian volcanic 
 rocks of Ayrshire. They are mere fragments of lava flows ; and some of 
 the points of eruption from which they were ejected are still visible in 
 the necks of agglomerate which rise through the coal-field. 
 
 76. Of the faults by which the Sanquhar coal-field is bounded and 
 intersected, by far the largest is that which has let down the coal-field on 
 the north-east side against the Silurian rocks. From the depth of Coal- 
 Measm-es which it throws out at the north-east or deepest part of the 
 field, it must be one of at least 1200 feet. Its most singular feature, per- 
 haps, is the remarkable bend which it makes when, in proceeding to the 
 north-west, it approaches within less than fifty yards from the great 
 boundary fault. Instead of touching that dislocation, it turns off sharply 
 to the left, and runs parallel with it for two miles, the space between the 
 two faults being sometimes not more than twenty yards. The line of the fault 
 is made conspicuous even at the surface, from the fact of its having been 
 taken by a massive dolerite dyke which extends along the fault for several 
 miles on both sides of the angle. About a mile and a half beyond the 
 angle, on the north-west side, this dyke cuts across the narrow inter- 
 vening strip of Silurian strata into the great boundary fault, along which 
 it continues to run until it is lost under the alluvium of the Nith. Parallel, 
 in a general sense, with the fault which has just been described, a number 
 of minor dislocations traverse the coal-field, with the effect of letting down 
 the beds by a series of steps towards the north-east or deepest part of the 
 field. Of these, the largest has been already referred to as having a throw 
 of ninety fathoms. It runs in a K.N.W. direction, and, as shown by the 
 workings in the Bankhead Colliery, brings down the Calmstone coal against 
 the Splint coal seam. Yet, as before remarked, it does not penetrate the 
 overlying red sandstones, the whole of the displaced rock on the upthrow 
 side of the dislocation having been removed by denudation before these 
 strata were deposited. 
 
 One distinguishing feature in the Sanquhar coal-field is the fact that 
 along the south-west half of the field the strata are traversed in a north- 
 westerly direction by at least three narrow doleritic dykes, which send 
 out intrusive sheets along the coal seams. The trap itself is much decom- 
 posed, having the same character as the white trap so common in the 
 Ayrshire coal-fields.* As in Ayrshire, the coals are so altered by it as 
 to be unworkable. In some places they have been converted into beauti- 
 fully columnar anthracite. 
 
 Z- Carron Water Basin. 
 
 77. A little to the south-east of the Sanquhar field, the Carboniferous 
 Limestone rocks, which appear as mere thin detached fragments near 
 Sanquhar, come in much more strongly in another of the ancient de- 
 
 * See Explanation of Sheet 14 of the Geological Survej' of Scotland, p. 22. 
 
 C 
 
34 
 
 pressions already described. While they have been removed entirely out 
 of the intervening portion of the Nith valley, they are still preserved in 
 the valley of the Carron Water, which then, as now, was a tributary of 
 the Nith. This side valley runs still, as it did in Carboniferous times, 
 deep into the flanks of the Lowther Hills. Its bottom is covered with 
 Carboniferous and Permian rocks,. which, sweeping southwards into the 
 Nith valley, expand over the basin of Thornhill. Along the whole of 
 the west side of the Carron Water valley the Carboniferous rocks rise 
 from under the Permian. On the east side, however, they are seen only 
 here and there, owing to the way they are overlapped by the later 
 formation. 
 
 78. In the southern part of the Thornhill basin the limestones of Close- 
 burn contain characteristic Carboniferous Limestone fossils. They are 
 associated with red sandstones and red shales, which, stretching north- 
 wards, appear to belong to the same group of strata as those which on 
 the present Map are represented as rising from under the Permian rocks 
 of the Carron Water basin. It has therefore been necessary to colour 
 the whole as Carboniferous Limestone. At the same time, it must be noted 
 that the Carboniferous rocks in the Carron Water area are undistin- 
 guishable from the red upper Coal-Measures of Sanquhar and Ayrshire. 
 No trace, however, of any undoubted Coal-Measure strata has yet been 
 detected here ; and, in the absence of other evidence, the whole of the 
 Carboniferous rocks of the Thornhill basin are grouped, with the lime- 
 stones of Closeburn, under the Carboniferous Limestone series. 
 
 79. Many good sections are to be seen of the Carboniferous rocks 
 between Drumlanrig and the north end of the basin, particularly in the 
 ravines which have been cut through them by the Nith, and also along 
 the course of the Enterkine Burn, and in the railway cutting at the north 
 end of the Drumlanrig Tunnel. The whole series of rocks strata is about 
 500 feet thick, resting unconformably on the Lower Silurian rocks (as 
 beautifully seen in the ravine of the Nith at Duncan's Linn), and over- 
 lapped by the porphyrites of the Permian series. They consist of red 
 and reddish grey sandstones, and lilac or mottled clays and shales. They 
 occasionally, as at Duncan's Linn, contain Stigmaria and other plant 
 remains. 
 
 Intrusive Rocks in the Carboniferous Series. 
 
 80. The Carboniferous groups represented on this map are traversed 
 by three forms of igneous rocks — sheets, necks, dykes. 1. The largest 
 intrusive sheets are those which have been injected along the horizon of 
 the upper limestones, New Cumnock and Aird's Moss. Others on a 
 smaller scale occur among the upper coals in the New Cumnock field, 
 and Ukewise in the Sanquhar district. All these sheets consist of basalt- 
 rocks. 2. Necks marking the position of former volcanic vents occur in 
 different parts of the Carboniferous district, and are probably all of 
 Permian age. They consist of pipes which descend vertically, and are 
 filled up with various fragmentary materials, which were ejected from the 
 orifice by volcanic action, and subsequently fell back into it, and were 
 consolidated there. Five of these necks occur in the Sanquhar coal-field : 
 four are shown on the Map as occurring in the Muirkirk area, while 
 another occupies a position on the Old Red Sandstone at the north-west 
 corner of the Map. The latter is the only example in this Map of a neck 
 occurring in any other than a Carboniferous area. 3. The Carboniferous 
 tracts, like the rest of the area embraced in the present Map, have been 
 invaded by many of the remarkable north-west and south-east dolerite 
 dykes by which the south of Scotland is so much traversed. These dykes 
 will be more particularly referred to in par. 88. 
 
35 
 
 Permian. 
 
 81. In two separate areas of the present Map are shown certain strata 
 which are referred to the Permian system. Of these, the one is an exten- 
 sion northward of the basin of Thornhill (Sheet 9) ; the other lies near the 
 northern edge of the Silurian region between Leadhills and Crawfordjohn. 
 Both these areas of Permian rocks occupy hollows in the Silurian uplands, 
 and, taken fn connection with the Carboniferous outhers already described, 
 they show at how early a date these uplands had undergone extensive 
 denudation, and had been worn into valleys. The hollows in which the 
 Carboniferous and Permian strata were deposited were no doubt, in great 
 measure, if not wholly, filled up and obliterated by these deposits, which 
 have since been cleared out again, so as to expose, though in a worn and 
 fragmentary state, the original valleys of Carboniferous and Permian times. 
 That the rocks occupyingthese hollows are referable to the Permian system, 
 is inferred from the following facts : — 1st, They overlie the Carboniferous 
 series unconformably ; 2rf, They are, to a large extent, identical with strata 
 which unconformably overlie the Coal-Measures in Ayrshire ; 3d, They are 
 the same as those which, in the Dumfriesshire basin, pass southwards 
 under the Trias of Cumberland. 
 
 »■ Carron Water Basin. 
 
 82. This area extends along the valley of the Carron Water north- 
 wards to the mouth of the Pass of Dalveen. While merely a prolonga- 
 tion of the Permian basin of Thornhill, the rocks in the valley of the 
 Carron Water differ from those of the same series further south, in the 
 greater abundance of volcanic rocks, and of volcanic detritus in the sand- 
 stone. The whole of the Permian series of the Carron Water basin is 
 full of evidence of contemporaneous volcanic activity, while southwards 
 this evidence dies out, and in the centre and south of the Thornhill area 
 ceases to be traceable. The following, in descending series, is the suc- 
 cession of rocks along the Carron Water :— 
 
 6. Brick-red sandstones full of trappean detritus, and with bands of trap-tulT, 
 
 and occasional thin sheets of porphyrite. 
 u,. Porphyrite, in different beds, resting on the Carboniferous series. 
 
 83 (a). The lower division of the Permian series here consists of 
 various beds of porphyrite and melaphyre, which rise from under the 
 brick-red sandstones, and form a marked ridge between these and the 
 underlying Carboniferous rocks along the west side of the basin. On the 
 east side they are partly overlapped by the red sandstones, and do not there 
 form so striking a surface-feature as on the other side. The trap-rocks 
 have a general dull purple or purplish grey or chocolate-brown colour. 
 They vary from a finely crystalline compact form to an earthy amyg- 
 daloid or an open scoriaceous rock. In the amygdaloids, steatite abounds 
 in the cavities and cracks. All of these rocks appear to consist of a base 
 of triclinic felspar, to which titaniferous iron, augite, and in particular a 
 red ferruginous decomposed mineral, are added in various proportions. 
 In most cases they are probably most properly classed under the general 
 term porphyrite, though, in some cases where the augite and titaniferuus 
 iron are conspicuous, they could not be separated from melaphyre. They 
 perfectly resemble the Permian volcanic rocks of Ayrshire.* 
 
 84 (b). Above the porphyrites comes a conformable series of brick-red 
 sandstones and tuffs, forming the basement beds of the Thornhill basin. 
 
 * See Geological Magazine for Jirne 1865, and Memoirs of Geological Survey, 
 Explanation of Sheet 1 4, p. 22. 
 
36 
 
 The whole of this series of rocks is more or less marked by the diffusion 
 through it of traj)pean detritus, sometimes in the form of minute grains, 
 sometimes as a gravelly intermixture, sometimes in large blocks and trap- 
 pean bombs, sometimes in regular interstratified bands of trap-tuff. 
 Occasionally, as at Durrisdeer Mill, a band of porphyrite is intercalated 
 in the series. As shown on the Map, a sUght roll of the porphyrite series 
 suffices to separate the overlying sandstones into two distinct areas, of 
 which the northern forms an independent outlier, while the southern passes 
 onwards into the Thornhill tract. It is in the former that the evidence of 
 contemporaneous associated volcanic action is most conspicuously ex- 
 hibited, as shown by the section in the Carron Water from the Railway 
 Viaduct north to near Nether Dalveen. To the south of the viaduct the 
 sandstones are less strongly intermingled with trappean -detritus, and 
 begin to assume the characteristic brick-red colour and false-bedded 
 stratification, so well seen in the streams and quarries to the east of 
 Thornhill. 
 
 85. In connection with the volcanic sheets of this district, reference 
 may here be made to the necks which occur to the north-west in the 
 Sanquhar coal-field, and dot the Aird's Moss and Muirkirk coal-field. 
 These, there can be little doubt, mark the site of volcanic orifices in 
 Permian times ; and as they continue through Ayrshire up even into 
 Renfrewshire, they show how abundant volcanic action was in the south- 
 west of Scotland during the later pateozoic periods.* 
 
 /3. Crawfordjohn District. 
 
 86. Between the villages of Leadhills and Crawfordjohn there occurs 
 a singular detached area of breccia about a mile broad and two miles 
 long. It fills a depression in the Silurian rocks, and may once have 
 stretched into and along the Duneaton valley, which, as we have seen, is 
 filled at Whitecleuch with Carboniferous deposits. From the similarity of 
 this breccia to some of those in Annandale, it is inferred to be of Permian 
 age. It has been entirely derived from the waste of the surrounding 
 Lower Silurian rocks, no fragment of Old Red Sandstone or conglomerate 
 or of any Carboniferous rock having yet been recognised in it. The stones 
 are angular and subangular, often of a somewhat flat form, and vary in 
 size up to a foot or more in length. They strongly resemble the form of 
 the stones in boulder-clay or moraine rubbish. Indeed, where the usual 
 stratification of the mass fails to appear, and the stones have been thrown 
 together irregularly, the resemblance to a glacial deposit is very striking. 
 The stones are commonly crusted with a thin coating of hsematite. A 
 careful search was made among them for striated surfaces, but without 
 success. The paste of the mass is scanty, and occurs as a red, sometimes 
 green, sandy clay. No rock like this breccia occurs anywhere in the Old 
 Red Sandstone series of this region, though it sometimes resembles part 
 of the upper Old Red conglomerate of the Lammermuirs. Nor is there 
 anything analogous to it in any part of the Carboniferous area. It quite 
 resembles, however, some of the coarse Permian breccias near Moffat, 
 though on a much larger scale. In the absence of other evidence, there- 
 fore, it is classed with these as Permian. 
 
 Igneous Rocks of Miocene Age. 
 
 87. The present Map contains several excellent examples of the system 
 of dolerite dykes, which were probably erupted during the Miocene period. 
 These are .shown, by the long narrow parallel stripes of crimson on the 
 Map, to have a prevailing N.W. and S.E. direction. They do not run in 
 
 * See Explanation of Sheet 14, p. 22. 
 
37 
 
 absolutely straight Hues, but their irregularities of outcrop are to a con- 
 siderable extent due to the inequalities of the ground, and to the fact that 
 the dykes, instead of being vertical, sometimes have a very considerable 
 incUnation or hade to one side. Each dyke retains a singular uniformity 
 of breadth, the larger ones averaging from fifty to sixty feet wide, with 
 sharply defined wall-like sides. It will be seen that these dykes cross 
 every other rock in the district ; and not only so, but even large faults 
 which they cut without the slightest deviation. This is particularly to be 
 noticed in the case of three dykes in the neighbourhood of Crawfordjohn, 
 which pass without deflection or alteration across the enormous boundary 
 fault. Yet the dykes have not themselves risen along lines of fault. The 
 clean cut fissures through which they have come show no elevation or de- 
 pression of the beds on either side of them. The two dykes which com- 
 pletely traverse this Map have each been traced for many miles to the 
 N.W. and S.E.* 
 
 Faults. 
 
 88. Two series of faults occur on this Map : the first and most power- 
 ful runs from S.W. to N.E., while the others run more or less perpendi- 
 cular to them, viz., in a N.W. and S.E. direction. Reference has fre- 
 quently been made in the course of the foregoing pages to the great 
 boundary fault which separates the Silurian uplands from the Old Red 
 Sandstone and the Carboniferous tracts on the north. It is a continuation 
 of the great fault described in the Explanation to Sheet 14, and continues 
 in the same straight hne north-eastwards across the present Map for many 
 miles, until it is overlapped by the Mid-Lothian coal-field. From the de- 
 tailed survey which has been made of the Old Red Sandstone, it is possible 
 to estimate the amount of throw which the fault has here. We know 
 the thickness of that formation to be fully 15,000 feet, and the fault must 
 be a dislocation to that amount at least. It is also evident that this great 
 dislocation is older than the Carboniferous period, although it may very 
 possibly have served subsequently and often as a line of weakness along 
 which movements afterwards took place. This is shown by the entire 
 absence of any Old Red Sandstone on the south side of the fault, and by 
 the occurrence of the Carboniferous Limestone and Coal-Measures lying 
 directly on the Silurian rocks. So vast a thickness of Old Red Sand- 
 stone could not have ended originally where the fault now is, but must 
 have swept southwards over the Lower Silurian uplands. Yet these 
 thousands of feet of sandstones, conglomerates, lavas, and tuffs were so 
 completely removed from the south side of the fault previous to the de- 
 position of the Carboniferous Limestone series and the Coal-Measures, 
 that not a fragment of them is anywhere to be seen between these later 
 formations and the Old Silurian floor. That the fault continued to be a 
 line of weakness along which movements took place in Carboniferous or 
 later periods, is proved by the way in which the Carboniferous Limestone 
 series is brought down by it against the Silurian region to the south of 
 New Cumnock. We have other evidence to the same eiTect in that re- 
 markable curving fault, which has been already described as running at the 
 north-west end of the Sanquhar field, parallel with and close to the great 
 boundary fault. A similar inference may be drawn from the position of 
 the faulted outlier at Whitecleuch. Several other N.E. and S.W. faults 
 lie to the west of the large one ; but these are of much less antiquity and 
 of less extent, seeing that their utmost effect has been to bring down the 
 Coal-Measures agauist the Lower Old Red Sandstone. 
 
 89. The second or N.W. and S.E. series of faults, although much 
 
 * For further information regarding Miocene dykes, see Explanation of Sheet 14 of 
 the Geological Survey of Scotland, and the references there given. 
 
38 
 
 more numerous, are far less powerful than those in the opposite direction. 
 They are cut off by the latter, and are seldom traceable for more than a 
 mile or two. 
 
 90. It will be seen that most of the faults represented on the Map lie 
 in the coal-fields. In the Muirku-k field the largest throw is one of sixty 
 fathoms, the general effect of the faults there being to throw down the 
 strata towards the S.W. The fault, however, which skkts the northern 
 margin of the Old Red Sandstone area of Wardlaw has a downthrow 
 towards its western extremity of at least 400 fathoms to the north. In 
 the Sanquhar field, also, the faults belong almost wholly to the N.W. and 
 S.E. series. Their general effects have been already referred to in par. 76. 
 
 Drift. 
 
 91. Evidence of the former movement of ice over the country is well 
 displayed in several parts of the area embraced in this Map. This 
 evidence consists of Scratched Bock-surfaces, Boulder-clays, Sands and 
 Gravels, Erratic blocks and Moraines. 
 
 92. Scratched Rock-surfaces. — Beneath the covering of superficial 
 accumulations, and on bare hill-sides, from which these deposits or the 
 coating of turf have been removed, the worn, polished, and striated sur- 
 faces, characteristic of ice-action, are found in many places. As the result 
 of the observations made in the course of the Geological Survey, it ap- 
 pears that the high grounds, ranging from the sources of the Afton 
 north-eastwards through the Lowther and Leadhills to the Clyde, have 
 served as a central axis of dispersion for the ice of the glacial period. 
 This is shown by the fact that the striae on the rocks diverge from this 
 axial line to the low grounds on the north and south. As the range of 
 high grounds was traversed then, as now, by the valley of the Nith, there 
 would necessarily be a point or pivot in that valley, from which the ice 
 would move in opposite directions. This is borne out by the direction 
 of the striations on the rocks, of which the more important of those 
 observed are marked on the Map. 
 
 93. Boulder-Clays. — These clays are of the usual stiff, coarse, stoney 
 character, quite unstratified, and differing in colour and composition 
 locally, according to the nature of the rocks of each district. Among 
 the Silurian hUls they are dull grey or fawn-coloured ; on the Old Red 
 Sandstone tracts they are dark brown or red ; while over the Carbonifer- 
 ous areas they are of a black or dark leaden-blue tint. Though it is 
 possible to recognise that there is a stiff lower boulder-clay, and a loose, 
 more gravelly, upper boulder-clay, these cannot well be separated in 
 mapping. The evidence yielded by these clays as to former ice-move- 
 ments agrees with that furnished by the striae on the rocks. Over the 
 whole of the districts lying to the south of the Silurian uplands the 
 boulder-clays have been mamly derived from the southern hills, as is 
 shown by the abundance in these clays of pieces of readily recognisable 
 Lower Silurian rocks. The Spango granite, for instance, is found as far 
 north as the Hagshaw Hills, on the left bank of the Douglas Water. 
 Pieces of the Afton Water and Knipes granite likewise occur over the 
 Carboniferous tracts to the north. Fragments of the Haggis Rock are 
 among the most easily detected stones in the boulder-clays, alike on the 
 Carboniferous and Old Red Sandstone areas. While the Spango granite 
 is found to the north, it occurs likewise in considerable quantity in the 
 boulder-clay which Mes in the valleys to the south and south-east, being 
 traceable up the Wanlock Glen for three miles. Pieces of Carboniferous 
 sandstone are also found over the same district. Small fragments of 
 gneiss and mica-schist are met with in the boulder clay of Glenmore and 
 
39 
 
 Guelt Waters. We have here, therefore, a repetition of the proof for- 
 merly adduced, that in Ayrshire lay the meeting-place of the masses of 
 ice which moved southward from the Highlands, and northward from the 
 Silurian uplands of Galloway, Nithsdale, and Clydesdale* 
 
 94. In some of the large valleys, as in those of the waters of Ayr, 
 Glenmore, and Guelt, the boulder-clay contains interstratified beds of 
 sand, clay, and gravel. These sometimes exceed forty feet in depth, 
 as at Bullion Scars on Glenmore Water, where they are overlaid with 
 boulder-clay, while their base is not seen. Such stratified intercalations 
 are thickest along the centre of the valleys, on either side of which they 
 die out, and disappear wholly over the hills. 
 
 95. Old River Channels below the Boulder Clay. — Indica- 
 tions of former river-courses are sometimes found under the drift in the 
 course of mining operations. Thus, in the valley of the Nith, to the west 
 of Kirkconnel, a series of borings showed the existence of a deep trench 
 worn out of the Carboniferous rocks, and filled up with boulder-clay. 
 This trench was probably at one time the water-course of the Nith, 
 which has since then been forced to cut a gorge for itself out of the rocks, 
 without regaining its old channel. In the coal workings between Old 
 Kelloside and Drumbuie, the Splint coal was found to be cut out by 
 boulder-clay, at a depth of ten fathoms. But mines were driven through 
 the obstruction, and the coal was regained, on the other side of what 
 seems to have been another portion of a river-channel. A little to the 
 east of Sanquhar a similar buried water-course was encountered in work- 
 ing the Daugh coal, and in this instance sand was found to lie between 
 the boulder-clay and the rocks below. 
 
 96. Sands and Gravels. — Several good examples of the Upper or 
 Kame or Sandy Drift occur in the area represented upon this Map. Some 
 conspicuous kames run in a north-westerly direction along the railway 
 valley near New Cumnock towards the plains of Ayrshire, and south- 
 eastward down the valley of the Nith to the beginning of the gorge 
 below Sanquhar. A straggling line of kames may be traced over the 
 moors between New Cumnock and Mnirkirk. At the latter village they 
 are seen in well-marked parallel ridges, chiefly on the south side of the 
 valley of the Ayr ; but they cross the Ayr valley and sweep by Glenbuck 
 over into the Lesraahagow district. A strip of gravel, not distinctly 
 ridged into kames, stretches over Burnfoot Moor across the Greenock 
 Water, and expands on the water-shed (about 1000 feet above the 
 sea) into a platform, which, though now much cut down by streams, seems 
 to suggest that it once ran up the Ayr valley into that of the Douglas. 
 Similar deposits are met with in the latter valley below Carmacoup. 
 
 97. Another much denuded platform of sand and gravel follows the 
 1000 foot contour line along the south side of Buckstane Hill and the 
 hills south-westwards to Thirstane round to WUdshaw. This area is 
 not connected with the Douglas Water area, but belongs to the Drift 
 series of the Clyde valley. The peculiarity of this deposit is the number 
 of striated stones found in it. 
 
 98. Erratic Blocks. — Boulders of the Spango granite are shown 
 over the hills northwards as far as the Hagshaw range. In like manner, 
 pieces of the Knipes granite are found over the New Cumnock area. 
 Blocks of the Cairnsmore granite occur abundantly to the north of that 
 hill, particularly up to and along a height of 1700 feet. The boulders 
 seem to have streamed through cols lower than 1700 feet, and are found 
 at that or a less height in the lower part of the valleys which have no col 
 at their top, but end in a corrie. Further to the east, fragments of the 
 
 * See Explanation to Shfi 14 of the Geological Survey of Scotland, p. 24. 
 
40 
 
 white Cairn Table sandstone are strewn abundantly over the hills to the 
 north and north-east, ranging even as far as the southern end of the 
 Pentland Hills. 
 
 99. Moraines. — The higher points of the Silurian uplands during the 
 late stages of the Glacial Period nourished groups of glaciers, which have 
 left traces of their existence in numerous rubbish heaps or moraines. The 
 most marked moraines are those in the high grounds to the south-west of 
 the Nith, the greater mass of elevated land in that district probably 
 allowing of the greater development and continuance of the glaciers. 
 Moraine stuff, either heaped into mounds or strewn over the valley bot- 
 toms, is found in most of the valleys diverging from the high grounds at 
 the south-west corner of the Map. 
 
 100. The best marked series of moraines occurs in the valley of the 
 Holm Burn, one of the tributaries of the water of Ken. From the point 
 where the south edge of the Map crosses the burn to its source there is 
 a regular series of moraine mounds on both sides of the valley, rising 
 tier above tier for some distance up the hill-sides. Some of the mounds 
 are of a conical shape, but most of them have the form of long winding 
 ridges, with a marked bend towards the centre of the valley. They 
 beautifully illustrate the common horse-shoe shape of moraines. About 
 half-way up the valley the largest of the mounds occur on the left side, 
 where the concentric arrangement is well seen ; and along this same side, 
 too, their upper limit is defined by a continuous line of small conical heaps. 
 The mounds of the Holm Burn vary in size from five to twenty feet in 
 height. Blocks of hard greywacke are seen perched on their tops, but 
 none of these are of large dimensions. A few massive ones are to be seen 
 on the right hill-slope near the col. Three of them were roughly esti- 
 mated to contain 480, 420, and 135 cubic feet respectively. The hollows 
 between the mounds are filled with peat and marshy vegetation. At the 
 junction of the AUwhanie Cleuch with the main stream, a pretty large 
 alluvial flat occurs, which probably marks the site of an old lochan, 
 dammed back by the large heaps of moraine stuff which occur at this part 
 of its course. Several excellent sections of the same detritus are seen 
 where the burn has cut through the mounds. It consists of a loose 
 gravelly and sandy earth, with well-rounded stones, varying in colour from 
 light blue to yellow, and without any bedded arrangement. In one sec- 
 tion the proportion of scratched stones was found to amount to one-fifth 
 of the whole. In others, the finding of a striated stone was not so easy. 
 On the left side the moraines rise to a height of 250 feet above the level 
 of the stream. The upper limit is about 1600 feet, and the lower about 
 950 feet, above the level of the sea. Some isolated mounds occur, just 
 beyond the edge of this sheet, on the right-hand side of the valley, which 
 resemble true moraines. These, however, will be alluded to in connection 
 with the sheet to the south. 
 
 101. Moraines, more or less perfectly defined, likewise occur in the 
 valleys of the Polvaddoch Burn, Long Burn, and Spout Burn, flowing 
 southwards from the chain of heights extending to the east of Oairnsmore 
 of Carsphairn, in the valley of the Clennoch Burn running westward, 
 and in those of the Montraw and Afton which trend to the north. Even 
 in the less elevated ground lying to the east of the head-waters of the 
 Ken, moraine mounds occur on the streamlet which joins the right bank 
 of the Shinnel Water near Troston Hill. Northwards also some distinctly 
 marked mounds of similar origin are scattered along the course of the 
 Euchan Water from Buchan Head for a distance of about three miles 
 down to Benzien Craig. In these and other examples the moraine stuff 
 distinctly rests upon a flow of boulder-clay which covers the bottom of 
 the valley. 
 
41 
 
 102. The more limited area of high ground forming the group of the 
 Lowther Hills appears also to have nourished a little independent group 
 of glaciers, for mounds, probably of morainic origin, occur in the valley of 
 the Shortcleuch Water near the foot of Glen Franka Burn, and in the 
 Windgate Burn and Dun Grain, all flowing down the north-west side of 
 the ridge. On the opposite or south-east side similar mounds are met 
 with at the head of the Dalveen Pass, among some excellent examples of 
 roches moitionnees; also in the course of the streamlets which descend from 
 the Lowthers into the Potrenick Burn, and in the Glengeith Burn. About 
 a mile below Nether Fingland a curious kame-shaped mound of angular 
 and subangular detritus has been cut through by the stream. This may 
 possibly mark the position of a moraine mound, once continuous as a 
 barrier across the valley. 
 
 Alluvium, Peat. 
 
 103. It is only along the bottom of the valleys, and chiefly those 
 traversed by the larger streams, that any noticeable quantity of alluvial 
 deposits occur. Two terraces (on the Nith, three) of gravel and sand 
 are frequently found bordering the streams, and in one place where the 
 Crawick and Spango Waters unite, these stream-terraces are as many as 
 six in number. Several examples of lacustrine deposits, marking the site 
 of former lakes, occur upon the Map. One of these is found at New 
 Cumnock, where the kames of sand and gravel have at one time ponded 
 back the waters of the Nith. The deposits accumulated in this ancient 
 lake are coarse and gravelly at the mouth of the Afton Valley, but 
 further east they pass into finely-stratified loam. Another old lake is 
 indicated by laminated brown brick-clays (sometimes yielding deer's 
 horns) at Cronberry Tileworks, near the south end of Aird's Moss. 
 
 104. Many of the hills in the Silurian have their flat tops covered 
 with a thin coating of hill-peat. This coating gets deeper in the cols, 
 but it is on the lower ground that the deepest and largest expanses of 
 peat occur. Thus Aird's Moss covers an area of about three square 
 miles, and is in many places more than twenty feet thick. Another large 
 peat-moss occurs at Burnfoot Moor, a Kttle further to the north-east. 
 
 Economic Minerals. 
 
 105. Building Materials.— In the Silurian tracts the harder grey- 
 wacke beds are used for cottages and for ' dry-stone dykes.' The 
 felstone- dykes of these districts are sometimes more capable of being 
 dressed into blocks, as is shown by the masonry of the Leadhills Inn, 
 though even there the corner-stones and lintels are usually of freestone. 
 The more flaggy and tough beds of the Lower Old Red Sandstone are 
 likewise used for fences, though further to the north, in the Lesmahagow 
 district, they are the common building material. The poiphyrites and 
 pink felstones of this formation are not adapted for building purposes, 
 except for dry-stone dykes. The sandstones or freestones of the Car- 
 boniferous series furnish admirable building stones. In the Calciferous 
 Sandstones an enormous quantity of admirable building stone exists, 
 though, from its lying mostly in the moorland tracts, it has not yet been 
 much worked. Sandstones belonging to the Carboniferous Limestone 
 series are quarried at Muirkirk; but the stone most wrought in this 
 region is the freestone at the base of the Coal-Measures in Nithsdale. 
 The upper red sandstones are also used. Since the opening up of the 
 country by railways, the red sandstones of MauchUne and Dumfries are 
 superseding the local stones for at least the finer kinds of masonry . 
 
 D 
 
42 
 
 106. Limestones- -These are practically confined wholly to the 
 Carboniferous districts. The cornstones belonging to the Caleiferous 
 Sandstone series are extensively worked at Craigdullyeart, to the north- 
 west of Corsoneone, being much in request for agricultural purposes. As 
 will be seen from the Map, a continuation of this cornstone runs as an 
 intermittent band at the base of the Caleiferous Sandstones, where these 
 repose upon the Old Red Sandstone. The most valuable limestones are 
 those occurring in the lower group of the Carboniferous Limestone series. 
 They are most exclusively worked in the Muirkirk and Lugar district, 
 where they serve as a flux in the smelting of iron. They are also worked 
 at Wildshaw and Whitecleugh, and have been quarried at Peiibreck and 
 Kennox. In the upper division of the Carboniferous Limestone series, 
 at least three limestones have been used, the uppermost or Blue Tour 
 limestone sometimes attaining a thickness of seventy feet. They were 
 formerly quarried on a more extensive scale than at present. 
 
 107. Road -Metal.— In the Silurian area the harder greywackes 
 are used for road-metal, but, as a rule, are not durable. The intrusive 
 felstones also, in the Silurian and Old Red Sandstone areas, where 
 they can be conveniently got at, are much in request for similar pur- 
 poses. The most serviceable rocks for making into road-metal are the 
 Miocene dolerite dykes, the line of which may be sometimes traced for 
 miles by the number of quarries opened along their course. In some parts 
 of the Silurian district the gravel of the streams is used for road-metal. 
 
 108. Hone-stones. — Some of the softer felspathic flags or shales in 
 in the Lowther group of the Llandeilo series might be used as water 
 hones. Hones might also be formed out of the Old Red Sandstone 
 shales of the Dippool. 
 
 109. Pottery-Clays. — The decomposing and least ferruginous va- 
 rieties of the pink felstones of Muirkirk might be used as pottery-clays. 
 Possibly, also, portions of the decomposing Spango granite might be 
 available for the same purpose. 
 
 110. Brick-Clays. — The blue tills or fireclays of the Cement-stone 
 group might be used for making bricks and tiles, as is now the case with 
 the fireclays and shales associated with the M'Douald limestone, which 
 are employed to furnish the bricks required in the Muirkirk Ironworks. 
 At Sanquhar, the red marls and clays lying in the upper part of the 
 Coal-Measures are available for making the coarser kinds of pottery and 
 terra-cotta. Bricks and tiles are made from the alluvial clays already 
 mentioned as occurring at Cronberry. Similar clays occm- in the valley 
 of the Ayr, and in other parts of the Map. 
 
 111. Ores. — The present Map includes one of the best known mineral 
 fields in Scotland — that of the Leadhills. 
 
 Lecid. — Galena has long been worked extensively in the Silurian rocks 
 of LeadhiUs and Wanlockhead. The direction of the veins is indicated 
 on the Map, and then* general character may be gathered from the fol- 
 lowing description of a part of the New Glencrieff vein, laid open in De- 
 cember 1868. The vein here hades to the east at 70°-75°. Beginning 
 at the east or ' hanger ' side, the order of metals is as under : — 
 
 a. Greywaeke ; part of the general Silurian rock or ' country.' 
 
 6. ' Black Jack ' (Zinc blende), decomposing into clay. ^ inch. 
 
 c. ' Vein stuff ; ' Greywaeke ground up, and mixed with quartz. 14 inch. 
 
 d. Calc-spar. 4 inch to 1 inch. 
 
 e. Galena. \ inch. 
 
 /. Vein stuff, similar to c. Quartzose, and graduating into pure Quartz near the 
 
 floor of the level. 2 to 3 inches. 
 a. Blue greywaeke ; joints veiaed with calcareous matter. 34 feet. 
 h. Hard, fine, compact Quartz, with iron pyrites in 'flowers ;' i.e. the crystals 
 
 are scattered through the mass, and are not connected. 7 inches. 
 
43 
 
 k. Alternating irregular layers of Barytes and Galena. 8 inches. 
 
 /. Vein stuff, similar to c. 4 inches. 
 
 m. Greywacke (the ' ledger side ' of the vein), marked with vertical slickensides. 
 
 The section is ahout six feet high. A ' string ' of Black Jack commences at the 
 roof of the level in g, and cuts through all the layers on to m, which it enters near 
 the floor, a, g, and m are ' country. ' The other layers and the string are pro- 
 perly the vein. The veins vary at every step, and are sometimes remaxkahly rich in 
 lead ores ; while, on the other hand, the levels are sometimes driven for many fathoms 
 without meeting with any. 
 
 Further westwards, a true vein of galena was tried at in the Silurian 
 rocks to the south of New Cumnock, but was abandoned. 
 
 Iron. — Haematite, but not in workable quantity, has been found on 
 the PonnelBurn at the north-west corner of the Map, also on the northern 
 slope of TewsgiU to the east of Abington. It occurs also among other 
 ores in the veins of the Leadhills and Wanlockhead tract. The most 
 valuable ores of iron are the black-band ironstone of Lugar, Muirkirk, 
 and Glespin, and the ordinary clay-band ironstones of Muirkirk. The 
 position of these beds is shown in the section already given (par. 63), 
 and also on the Map. 
 
 Antimony. — A rich vein of antimonite, or sulphuret of antimony, was 
 formerly worked on part of the Knipes granite at a place called Hare 
 Hill, to the south-east of New Cumnock. Owing to the death of the 
 proprietor, the workings have been discontinued, but many tons of the 
 ore are still to be found near the mouth of the old mine. Small quan- 
 tities of antimony are also met with in the mineral veins of the Leadhills 
 tract. 
 
 Manganese.— r-On the old Sanquhar road, about a mile north-east from 
 Wardlaw Hill, a vein of barytes occurs, containing small quantities of 
 finely mammillated pyrolusite. The same ore is met with also in the veins 
 of Leadhills and Wanlockhead. 
 
 Zinc. — ' Black Jack,' or sulphuret of zinc, is a common constituent 
 of the galena veins, and occurs there sometimes in considerable quantity. 
 
 Copper. — Copper-pyrites is likewise an occasional constituent of the 
 Leadhills and Wanlockhead mineral veins. 
 
 Silver. — The galena of Wanlockhead is sufficiently argentiferous to 
 allow of the extraction of the silver with profit. 
 
 Gold. — ^For more than three centuries gold has been collected in small 
 quantities from the alluvia of the streams in the Leadhills and Wanlock- 
 head district. 
 
 Barytes. — In this place may be mentioned the existence of a barytes 
 vein, which is in many places fifteen feet thick, and may be traced from near 
 the head of Gass Water for two miles in a north-westerly direction as far 
 as Knockbreck. Another barytes vein, about three feet thick, sometimes 
 containing haematite, occurs on the flank of Auchensaugh Hill, lying to 
 the east of the Douglas coal-field. 
 
 112. Fuel. — Except peat, no fuel exists in the Silurian or Old Red 
 Sandstone districts. The carboniferous tracts, however, furnish the coals 
 of the Muirkirk, Cumnock, Glespin, and Sanquhar coal-fields, which have 
 been already referred to. In some of these fields the shales are suffi- 
 ciently bituminous to be capable of being used for the manufacture of 
 paraffin oil. 
 
MUEEAY AND OIBB, EDINBURGH, 
 PKINTEliS TO HEE MAJESTY'S STATIONERY OFFICE. 
 
V -Geological Memoirs, to accompany the Sheets of the One-inch 
 
 Sheet 7. Ayrshire, South-Western District. 3d. 
 
 „ 13. Ayrshire, Tumberry Point. 3d. 
 
 „ 14. Ayrshire, Southern District. 3d. 
 
 „ 15. Dumfriesshire, N.W.,; Ayrshire, S.E. ; and Lanarkshire, S. 
 corner. 3d 
 
 „ 22. Ayrshire, Northern District, and Southern parts of Renfrew- 
 shire. 3d. [Nearly ready']. 
 
 „ ,24. Peeblesshire. 3d. 
 
 „ 32. Edinburghshire and Linlithgowshire. 4s. In cloth boards, 5s. 
 
 „ 33. Haddingtonshire. 2s. 
 
 „ 34. Eastern Berwickshire. 2s. 
 
 A Detailed Catalogue may he had gratis, on aj:plication to Messrs. W. ^ A. K. 
 Johnston, 4 St. Andrew Square, Edinburgh, or to Messrs. Smith Sr Son, St. Vincent 
 Street, Glasgow. 
 
 Agents appointed for the Sale of the Publications of the Geological Snrrer. 
 
 London — ^Messrs. Letts & Son, Royal Exchange, E.G.; Messrs. Longman, Pater- 
 noster Row; Mr. Stanford, 6 Charing Cross, W.C; Mr. Wyld, 11 and 12 
 Charing Cross. 
 
 Edinburgh — ^Messrs. Johnston, 4 St Andrew Square. 
 
 Dublin — ^Messrs. Hodges & Smith, 104 Grafton Street, 
 
LIST OF PUBLICATIONS 
 
 OF THE. 
 
 GEOLOGICAL SURVEY OF SCOTLAND. 
 
 I.— Maps on One-inch Scale. 
 
 7._ Ayrshire,. South-Western Districts. 6s. 
 
 13. Ayrshire, Turnberry Point. 4^. 
 
 14. Ayrshire, Southern Districts.. 6s. 
 
 15. DumfriesshirejN.W.; Ayrshire,S.E.; and Lanarkshu-e, S. Corner. 6s. 
 22. Ayrshire^ Northern District, and Southern parts of Renfrewshire. 6s. 
 24. Peeblesshire. 6s. 
 
 32.' Edinburghshire and Ijinlithgowshire. 6s. 
 
 33. Haddingtonshire. 6s. 
 
 34. Eastern Berwickshire. - 4s. 
 40. Fife and Kinross. - 6s. 
 -41. Fife, East part. 6s. 
 
 II.— Maps on Six-inch Scale, illustrating the Coal-fields. 
 
 Edinburghshire. 
 
 Sheets 3, 8, 14, 17< 4s. 
 
 J) 
 
 Sheets 2, 6, 7,12, 13, 18. 6s. 
 
 HaddingtonsMrp. 
 
 Sheets 8, 13. 4s. 
 
 1) 
 
 Sheets 9, 14. 6s. 
 
 Fife. 
 
 Sheets 33, 37. 4s. 
 
 ?1 
 
 Sheets 24, 25, 30, 31, 32, 35, 36. 6s. 
 
 Ayrshire. 
 
 Sheets 26, 31. 4s. ' 
 
 ?? 
 
 Sheets 12, 13, 16, 18, 19, 23, 24, 27, 28, 29, 30, 
 
 
 33, 34,35, 36, 40, 41, 42, 46, 47, 50, 52. 6s. 
 
 Renfrewshire. 
 
 Sheets 13, 17. 4s. 
 
 9? 
 
 Sheet 16. 6s. 
 
 Lanarkshire. 
 
 Sheets 1, 5. 4s. 
 
 ^1 
 
 Sheets 31, 32. 6s. 
 
 Dumfriesshire. 
 
 Sheet 1. 4s. 
 
 31 
 
 Sheets 5, 6, 7. 6s. 
 
 DumbartOHshire. 
 
 Sheet 28 including 29. 4s. 
 
 III.— Horizontal Sections. 5s. per Sheet. 
 
 Sheet 1. Edinburghshire and Haddingtonshire. 
 „ 2. Edinburghshire and Haddingtonshire. 
 „ 3. Peeblesshire, Edinburghshire, Linlithgowshire. 
 „ 4. Ayrshire Coal-fields (west side). 
 „ "^ 5. Ayrshire Coal-fields (east side). 
 
 IV.— Vertical Sections. 3s. 6d. per Sheet. 
 Sheet 1. Edinburgh Coal-field. 
 „ 3. Kilmarnock Coal-field. 
 
 [List of Publications continued on page 3 of cover.