' S64 
 
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Cornell University Library 
 QE 81.S64 
 
 Sketch of the geology of Alabama / 
 
 3 1924 004 885 558 
 
 ENQN. JUN2819II 
 
 CORNEa UNIViMfft 
 ITHACA, N. y. 14111 
 
 iMff 
 
SKETCH 
 
 Geology of Alabama. 
 
 By EUGENE ALLEN- SMITH, Ph. D. 
 
 State Geologist. 
 
 1892, 
 
LIBRARY OF THE 
 
 PRESENTED BY 
 
 
SKETCH 
 
 Geology of Alabama. 
 
 By EUGENE ALLEN SMITH, Ph. D., 
 
 State Geologist. 
 
 The five great divisions, based upon the peculiarities of the 
 organic life of each, into which, according to Professor Gekiei, 
 the geological record has been classified are: (1) the Archaean, 
 sometimes called the Azoic (lifeless) or Eozoic (dawn of life) ; 
 (2) the Paleozoic (ancient life) or Primary; (3) the Mesozoic 
 (middle life) or Secondary ; (4) the Cenozoic (recent life) or 
 Tertiary, and (5) the Post-Tertiary or Quaternary. 
 
 The following table shows the order^'of succession of the 
 stratified formations of Alabama, together with the position in 
 the geological column of those formations either wanting or 
 not yet recognized as occurring in the, State: 
 
GEOLOGY OF ALABAMA. 
 
 TABLE OF GEOLOGICAL FORMATIONS. 
 
 TT 
 
 aSnS 
 ■< n Q 
 
 Recent 
 
 Pleistocene. 
 
 . . Soils and alluvium . 
 
 f Hiloxi or coast formations. ^ 
 { River terraces (second bottoms). 
 (Ozark sands. 
 
 Pliocene (?). 
 Miocene.. . 
 
 o 
 
 K 
 
 m 
 o 
 
 Eocene . 
 
 .Lafayette sands and pebble beds. 
 .Pascagoula and Grand Gulf formations. 
 
 Ji^l^ir^}-Mte limestone. 
 
 Claiborne. 
 
 Buhrstone. 
 
 Hatchetiebee. 
 
 Bashi or Wood's bluff. 
 
 Tuscahoma. 
 
 Nanafalia. 
 i Naheola. 
 
 Suearnochee. 
 [ Clayton or Kutledge. 
 
 § = § 
 
 CO " 
 
 r Ripley. i 
 
 Cretaceous ] iStaw. "™*^"'"*- 
 
 [ Tuskaloosa. 
 
 Jurassic Wanting in .Allabama. 
 
 Triassic Wanting in Alabama. 
 
 Permian Wanting in Alabama. ' 
 
 f Coal Measures . 
 
 Carboniferous i (-Mountain limestone, ( i 
 
 I .Oxmoor sandstone {Sa 
 
 ( Sub-Carboniferous. .-{ and shale. (§" 
 
 St. Louis or Huntsville, 
 LLaiidjerdalo (Keokuk). 
 
 Devonian Black shale. 
 
 I Clinton or Red mountain, 
 Trenton or Pelham limestone. 
 Knox dolomite and chert. 
 
 ( Choecplocco or Montevallo shales, including the 
 
 Cambrian { Weisner quartzite. 
 
 ( Coosa sha:l«s. 
 
 Archaean Crystalline schists. 
 
 S 
 
 In giving the details concerning these formations, it will 
 be, for many reasons, most convenient to consider them in 
 historical order. 
 
GEOLOGY OF ALABAMA. 
 
 CRYSTALLINE SCHISTS. —ARCH/EAN. 
 
 These rocks occupy a somewhat triangular shaped area in 
 the eastern part of the State, bounded by a line running ap- 
 proximately as follows : From the Georgia line, near the north- 
 eastern corner of Cleburne county, southweslward through 
 Clay and Coosa into Chilton, and thence eastward through 
 Elmore, Tallapoosa, Macon and Lee to the Georgia line again, 
 about opposite Columbus. These rocks differ from the other 
 rocks of the State in being made up of distinct, often well 
 crystallized minerals, of which quartz, feldspars, micas, and 
 hornblende form the great mass of the rocks in question, while 
 subordinated to these, other minerals occur; either forming 
 rock varieties of limited distribution, or as ores of valuable 
 metals, as minerals of economic value, or otherwise of interest. 
 
 As before stated, the great mass of these crystalline rocks 
 are aggregates of the minerals, quartz, feldspar and mica, often 
 associated with hornblende. Of these the quartz and horn- 
 blende alone sometimes form great rock masses. Granite, 
 gneiss, mica schist, quartzite and hornblende schist, or slate, 
 are the most abundant of these rocks, while soapstones, or 
 steatites, and limestones, are of much more limited occurrence. 
 They are all disposed in beds of varying 'thickness, which are 
 seldom in horizontal position, but are usually tilted at some 
 considerable angle to the horizon, the dip or slope of these beds 
 being prevalently to the southeast, while the trend or strike of 
 their upturned edges is, as a rule, to the northeast and south- 
 west. In crossing this country from the northwest to the 
 southeast, it can not fail to strike the observer that, as he ap- 
 proaches the southeastern border, he has evidences of con- 
 stantly increasing amount of decay among the rocks. Along; 
 this southeastern border they are often nothing more than 
 stratified clays, which are the result of their decay from the 
 action of the atmospheric forces. This decay often reaches to 
 a depth of fifteen or twenty feet from the surface, as may be 
 seen in many of the railroad cuts. Iri these clays, ledges or 
 thin sheets of quartz, which is practically unaffected by the 
 weather, may be seen protruding ; or broken down by alterna- 
 
GEOLOGY Off ALABAMA. 
 
 tions of heat and cold, they cover the ground with angular 
 fragments, that in process of time are worn into the rounded 
 pebbles that are so widely distributed over the rest of the 
 State. The conclusion seems unavoidable, that the southeast- 
 ern part of these crystalline rocks is older, or has been longer 
 subjected to sub-serial decay, than the parts further to the 
 jQorthwest. 
 
 The Crystalline Schists, or Archaean Rocks, have, in other 
 ■parts of the United States, been arranged in two series, called 
 Huronian and Laurentian, the latter being the older of the two 
 and presumably the oldest rocks of which we have any knowl- 
 edge. By some geologists these are considered as older than 
 any of the stratified fossiliferous rocks, while by others they, 
 as well as the Huronian, are thought to be the altered and 
 •crystallized sediments of the Cambrian, Silurian,, and perhaps 
 later ages. 
 
 Without attempting to decide any of these matters for. 
 Alabama, we may again recur to the fact that the rocks near 
 the eastern border of this region appear to be much older, or 
 at least to have been very much longer exposed to the disinte- 
 grating action of the atmosphere than those towards the west, 
 or northwest, and it is almost certain that some of the rocks 
 along this northwestern border are nothing more than the 
 Choccolocco or Montevallo shales and the Weisner quartzite 
 metamorphosed, or changed to crystalline schists. 
 
 Materials of Economic Value. — The granites and gneisses 
 above named are used in some slight degree as building stones, 
 and deserve more attention than they have received from quar- 
 rymen. The same rocks, especially the granites, which are 
 found chiefly along a belt running northeast from near Brad- 
 ford, in Coosa county, are also largely used for the manufacture 
 of millstones. 
 
 Marbles and Dolomites. — Near Talladega and Sylacauga 
 occurs a bed of good crystalline marble that has been worked 
 at a number of localities, and has yielded some fine material. 
 In Lee county, near Opelika, there is a crystalline dolomite 
 which is white, and would make a fine ornamental and build- 
 ing stone, hardly to be distinguished from marble. This sub- 
 stance has for years supplied the Chewacla lime works and 
 gives a lime of very superior quality. 
 
GEOLOGY OF ALABAMA. 
 
 Soapstone or Steatite. — This rock is found in several parallel 
 belts running northeastward from the Coosa river. It has been 
 quarried in Chambers, county for the manufacture of mon- 
 uments, headstones, and the like, and for furnishing flre-proof" 
 lining to the Chewacla lime kilns, for which purpose it answers- 
 admirably. 
 
 Porcelain Clay. — The decomposition of the feldspar of 
 granites, and other rocks, gives rise to the formation of clays- 
 whicli, when not mixed with other substances, are suitable fox' 
 the manufacture of porcelain and fine wai^e. The best known 
 occurrences of this clay are near Louina, Randolph county, and 
 near Socapatoy, in Coosa, and Notasulga, in Macon. 
 
 Glass Sand. — There are some friable white sandstones in 
 Chilton county that crumble readily between the fingers, which, 
 with proper selection, would furnish pure silica fit for the 
 manufacture of glass. 
 
 Asbestos. — This substance occurs at various localities in 
 Coosa, Tallapoosa and Chambers counties, near the deposits of 
 corundum, below to be noticed. Nothing has yet been done 
 toward the development of these beds, and it is not known that 
 they exist in sufficient quantity to be of value. 
 
 Mica. — In some of the mica schists and gneisses, especially 
 in the northwestern part of the region of the crystalline rocks 
 there are veins filled with large crystaUized masses of quartz, 
 feldspar and mica, and it is these masses of mica that furnish 
 the mineral in quantity. We have as yet no regular works 
 among the mica veins, but enough has been done to show that 
 mica plates of very good size can be gotten in many places. 
 The ancient excavations that are found along the belt of coun- 
 try from Chilton to Cleburne county, mark the spots where 
 mica has been mined in the past, and the experience of the 
 mica miners in North Carolina goes to show that the best mica 
 is, usually to be found by reopening these old mines. 
 
 Corundum — Has been found in considerable quantity near 
 Dudleyville, in Tallapoosa county, and also near Bradford, in 
 Coosa cojinty. That in Coosa is usually very much altered, 
 and it would be probably difficult to use it because of the 
 alteration which it has suffered. The Tallapoosa corundum 
 is, so far as yet known, in fragments, the solid bed having 
 never been uncovered. 
 
6 GEOLOGY OF ALABAMA. 
 
 Zircon — Has been found near Bradford, in Coosa county, 
 nearly transparent and well crystallized. The best specimens 
 of this- mineral are sometimes used as gems. 
 
 Graphite— Is widely disseminated in small quantities in 
 many of the crystalline rocks, sometimes impregnating alum- 
 inous slates to such an extent as to render them suitable for 
 lubricating purposes. Some very fine seams of graphite have 
 recently been found near Enitachopka, in Clay county, and it 
 is probable that it will be found in other counties in suifioient 
 quantity and of sufficient purity to be valuable. 
 
 Gold. — Most of the gravels and sands of this region have 
 in the past been profitably worked for gold. Arbacoochee, 
 Chulifinnee, Pinetucky ahd Goldville are well known localities. 
 For many years, however, this kind of work has ceased, and 
 so has the working up of the quartz in stamp mills. There is 
 reason for thinking that, with the new processes for the 
 extraction of gold from low grade ores, many of our ores can 
 yet be worked with profit. The geological survey is at 
 present engaged in the investigation of these processes in 
 connection with the Alabama gold ores.* 
 
 Copper. — The history of the copper mining in Alabama is 
 similar to that of gold. Some years ago a good deal of money 
 was invested in a copper mine in Cleburne county, and the 
 works flourished until the rich surface ore was, used up. The 
 mundic or main body of the vein, containing only a' small 
 percentage of copper, could not be profitably smelted, on 
 account of distance from lines of transportation, etc., and 
 work there has been suspended for a number of years. Cop- 
 per is known to occur in very many localities in this region, 
 but the mine above named is the only one where any system- 
 atic work has been done of late years. 
 
 Manganese. — Although manganese is very extensively dis- 
 tributed through this region, no large deposits of it have yet 
 been found. 
 
 Iron Ores. — The important iron ore of the crystalline rocks 
 is magnetite, and it has been found in most of the counties of 
 this region of the State, but not, so far, in great quantity, 
 although search has been very persistently made for it. Good 
 
 * A bulletin (No. 4) on the lower portion of the gold region has been published 
 since the above was in manuscript. 
 
GEOLOGY OF ALABAMA. 
 
 sized fragments of magnetite, indicating a bed of considerable 
 thickness, have, been found in Cleburne, Clay, Randolph, Cham- 
 bers and Tallapoosa counties. In Talladega county there is a 
 sandstone impregnated with magnetite to such a degree as 
 almost to make it a workable ore of iron. 
 
 Jlemutite or Specular Ore— Is, also common in many of the 
 rocks of this region, but no large beds of it are yet known. 
 
 Limoiiite — Is also abundant in many cases as "gossan," 
 i. e., the result of the decomposition of pyritous ores. Some 
 of the limonite, however, which was once used in the old 
 Catalan forges appears to be of a different kind. In all the 
 region where the rocks are partly or entirely composed of 
 hornblende, these iron ores of various kinds are more or less 
 abundant. 
 
 Pi/rite. — Extensive beds of iron pyrite or pyrites are known 
 in Clay county, of this State, but have not yet been worked. 
 Most of the copper ore of the State is pyrite with a certain 
 percentage of copper. In concentrating these ores, the sul- 
 phur of the pyrite is allowed to go to waste. In the English 
 works, this is utilized, ,in manufacturing sulphuric acid, the 
 profit upon which alone pays well, whilst the copper and also 
 the iron are pure gain. With capital suflBcient to provide for 
 manufacturing sulphuric acid, copper works will be made to 
 pay a much greater profit than they do now. In view of the 
 recent discoveries of phosphate in Florida, it might be well to 
 take into consideration the possibilities of our pyrite beds as 
 furnishing material for the manufacture of. sulphuric acid, 
 used in the production of super-phosphates. 
 
 Rutile or Titanic Acid — Is a mineral of very general 
 occurrence. Good specimens have come from Coosa and Chil- 
 ton counties. Its uses in the arts are limited, but its value as 
 a cabinet specimen, well crystallized, will command a ready 
 
 Tantalite. — This rare mineral has been found for the first 
 time in this State, in Coosa county, near Rockford. The anal- 
 ysis of it, by. J. Lawrence Smith, of Louisville, Kentucky, was 
 published in the first edition of this book. 
 
 Beryl. — This mineral has been obtained from Coosa county 
 in .crystals, which have yielded very handsome gems when cut. 
 
GEOLOGY OF ALABAMA. 
 
 PALEOZOIC FORMATIONS. 
 
 Classification and Lithological Characters.— The geolog- 
 ical formations of the above list, from Carboniferous to the 
 Cambrian inclusive, have been grouped together in one divis- 
 ion, called Paleozbic (ancient life), in allusion to the want of 
 resemblance to the present existing forms of the animal and 
 plant remains contained in them. 
 
 In the following account of the distinguishing characters 
 of the rocks of Qach of the great groups of formations — Cam- 
 brian, Silurian, Devonian and Carboniferous, which constitute 
 the Paleozoic — we shall follow pretty closely what has already 
 been printed in the report on the Cahaba coal fields. 
 
 The Cambrian. — The rocks of this formation are con- 
 glomerates, sandstones and shales in the Coosa valley region, 
 and shales and shaly limestone in the valleys further west, the 
 maximum thickness of the whole being put at 10,000 feet; but 
 this great thickness is seen only in ^e eastern part of the 
 Coosa valley. In the other valleys the thickness is less than 
 half of the above. 
 
 The subdivisions of the Canibj-ian which we recognize in 
 Alabama are as follows : The Coosa shales, the Choccolocco or 
 Montevallo shales, and, interbedded with the last named, the 
 Weisner quartzite. These subdivisions are based rather upon 
 the lithological characters than upon the chronological succes- 
 sion, which cannot at this time be given with certainty, for the 
 calcareous shales, which we class with the Coosa, have recently 
 been found to contain upper Cambrian fossils, while some of 
 the shales of the Montevallo type have yielded lower Cambrian 
 fossils. On the other hand, some of the Montevallo type of 
 shales may be seen in places immediately underlying the 
 strata of the Knox dolomite, while in other places the Coosa 
 or flatwoods type of shale has apparently the same position. 
 It is very probable that the difference in the composition of 
 the Cambrian shales — i. e., whether calcareous or sandy:^-is 
 due to the geographical and other conditions existing during 
 their time of deposition, and that both kinds were formed 
 contemporaneously — a part near the shore line ; a part further 
 
GEOLOGY OF ALABAMA. 
 
 out to sea. In certain parts of the Coosa valley, where both 
 types of shales occur together, the calcareous shales of the 
 Coosa type appear very generally to underlie those of the 
 siliceous or Montevallo'type. 
 
 Coosa iShales. — In the valleys above meiitioned, the rocks 
 of this division are thin bedded limestone, with clay seams 
 between — usually very greatly contorted and tilted at high 
 angles. Where these rocks come to the surface, there results 
 from their decomposition a very stiff calcareous clay soil. 
 These lands being very level, and hence very badly drained, 
 are not much'cultivated in Alabama, and are generally known 
 as"flatwoods." The shaly limestones that give rise to these 
 flatwoods we have called Coosa shales. 
 
 Montevallo IShales. — In the Coosa valley, and especially in 
 its eastern parts, and in the southwestern part of the Cahaba 
 valley, towards Helena and Montevallo, we find a considerable 
 thickness of siliceous or sandy shales of great variety of colors, 
 such as olive green, chocolate, yellowish, etc. The original 
 material was a calcareous matter has mostly been pretty 
 thoroughly leached out, and only the more siliceous parts left. 
 These shales crumble up in places to small fragments about 
 the size and shape of shoe pegs. Sometimes they are more 
 tough, and, especially towards the east, assume gradually the 
 characters of the semi-crystalline rocks, and it is capable of 
 demonstration that some of the partly crystalline slates of the 
 eastern part of the Coosa valley are only the changed or meta- 
 morphosed representatives of this division, which has been 
 called the Montevallo or Choccolocco shales, from the character- 
 istic occurrences in those localities. In the upper part of the 
 Montevallo shales we find beds of blue limestone and gray 
 dolomite, which it is often difficult to distinguish from the 
 similar rocks occurring in the next overlying the formation. 
 In fact, the line between the shales e^d. the Knox dolomite is, 
 so far as Alabama is copcerned, rather an arbitrary one. 
 
 Weisjier Quartzite. — In the shales just described, and most 
 commonly in their lower parts, are found in the eastern part 
 of the Coosa valley great beds of quartzite and conglomerate, 
 many hundred feet in thickness, but often of very limited ex- 
 tent geographically. The quartzite always forms high and 
 rugged mountains, sometimes stretching for miles in an un- 
 
10 GEOLOGY OF ALABAMA. 
 
 broken range, but as often forming detached and isolated peaks 
 rising suddenly out of the plains and as suddenly sinking down 
 to the same level. The "mountain" near Columbiana, the 
 Kahatchee hills, Alpine mountain. Mount Parnassus, at Talla- 
 dega, Coldwater mountain and Blue mountain, near Anniston, 
 the Ladiga mountain, above Jacksonville, and the Weisner 
 mountain, east of Jacksonville, are instances of occurrences of 
 this quartzite. The Weisner mountain has been most studied, 
 and its stratigraphical relation to the Coosa shales, and to the 
 Choccolocco shales, most clearly made out, for which reason we 
 hav6 used the term — Weisner quartzite — to designate this 
 member of our Cambrian, which occurs interpolated in the 
 shales, as local masses of lenticular shape, often of very great 
 thickness. 
 
 Prof. Safford, of Tennessee, has given the name Chilhowee 
 to similar great masses of sandstone and quartzite occurring in 
 that State, apparently below the shales above named. Prof. 
 Safford places these sandstones always below the shales, but 
 this does not seem to be their position in Alabama, as the 
 masses of sandstone occur at different horizons, interbedded 
 with the shales. For this reason we have not used Prof. Saf- 
 ford's name to designate the rock. Similarly, it appears neces- 
 sary to adopt a distinct name for the thin-bedded limestones 
 with clay seams, of our " flatwoods," since they play a very 
 subordinate part, if they occur at all in Tennessee. In general 
 the Choccolocco and Coosa shales, as above defined, are partly, 
 at least, the equivalents of the Knox sandstone and shale of 
 Tennessee, but apparent important differences in the strati- 
 graphy of these beds, in the two States, make it impossible as 
 yet to correlate them strictly, hence our adoption, provisionally 
 at least, of different names. 
 
 The Silurian. — We have not yet, in Alabama, found it 
 practicable to arrange our Silurian formation in more than 
 three principal divisions, which, beginning at the lowest, and 
 coming upward, are as follows : Knox dolomite, Trenton or 
 Pelharn limestone, and Red Mountain or Clinton. 
 
 Knox Dolomite. — This name has been given by Dr. Safford 
 to a series of rocks occurring in the vicinity of Knoxville, Ten- 
 nessee, and inasmuch as the rocks of this horizon in Alabama 
 are identical with those described by him, we have retained 
 
GEOLOGY OF ALABAMA. H 
 
 the name in the Alabama survey. This is one of the most im- 
 portant and widely spread of our older geological formations, 
 and its .characteristic rocks are magnesian limestones, or dolo- 
 mites, sometimes quite pure, but more often impregnated with 
 siliceous matter. This siliceous matter is sometimes found as 
 -a sandy impurity in some of the dolomites, upon the weather- 
 ing of which it becomes quite prominent. For this reason 
 many of the dolomite beds of the lower part of the Knox dolo- 
 mite, when exposed to the weather, show a rough and sandy 
 surface, marked by shallow cracks running in every direction, 
 as if the "rock had been hacked or gashed by some cutting in- 
 strument. These purer and sandy dolomites, together with 
 some beds of tolerably pure blue limestone, occur near the base 
 of the Knox dolomite, and are very closely related to the beds 
 of the shale division already described.* On the other hand, 
 the siliceous matter in the upper part of the formation is usu- 
 ally found in masses of chert, of concretionary origin, impreg- 
 nai^ting the dolomite, and on the breaking down of these rocks, 
 under the action of the weather, the calcareous parts are 
 leached out, while the siliceous parts usually remain in the 
 form of angular, flinty gravel, which forms the very character- 
 istic ridges of Knox dolomite. The weathering of the lime- 
 stones and the dolomites, near the base of this division, has 
 given rise to the formation of gently undulating terranes, with 
 a deep red-colored sandy loam soil, of more than average fer- 
 tility, which is the base of the best farming lands in all these 
 valleys. The red lands about Elyton, and in parts of Birming- 
 ham, and in the Alexandria valley, across the Coosa, are good 
 examples. In the upper part of the dolomite the cherty, or 
 siliceous matter, is more abundant as a surface material than 
 the calcareous, and the country is broken or ridgy, rather than 
 undula'ting. Some of these flint ridges extend for long dis- 
 tances unbroken. Good examples are the ridges of the north 
 and south highlands about Birmingham. In fact, this angular, 
 cherty gravel is found upon all the lands made by the Knox 
 dolomite, but is much more abundant and characteristic in the 
 upper part. The Knox dolomite contains very few fossils, and 
 these belong to the lower Silurian horizon of the paleontolo- 
 
 * Recent investigation appears to show that part of tliese limestone beds belong, 
 in all probability, to the Cambrian formation. 
 
12 GEOLOGY OF ALABAMA. 
 
 gists, but we have in the chert itself a characteristic by which 
 we can, as a rule, distinguish it from the chert of other forma- 
 tions — that is, in most of it are small, angular cavities of 
 clearly defined shape, which are usually thought to mark the 
 place once occupied by rhombohedral crystals of dolomite, sub- 
 sequently dissolved out. Prof. Saft'ord was the first to call 
 attention to this mark, which we have found to be an extremely 
 useful one.* The Knox dolomite, as well as the upper, part of 
 the underlying formation, seems to have held originally much 
 ferruginous as well as siliceous matter, and throughout the. 
 region formed both by the doloihite and the upper part of the 
 shale, occur the beds of the brown iron ore, or limonite, which 
 play so important a part in the economic history. of all this 
 region. The iron ore seems to have been derived from these 
 older rocks. As instances of the occurrence of limonite banks 
 connected with the dolomite and shale, I may mention the Ed- 
 wards ore bank, near Woodstock, the mines at Greely and 
 Goethite, in Jones valley, and the great beds at Shelby, over 
 the Coosa. The great bulk of the brown iron ores of Alabama 
 is from this horizon. 
 
 At the top of the Knox dolomite, and belonging perhaps to 
 the next succeeding division, there is rather a peculiar rock 
 occurring at intervals along Jones valley and elsewhere. It is 
 a breccia, made up of angular fragments, chiefly of the chert of 
 the Knox dolomite, cemented together into a rock which is a 
 good many feet in thickness. This rock, being made of frag- 
 ments of the Knox dolomite, is,, of course, younger, though, on 
 account of its materials, we have usually classed it along with 
 the Knox dolomite. It is seen in the greatest volume in the 
 Salem hills, southwest of Bessemer, but occurs upon the flint 
 ridge forming the north highlands at many points, e. g., Bir- 
 mingham and Gate City, and also west of Springville. ' It has 
 been called the Birmingham breccia by Mr. Russell of the 
 United States survey, and Salem breccia by us in the State 
 survey. It is of interest as showing that a period of disturb- 
 ance intervened between the time of the formation of the 
 Knox dolomite and that of the Trenton limestone. 
 
 Trenton or Pelham J^imestone. — As its name implies, this 
 
 » Similar angular cavities have recently been observed in tlie dust of other form 
 ations, so that this is not an altogether characteristic mark of the dolomite. 
 
GEOLOGY OF ALABAMA. ^ 13 
 
 division is mostly calcureous. It may be perhaps, as a maxi- 
 mum, 800 feet in thickness, and varies considerably in quality, 
 the lower part being usually impure and shaly, while the 
 upper part is mostly a pure limestone, often used for the pur- 
 pose of making lime and as a flux in the furnaces. The lower 
 part usually holds great numbers of shells of Madnrea magna, 
 a characteristic fossil of the Chazy limestorie of the New York 
 geologists. The purer limestone above is also quite full of 
 fossils, which, as a group, are those of the Trenton limestone 
 of New York. 
 
 In places, particularly in the region south of the Cahaba 
 field in Bibb county, the uppermost beds of this formation, 
 above the purer limestone mentioned, are calcareous shales 
 and shaly limestones, often full of the fossil forms known as 
 graptolites. Where these thin bedded shaly limestones form 
 the surface they make cedar glades. 
 
 The valley between the Cahaba and Coosa coal fields 
 shows a wide belt of Trenton limestone, which is particularly 
 pure and well developed near Pelham and Siluria, in Shelby 
 county, and southwards. Near Pratt's ferry, on the Cahaba, 
 and, stretching thence northeastward, there is another great 
 belt of it, containing some fine marbles, which have, in a small 
 degree, been worked at Pratt's ferry. 
 
 The Clinton or Red Mountain Formation. — This is the 
 third and uppermost of the divisions of the Silurian which we 
 make in this State. The mass of the rocks of Red mountain 
 are sandstones and shaleS, which show a great variety of color, 
 yellow, red, brown, chocolate and olive green, in this respect 
 resembling the Montevallo shales. Along with these are some 
 calcareous and ferruginous rocks, the latter passing into beds 
 of red iron ore, made up of small fiattened nodules, shell casts, 
 etc., of ferric oxide. In many places where mining has pene- 
 trated the ore bed beyond the reach of atmospheric agencies, 
 the ore is seen to be quite calcareous ; in fact, a kind of highly 
 ferruginous limestone, which, when used in the furnace, often 
 contains lime enough to fiux itself. At the outcrop the ore is 
 seldom calcareous, though often sandy. So far as I know, 
 there has been no very satisfactory explanation of the mode 
 of formation of this ore. It is of a very variable thickness, up 
 to twenty feet, and is in more than one bed. It is a remark- 
 
ii GE0LO9Y OF ALABAMA. 
 
 able fact that, while near Oxmoor the ore is some twenty feet 
 in thickness, just across the Cahaba coal field, in the Cahaba 
 valley, about six miles distant, the Red mountain, or, rather, 
 , its representative, contains no ore at all in the greater part of 
 its length, nor does it seem, except at intervals, to contain any 
 of the Clinton rocks, but only those of the Devonian and sub- 
 carboniferous. As is well known, this formation furnishes 
 the greater part of the material used in our furnaces. In 
 places, the ferruginous limestone of this formation wbuld 
 make a fine building stone, and the same is trhe of the sand- 
 stones. It would be diflBcult to give the average thickness of 
 the Red mountain rocks proper; 100 feet might perhaps be a 
 fair average, for t he Red mountain, as a topographic featuj-e, 
 is made of the rocks of, difl:'erent ages — Trenton, Clinton and 
 sub-carboniferous, together with the usually very thin black 
 shale of the Devonian. 
 
 The thickness of the whole Silurian, as usually given at 
 about 5,000 feet, is only an estimate. The true thickness it 
 would be very difficult to determine, especially in the case of 
 the most important member, the Knox dolomite, since it, is in 
 great part made up, so far as surface materials are concerned, 
 of loose fragments of chert in which the bedding planes are 
 seldom to- be seen. A greater part of the area of our valleys 
 is held by this formation than by any other, and its impor- 
 tance is still further enhanced by the fact that it is the chief 
 source of the brown iron ores of the State. Many of the 
 noted " big springs " issue from this formation. , 
 
 The Devonian.— The only representative in Alabama of 
 this system of rocks, which in the States further north is of 
 great thickness and importance, is a thin bed of black shale, 
 averaging perhaps ten or fifteen feet, but being apparently 
 absent altogether in some places. A few fossils have been 
 found in it in the valley of the Tennessee in North Alabama, 
 which serve to fix its position as a member of the Devonian. 
 The shale, being soft and somewhat easily eroded, is usually 
 covered and concealed by the debris of the adjacent rocks, so 
 that it does not commonly come under notice even where it is 
 present. It is of importance chiefly, perhaps, as being the 
 source of some of our best known sulphur springs. The shale 
 usually contains a large amount of pyrite in the form of 
 
GEOLOGY OF ALABAMA. 15 
 
 nodules or kidney shaped concretions, the decomposition of 
 which supplies the sulphur of these springs. In north Ala- 
 bama the thickness of the black shale, as tjiis formation has 
 been called, may go up as high as 100 feet, but so extreme a 
 thickness is rarely seen further south.' 
 
 The Carboniferous. — This we conveniently divide in 
 Alabama into two parts — a lower, or sub-carboniferous, and 
 an upper, or coal bearing part, the true coal measures. The 
 thickness of t^e latter is placed by Mr. Squire at 5,525 feet, 
 and the former at 1,200 feet, making a total of between 6,000 
 and 7,000 feet. 
 
 Suh-Carbonijerfus. — Professor Safford divides this forma- 
 tion in Tennessee into an upper or calcareous member, and a 
 lower or siliceous one. This division will also apply equally 
 well to that part of Alabama north of the Tennessee river, 
 but to the south, and everywhere in the narrow anticlinal 
 valleys of the State, this distinction cannot well be made. 
 
 In the Tennessee valley the siliceous member of the sub- 
 carboniferous consists of a great series of cherty limestones 
 somewhat analogous to the Knox dolomite, but with the lower 
 part more cherty than the upper. This lo,wer part (lower 
 siliceous of Professor Safford ; probably the Keokuk of the 
 western geologists) gives rise to rather poor siliceous soils, 
 and the region of its occurrence, both in Alabama and Ten- 
 nessee, is known as the "barrens." The upper part of the 
 siliceous member (upper siliceous of Safford ; St. Louis group 
 of the western geologists) is more calcareous, and the soil 
 derived from its disintegration is a red loam of more than 
 ordinary fertility, well known in the Tennessee valley as 
 making the best farming lands in that section. Here again 
 there is an analogy to the Knox dolomite, which affords,- on 
 the one hand, rich, red loam soils and, on the other, poor, 
 cherty ridges. 
 
 The chert of the sub-carboniferous is in general very 
 similar to that of the Knox dolomite, but differs from it 
 in being usually very highly fossiliferous, containing the 
 casts or moulds of shells that have been leached or dis 
 solved out. 
 
 This character of the sub-carboniferous chert and the 
 presence of the rhombohedral cavities in the chert of the 
 
I 6 GEOLOGY OF ALABAMA. 
 
 Knox dolomite enable us in almost every case to distinguish 
 between the two. 
 
 Now, in the anticlinal valleys south of the Tennessee river 
 we find it impossible to carry out this two-fold division of the 
 lower or siliceous member of the sub-carboniferous, for the 
 entire member shows, upon the surface at least, little else than 
 chert, which appears in a mantle of angular fragments, cover- 
 ing usually one side of all our Red mountain ridges. 
 
 We fiave called this the I^ort Payne c/iert, and it is prob- 
 ably the representative of both sub-divisions of the lower 
 sub-carboniferous or siliceous group of north Alabama and 
 Tennessee, as long ago conjectured by Professor Safford. Its 
 thickness is not very great, as compared with that of the 
 upper member.* 
 
 The upper calcareous member is variable in composition. 
 In north Alabama it is chiefly limestone — called mountain 
 limestone, from the fact that it forms the flanks of rnost of the 
 mountains in that section that are capped with coal measures. 
 Within this limestone there is interbedded a layer of sand- 
 stone of variable thickness — perhaps 100 feet, at a maximum, 
 in the Tennessee valley, while the over and underlying lime- 
 stones are many times that. As we come southward the 
 sandstone becomes more important, and the lower section of 
 the limestone (below the sandstone) appears to give way to, or 
 to be replaced by, a series of black shales closely resembling 
 those of the Devonian, but many more , times massive. In 
 many places in the anticlinal valleys, and especially the further 
 south we go, the upper limestone also appears to be wanting 
 or to be replaced by the shales and sandstones above named. 
 
 The limestone which comes next below the coal measures 
 is well exposed at many places, as at Bangor, Blount Springs 
 and Trussville, where it is very extensively quarried for use 
 as a fluxing material in the furnaces, as it is in part a very 
 pure limestone. But south of the latitude of Birmingham it 
 is very rarely seen, and in its stead we find the black shales 
 mentioned. These shales are often interstratitied with dark 
 
 * In tlie anticlinal ralleys there may usually be seen between the Red mountain 
 ridges and the rim of the valley a narrow sub-valley with very good reddish loamy 
 soils, nearly always in cultivation. This soil may be in part derived from the rocks 
 of the St. Louis group of the siliceous, though possibly from the shales of the 
 Oxmoor horizon. We have found no fossils to determine this point. 
 
GEOLOGY OF ALABAMA. 17 
 
 colored limestones, and sometimes with tolerably pure lime- 
 stones, but these are unimportant in thickness as compared 
 with the shales and sandstones. The greater part of Shades 
 valley is based upon these sandstones and shales, though the 
 limestone appears in several places, and southwestward, be- 
 yond the end of the Cahaba coal field, these rocks make a very 
 prominent topographic feature. 
 
 The sandstone which in north Alabama lies between the 
 two beds of mountain limestone has a very close resemblance 
 in texture and other characters to the lowermost rocks of the 
 coal measures, commonly called the millstone grit, and it 
 makes its appearance in that part of the State either as a 
 bench along the sides of the Cumberland mountain spurs or 
 else as the capping and protecting rock of a detached ridge 
 separated from the Sand mountain (coal measures) by a 
 narrow valley of erosion. In the anticlinal valleys further 
 south, this sandstone with the lithological characters above 
 named appears commonly as a distinct ridge running parallel 
 to the escarpment of the coal measures, with a narrow valley 
 of shales between. It appears to best advantage on one of 
 the detached ridges above spoken of, near Tuscumbia, at the 
 site of the old college town of LaGrange, and we have often ' 
 used the name LaGrange sandstone to designate it; but the 
 name LaGrange has been used to denote an entirely different 
 formation, v/hich has caused us to replace it by the name 
 Oxmoor, where the rocks are also well exposed and where the 
 shales are more conspicuous than at LaGrange. 
 
 Coal Measures. — The strata of the coal measures are 
 sandstones, conglomerates, shales and coal beds in many alter- 
 nations, and at one horizon, at least, occurs a thin bedded 
 limestone. The thickness of the measures of the Cahaba coal 
 field is estimated by Mr. Squire to be 5,525 feet, and the esti- 
 mate for the Warrior field, by Mr. McCaliey, is about the 
 same. The conglomerates are found principally at the base of 
 the measures, though a very heavy bed of .this rock occurs also 
 at the top of the measures in Shelby and Tuskaloosa counties. 
 We have good reason for thinking that all our coal fields were 
 at one time continuous and have been separated by subsequent 
 changes into the three distinct fields — named by Prof. Tuomey 
 from the rivers which drain them — the Coosa, Cahaba and 
 
18 GEOLOGY OF ALABAMA. 
 
 Warrior &e\ds. We should expect to, find the. succession of 
 the coal searas and of other strata the same in all three fields, 
 and undoubtedly such a similarity or equivalency will one 
 day be thorougbly made out. At the present, however, our 
 knowledge of the fields is so limited that it is not possible to 
 correlate ' their ,seams fully, though some identifications' have 
 been very satisfactorily made. 
 
 In the reports of Messrs. Squire and McCalley on the 
 Cahaba and Warrior fields full particulars will be found con- 
 cerning these fields, and the reader is referred, to these reports 
 for information as to details. In the Warrior and Cahaba 
 fields there are about forty coal seams, of which twelve to 
 fourteen have a thickness of two and a half feet and upwards, 
 of coal, which can be profitably mined. Much of the coal, , 
 however, which is actually mined now comes from a much 
 smaller number of seams. In another place we shall give a 
 -few particulars concerning each of the three fields above 
 named. 
 
 GEOGRAPHICAL DISTRIBUTION IN ALABAMA OF 
 THE PALEOZOIC FORMATIONS. 
 
 It is a commonly received opinion among geologists, arid 
 one capable of demonstration, that the older stratified rocks of 
 the Appalachian region of the United States, of which the 
 Paleozoic rocks of Alabama form the southwestern termination, 
 are formed principally out of the detritus of a previously ex- 
 isting land area lying eastward of the present shore line of the 
 Atlantic ocean, washed down and deposited upon the floor of 
 the inland sea, which formerly occupied the greater part of 
 what is the present United States. Naturally, by far the 
 greater part of this land waste would be deposited close to the 
 shore line, while only the finer sediments, such as silt and 
 mud, would be held in suspension long enough to be carried 
 out and deposited at a distance from the shore. As a matter 
 of fact, in Alabama, in going from the northwest to the south- 
 east, across the region made by our Paleozoic rocks, we find a 
 
GEOLOGY OF ALABAMA. 19 
 
 gradual increase, not only in the thickness of the strata, but in 
 the coarseness of the material; heavy bedded sandstones and 
 conglomerates being much more abundant in the eastern part 
 of this area than farther west. The maximum thickness of the 
 Paleozoic rocks in Alabama, along their eastern border, is not 
 less thkn iJO,000 feet, but further westward it is probably not 
 much more than half this amount. After the deposition of the 
 Carboniferous strata, there followed movements of the earth's 
 crust by which all these Paleozoic deposits were elevated above 
 the sea, and pressed or squeezed laterally from southeast to 
 northwest into a much narrower space than they occupied 
 when spread out upon the floor of the sea. This compression 
 into narrower limits could ta-ke place either by the crushing 
 together laterally of the beds and their corresjponding swelling 
 up vertically ; or by the warping of the strata into more or 
 less closely folded waves or ^yrin-kles running at right angles 
 to the direction of the compressing force ; or by fracture along 
 the same line at right angles to the compressuig force, and the 
 sliding of one part of the strata over another. It is easy to 
 recognize in Alabama instances of all these results of compres- 
 sion ; for we find our Paleozoic rocks seldom in their ,original 
 position ; they are mostly tilted at high angles to the horizon ; 
 the same beds are repeated many times, and sometimes strata 
 are now found in juxtaposition which are many hundreds of 
 feet apart in the geological column. The direction of the dip 
 of these tilted beds is mostly towards the southeast, and the 
 amount of the tilting and deformation is greater in the same 
 direction, gradually diminishing in intensity as we go north- 
 west. After the uplifting, faulting and folding above indicated, 
 there began a gradual degradation of the strata by atmospheric 
 agencies. The places most elevated by these movements, or 
 most weakened by fracture, would suffer most by these means. 
 So we find, as a rule, the valleys now occupying what were 
 formerly the crests of the folds or waves of the strata, and it is 
 consequently in these valleys that we find exposed the lowest 
 or oldest rocks in the series, and the depth of the exposure 
 in proportion to the amount of the previous elevation. 
 
 In accordance with these general principles, we find that 
 the oldest of our Paleozoic rocks have their greatest develop- 
 ment as surface rocks along the eastern border of the region of 
 
20 GEOLOGY OF ALABAMA. 
 
 their occurrence, i. e., in the Coos^ valley region. Here also 
 we find the strata most disturbed and deformed, while the 
 rocks of- the Clinton, Devonian, or Carboniferous formations 
 occur sparingly in the Coosa valley, except along its western 
 limit. It is only to the westward of the Coosa valley that 
 these upper strata of the Paleozoic formations are widely 
 distributed. 
 
 The areas of our coal measures are separated by valleys, in 
 which the older rocks are exposed by denudation as above 
 described. All these valleys have what is called the anticlinal 
 structure, i- e., they have been eroded out of the crests of folds 
 in the strata ; but this structure is generally obscured by the 
 occurrence of faults where the beds on one side of the line of 
 fracture have been pushed up over on tjiose of the other. These 
 valleys are, in succession, going to the northwest : The Uahaba 
 valley, lying between the Coosa and the Cahaba coal fields ; 
 Wills' valley, between Lookout and Sand mountains ; Rowp's 
 and Jones' valley, between the Warrior and Cahaba coal fields; 
 Murphree's valley, which is a prolongation of Jones' valley and 
 separates two parts of Sand mountain ; and Brown's or Big 
 Spring valley, extending down from Tennessee, as a prolonga- 
 tion of the Sequatchee valley, separating likewise two parts of 
 the Warrior field. In the last-named valley, south of the Ten- 
 nessee river, the sub-carboniferous rocks form the greater part 
 of the surface, and the underlying and older rocks are exposed 
 only in isolated tracts. North of the river, the elevation of the 
 fold has been greater, and the consequent exposure, by erosion 
 of the valley, deeper. In the Tennessee valley likewise, the 
 sub-carboniferous rocks occupy the greater part of the surface. 
 Each of the valleys above enumerated has its peculiarities, but 
 to go into details would lead us too far. We may, however, 
 add a few words to what has already been said about the coal 
 fields. 
 
 Materials of Economic Value in the Paleozoic Region. 
 Goal. — The Alabama coal fields, occupying, as they do, the 
 troughs between "the folds or wave crests above mentioned, 
 are more or less basin-shaped, but the axis of the basin in each 
 case lies close to one side, usually the southeastern, instead of 
 being in the center, and the slope or dip of most of the strata 
 is consequently towards the southeast. In going from the north- 
 
GEOLOGY OF ALABAMA. 21 
 
 east toward the southwest, we find the strata of these fields 
 gradually sinking. Thus, on Sand mountain, near the Georgia 
 line, the base of the coal measures is six or seven hundred feet 
 above drainage level, especially along the elevated rim of the 
 basin, while at Tuskaloosa, the base of these measures lies 4,000 
 feet, or more, below drainage level. For convenience, we have 
 designated those parts of the coal fields which are high above 
 the, drainage level, as the plateau region, in contradistinction 
 to the basin region, where they are at or below drainage level. 
 This distinction applies mainly to the Warrior field and Look- 
 out mountain, the Cahaba and Coosa fields having measures 
 generally below the drainage level ; but a gradual southeast 
 sinking of the measures is very clearly seen in them also. 
 
 The Goosu Field. — This has less of what are called the flat 
 measures than either of the others. It has suft'ered most from 
 denudation, and has the least thickness of coal measures, and 
 consequently of coal seams; nevertheless, two or three seams 
 of workable size are known in the field, and mines are in opera- 
 tion in two or three localities — Broken Arrow, Ragland, Trout 
 Creek, etc. The rocks and coal seams in this field appear to 
 be more faulted than in the others. 
 
 The (Jahaba Field — This field has been recently thoi'oughly 
 described by Mr. Squire, and his report is accompanied by a 
 large and detailed map. It extends from Canoe creek, in St. 
 Clair county, to Haysop creek, in Bibb county, its form very 
 closely resembling the human foot and leg, Montevallo being 
 close to the heel, and the part repesenting the toe being on 
 Haysop creek, four or five miles west of Scottsville. The field 
 begins to widen at Helena, and opens out gradually as it con- 
 tinues southward until it attains a maximum width of fifteen 
 and a half miles, on a line due east and west from Blooton. The 
 length of the field on an air line is sixty miles, and its area 
 about 390 square miles. Mr. Squire describes eleven subordi- 
 nate basins in this field, besides the overturned measures at 
 the southern end of the field. In consequence of the gradual 
 dip of the basin as a whole toward the southwest, the greatest 
 thickness of the measures in this field is found in the south- 
 western end. Active mining is now going on at Blocton, Gur- 
 nee, Montevallo, Helena and Henry- Ellen, the seams worked 
 being: At Blocton, the Thompson, or Underwood, and the 
 
'2-2 GEOLOGY OF ALABAMA. 
 
 Woodstock seams ; at Gurnee, the Clark and Gholson seams ; 
 at Montevallo, the Montevallo seam ; at Helena, the Wadsworth 
 jind Helena seams ; at Henry- Ellen, the Mammoth seam. Mr. 
 Squire estimates that this field has eleven seams of coal over 
 two and a half feet in thickness, aggregating forty feet of 
 marketable coal. Coke is made in large quantity at Blocton 
 and other mines in this field. 
 
 Warrivr Meld. — The area of this field is estimated at about 
 7,800 square miles, and the thickness of the measures varies 
 with the localities, it being only a few hundred feet in the 
 northeast part of the plateau region, and nearly 5,000 feet at 
 the southwestern end of the field. The number of coal seams 
 varies in the same sense. Mr. McCalley gives about forty 
 seams in this field, fourteen of which are two and a half feet 
 and upwards in thickness. The localities wher& most mining 
 is done are : Pratt Mines, Mary Lee mines, and others near 
 Birmingham ; Blue , Creek mines, below Bessemer ; several 
 mines at Newcastle and Warrior, in Jefferson county ; at Cor- 
 dova, Horse Creek, Carbon Hill and Corona and other localities 
 in Walker county; Brookwood and Coaling, in Tuskaloosa 
 county. For details concerning the field, the reader is referred 
 to the report of Mr. McCalley on the Warrior basin of the 
 plateau region. Coke is made in the largest quantity from 
 the coal of the 'Pratt, Blue Creek, Mary Lee and Brookwood 
 mines. 
 
 Red Iron Ore. — The Clinton or Red Mountain formation 
 carries a varied thickness of red fossiliferous ore. This forma- 
 tion occurs on the ridge on each side of the anticlinal valleys 
 above named, and in each of these, at one or more points, the 
 ore is of quality and quantity which make it of commercial 
 importance. The great bulk of this ore mined in Alabama 
 comes from Red mountain ridge, along the eastern side of 
 Jones valley, from Reeder's Gap to Gate City. At one place 
 the ore is twenty feet, or more in thickness. On the west side 
 of Murphrees valley, along the western border of the Coosa 
 valley above Springville, and at Attalla near the base of Look- 
 out mountain, and along the eastern foot of Lookout at inter- 
 vals up to Round mountain, the ore is also extensively mined. 
 
 Brown Iron Ore. — This ore is usually associated with the 
 strata of the lower Silurian ( Knox dolomite) and the upper 
 
GEOLOGY OF ALABAMA. 23 
 
 part of the shale formation in all the valleys above enumer- 
 ated. In the Coosa vallej' it is mined extensively near the 
 Shelby Iron Works, and also in Talladega, Calhoun and Cher- 
 okee counties. 'In the Cahaba valley, near Briarfleld ; in 
 Roups and Jones valley, near Woodstock, and again at points 
 near Tannehill station ; in Murphrees valley, in Blount county, 
 above Oneonta; in Wills valley, there are several mines be- 
 tween Attalla and the Georgia line. In Franklin county, near 
 Russellville, the ore is associated with cherty limestone of the 
 sub- carboniferous formation. Near Vernon, in Lamar county, 
 it occurs with pebbles and bodies of a much later geologic 
 period. 
 
 Limestone. — The mountain limestone, which comes directly 
 below the coal measures of the plateau region, is usually very 
 pure and well suited as a flux, and is extensively quarried at 
 Tnissville, Bangor and Blount Springs. 
 
 Among the cherty limestone of the lower sub-carboniferous 
 formation occur heavy beds of variegated and gray fossilifer- 
 ous limestone. The latter is extensively quarried in Colbert 
 county, and the same stone is found abundantly in Lauderdale, 
 Franklin, limestone and the other counties of the Tennessee 
 valley. 
 
 The Clinton formation also furnishes a highly ferruginous 
 limestone that will one day be used for ornamental purposes. 
 
 The Trenton limestone of the Silurian formation is now 
 being quarried at Gate City for the furnaces, and at Siluria 
 and near Calera for use in lime kilns. The limestone of this 
 age occurring about Pratt's ferry forms a beautiful variegated 
 marble, and it has been quarried and worked on a small scale. 
 A line red or v£(!riegated marble also of this age is found in 
 the southwestern part of Jefferson county, west of McCalla. 
 
 White Crystalline Limestone or Marble — Occurs at nw-ny 
 points along the eastern border of the Paleozoic region, in Tal- 
 ladega, especially near Sylacauga, where it has been worked 
 to some extent in past times. 
 
 Of less importance than the foregoing, we may mention 
 the following minerals occurring in these formations : 
 
 Barite — Is found associated with the Trenton limestone in 
 many localities in Bibb, Shelby and Talladega counties. 
 
 Halloysite or Porcelain Clay - - Is" mined near Sulphur 
 
24 GEOLOGY OF ALABAMA. 
 
 Springs, in DeKalb county, but occurs in small quantities in 
 several localities in the sub-carboniferous formation. 
 
 Manganese Ore — Like the brown iron ores, is usually found 
 associated with the sub-carboniferous or the lower Silurian 
 beds, e. g., in Blount, Tuskaloosa, St. Clair, Calhoun and other 
 counties, but it has nowhere yet been found in sufficient quan- 
 tity to be of great commercial importance. 
 
 ^Sandstone — For building purposes has been quarried from 
 the strata of the coal measures near Cullman, from the Clinton 
 formation in Wills valley, and elsewhere from the Cambrian 
 formation in many localities. 
 
 jSiderite or Spathic Ore, or Clay Iron Stone — Is common 
 in the coal measures, but not as yet mined. 
 
 Black £and;~Is also not uncommon in the same formation. 
 
 Rauxiter. — This important mineral, used as a source of 
 metallic alluminum, is now being shipped in large quantity 
 from Cherokee county. It is associated with the brown iron 
 ores of that region. Other occurrences are known in Calhoun 
 county. 
 
 MESOZOIC AND CENOZOIC FORMATIONS — CRETA- 
 CEOUS AND TERTIARY. 
 
 After the accumulation as above described and the eleva- 
 vation above the sea of the sediments which make up the 
 Paleozoic formations, they constituted the land area of Ala- 
 bama. This ancient land area was in the northeast part of 
 the State, its gulf border being then along a curved line 
 passing from the northwest corner of the State, through 
 Fayette Court House, Tuskaloosa, Scottsville, Centreville and 
 Wetumpka, to Columbus, Georgia. During the next following 
 geological periods, which have been named Cretaceous and 
 Tertiary, this land mass, disintegrated by atmospheric agen- 
 cies, furnished the material which was carried down by rains, 
 rivulets and rivers to the gulf and spread upon its floor in the 
 form of beds of pebbles and coarse sand near the shore and in' 
 the shallow places, in the form of line sand and clays in the 
 
GEOLOGY OF ALABAMA. *^t) 
 
 deeper parts and farther from the shores, while in still deeper 
 waters, not reached or only partially affected by the washings 
 from the land, flourished the corals and other marine animals 
 which formed the limestones. ' 
 
 During all this time there was a gradual elevation of the 
 land — varied at intervals by periods of rest and even of down- 
 ward movement — in striking contrast to the manner in which 
 the l^aleozoic deposits were elevated and compressed together, 
 folded and faulted. The result of this movement was to 
 transfer southward, step by step, the shore line of the gulf 
 and to add to the dry land, in successive belts, the sediments 
 which had accumulated along the coasts. As each belt of 
 these deposits was added to the dry land, it, in turn, was sub- 
 jected to erosion, and contributed its share to the materials 
 carried down by the streams and deposited upon the bottom 
 of the sea, to form the strata of the newer formations, them- ■ 
 selves in time and in similar way to be added to the firm land. 
 
 From this account, it will be seen that our Cretaceous and 
 Tertiary formations consist of strata having a gentle slope 
 toward the south and coming to the surface, or outcropping, 
 in approximately parallel belts across the State — the oldest 
 beds farthest north and the newer beds occupying the surface, 
 one after the other, as we go southward in the order of their 
 relative age. 
 
 By making careful examinations and measurements of the 
 various strata, as exposed along our rivers, in gullies and other 
 natural sections, and by making use of the records of artesian 
 borings, the quality and thickness of the sediments of these 
 itwo formations have been worked out with some accuracy. 
 If all the strata could be penetrated by a single boring, we 
 should find about 2,500 feet of them belonging to the Creta- 
 ceous, and some ] ,800 feet to the Tertiary, and we should also 
 find, as might be expected from their mode of deposition, that 
 the greater part of these sediments consists of sands inter- 
 stratified with thin sheets and, in some instances, with thick 
 beds of clay. 
 
 At two horizons, viz : in the uppermost of the Cretaceous 
 and at the top of the Tertiary also, we find important calca- 
 reous deposits,' the rotten limestone of the Cretaceous, which 
 forms the basis of our prairie lands, being about 1,000 feet 
 
26 
 
 GEOLOGY OF ALABAMA. 
 
 thick, and the white limestone of the Tertiary, which also 
 forms prairie or lime lands, being 200 or 300 feet thick. In 
 the eastern half of the State one of the lowermost of the 
 Tertiary beds is a limestone. ' 
 
 Among the sandy strata of the Tertiary we find several 
 important beds of marine shells which can be used as marls, 
 and also beds of lignite or brown coal, which, though small of 
 value as fuel, has recently been found to be the best material 
 to be used in the clarifying of sugar. 
 
 Cretaceous. — At the bottom of the Cretaceous, we find 
 about 1,000 feet of clays and sands, more clayey below and 
 sandier above, constituting what has been called the Tuska- 
 loosa formation. These beds are much thinner, going eastward, 
 and on the Chattahoochee river, are less than 100 feet. In the 
 lower part of this formation there are important beds of clay, 
 in which purple colors are conspicuous. Some of these clays 
 will one day come extensively into use in the manufacture of 
 flre brick and various kinds of earthenware. In the same for- 
 mation are "found beds of yellow ochre, which have been mined 
 in two or three localities. A fairly good quality of iron ore is 
 likewise found in many places in this formation. Next above 
 the Tuskaloosa come about 300 feet of strata chiefly sandy, to 
 which the name Eutaw has been given. These beds, along the 
 Tombigbee and Alabama rivers, have yielded very few fossil 
 remains, but going eastward, they become highly fossiliferous. 
 
 Next above the Eutaw follow the calcareous ' beds of the 
 rotten limestone^* 1,000 feet thick along the Tombigbee and 
 Alabama rivers, but becoming much thinner toward the east, 
 and giving out entirely before the Chattahoocbe is reached. 
 This formation gives rise to the calcareous soils of the black 
 belt, or canebrake,^ne of the most noted farming regions in 
 the State. At the base and at the top of this formation are two 
 beds of phosphatic green sand, to which special attention will 
 be directed later. ' 
 
 The uppermost division of the Cretaceous has been named 
 Mipley. The strata are, in the western part of the State, cal- 
 careous below and sandy above ; toward the east this formation 
 
 *A part of this rock is a true clialk Tormation, rather than a limestone. The 
 name, rotten limestone, is open to many objections, chief among which is the fact 
 that the g:reater part of the formation is not a limestone at all, strictly speaking. 
 
GEOLOGY OF ALABAMA. 27 
 
 becomes much thicker, being 1,000 feet on the Chattahoochee 
 river. In the eastern part of the State the most important 
 strata of the Ripley are the blue micaceous marls which play 
 so prominent a part as a soil maker. 
 
 Materials of Economic Importance in the Cretaceous. — 
 The most important materials in this formation are the phos- 
 phates. These occur as nodules of nearly pure phosphate of 
 lime, similar to the phosphates of South Carolina, but which 
 have nowhere been found in great abundance, or as phosphatic 
 green sand, more or less calcareous, containing up to five per 
 cent, of phosphoric acid, occurring in large quantity. As 
 above indicated, there are two horizons where these materials 
 occur, namely, at the base and at the top of the rotten lime- 
 stone, and they outcrop across the Stajbe in two belts, one 
 immediately north and the other immediately south of the 
 black or prairie belt. In the Alabama Geological Reports, 
 and in occasional papers, much detail has been given concern- 
 ing these marls ; their capabilities have been fully shown by 
 experiments in several localities. It will, however, be a long 
 time before they come into general use, as a mountain of preju- 
 dice and conservatism will have to be first removed. Materials 
 of exactly similar quality have for many years been used with 
 the best results in New Jersey. Apart from these marls and 
 phosphates, the Cretaceous has little to show of valuable mate- 
 rials, except the clays and ochres in the Tuskaloosa series 
 above alluded to. The clays are mined at several points along 
 the Alabama Great Southern Railroad in Jefferson and Tuska- 
 loosa counties. Yellow ochre from this same formation has 
 been mined for a number of years in Elmore county, near 
 Coosada station. 
 
 • Tertiary. — The sub-divisions of the Tertiary have been 
 given fully in the table at the head of the present article. A 
 few words of explanation may be added : 
 
 At the base of the Tertiary is found an impure limestone, 
 thin and inconspicuous in west Alabama, but thickening east- 
 ward until, on the Chattahoochee river, it is fully 200 feet. 
 
 This we have called the Clayton limestone, formerly known 
 as our Midway group, from a locality on the Alabama river. 
 
 Next above the Clayton, we find on the Tombigbee river, a 
 series of black clays, 100 feet in thickness, well expos 
 
'^8 , GEOLOGY OF ALABAMA. 
 
 Black Bluff, on the Sucamochee river, and, threfore, called by 
 the latter name. These clays thin down rapidly, becoming 
 more calcareous toward the east, and in Wilcox county form 
 the base of some fine prairies. Beyond Wilcox county, toward 
 the east, this section of the Tertiary has~not yet been identified. 
 
 Next succeeding the Sucarnochee, or Black Bluff grotip, is 
 the Mathews' Landinc/, or Naheola series, composed of gray 
 sands and clays, with a highly fossiliferous bed at its base, and 
 a thick bed of lignite at the top. On the Tombigbee river this 
 group is nearly two hundred feet in thickness. Eastward, it) 
 decreases in thickness, and is lacking entirely on the Chatta- 
 hoochee river. The next group, called the Nanafalia series, 
 maintains a tolerably uniform thickness across the State from 
 the Tombigbee to the Chattahoochee. The beds are mostly 
 sandy, but contain a great number of shells of a small oyster 
 called gryphcea thirsa;,. Near the Alabama river, and eastward, 
 the upper part of this group contains a gray aluminous rock, 
 which very closely resembles the buhrstone below described, 
 and, from this resemblance, called by us " pseudo-buhrstone." 
 
 The Tuscahoma. — This series consists mainly of gray and 
 yellow laminated, cross-bedded sands and sandy clays, gener- 
 ally poor in fossils, except at Yellow Bluff and Bell's Landing, 
 on the Alabama river. It maintains a pretty uniform thickness 
 across the State of about 140 feet. 
 
 The Bashi. — The characteristic feature of this group in 
 wastern Alabama is a bed of green sand marl, highly fossilif- 
 erous, having its greatest development at Wood's Bluff', on the 
 Tombigbee river. Immediately below this marl we find several 
 beds of lignite. East of the Sepulgah river, according to Mr. 
 Langdon, the lignite is wanting. The thickness of this group 
 varies, it being on the Tombigbee about eighty feet, and on Pea 
 river 150 feet, while on the Chattahoochee river it is only forty- 
 four feet, and nearly devoid of fossils. 
 
 The Hatchetighee. — This member consists of brown, purple 
 and gray laminated, sandy clays, and cross-bedded sands, about 
 175 feet thick, on the Tombigbee river, where a great abund- 
 ance and variety of fossils are met with. Eastward, these beds 
 thin down, and on the Chattahoochee river the thickness is not 
 more than ten feet, but the lithological features remain practi- 
 cally constant. 
 
GEOLOGY OF ALABAMA. 29 
 
 The £uhrstone. — In the western part of the State the most 
 prominent rocks of this series are aluminous sandstones, or 
 siliceous clay stones, varying slightly in composition, and. poor 
 in fossils. In eastern Alabama the percentage of clay decreases 
 and the rocks become more calcareous, and the fossils more 
 abundant, and in place of the silicifled casts characterizing 
 them on the Tombigbee and Alabama rivers, are extensive 
 beds of shells, of which oysters form a very large proportion. 
 On the Tombigbee the thickness of this series is estimated at 
 400 feet, and this thickness decreases until, on the Chattahoo- 
 chee river, it is less than 200 feet. 
 
 The Claiborne. — The thickness of this group on the Ala- 
 bama river is about 145 feet, and at Claiborne Bluff several 
 distinct strata have been described. The most important of 
 these occurs at the top, and is a bed of sand seventeen feet in 
 thickness, filled with the beautifully preserved shells which 
 have made this locality famous. Below this comes a series of 
 beds, in which an oyster called ostrea sellmformis is the most 
 abundant and characteristic fossil. Below these ostrea sellse- 
 formis beds we find another highly fossiliferous stratum, ex- 
 posed along the Alabama river at Lisbon Landing. The most 
 persistent member of this series is that which is characterized 
 by ostrea sellsetormis, and this is the only representative of the 
 Claiborne formation on the Chattahoochee river, where the 
 thickness is only seventy-five feet. 
 
 The White Limestone. — This is the uppermost member of 
 the Eocene in Alabama. The most abundant and characteristic 
 rock is a white, friable limestone ( Vicksbicrg limestone) which 
 when freshly quarried can easily be cut with a saw or axe, and 
 is used extensively, in the region of its occurrence, in the con- 
 struction of chimney and pillars for houses. The characteris- 
 tic fossil of the white limestone is the orbitoides lyelli. The 
 thickness of the formation in Western Alabama is about 200 
 feet, which thickness it maintains across the State, being at 
 least 275 feet on the Chattahoochee. The lower pa,rt of this 
 series is made of an impure, clayey limestone {Jackson), which, 
 in disintegrating, gives rise to black, calcareous soils, similar 
 to those of the black belt of the Cretaceous ; but the topogra- 
 phy in these Tertiary prairies is extremely broken, and the 
 region of their occurrence is usually known as the lime hills. 
 
30 GEOLOGY OF A LABAMA. 
 
 The Grand Gulf. — Southward of the region of the occur- 
 rence of the white limestone we have recently found, in Wash- 
 ington, Mobile, Baldwin, and Escambia counties, sandstones 
 and clays of variegated color, which are characteristic of th« 
 Grand Gulf formation of Dr. Hilgard. It is always exceedingly 
 diiBcult to discriminate between the disintegrated portions of 
 the rocks of this formation and the surface beds of drifted 
 materials which oveilie that whole region, and for this reason 
 the presence in Alabama of the Grand Gulf beds has not until 
 lately been defflnitely ascertained. These beds belong, most 
 probably, to the Miocene division of the Tertiary, but the ab- 
 sence of well-defined fossils prevents our arriving at certainty 
 on this point. 
 
 The Fascagoula Formation. — Among the materials 
 brought up by an artesian boring in Mobile recently are some 
 shells that have been recognized as characteristic of the Mio- 
 cene horizon. Inasmuch as no marine shells have as yet been 
 found in the Grand Gulf beds, it seems best to give a distinct 
 name to this Mobile shell-bearing stratum. A fossiliferous 
 stratum with the same shells as those from the Mobile > boring 
 has lately been discovered by Mr. L. C. Johnson, of the United 
 States geological survey, on the Pasoagoula river, in Missis- 
 sippi. This bed lies immediately over strata of undoubted 
 Grand Gulf characters, and it may be a marine phase of the 
 Grand Gulf, but withal so entirely diflferent from the other 
 beds of this formation as to be worthy of a name of its own, 
 and Mr. Johnson has suggested Pascagoula, from the original 
 locality. 
 
 Mr. Johnson, has also recently traced the Miocene fossilif- 
 erous deposits of Alum Bluff, on the Chattahoochee river, in 
 Florida, westward and northward to within a few miles of the 
 southern boundary of Covington county. It seems altogether 
 probable that this phase of the Miocene will be found to 
 extend into Alabama, and it may turn out to be identical with 
 our Pascagoula, as above defined. The deep beds of sand 
 which overlie this whole southern country stand in the way 
 of geological ex;amination, and the only chance of finding 
 exposures of the Tertiary beds which underlie these sands is 
 in the bluffs and banks of the creeks. The recently discov- 
 ered phosphates of Florida are all associated with Miocene 
 
GEOLOGY OF ALABAMA. 31 
 
 deposits, which leads us to hope that these same deposits may 
 yet be traced into Alabama, but whether, so far westward and 
 inland, these beds will be found to contain a large amount of 
 phosphate, or not, is an open ques1;ion. 
 
 The Lafaj'ftte or Orange Sand.— With the addition to 
 the dry land area of the State of the Paleozoic, Cretaceous and 
 Tertiary beds above described, the rocky sub-stratum of Ala- 
 bama was practically completed. The land stood then above 
 the sea with substantially the same outline that it now pre- 
 sents. It was for a long period of time subjected to the action 
 of rains, rivers, frosts, and other disintegrating and denuding 
 agencies, until the surface topography was essentially the same 
 as now. 
 
 The next epoch in the geological history of the State was 
 marked by the spreading of a mantle of sandy loam, sand and 
 gravel over all the area of the Cretaceous and Tertiary, and 
 over a tolerably wide belt of the Paleozoic portion also. This 
 tells, according to Mr. McGee, of a subsidence of the land 
 until the waters of the gulf covered all the Cretaceous and 
 Tertiary and lapped far up on the Paleozoic. From the north 
 were washed down, by widely spread and rapidly flowing 
 currents of fresh water, great bodies of sand and pebbles, 
 which came to rest in great part near the new shore line, 
 i. e., near the line of , junction of the Paleozoic and newer 
 formations. Then came, apparently, a gradual elevation, 
 which permitted these materials to be carried further and 
 further southward, so as to cover in time the whole surface 
 down to the present gulf shore. The main mass of the pebbles 
 occurs approximately along the curved line above indicated as 
 marking the old gulf shore-line, and beyond the Umits.of the 
 State, in similar position at the junction of the Paleozoic with 
 the newer formations far to the northeast into Virginia and 
 Maryland. 
 
 Besides this, the main body of the pebbles, they are found 
 in streams along the lines of drainage of the principal rivers, 
 occupying an area along each of these streams averaging 
 thirty miles in width. , Some of these pebbles have been carried 
 down almost to the shores of the gulf. These beds were long 
 ago carefully studied by Dr. Eugene W. Hilgard, when State 
 Geologist of Mississippi, and designated by him orange sand. 
 
32 GEOLOGY OF ALABAMA. 
 
 The formation has recently been further studied by Mr. 
 McGee, from the Mississippi to the Potomac, and named by 
 him Appomattox, but recently an older name of Dr. Hilgard has 
 been adopted, namely : Lafayette. It is one of our most im- 
 portant formations, ina.smuch as it makes the basis of the 
 greater part of the soils of the lower part of the State. These 
 sediments, like the alluvials, have no necessary connection with 
 the rocks upon which they are now found, though in many 
 cases to some extent modified by them, and their distribution 
 is such as to preclude the idea thst they have been transported 
 and deposited by any stream at present existing. Indeed, many 
 of the phenemena, seem to be explicable only on the supposition 
 that they are carried along by rapid currents of water, flowing 
 from the north to the south, and spreading over the entire 
 width of the State from the east to the west ; more than this, 
 the same deposits in the adjoining States show that this great 
 flood was not confined to narrow limits, but extended over the 
 whole width of the Gulf and Atlantic States. The thickness 
 of these beds in Alabama will perhaps average about fifteen or 
 twenty feet, but we often find the older valleys excavated in 
 the Cretaceous and Tertiary strata, which have been subse- 
 quently filled in with these beds of pebbles and sands to a depth 
 of fifty or seventy-five feet. The pebbles occur commonly near 
 the base of the formation, and above them come the sands and 
 the red loam, which latter usually forms the surface, except 
 where removed by denudation. The beds of this age are usu- 
 ally spread, as a mantle of comparatively uniform thickness, 
 over hill and dale of" the older formations. In this way the red 
 loam of the Lafayette group has come to be the sub-stratum of 
 the best farming lands of the southern half of the State, and 
 its excellence is enhanced by the admirable under-drainage 
 aft'orded by the pebbles upon which it so aften rests. This 
 formation occupies in Alabama perhaps five times the super- 
 ficial area of any other single formation. 
 
 This formation until recently has been considered as a 
 member of the Pleistocene, and the characters of its materials 
 and the peculiar distribution of the formation, so utterlv 
 unlike those of the other Tertiaries, might well be considered 
 as favoring this interpretation of the age ; but, on the other 
 hand, Messrs. McGee, Chamberlin and Salisbury have traced 
 
GEOLOGY OF ALABAMA. 33 
 
 some yellow gravel, which they consider Lafayette, beneath 
 certain deposits, which they make the lowest of the Pleistp- 
 cene. If this yellow gravel is of Lafayette age, it ■ seems 
 necessary to assign it to the later Tertiary or Pliocene. There 
 seems to be reason for hoping that fossil remains will yet be 
 found in the Lafayette that will fix definitely its geological age. 
 
 QUATHNARY FORMATIONS. 
 
 Pleistocene. — In the tabular view of the Pleistocene 
 formations of Alabama, and in the description which follows, 
 the arrangement must not be understood to be chronological, 
 for it is certain that, to some degree at least; these formations 
 were contemporaneous, and they very plainly grade into each 
 other. Being accumulated under different conditions, they 
 are rarely to be seen together, so that their precise strati- 
 graphical relations are not easily made out.' In two instances 
 I think I have seen the gray Ozark sands overlying the second 
 bottom loams, but in neither case could I be perfectly certain- 
 of the identifications. 
 
 River Terrace or Secofid JBottom Deposits. — The rivers and 
 other larger streams of Alabama, especially those traversing 
 the region over which the mantle of pebbles and sand above 
 described has been spread, flow along valleys of varying width 
 (often four to eight miles) cut down into the rocks of the 
 country (Cretaceous and Tertiary"). The immediate channels 
 of these streams, always more tortuous than the valleys above 
 mentioned, are excavated out of materials which have in the 
 past been deposited by the stream itself, or, at least, by the cur- 
 rents which once occupied the valleys between whoes widely 
 separated borders the present streams pursue their winding 
 courses, touching these bordiers, now on the one side, now on 
 the other. These constitute the second bottom deposits^ which 
 are always above overflow, and vary in thickness from sixty 
 feet upwards, in the central part of the State, to less than ten 
 feet, near the gulf. In composition they are uniform, and no 
 one familiar with our lower rivers can fail to have noticed 
 
§4 GSOLOGY OF ALAllAMA, 
 
 the comparatively low bluffs which form the banks on at least 
 one side of the river. The second bottoms form a nearly level 
 terrace, sometimes a mile or two in width, slightly above the 
 high water mark of the rivers on which they occur. The first 
 bottoms or flood plains, annually overflowed, form a narrow 
 terrace on one or both sides of the stream, of course lower 
 than the main mass of the second bottom deposits out of 
 which they have been excavated. The materials of the second 
 bottom are sand and clay in varying proportions ; these pre- 
 sent usually very indistinct marks of stratification, especially 
 in the upper parts, which are commonly stiffer and more 
 clayey than the lower and are universally used in the manu- 
 facture of brieve. In many places we find near the base of the 
 terrace deposits a clay filled with fragments of twigs and other 
 vegetable remains, and in this clay are the roots of the stumps 
 mentioned below. As above stated, the im mediate channel of 
 the stream is cut into this material, and the lower beds being 
 much more sandy than the upper, there is a constant under- 
 mining and caving off going on on the outer side of the bends. 
 As this caving progresses, stumps and logs are frequently 
 brought to view which have been buried under these deposits. 
 These are commonly supposed to be cypress stumps, and are 
 usually in a fair state of preservation. All the other phenom- 
 ena of the second bottom deposits go to show that they were 
 connected with the now existing systems of drainage, but 
 were formed when the general level of the waters was higher 
 than at present, or before the streams had cut their channels 
 to the present depths. The second bottoms, are less local in 
 character and less closely connected with existing streams 
 than the first bottoms ; but, on the other hand, much more 
 restricted and closely related to these streams than are the 
 various materials constituting the Lafayette series. Our 
 ^econd bottom deposits are probabl'y nearly equivalent in time 
 to the Port Hudson and overlying beds of the Mississippi 
 river, but the material of the latter is quite different from 
 that of our rivers, the difference being probably due in the 
 main to the fact that the Mississippi river reaches up into the 
 region once occupied by glaciers. The Port Hudson deposits 
 are built up mainly of the materials of glacial origin. The 
 only organic remains which the second bottoms are known to 
 
GEOLOGY OF ALABAMA. 35 
 
 contain are the cypress stumps above mentioned. Some of 
 the most productive soils of Alabama are formed of these 
 second bottom materials and most of the celebrated river 
 plantations of former times rest upon these deposits. 
 
 Ozark Sands. — While the terrace deposits just mentioned 
 are confined to the immediate vicinity of the rivers and larger 
 w^ater courses, and are rarely elevated more than fifty feet 
 above these waters, we find, especially in the southern pairt of 
 the State, a mantle of gray sands, with pebbles at the base,, 
 overspreading the country between the water courses up to 
 altitudes as high as ISO to 200 feet above sea level. These 
 sands correspond to the interfluvial phase of the Columbia 
 formation of Mr. McGee, as the second bottoms are the repre- 
 sentative of the fluvial phase. 
 
 The Ozark sands usually lie unconformably upon the red 
 loam of the Lafayette formation, with a sharp and distinct 
 line of demarkation between the two, and, while scarcely ever 
 more than four or five feet in thickness and holding very little 
 gravel upon the divides, they increase in thickness and in the 
 percentage of pebbles along the slopes leading down to the 
 minor streams, often forming sandy terraces one-fourth of a 
 mile in width along the creeks. As above stated, the strat- 
 igraphical relations of these sands to the second bottom 
 deposits are not easily made out, since they rarely occupy 
 the same areas, yet they often form a sort of third or higher 
 terrace along some of the larger rivers, a few feet above the 
 second bottoms and quite as wide. 
 
 Biloxi — (-00.81 Sands. ---This includes the immediate gulf 
 coast and islands of Mobile and Baldwin counties and an exten- 
 sion up the bay of Mobile to an undefined limit. The name 
 should not be understood as implying sterility, for much of the 
 region is the choice of the " truck farmers." Mr. L. C. Johnson, 
 •who has recently given this part of the State some study, de- 
 scribes the coast sands as consisting essentially of thin alter- 
 nating layers of sand and sandy clay. The formation is quite 
 variable because, in the course of its structure, old beaches and 
 marshes, both salt and fresh, were worked in with the regular 
 strata, and now, when exposed along the shore, appear as a 
 patch of black bottom often studded with old stumps. Mr. 
 Johnson thinks that these deposits on our coast are the result 
 
36 GEOLOGY OF ALABAMA. 
 
 of three principal agencies, viz : the tides 6t the gulf, the 
 Mississippi river, and the united rivers that pour into Mobile 
 bay. The time of their accumulation was probably, in part 
 at least, contemporaneous with the formation of the second 
 bottom deposits, but, inasmuch as the same agencies are active 
 at the present time that have been for ■ ages, these coast 
 sands grade into the recent shore deposits. Mr. Johnson has 
 recently shown 'how the waters of the Mississippi in 1890, 
 breaking through the levee at the Nita plantation, poured 
 through Ponchartrain and other lakes into Mississippi sound, 
 carrying its sediments to the very mouth of Mobile bay. 
 Naturally the contributions of the Mississippi river are more 
 pronounced as we go westward, and at Biloxi a boring for an 
 artesian well has given a good section showing the alternations 
 of coarse sand with marsh mud down to a depth of eighty feet. 
 Mr. Johnson has proposed the name JBiloxi as a substitute for 
 coast sands. ^ 
 
 Recent. — Under this head are included all " soils, first 
 bottom deposits, sand bars, etc., now in progress of formation 
 or attributable to causes now in operation." 
 
 Alluvial — Flood Plain Deposits — Swamp and First Sot- 
 torn Lands. — The current of a river is rarely so sluggish as 
 to allow the complete deposition of the finer matters held 
 in suspension in its waters, but gently flowing streams con- 
 stantly leave on their banks, where the retardation of the 
 current by friction is greatest, a mixture of fine sand and 
 clayey matter. When, however, the waters rise above the 
 banks and spread over the flood plains, the matter held in 
 suspension will be deposited in parallel zones — the pebbles, 
 sands and coarser meterial on the immediate bank of the 
 stream, where the current is swiftest, and the fine sand and 
 clay further back in the swamp, where the comparative still- 
 ness of the water permits the complete settling of all the 
 matter held in suspension. The soils of the river swamps, 
 thus accumulated, are of extraordinary fertility, but have the 
 serious drawback that they are liable to periodical overflow. 
 These deposits are being made at the present time, and they,, 
 therefore, represent the most recent geological formations and' 
 form the natural transition to the soils, which will be discussed 
 in another article. 
 
EGBERTS & SON, 
 
 Lithographers, Printers and Binders, 
 
 BiRMisesAM, Ala.