3471 iEx ICtbrts SEYMOUR DURST When you leave, please leave this book Because it has been said " Ever thing comes t' him who waits Except a loaned book." Avery Architectural and Fine Arts Library Gu t of Seymour B. Durst Old York Library Merrill, F. J, H 3471 Reprints Vol, I 1. The Geology of Long Island 1886 2. On The Met amorphic Strata of Southeastern New York 1890 3. The Geology of the Crystalline flocks of Southeastern New York 1896 Digitized by the Internet Archive in 2014 http://archive.org/details/ongeologyoflongiOOmerr TH Geology of Long Island, BY F. J. H. MERRILL, [From the Annals of the New York Academy of Sciences, Vol. Ill, Nos. 11 & 12, 1886.] Geology of Long Island. 341 XX. — On the Geology of Long Inland. BY F. J. H. MERRILL. Read November 7, 1884. The following contributions to the Geology of Long Island are the result of some five weeks' exploration and study of that well- known and interesting region, during the summer of 1883. This paper is but preliminary ; and many questions which have been merely touched upon or wholly neglected, the writer hopes to discuss at length when more extended research and deeper exca- vations have given him further data. The surface geology of this region has already been minutely described by Mather in his Report on the Geology of the First District of New York, 1843, and also, with special reference to the glacial deposits, by Mr. Warren Upham, in his articles on " Terminal Moraines of the North American Ice Sheet," Am. Jour. Sci., Ill, 18. I shall therefore review very briefly the physical characteristics of the island and endeavor to throw what additional light I can upon its geological history, from the study of sections of strata recently exposed, and such other phenomena as it has been my fortune to observe. Long Island as a whole is comparatively low and flat, but throughout the central part is a range of hills extending from Bay Ridge northeasterly to Roslyn, and thence continuing to Montauk Point in a series of elevations, the more important of which are known as West, Dix, Comae, Bald, and Shinnecock Hills. The average height of this chain is about 250 feet ; but at some points it is much greater. Harbor Hill at Roslyn is 384 feet above tide ; Jane's Hill is 383 feet high ; Reuland's Hill has an elevation of 340 feet, and Wheatly Hill is 369 feet above the sea. There is also, along- the north shore, an elevation which usually follows the contour of the numerous deep bays and inlets, vary- ing in bight from 30 to 2C0 feet, and almost continuous from 342 Geology of Long Island. Astoria to Orient Point. These two ranges of hills are the re- sult of glacial action, and the more southern chain marks the southern limit of the drift. Upham and others, in speaking of these ranges, have called them moraines. If the word moraine is to be thus used, and present custom in the United States appears to sanction the use, it must be taken in a different sense from that accorded to it in most regions of glacial action. In Switzerland and other moun- tainous countries, the term is applied to great accumulations of boulders and rock detritus, piled up along the sides or front of a glacier. Throughout most of Long Island and at many points on the New England coast, however, the thickness of the drift on the ridges marking the southern limit of glacial extension is very slight and in some cases it is wanting. In these cases, the term moraine would be synonymous with the southern limit of the continental glacier. South of the backbone, as the central range of hills is called, the surface is nearly level, gently sloping southward in an unbro- ken gravelly plain ; while between this ridge and the north shore is a second plain with an elevation of 50 to 100 feet, and espe- cially noticeable between Port Jefferson and Eiverhead. From many of the deep bays on the north shore, valleys extend through the hills in a southerly direction. These depressions, thirty in number between East New York and Eiverhead, have been ex- plored by Mr. Elias Lewis, Jr., of the Long Island Historical Society.* He finds them to average about 25 feet in depth and to be occupied usually by small streams most of wdiich flow south- ward. These valleys are evidently the beds of rivers formed by the melting of the ice sheet in the Champlain Period. There are no important lakes or rivers now on Long Island, but there are numerous ponds of clear cool water, without visi- ble inlet or outlet. The existence of these ponds depends on the fact that in the stratified sands of the island, which are under- lain by clays, a uniform water-level, or plain, exists,! which rises northward from low-tide-level on the south shore at the rate of 121 feet per mile. Wherever a basin has been excavated * Am. Jour. Sci., Scries III, Vol. XIII. f Dana, Manual of Geology, p. 664. Geology of Long Island. 343 below the surface of this plain, it would necessarily be filled by these subterranean waters, which, by their constant percolation through the sand, would remain pure and clear, without material or sudden change of level under average conditions. The largest of these ponds is Lake Ronkonkoma, which is three miles in cir- cumference, and has a maximum depth of 83 feet. The coast-line of Long Island is strikingly irregular. Along the north shore are eight deep and extensive bays, which form excellent harbors, and also a large number of inlets, most of which are navigable. At the heads of these bays, numerous springs of pure water issue from the hillsides, indicating the presence of an impervious stratum within the hills. The east end of the island is penetrated by Great and Little Peconic Bays to a depth of 22 miles, while the south shore west of Southhamp- ton for about 95 miles, consists of an intricate series of shallow creeks partly surrounded by salt marsh, tributary to Shinnecock, Moritches, Great South, Hempstead, and other bays, which are divided from the ocean by long sand beaches, or reefs intersected in places by narrow inlets. Shelter, Eobbin's, Plum, Gull and Gardiner's Islands, which form part of Suffolk County, New York, do not differ from Long Island essentially in physical or ge ol og i c al c h ar ac t e r i s t i c s . The lithology of the island is comparati vely simple, the crys- talline rocks being confined to quite a limited area. The greater part of the region consists of gravel, sand and clay, overlain along the north shore and for some distance southward, by gla- cial drift. This material forms an important element of the surface formation, and though it has been already described by Mather and Upham, I shall devote a short space to its discussion. For the sake of clearness, we may describe the drift as of two kinds : 1st, the till or drift proper, a heterogeneous mixture of gravel, sand and clay, with boulders, and 2d, the gravel drift, a deposit of coarse yellow gravel and sand, brought to its present place by glacial and alluvial action, but existing near by in a stratified condition, before the arrival of the glacier. This yellow gravel drift, which in a comparatively unaltered condition forms the soil of the pine barrens of southern and eastern Long Island, and is exposed in section at Grossman's brickyard in Huntington, is equivalent to and indeed identical Geology of Long Island. wiili the yellow drift or preglaeial drift of New Jersey, a forma- tion of very great extent in that State, and of which the origin and source have not yet been fully explained, though it is always overlain by the glacial drift proper where these formations occur together. In the hills near Brooklyn the till attains its maximum depth. This has never been definitely ascertained, but is probably be- tween 150 and 200 feet. The only information we have on the subject is from a boring in Calvary Cemetery, where the drift was 139 feet deep, and this point is nearly five miles north of Mt. Prospect, which is 194 feet high and probably consists for the most part of till. The occurrence of this till is quite local and very limited along the north shore between Roslyn and Hor- ton's Point. From the former locality eastward the hills are mainly composed of stratified gravel and sand, probably under- lain by clay. On the railroad between Syosset and Setauket. is an abundance of coarse gravel with but slight stratification. East of Setauket for some distance the drift is a fine yellowish sand which washes white on the surface, and at Wading River the drift with cobble-stones was only eighteen inches thick where exposed, being underlaid with fine yellow, sand. Along the re- mainder of the north shore to Orient Point, G feet was the max- imum depth of drift observed. Under this were stratified sands, gravels and clays, usually dipping slightly from the shore. On Brown's Hills, north of Orient, the drift is overlaid by 3 feet of fine micaceous sand, which has probably been carried to its pres- ent position by the wind. The drift at this locality is a clayey till, and its surface is strewn with an abundance of boulders of coarse red gneiss. On Shelter Island are high ridges of gravel overlain by a few feet of till. The hills from Sag Harbor east- ward are also composed partially of unmodified drift, but the most extensive deposit on the east end of Long Island is between Nepeague Bay and Montauk Point. Here the drift is disposed in rounded hillocks from 80 to 200 feet above the sea, with bowl and trough-shaped depressions between. The bluffs along the south shore, which are rapidly yielding to the action of the waves, consist for the most part of boulder clay and hard-pan of consid- able depth, covered by a shallow layer of till. At a few places, however, on the south shore, west of the point, laminated blue Geology of Long Island. 345 clay streaked with limonite occurs, intercalated with the till. At the end of the point, a similar bed of clay is exposed, over- lain by stratified sand. From the extremely limited character of the exposures, I am unable to determine whether the clay un- derlies the whole of the point or is merely local in its occurrence. In character and position, however, it is analogous to beds occur- ring on Block Island. The boulders of Long Island attract the attention of the geol- ogist by their size and variety. They represent almost every geological age ; fossiliferous rocks of the Helderberg, Oriskany and Cauda Galli, Hamilton, Chemung and Eocene periods having been found in the drift. Examples of these are in the collection of the Long Island Historical Society. There are also various members of the Archaean series, viz., gneiss, granite, syenite, hornblende, chlorite, talcose and mica schist, limestone, dolo- mite, and serpentine : and the Palaeozoic and Mesozoic ages are represented by Potsdam sandstone, Hudson River slate, Oneida conglomerate or Shawangunk grit, Catskill sandstone, and Tri- assic sandstone and trap. As the lithology of the boulders has been described in detail by Mather,* it would be superfluous for me to undertake a similar description. In addition to the rocks mentioned above, ^ ferruginous sand- stone and conglomerate occur abundantly in fragments along the east shore of Hempstead Harbor, and in the drift between Glen Cove and Oyster Bay. Many of these fragments contain vegeta- ble impressions, but in only two localities have any leaf prints been found. These were West Island, Dosoris, and the well of the Williamsburg Gas Co. The prints are supposed to belong to Cretaceous plants, but the evidence is incomplete. Many of the erratic blocks are of immense size, one in particu- lar, of gneiss, on Shelter Island, near Jennings' Point, con- tained as a solid mass over 9000 cubic feet. It has split in three pieces since it was deposited. Matheif mentions a mass of gra- nite near Plandome, which was estimated to contain 8000 cubic yards above 'the surface of the ground. Having thus briefly reviewed the characters of the surface * Geol. 1st Dist. X. Y., pp. 16.5-177. f Geol. 1st Dist., p. 174. Geology of Long 1 si and. drift, we will now consider in detail the strata which underlie it. The crystalline rocks outcrop along the shore at Hellgate and over a limited area in the vicinity of Astoria. They consist of finely laminated gneiss and schists, tilted at a high angle, and belong to the same formation as the rocks of Manhattan Island. I am informed by Mr. Elias Lewis, Jr., that in boring an artesian well in Calvary Cemetery, near Brooklyn, a bed of gneiss was encountered at a depth of 182 feet. Farther than this, we know nothing of the extent of the crystalline rocks on Long Island. The section obtained in the boring mentioned was as follows : Surface loam and drift, - - - 139 feet. Greenish earth, 39 " AVhite clay with red streaks, - - 4 " Gneiss, 400 " Total, - - 582 feet. The greenish earth referred to, lost its color on being treated with hydrochloric acid, and the white residue examined under the microscope appeared to consist of minute fragments of kao- linized feldspar, with occasional grains of quartz sand. The acid solution gave a strong reaction for iron, indicating a proba- ble admixture of glauconite with the material. It is stated in Cozzens' Geol. Hist, of N. Y. Island, that a shell of Exogyra costata, with green-sand adhering, was found between Brooklyn and Flatlands, at a depth of 60 feet. This locality is about live miles south of the well just mentioned, and would indicate the presence of Cretaceous strata near Brooklyn. The following data, also furnished by Mr. Lewis, of a well dug by the Nassau Gas Light Co., in Williamsburg, will give an idea of the formation at that locality : Surface loam, 3 feet. Quick-sand (so called), - 2 " Boulder clay, somewhat sandy, - 7<) " Blue clay with pebbles. - - 27 ' 4 Ovster shells, .... 6 inches. Total, - 102 feet inches. Geology of Long Island. 347 The shell-bed was underlain by quicksand bearing water. In the vicinity of Manhasset, on the road to Port Washington, are extensive exposures of stratified sand, more or less inclined from the horizontal. About 200 yards south of the post office, on the west side of the road, is a bank about 40 feet high, com- posed of a white, coarse, laminited sand, streaked with hydrous peroxide of iron, the layers dipping S. E. 13°. A little north- east of the post office, along the road, there are banks of red sand cemented together in places by sesquioxide of iron and re- sembling the Cretaceous red sand bed of New Jersey. On the shore of Manhasset Bay, near Port Washington, are high banks of coarse yellow stratified sand and gravel. This de- posit is very irregular in its stratification, as it shows in many places the "flow and plunge" structure described by Dana, and which is evidently produced by swift currents. The depth of this formation cannot be determined, it is probably not less than 150 feet, and possibly is much greater. These beds dip about 15° W. ; the strike is nearly due north and south. Along the shore of Manhasset Bay, from Port Washington to Barker's Point, are extensive banks of stratified sand and gravel, much stained with iron and dipping westward. At Prospect Point and Mott's Point, the banks are composed of coarse gravel simi- lar to that at Port Washington. Between Roslyn and Glen Cove, there are high banks of red and flesh-colored sands, while at Carpenter's clay pits a most interest- ing section is presented (fig. 1). The greatest hight of this sec- tion is 73 feet, the strike of the beds being X. 80° W. and the dip about 37° northerly. The layers here are composed of coarse white gravel and sand, apparently consisting of quartz, but sus- ceptible of being easily crushed in the hand. The pebbles are traversed by innumerable cracks, and appear to have been sub- jected to the action of an alkaline solution. Interstratified with the gravel are layers of fine white clay, from six inches to one foot in thickness, stained pink in some places, and containing occasion- al fragments of a soft hematite or red ochre. Besides these beds, there is a deposit of kaolin farther south, but its stratigraphical relations to the layer exposed could not be determined. This kao- lin is a soft white granular clayey substance, consisting chiefly of hydrous silicate of alumina from the decomposition of feldspar. Geology of Long Island. In fad the whole deposit would seem to be the decomposition product of a granulite rock such as occurs abundantly in West* Chester Co., X. Y., and in southwestern Connecticut. Lu the north end of the bank is an un conform ability, the gravel beds, which dip 37°, being overlaid by stratified sand dipping 15° in the same direction. The layers shown in this section form che north slope of an anticlinal flexure, the lowest beds being, I am informed by Mr. Coles Carpenter, one of the proprietors, almost vertical. An excavation made about 100 yards W. S. W. of the main pit, for the purpose of obtaining some leaf-prints, exposed the fol- lowing section : Gravelly drift, ... 6 feet. White sand, - 18 inches. Coarse " 6 " Reddish clay, - - - - 2 " (J i ey sandy carbonaceous clay with leaf-prints, - - 4 " 14 feet. These beds dipped about 15° S. W., the locality being on the south slope of the anticlinal. Owing to the sandy nature of the clay, and the dryness of the season, no satisfactory specimens could be obtained. The prints retain no carbon, but simply show the venation of the leaves. North of Sea Cliff, along the shore of Hempstead Harbor, to the Glen Cove steamboat landing, is a series of clay beds out- cropping on the beach and dipping N. by E. about 10° ; these beds are of various colors, blue, yellow, reddish, white and black. The reddish clays contain fragments of a soft hematite, and one of the blue layers is overlaid by about two inches of lignite in small fragments. Other layers contain pyritized lignite and nodular pyrites, but it is impossible to determine the nature and order of these beds accurately, without extensive excavations. Dark clays, with pyrites, are also reported to occur in Carpenter's pits at a considerable depth. In the beds of decomposed gravel already mentioned, are many geodes of sand cemented together by hydrous and anhydrous sesquioxide of iron, containing a dark granular mass which analysis shows to consist chiefly of decomposed pyrites. The conclusion is therefore justifiable that the nodules of marcasite which once existed in the gravel beds Geology of Long Island. 349 have decomposed by oxidation, and the resulting ferric oxide , has cemented the sand about them into a hard crust, while the nodules in the clay beds which were protected from oxidation have remained unaltered. North of Glen Cove, clays of various kinds occur at East and West Islands, Dosoris', and at Matinnecock Village. At the East Williston brickyard, near Mineola, there is a local deposit of grey micaceous clay. The depth of this, where excavated, varies from 7 to 18 feet. The clay overlies white laminated sands, stained with limonite, the upper surface of the sand being cemented together for the depth of an inch by the yellow oxide. Over the clay is about six inches of black alluvial earth. At the brick-yard on Centre Island, in Oyster Bay, there is a deposit of brown sandy clay over a bed of more homogeneous and tougher clay. These beds undulate in an east and west direction or away from the shore, and the lower stratum contains shaly concretions or claystones. About a mile north of the brick-yard, it is said that a bed of white fire clay has been found at a depth of 25 feet under the drift and sand. A little west from the U. S. Fish Hatchery, at the head of Cold Spring Harbor, is a bank of stratified gravel 70 feet high. About 40 feet below the top of this bank is an exposure of laminated sand and sandy clay stained red, brown and yellow with oxide of iron, and a short distance below, a chalybeate spring issues from the bank. The clay deposit at Stewart's brick-yard, at Bethpage, is about 60 feet in depth. The surface stratum is a yellowish micaceous clay, the lower part being mottled blue and yellow. It probably was originally a gray or blue clay, its present yellow color being due to the peroxidation and hydration of the iron contained. Of this stratum there is about 35 feet ; below is about five feet of reddish sandy clay, and beneath this a blue-black sandy clay containing nodules of white pyrites. This stratum is about 25 feet deep and is underlaid by white sand. The beds are some- what disturbed and folded, the uppermost being slightly undu- lating, while the two lower appear to be raised in a fold trending nearly E. and W. I am indebted to Mr. Lewis for the following section obtained in digging a well at Jericho in 1878, on the premises of Mr. Jules Kunz : 350 Geology of Long Island. Surface loam, .... 15 ft. Drift, 36 ' ' Yellow gravel, - - - - 81 " Sand, 15 " Sandy clay with a carbonized branch, 4 " Yellow clay, 3 " Blue and gray sandy clay with pyrites, 30 " Micaceous sand, - - - - 14 " G in. Total, - - 198 ft. 6 in. From the same authority I have the following section of a well on Barnum's Island : Sand and gravel, stratified, - - ?0 ft. Clay and clayey sand with lignite, - 56 " Gravel and fine sand with clayey sand, 44 " Blue clay, clayey sand and silt, with lig- nite and pyrites, - - - 168 *' Total, - - 338 ft. In the third stratum, at a depth of 168 feet, a fragment of the stem of a crinoid was found which, together with a complete set of specimens from the well, is in the collection of the Long Island Historical Society. The fossil fragment is probably from some Palaeozoic formation, and has no special importance. At Crossman's brick-yard in Huntington, on the east shore of Cold Spring Harbor, we have the section shown in Fig. 2 of plate XXVII. The ridge which is intersected here trends a little E. of N. The section is as follows : Till and stratified drift, ... 10 ft. Quartz gravel, 45 " Red and blue "loam" or sandy clay, 20 " Diatomaceous earth, - - - 3 " Y T ellow and red stratified sand, - - 20 " Red plastic clay, - - - - 20 " Brown " " 25 " Total, - 143 ft. Geology of Long Island. 351 The bed of diatomaceous earth is of undetermined extent, and appears to be replaced a little to the east by a blue clay, which however contains some diatoms. It is undoubtedly equivalent to the bed of ochre which overlies the sand throughout the re- mainder of the section. At Jones's brick-yard, adjoining Cross- man's, there is a similar fold nearly at right angles to the first, but the upper portion has been removed by ice or water down to the sand. This stratum, which is yellow and brown in the north part of Crossman's yard, is dark red in the south end *and at Jones's. It appears to be mixed with a fine red clayey matter which separates on washing. The formation on Lloyd's Neck is similar to that at Cross- man's, with regard to the composition of the strata. On the north side of East Neck, at Eckerson's brick-yard, is a deposit of reddish clay underlain by brown clay very similar to that at Crossman's. To the west of this is a bank of white quartz gravel, while on the east is an extensive deposit of fine white quartz sand, laminated with red, yellow and brown waved streaks. The exact relations of these strata I was unable to determine, but from their analogies to other deposits I am inclined to con- sider the. laminated sand as the more recent, On the north end of Little Neck there is another large deposit of these laminated sands. At this point they dip S.E. about 15°. The following section given in Mather's Report Geol. of 1st Dist., p. 254, is more complete than any I could obtain at the time of my visit : 1. Loose surface sand, ------ n ft. 2. Dark colored loamy sand and clay, 3 3. Yellowish and reddish sand, waved lamina?, H (( 4. White sand tinged with yellow, 4 it 5. Sand similar but ditfering in color and direction of laminae, 4 a 6. Sand red, waved laminae, - 30 (( 7. White clay, 4 i i 8. White sand tinged with red or yellow, 4 (( 9. Clay, white like No. 7, 3 i ( 10. Sand, white like No. 8, 3 (( Geology of Long Island. 11. White clay like No. 7, 5 ft. 12. White sand like No. 8, 5 " Total, 70 ft. South of this deposit, about half a mile, is a clay-pit which is worked by Capt. Sammis, of Northport. Here the stratification is as follows : Surface loam and drift, - - - 3 or 4 ft. Sandy kaolin, 10 " Yellowish clay, 4 " Dark blue sandy clay, - - - - 15 " Dip, 5° W. The lowest stratum is separated into thin laminae by equally thin layers of sand, in which are numerous impressions of frag- ments of vegetable matter, but only one leaf-print has been found ; this is in the museum of the Long Island Historical So- ciety. It is a small, broadly elliptical leaf, about f in. long. In this same bed was found several years ago a shark's tooth which has been identified as Carcharodon angustidens or megalodon. It is difficult to determine the relation of this stratum to the other layers in the vicinity, but it is probably of the same period as the laminated sands, and seems to be identical with a bed which Mather describes as occurring on Eaton's Neck. (Geol. 1st Dist., p. 228.) At the brick-yard near West Deer Park, beneath the gravel and drift, is a stratum of flesh-colored clay, underlaid by dark blue clay containing pyrites. I was informed by the owner, Mr. Conklin, that in the centre of the hill of gravel the clay rises up in a fold. Between Bethpage and West Deer Park is a deposit of ferruginous conglomerate and sandstone formed by the solidi- fication of the stratified gravel and sand or yellow drift. This rock is very similar in composition and appearance to one which occurs in fragments in the glacial drift and contains vegetable impressions. At Provost's yard, near Fresh Ponds, are quite ex- tensive beds of brown sandy clay, reddish clay, and chocolate- brown clay, dipping from the shore. The red and chocolate Geology of Long Island. 353 clays are probably identical with the similar beds at Grossman's in Huntington. Lake Ronkonkoma is in a basin of which the bottom is about 210 feet below the high ground on the south. Its southern bank is composed of laminated sand streaked with oxide of iron, and the rest of the shore appears to be formed of the same material. At Oiine Keck Point are bluffs, 60 feet high, of sand and gravel containing masses of ferruginous sandstone of recent date. At Herod's Point the bluffs consist of fine yellow sand and gravel, slightly stratified, and dipping a few degrees south. Limonite concretions are here abundant. The bluffs at Friar's Head are about 120 feet high, and consist of yellow stratified sand with pebbles. Over these is a dune of yellowish drifted sand 90 feet high, making the total hight of the peak 210 feet. On the west side of Bobbin's Island is an exposure of blue clay overlaid by laminated ferruginous sand. The depth of this clay-bed has not been determined, but it is similar in appearance and quality to some of the clays near Huntington, especially at Grossman's brick-yard. A chalybeate spring issues from the laminated sand on the shore, a little to the south of the clay-pit. The clay bed appears to dip southward about 10° throughout the whole extent of the island. Near the railroad between Southold and Green- port are two brick-yards. At the more easterly of the two there are various deposits of stratified sand and clay very much folded and tilted. At this place the section exposed shows two parallel folds, the axes of which trend a little N. of E. The upper stra- tum of brown clay contains angular fragments of mica schist. (See fig. 3.) At the other yard they are working a bed pre- cisely similar to that just mentioned and also containing angular fragments of rock. On Shelter Island are high hills of gravel with a thin covering of till ; the highest point is about 180 feet above tide. West of the village of Orient is a narrow isthmus of sand beach and salt meadow, about a mile and a half long and not more than ten feet above tide. East of this, on the north side of the peninsula, Brown's Hills extend along the shore for a mile and a half, the highest point being 128 feet above Long Island Sound. The structure of these hills is difficult to determine, as extensive land slides have occurred, and the slopes are covered with grass and bushes. One exposure gave the following section: Geology 0/ Long Island. Drift, - 3 feet 8 " Fiue yellow Band, - M icaceous clay, Micaceous sand. - 1 " 25 " Total, :37 feet. The micaceous sand occurs at the foot of the bluffs along the shore in this vicinity. It may also be seen half a mile west of Orient, in a bank by the road-side. On Gardiner's Island a very complete section is exposed on the southeast shore, which exhibits the strata to the depth of about 250 feet (see figs. 4& 5). Here stratified sands and clays of vari- ous kinds and colors are raised up in t wo parallel anticlinal folds. In the southerly fold, the stratum is a light red, fine, plastic clay, very similar to that at Grossman's in Huntington ; it is here ex- posed to a depth of about 100 feet and is upheaved at a high angle, its outer slopes dipping about 45°, while along the axis of the fold the laminae are vertical. The northern anticlinal has about 15° dip on either side, and in its north slope is a stratum of yellowish clayey sand containing a bed of post-pliocene shells, at an average hight of 15 feet above the sea. The formation which is here brought to view probably underlies the whole of the island, as it is exposed at various other points. On the north and southeast shores the beds are very much disturbed and folded, and the surface of the island is raised in a series of par- allel ridges corresponding in position to the folds and having a general trend of N. 65° E. The highest point on the island is 128 feet above the sea ; the bluffs along the shore being from 25 to 70 feet high. The fossiliferous stratum is about 20 feet hmg and 4 feet thick, containing an abundance of shells, most of which appear to have been crushed by superincumbent pressure. The locality was visited in 18G3 by Prof. Sanderson Smith, who describes the bed as 150 to 200 feet long. Prof. Smith has iden- tified the following species* all of which are recent : ^Yassa trivittata, N. vibex, Fusus decemcostatus, Purpura lapillus. Coin nib ell a lunula, ^Natica duplicata, JY. heros, Ghemnitzia * Annals N. Y. Lyceum of Nat. Hist.. Vol. VIII, 18G5. f Species also collected by the writer. Geology of Long Island. 355 interrupta, Crepidula fornicata, *C. plana, Tornatella puncto- striata, Bulla canaliculata, * Venus mercenaria, * OstreaVirgini- ana, Pecten Islandicus, P. Magellanicus, Area transversa, A. pexata, Cardita borealis, *Astarte sulcata or undata, Mactra la- teralis, La cin a radula, *Mya arenaria ; fragments of a Bala- aas ; a coral, Astrangia Dame. Napeagne Beach, east of Amagansett, is three miles long and one quarter of a mile broad, consisting entirely of white quartz sand. Along the shore on the north and south are dunes of drifted sand 20 or 30 feet high, but the main portion of the beach probably averages less than 10 feet above the sea. East of the beach, the country for twelve miles to the end of Montauk Point, is chiefly a terminal moraine, and as such I have already briefly described it. Historical Geology. Having thus reviewed in detail the various strata underlying the drift, we come now to consider their age and history. AVith- out attempting to decide the geological equivalence of the crys- talline rocks at Astoria, we will discuss the unsolidified deposits which have just been described. From the posiiion and strike of the Cretaceous strata in New Jersey and Staten Island, it has been surmised by geologists that they underlie Long Island throughout the whole or a portion of its extent. The locality at which the strata most resemble the Cretaceous beds of New Jersey is Glen Cove, where the clays already described are probably of this age. If the Cre- taceous formation extends under the whole of Long Island it must occur at a very great depth, since deep sections at points east of Glen Cove do not reveal its presence. In regard to this formation and the following, it should be un- derstood that sufficient data have not yet been obtained to war- rant an attempt to map out their extent. The only exposures are in vertical sections along the shore and in various clay-pits or similar excavations ; and there being an immense amount of quaternary material overlying them, no satisfactory degree of accuracy can be as yet attained in this regard. * Species also collected by the writer. Geology of Long Island. The Tertiary strata of Long Island cannot as yet be identified with m iuli more certainty than the Cretaceous. From their character and position we may surmise that the brown and red plastic clays of Huntington, Gardiner's Island and else- where, belong to the age in question, but we have no palaeon- tological evidence except from the shark's tooth found on Lit- tle Neck, which would identify the bed in which it occurred as Eocene or Miocene. The stratified sands and gravels however, which overlie the supposed Cretaceous and Tertiary beds, and in turn are overlain unconformably by surface drift and till, we may accept as Post-pliocene, from the analogy of their composi- tion, structure and position to the deposits of Gardiner's Island and Sankaty Head, of which the fossils determine the age beyond question ; unfortunately, however, there is no unconforrnability, to show where the Tertiary ends and the Quaternary begins. At various times and places, fossil shells and lignite have been found on Long Island. J append a synopsis of a list of these compiled by Elias Lewis, Jr., from Mather's Report and from other sources : Geology of Long Island. 357 Mature of Fossil. Locality and Date. Recent shells. Ft. Lafayette. Pvrula, clam, New Utrecht, oyster. Clam and oyster Well in Prospect Park, shells. Clam and oyster Well at Flatbush Alms shells. house. 2 Petrified clams Flatbush. Depth. -53 ft. -67 ft. 40—50 feet, 100 ft. flxogyra costata, Bet, Brooklyn and Flat- 60 ft. ' withgr'n s'nd. j lands. Oyster shells. Hio:h grounds in Brook- 73 ft. > I lyn. Clamshells. Fort Greene, 1814. 70 ft. \Anomiaephip- Cor. Jay & Front Street, 15 ft. j pium. Brooklyn. Oyster shells. . Nassau Gas Light Co., 127ft. 6 in Williamsburg. Log of wood. Bus'hwick. 40 ft. Shells. jNewtown. 70 ft, Clam shells. East New York. 80 ft, Wood. 3 miles W. of Jamaica. 25 ft. Authority. E. Lewis, Jr. Thompson's Hist. of L. I. E. Lewis, Jr. W. J. Furman An- tiquities of L. 1. Dr. J. C. Jay, Ann. of Lyc. Nat, Hist., 1842. |Furman's Antiqui- I ties. E. Lewis, Jr. Thompson's Hist. Clam and oyster Lakeville. I shells. C 1 a m . oy st er and La ke vil 1 e . i scallop shells.' 85ft. above^ tide 140 HenryOnderdonk. tol60tf. Jr. 2d. 21. 22. 2:!. U 25. 26. 27. 28. 29. 30. 81. 32. 33. 34. Wood. Oyster shells. Shells. Stem of Crinoid. Lignite. Wood. Wood. Carb'nized wood Lignite. Lignite. Wood. CareJiarodon an- gustidens. Log of wood. Clam shells. Shells. Bones of Masto- don. Venus mercenaria Great Neck, 1813. Manhasset, 1813. Bet. Manhasset and Ros- lyn. Barnum's Island. Near Westbury. Hempstead Plains, 1804. Sea Cliff. 1845. Glen Cove, 1834. Jericho, 1878. Cold Spring. Little Neck. Strong's Neck. Shelter Island, 1898. Wells at Amagansett. Jamaica Pond, 1846. 200 feet above tide. 47 ft. 50 ft. 78 ft. 140 ft. 168 ft. 100-383 ft. Great d'pths 100-108 ft. 94 ft. 40 ft. 96 ft. 110 ft. 40 ft. 57 ft. J. H. dieu. L'Homme Yaphank. Osh vjiniana S-dg Harbor, 1864. ( 100 feet ■ - above tide. ( 20 ft. 180 ft. above ; tide. Thompson's Hist, E. Lewis, Jr. Thompson's Hist. D wight's Travels. Isaac Coles. E. Lewis, Jr. Thompson's Hist. P. B. Sills. Thompson's Hist. E. Lewis, Jr. E. Lewis, Jr. Dr. Cook. Geology of Long Island. In view of the fact that we have nowhere else any good evidence of a change of sea level amounting to 200 feet in t lie vicinity of New York during the Glacial epoch, we can only account for the high elevation of some of these fossils by supposing that they, with their containing beds, have been raised to their present position by glacial action in the manner I shall describe. Of the physical conditions under which the presumed Creta- ceous and Tertiary beds were deposited, we know nothing; though it is reasonable to conclude that they consist of the debris of New York and New England rocks carried down from the highlands and deposited along the coast by rivers or by other agencies of transportation. The overlying deposits of strati- lied gravel, sand and clay, part of which, as before stated, arc equivalent to the "yellow drift" of New Jersey, are also difficult to account for. They consist largely of transported material from older beds, and by their structure indicate that they have been formed by swift currents which carried along and deposited coarse and fine material mingled together. Their fossils, so far as we know, exclude them from the Tertiary, and they underlie the drift unconformably, although by definition the Glacial pe- riod begins the Quaternary age. If, however, we assume in the Quaternary a succession of glacial epochs, or alternate periods of advance and retreat of the ice-sheet, as suggested by Croll's theory, we can explain the origin of the beds in question by supposing that during the epoch of glaciation immediately preceding their deposi- tion, the ice-sheet did not reach so far south, while the floods of of the succeeding warmer epoch modified and spread over the sea-bottom the drift thus formed. In order to appreciate more exactly the relations of these Post- pliocene beds to the glacial drift, it will be necessary to consider some very interesting phenomena. Along the north shore of Long Island from Flushing to Orient Point, are exhibited most striking evidences of glacial action. We find the stratified era- vels, sands and clays upheaved by the lateral pressure of the ice- sheet and thrown into a series of marked folds at right angles to the line of glacial advance, which, judging from the grooves and striae on the rocks of New Y r ork and Connecticut, was about S. 30° E. The glacier having thus crumpled and folded the un- Geology of Long Island. 359 derlying strata, it evidently rode over them and continued its course southward, pushing before it an immense mass of sand and gravel, together with debris from the rocks of New York and New England. The theory that Long Island Sound was a body of water pre- vious to the arrival of the ice-sheet, would seem to be sustained by the character of the detritus deposited by the ice on Long- Island. From Brooklyn to Whitestone, where the sound is nar- row, the till or drift proper is quite conspicuous ; east of this it becomes less noticeable, and beyond Eo^lyn, as before stated, it does not again occur in abundance until we reach the vicinity of Greenport, where the Sound again grows narrow. This seems to be due to tl^e fact that the finer debris of the northern rocks was carried along imbedded in the lower part of the glacier. The channel of the East Eiver, owing to its narrowness, was filled up and passed over, the till being deposited to form the range of hills near Brooklyn ; but in crossing the broader part of the Sound, the ice probably lost the greater portion of its load of till, and only carried over the boulders which were on the sur- face or in the upper part of the glacier. On reaching the north shore of the island the alluvial gravel and sands were scooped up and pushed forward in front of the ice-sheet, to form the " mo- raine," and the boulders, when the ice melted, were deposited on the surface. The map shows that the principal bays on the north shore penetrate the land in a direction identical with that of the advance of the glacier. We may reasonably infer from this fact, that these indentations were ploughed out by project- ing spurs of ice, and the inference is supported by the fact that the bays are walled in by high ridges which have been formed largely through the upheaval of the beds by lateral thrust. The best example of this displacement in the formation of a bay is shown in the section at Grossman's clay-pit in Huntington, (Fig. 2) which I have previously described. Harbor Hill, which stands at the head of Hempstead Harbor, is 384 feet high, and chiefly consists of gravel and sand more or less stratified. Jane's Hill, four miles S.S.E. of the head of Cold Spring Harbor, is 883 feet high, and is composed of the same materials. In the vicinity of each of these hills, moreover, there are other ridges and elevations averaging about 300 feet in height. Southeasterly 360 Geology of Long I si a nil. from Huntington Bay we have the Dix Hills and Comae Hills rising about 250 feet. Southeast of Smith town Harbor, we have Mi. Pleasant, 200 feet in height ; in a like direction from Stony Brook Harbor, are the Bald Hilly, also 200 feet high. Again we have Beulands Hill, which is 340 feet m height, and has the seme general bearing from Port Jefferson Harbor. About South 30° East from Wading River, where there is quite a deep valley, we rind Terry's Hill, 175 feet high. South of Great Peconic Bay rise the Shinnecock Hills, 140 feet, and southeasterly from Little Peconic Bay are the Pine Hills about 200 feet high. Prom these instances it will be seen that the areas of high elevation bear a very marked geographical relation to the deep indentations of the coast. That this relation is due to glaciaJ action, seems more than probable, as it can scarcely be an accidental coinci- dence that the highest hills on the island should be in a line with the deepest bays on the northern coast, and that the course of these bays should coincide with that of the glacier. At every point along the north shore where a section of the strata is exposed, the flexed structure of the beds under the drift may be observed. On Gardiner's Island, these folds are remark- ably prominent, the surface of the island being broken with nu- merous parallel ridges having a general trend N. G5° E. These ridges correspond to folds in the stratified beds, which the sur- face drift overlies unconformably. and as they are at right angles to the line of glacial advance it is difficult to conceive any agency which could have produced them except the lateral thrust of the ice-sheet, Unless these phenomena can be referred satisfactorily to some other cause, and of this I very much doubt the possi- bility, we have in these folds a strong argument against the ice- berg theory, as it seems evident that a mere drifting berg could not develop sufficient progressive force to do the work here shown. A similar origin may be attributed to the ranges of hills which form the so-called "back-bone" of the island; as t heir structure indicates that they have been formed partly of gravel and sand transported from the north shore, and partly through the upheaval of the stratified beds by the friction of the moving mass of ice. As the downward pressure of the glacier was about 450 lbs. per square inch for 1,000 feet of thickness, and its progressive force was only limited by the resistance of the ice, it Geology of Long Island. 361 is quite reasonable to assume it capable of producing such a re- sult. At one locality, West Deer Park, this is manifestly the case, and I have no doubt that in time it will be found generally true. The numerous springs that issue from the hillsides along the north shore also lead one to infer that the substratum of clay has been raised up in the centre of the hills. The occurrence of the springs might be accounted for hypothetical^ by supposing that these hills are the remnants of unequally eroded horizontal strata of sand underlaid by clay ; but this we know is not the case. Mr. Upham, in his discussion of the moraines, attributes all the stratified deposits to diluvial and alluvial action in the Cham- plain period, to which the Gardiner's Island deposit has been erroneously referred. He also concludes that the more southern drift hills, which are from 200 to 250 feet high, were formed in ice-walled river-channels formed upon the surface of the gla- cial sheet when rapidly melting. That this process has taken place in some cases, is quite probable, as there are undisputed kames in certain places, but from the analogy of the deposits in question to the others described, I am inclined to refer them generally to the same causes. The changes which have occurred on Long Island since the retreat of the glacier, have been mainly topographical, and un- questionably very extensive. The streams of the Champlain epoch carried down the drift from the morainal hills and distri- buted it on the plain to the south, forming in many places local beds of clay. In the vicinity of Bethpage and elsewhere, are hillocks of stratified sand similar in appearance to the New Eng- land kames. The valleys mentioned above, which have been ex- amined by Elias Lewis, Jr., are unquestionably the channels of streams resulting from the melting of the glacier. The coast line of the island is rapidly changing, on account of the action of the swift westerly cm-rents which are wearing away the east end and depositing the sediment along the north and and south shores. By this means the bays which open into the Sound are rapidly becoming shallow. The Great South Beach is also an evidence of the action of the waves and currents in changing the outline of Long Island. We have moreover abund- ant evidence that the south shore has been gradually sinking. Geology of Long Island. This subsidence probably began in the later Quaternary and may be still continuing. Economic Geology. Magnetite : this is the only metallic ore found on Long Island, and occurs almost everywhere on the benches in the form of sand. It is not, however, sufficiently abundant in any one locality to render its collection profitable. A company was started some time since for the purpose of separating the ore, in the vicinity of Quogue, from its associated quartz and garnet sand by means of powerful electro-magnets, but the enterprise proved unsuc- cessful. Iron Pyrites in its white variety, or marcasite, is common in the lower clay-beds, but does not occur in sufficient abundance to pay for utilizing it. Lignite occurs only in small quantities and usually at great depths. Peat of an inferior kind, composed of the matted roots of grasses and other plants, occurs at the heads of most of the bays on the south shore, but is not used to any extent. Although not productive of any of the valuable minerals, Long Island may be considered peculiarly rich, from the fact that almost the whole of the island can be utilized in the arts and trades. Its sands and gravels are of every kind in use, and its clays are suited for the manufacture of fine grades of brick and pottery. The former materials are largely shipped from Port Washington and the vicinity, for building purposes. The most extensive deposit of fine pottery clay occurs at Glen Cove, on the premises of the Messrs. Carpenter. This clay is very plastic and burns a light cream-color. The friable quartz pebbles described above, produce when ground the finest quality of white sand for glass and pottery. The deposit of kaolin is also unsurpassed. In addition to these materials, this locality furnishes fire-sand for pottery, grey and blue pottery clays, and an excellent fire-clay. The next locality of note is Huntington. In this town is an immense deposit of the finest brick-clay, upheaved to such an elevation that it is easily accessible. The beds are worked at Geology of Long Island. 363 Grossman's and Jones's brick-yards, and extend throughout Lloyds' Neck. Between Huntington and Cold Spring a large deposit of white pottery-clay has been worked for many years. The brick-clay extends east over ten miles, and is worked at Eckerson's yard on East Neck, and Provost's at Fresh Ponds. At Eckerson's and at Sammis's pits on Little Neck, are immense deposits of fire-sand which extend over Eaton's and Lloyd's Necks. A little west of Greenport are two brick-yards at which a bed of glacial clay is being worked. Between these two yards is a bed of mottled blue clay used for making flower pots. The most ex- tensive deposit of all, however, is that on Gardiner's Island. This clay is unsurpassed for the manufacture of bricks, and from the abundant supply of moulding-sand and the easy accessibility of the locality by water, must in time prove an important source of revenue. DESCRIPTION OF PLATE XXVII. Fig. 1. Scale 1 ixcn=60 feet. Section at Carpenter's clay-pits, Glen Cove, looking east. a. Glacial drift. b. Yellow sand. c. Friable quartz gravel and sand. d. Fire-clay. Fig. 2. Scale 1 incii=60 feet. Section at Crossman's brick-yard, Huntington, looking north. a. Glacial drift. b. Quartz gravel, stratified. c. Sandy clay or " loam," — upper half yellow, lower half blue. (1. Diatomaceous earth mixed with clay. e. Yellow sand, stratified. /'. Tied laminated clay. g. Brown laminated clay. Fig. 3. Scale 1 inch=30 feet. Section at Fulmer's brick-yard, Greenport, looking north. a. a. Reddish glacial clay, with fragments of mica schist. b. Red clay. c. Micaceous sand, laminated. 364 Geology, of Long Island. Figs. 4 & 5. Scale 1 inch=00 feet. Section on southeast shore of Gardiner's Island, looking west. a. Glacial drift. b. Laminated white sand. c. " white sand streaked with limonite. d. " yellow and blue clayey sand. e. " white and yellow sand. /. " grey and yellow sand. {j. " yellow sand with blue clay. h. " gre}^ sand with red clay. i. " red clay and grey sand. j. " grey sand with red clay. h. " sand, top streaked with limonite. I. Dark greenish clay. V " " " somewhat granular. m. " grey clay and sand, laminated. m' Beach sand streaked with limonite. ii. Laminated sand, stratification obscured by a slide and possibly in- terrupted by a fault, o. Laminated greenish sand. p. " white and yellow sand. r. " green and yellow clayey sand. s. " reddish clayey sand with fossil shells. t. Dark greenish clay. u. Fine laminated sand. PLATE XXVIII. Map of Long Island, showing the southern limit of glacier action. (Pre- pared on the basis of the U. S. Coast Survey Map.) Anna i.-. Vol. III. No. 11. Plate XXVII.