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Mey ce gs ty aes} PLEISTOCENE MARINE SUBMERGENCE 13 5 Evidence from the Connecticut Valley and Long Island Plate 3 The Connecticut valley, like the Hudson, is filled with clay and sand plains, deltas, terraces and occasionally beaches due to deep standing water. The valley held an estuary contemporaneous with the Hudson-Champlain estuary. The facts for the Connecticut valley have been concisely given in a former publication (69). The isobases in plate 9 were originally drawn to connect points of equal altitude on the marine shores of the Connecticut and the Hudson valleys; and they are found to be in accord with all knowl- edge to date. An examination of Long Island shows that it was also sub- merged to the extent indicated by the isobases; and the facts are on record in a recent paper (55). The proofs of Long Island sub- mergence, especially at the eastern end of the island, are so abundant and evident that it seems strange they should have been so long overlooked. It will be found that these isobasal lines of plate 9, with some greater curvature, will mark the amount of the Postglacial submer- gence and subsequent uplift of New England and the Maritime provinces. 6 Postglacial Submergence of New England and Canada It is well known that New England and eastern Canada have been elevated since glacial time. The occurrence of abundant marine fossils in extensive areas and far above present sea level is indisputable proof of submergence. But the extent of the sub- mergence has probably not been appreciated, and certainly has not been accurately determined. The Canadian geologists have recorded many evidences of stand- ing waters and many localities of marine fossils at high altitudes in the St Lawrence and Ottawa valleys, and eastward, to which the geologists of the United States have not given sufficient attention. The occurrence of marine fossils far over present sea level and other evidences of deep glacial and postglacial submergence caused the Canadian geologists to place some overemphasis on the work of floating ice and icebergs in explanation of the glacial phenomena. But it must be admitted that in the fact of deep marine waters over eastern Canada the Canadian students had very good basis for their ice-flotation theory. The recognition of the work of the Labradorian ice sheet over 14 NEW YORK STATE MUSEUM most of the glaciated territory as that of land ice has resulted in the neglect, especially by the geologists of the United States, of the evidences of deep marine submergence in Canada and New Eng- land. With the emphasis on land glaciation we have discounted or ignored the former observations of the “ diluvialists” and “ice- bergists,” and have minimized the amount of land depression during the removal of the ice sheet, and have neglected its study. The writings of Robert Bell, J. W. Dawson, R. W, Ells, Robert Chalmers and A. P. Low contain much reliable data concerning the occurrence of marine organisms at high altitudes and of broad sand plains and extensive deep clays, all pointing to widespread and deep oceanic waters. A few of the writings of the authors named above, and of A. P. Coleman for the Ontario district, are listed im the bibliography. A good resumé of the studies up to 1897 is given by Ells (143). The Canadians found evidence of submergence to 1000 feet or over as far west as Montreal and the Ottawa valley. Sir William Dawson’s claim of shore features at a height of 750 feet on Mount Royal is probably true, for it now appears that the marine waters passed over the summit. The marine plane is 800 feet at the south end of Lake Memphramagog. 7 Testimony of Former Students All the earlier geologists in referring to the features of the Hud- son valley assumed their estuarine character. As early as 1843 Mather listed the larger deltas north of Newburgh and Fishkill, and in his summary said: “It is considered evident that a vast inland sea once occupied what may be called the basin of the St Lawrence and Hudson valleys since the period of the drift deposits.” (28, page 157). | In 1891 F. J. H. Merrill published two papers in description of the Hudson deposits and recognized their estuarine character, and the delta origin of the Albany-Schenectady plain. His figure for the submergence at New York City was 80 feet, which is correct for the north end of Manhattan island. In this paper he noted the terraces on Staten island, and correlated them with the broad sand plains of the south side of Long Island and with the plains in the Hudson valley. He seems to have been the first geologist to appre- ciate the relationship of these detached features. And he showed his insight and appreciation of the problem by giving the first explanation, and a true one, for the absence of beaches. This ‘point will be considered later. PLEISTOCENE MARINE SUBMERGENCE 15 In 1891 and 1892 Heinrich Ries published descriptions of the massive clays of the Hudson valley (33, 34), from Croton Point to Albany, and in later publications (35, 36) gave detailed description which proved their estuarine origin. N. H. Darton, in 1894, published descriptions of the Pleistocene deposits of the counties of Albany (38) and Ulster (39). He also regarded the deposits as the “products of a submergence at the close of the Glacial epoch,’ and drew a map of the “Champlain submergence” of the Albany district (38, page 359). An admirable description of the delta of the Catskill in the Hud- son estuary was published by W. M. Davis in 1892 (37). He clearly recognized that the Champlain submergence involved the Hudson valley. His value for the summit of the Catskill delta, about 275 feet, is precisely correct, as shown by the profile, plate 10. In his Glacial Geology of New Jersey, R. D. Salisbury describes the features due to Postglacial submergence, and says that the water plane has about 100 feet altitude at the north border of the state. This is in accordance with the plotted profile. Some later writers on Long Island stratigraphy and glacial beds have assumed or asserted an uplifted attitude of the lower Hudson district, but have passed over the earlier writings and entirely ignored the clear and positive evidence of submergence. For the Connecticut valley the detailed studies of B. K. Emerson show conclusively that the high sand plains and the extensive clay fields were the products of standing water, which he called “ Con- necticut lakes,’ and could not be the results of a swollen river (66, 67). His altitudes for the water plane on the north and south lines of Massachusetts are values used in the map of isobases, plate 9. Students of the Champlain section of the great valley have made too much distinction between the lower deposits which carry salt- water fossils and the upper plains and terraces without fossils. There is probably also a psychologic factor involved. The invoking of “glacial waters’ may have been due in part to a tendency to utilize the new thought in Pleistocene geology, the existence and effect of ice-dammed waters. The recognition of glacial lakes came during the seventies of the past century,t and has been a most useful conception. But it was always incumbent on an author » who postulated glacial waters to find the control, or locate the out- let and correlate the levels and beaches with their outlets. There * Proc. Amer. Assn. Adv. Sci., 47: 285-287; Amer. Geol., 22: 183-86. 18098. 16 NEW YORK STATE MUSEUM has been too much reference of static water features of unknown relationship to “glacial” without proving the fact. The writer can not be charged with any prejudice against glacial lakes; but he has named no lake without knowing its control. ABSENCE OF MARINE LIFE IN THE HUDSON VArrEy No well-attested marine fossils have been found in the Hudson valley, or in the higher water-laid deposits of the Champlain valley. Partly for this reason the appeal has been made to glacial waters. The tides are felt in the Hudson “ river” to Albany, but brackish water reaches only to about Poughkeepsie, and salt water organisms pass up the Hudson only to the Highlands. The problem relating to the Pleistocene waters becomes simply the exclusion of salt water. When the receding ice front was slowly giving place to the deep estuarine water in the Hudson valley these were loaded with silt, for the land drainage was gathering in the freshly laid mantle of drift and the melting glacier was contributing its load of rock flour. The thick clay beds resting on the till or glaciated rock are suffi- cient evidence. The waters were cold and muddy, and unfavorable to nearly all forms of marine life. Another deterrent factor was the volume of fresh water. The ablation of the glacier probably supplied, even in the lower Hud- son, sufficient fresh water to exclude the salt-water fauna. And when the ice front receded to Albany the flood from the Ontario basin swept into the Hudson, and for long ages subsequent all the drainage now represented by the St Lawrence, plus the water from the melting of the ice sheet for a thousand miles on the west, were forced south through the narrow passes at Whitehall, West Point and the Palisades. And during this stage the wave uplift of the glaciated territory had probably lifted the lower Hudson valley to nearly its present height. Such uplifted condition is indicated in the maps, plates I and 2. When the ice front reached Covey hill the outdrainage of the Laurentian basin was merely shifted from the Mohawk pass to the Covey pass, and the cold, fresh waters still passed south. When the ice front recession let Lake Irqquois fall and blend into the sea-level waters, so that the latter occupied the Ontario basin (see plates 2, 3, 5), the ultimate outlet was the same. And this south- ward flow through the Hudson of all the glacial waters, and the land drainage, from Duluth to Maine, persisted until the waning of PLEISTOCENE MARINE SUBMERGENCE Wf the ice margin on Maine and New Brunswick opened a strait to the St Lawrence gulf. Then, but not before, salt waters entered the lower St Lawrence valley, and slowly worked up into the Cham- plain valley. However, by the time salt water reached the Champlain valley a decided change in the physiography had occurred. During the many thousands of years in the history_sketched above land uplift had been in progress in the areas relieved of the burden of the ice cap, and the earlier shore lines of the Hudson-Champlain had undoubtedly been raised much above the waters. How much eleva- tion had occurred before salt-water life entered the Champlain waters we can not now determine. A lifting of 300 feet at Fort Edward, of the 450 feet total rise, would have entirely broken the connection between the Champlain and the Hudson waters. And long before the connection was broken the long stretch of the narrow strait with its receipt of land drainage from a large terri- tory from both Vermont and New York would have discouraged marine life from making the southward journey. It would appear from the known history and the probable physical conditions that marine fossils should not be found in the Hudson valley or in the higher Champlain deposits. PUBSIIINGE Ole IBA CiaveS) ION IMsUs, SIAN aING ISIE UNG) REGION No continuous beaches (bars, cliffs and terraces) would be expected in the narrow stretches of the Hudson valley. But the absence of distinct, positive beaches on the New Jersey coast, Staten Island and Long Island has been a cause of perplexity even to those who accept postglacial submergence. ‘The necessity for beaches on a submerged land has been tacitly assumed by most writers. It is believed that this assumption is wrong. Merrill realized this difficulty, and was the first writer to sug- gest an explanation (30, pages 105-9). In a recent paper the writer quoted liberally from Merrill’s argument (55, pages 299, 301), but for the present purpose it may be sufficient to quote the conclusion of his analysis of the mechanics of beach erosion: : for the present purpose which is simply to point out the fact that a land surface in process of subsidence or emergence may be subjected to wave action without being incised with distirict shore lines, and also that wave action may produce an inclined plane as well as a terrace or base level. It is therefore evident that submergence would not leave a deeply cut shore line as its record unless the rates of land movement were so adjusted as to 18 NEW YORK STATE MUSEUM permit of it. In fact no very distinctly cut shore lines are to be found on the drift about New York even at an altitude corresponding to that of the Hudson estuary deposits. Apart from the still-water deposits the 80-foot postglacial depression about New York can only be traced by change of surface slope and material at this level. .Even these two varieties of evidence are not always coexistent. Beach phenomena have scarcely been recognized on territory of New England which was ‘almost certainly submerged during the removal of the ice sheet. Professor Shaler explained the lack of beaches on Martha’s Vineyard and Nantucket by the too rapid Iift- ing of the shores.* To the above sound and quite sufficient argument something may be added. On the open sea shores of Long Island and Staten Island there was an inhibiting factor besides the rising of the land, namely, the tidal fluctuations of level. A very little change in the water level may effect large difference in the force and direction of shore currents and effectively change the plane of bar construction or of beach erosion. However, there is an erosion cliff on the face of Staten island and on the west end of Long Island as far as Lake Surprise, 6 miles beyond Jamaica. This has been recognrzed as a possible beach, and Fuller has given a clear description of it as “ the great inland cliff of western Long Island” (54, page 54). He clearly proves the origin of the cliff as by marine erosion, but makes it earlier than the end of the Wisconsin epoch. But the altitude and slant of this and the Staten Island cliff agree with our map, plate 9. The above discussion relates particularly to erosional shore fea- tures. Constructional features, bars and embankments are more common and under favorable conditions more readily produced by waves. It might properly be expected that bars and beach ridges would appear, especially on the broad sand plains of the south side of Long Island. The lack of such phenomena has been a strong point for these who assert nonsubmergence. Students of ancient shore lines find gaps along beaches that are commonly strong. It requires considerable time for wave and shore currents, even at steady levels, to bridge unfavorable stretches. On shores as strong as those of the glacial Lake Warren and Lake Iroquois localities are found with only smooth, wave- washed slopes comparable to the low surfaces of Long Island and Staten Island. Following the removal of the sheet the land rose * Geology of Martha’s Vineyard. Seventh Annual Rep’t, U.S. Geol. Sur- vey, 1888, p. 321. PLEISTOCENE MARINE SUBMERGENCE 19 rapidly (or slowly, according to mental viewpoint) and the mechani- cal conditions produced by the constant shifting of the zone of wave attack were unfavorable for bar construction, especially in tidal waters, the same as for erosional work. And there is another deterrent factor which has not been recog- nized im this study, of perhaps even more effect than the change of water level. Plates 3-5 show the location of beaches about the Covey Hill salient. The summit marine shore is very strong on the Champlain side of the highland, being represented in places by remarkable vertical series of strong cobble bars and gravel banks as far south as the parallel of Port Kent, the south edge of the Dannemora quadrangle, plate 8. On the lower slope of Covey hill at an elevation of 525 feet, 215 feet below the summit shore, is a splendid series of heavy cobble bars, which was formerly thought to represent the marine sumnut. The top of this inferior series of bars lies at Covey Hill post office, and curves westward about the hill at Stockwell, Maritana and Franklin Center, and enters New York north of Chateaugay. When we follow this shore line south from Covey hill we find a notable set of bars one mile south of the international boundary, and a good display at Sciota and also west of West Chazy. But as we pass farther south, on to the Danne- mora quadrangle the shore features of the Franklin Center series practically disappear. On the north edge of the sheet, 2 miles northeast of West Plattsburg, this level of the lowering waters is only a rolling plain of sand, like many other broad stretches in the submerged Champlain region all devoid of beach phenomena. But the waters stood here just as long as they did at Covey Hill post office and Franklin Center, and the conditions of slope, exposure, open sea, etc., were just as favorable for bar-building. What is the explanation? Apparently the difference was due to the char- acter of the material withm the grasp of the waves. All the bars in the district are coarse gravel or cobble, never sand. Along the marine summit the glacial drainage built wide tracts of very coarse material, which the waves quickly piled into bars. When the gravel tracts were lifted above the waters and the waves found only sand they were unable in the time permitted to bank it at any particular level. All the strong beaches of the sea-level waters of the Hudson, Champlain and St Lawrence valleys are coarse material, never sand. Even the steadier level of Lake Iroquois produced only cobble bars in the stretch of shorter lived waters between Water- 20 NEW YORK STATE MUSEUM town and Covey pass. On extensive delta plains with superabund- ance of sand all beach features are wanting. Even where there was considerable coarse material an abundance of sand appears to have inhibited bar construction. It appears that wave work can much more quickly pile cobble into ridges, but that sand requires more time. The small sand bars that have been found were in sheltered localities with weak wave action. The combined deterrent effect of shifting water level, tidal fluc- tuation, and dominance of sand or silt seems to be, in the light of facts from other districts, sufficient explanation of the absence of high-level beaches in the sandy areas along the sea coast. EXPLANATION OF MAPS AND DIAGRAMS PEALE Si Plates 1 and 2. These maps are im completion of the series of maps showing the recession of the ice sheet over New York State, published in New York State Museum Bulletin 160, plates 9-17. Plate 1 shows the relation of the ice margin to the Iroquois and marine waters during the second, and closing, stage of the glacial Lake Iroquois, with the outflow at the pass on the international boundary, on the south side of Covey hill. Lake Iroquois is here at its greatest extension. In the earlier maps the waters in the Hudson-Champlain valley were wrongly represented as glacial. This is now known to be an error. The low attitude of the land at the time of the ice removal permitted the oceanic waters to enter the great valley and per- sistently lave the receding ice front. At the time represented in these two maps the sea-level or estuarine waters had become con- tracted, diminished in depth and width, in consequence of the uplift of the land, which as a progressive wave had passed north- ward, subsequent to the ice removal. Plate 3 shows the full amount of the land submergence and the greatest extent of the sea-level waters. In the Hudson valley it is probable that the land uplift never overtook the retreating ice front; but it is possible that some little uplift occurred in the Champlain district while the ice had the position indicated in plate 1. The effect on the shore line will be considered under plates 5, 10. Plate 2 represents the ice margin as removed from Covey hill, thus allowing equality of level between the waters of the Cham- plain and St Lawrence valleys. Lingering points of the ice lobes are hypothetically depicted on the north edge of the map. PLEISTOCENE MARINE SUBMERGENCE 21 The difference in time between the stages shown in plates 1 and 2 is relatively small, and no attempt is made to show the slightly greater constriction of the valley waters in the Hudson during the second stage. Plate 3. This map does not show the geography at any moment of time, but the greatest submergence and widest extent of the sea-level waters in all districts, as indicated by the summit shore features. The land uplift as a progressive wave, moving north- ward, produced constant reduction of the estuary on the south, while near the ice front the land was at, or near, its greatest depres- sion and the waters at their maximum extent. This is illustrated in plates I and 2. The amount of marine submergence and postglacial uplift is shown approximately by the lines of equal uplift, or isobases. Plate 4. This map is intended to show the locations of the shore lines in the northern part of the State, east, north and west of the Adirondack highland. In the Champlain valley only the sea-level waters, the marine inlet, existed, but in the St Lawrence valley the glacial Lake Iroquois preceded the ocean-level waters. The vertical interval between the Iroquois and the marine planes is 290 feet (see plate 11). The marine plane passes under Lake Ontario at the south edge of the area here shown, or approaching Oswego. The rise of the land, over 500 feet, at the head of the St Lawrence (plate 9) has lifted the surface of Lake Ontario to 246 feet above the sea, and buried the southwest shore of the sea-level waters (Gilbert gulf), where the land uplift was less. Plate 5. We havein this map the shore phenomena plotted on the topographic sheets. The legend and notes make the map quite self-explanatory. Plate 6 joins the west edge of plate 5, and plate 8 joins the south edge. In his map of the Mooers sheet Woodworth indicates many fragments of beaches which are not here shown (81, with map). However, the lower shore features do not involve any important element in the history, as such are to be expected, under favoring conditions, at all inferior levels. ‘Weak bars occur irregularly at points where the several factors favoring their construction were present in sufficient degree. The lower bars in this map belong mostly to the Franklin Center- Stockwell-Covey Hill post office shore line. This shore with its great series of strong cobble beaches represents a level 215 feet beneath the summit plane, and possibly records an episode of some- to NEW YORK STATE MUSEUM what slower uplift of the district. But this shore series is prac- tically limited to the area of this map. It is not found on the Danne- mora quadrangle (plate 8), and is not recognized farther south. The contouring of the Mooers sheet is not correct and no precise elevations are given; and the location of bars and of the inter- polated shore line may need some correction. The Mooers quadrangle includes the extensive bare-rock areas, due to the stripping of drift from the Potsdam sandstone by the copious glacial waters (see plate 5). The remarkable development of cobble bars indicated in the northwest and southeast parts of the Mooers sheet was due to the abundance of coarse material swept down by the glacial ice-border rivers to within reach of the standing waters. The cobble tracts are the deltas of the glacial streams. Long stretches of the summit shore have not been closely examined. More detailed description of the features of the map will be given in a later chapter. Plate 6. This map, the Malone sheet, shows the westward extension of the shore lines, the map joining plate 5. Below the marine plane the deltas are mapped only for the Salmon and Trout rivers, but sand and silt plains occupy most of the northern‘ part of the area. On the Moira quadrangle, lying west of the Malone, the shores merely cross the southeast corner, without significant features for the Iroquois and the marine summit, though a lower beach has strong development between Moira and Lawrenceville and west of the latter village. The quadrangle south of the Moira has not been mapped, but it carries heavy deltas and bars on the St Regis river at Dickinson Center and Nicholville. The next sheet avail- able for our purpose is the Potsdam. Plate 7. The Potsdam quadrangle, carrying the deltas of the west branch of the St Regis and the Raquette rivers, has good dis- play of the shore features. Interesting features occur on the Canton quadrangle, lying on the west of the Potsdam, but as Professor Chadwick plans to pub- lish the Pleistocene geology of that area, it is not here included. Plate 8. This map, the Dannemora quadrangle, joins the Mooers sheet (plate 5) on the south. As on the Mooers sheet, the highest reach of the sea-level waters is marked by the termination of the land and ice-border rivers, with their correlating deltas. West of Peru a few gravel bars lie above the theoretic marine plane, but series of heavy bars are beneath the summit level, which is the prevailing relation on all the shores of the marine inlet. NEW YORK STATE EDUCATION DEPARTA SCIENCE DIVISION ARS MAP ‘+ STATE OF NEW Y¥ AND ITS ENVIRONS N a pemna tN ee ea eg CHOMGIAN Ivy \ a al a Casa ‘ WA [Wags ‘| agw Fo he Pe ; Na AO ‘i OF NEW YORK eal 4 The 1sobasa/ /ines, inciined 20 degrees 7 Go ™ trom the latitude. parallels, jogicare => the total srrount ok fond tolit? since fhe (~° 11 removal of the Labracorian 16€ Cap. ") The live A-B /s the location of rhe prothe 10 the cagram, plate fo. A yew critical ports are arKed The ine 6-0 1s the position of #hé protiles shown in plate 11. Stations Used ja. the pabilared gata, plore 12, are waicuted © AL Fairchild 19:7, a epye eal | Te MAP Ne ; ‘ = STATEOFNEWYORK “Sx ENVIRONS \ e WLIFT KP yoRK ot” ok pee And 13 the aeetion of he fhe CngreR, ee we merits O Baer Cmsd os fhe toe af the sisi wand on the pabodated a are receted -” PLeIstoceNe upLirt or New York PLEISTOCENE MARINE SUBMERGENCE 23 Plate 9. This map relates to the diastrophic problem, the deformation of the continental surface. The amount of uplift out of the sea is approximately shown by the isobases for all of the State and the neighboring territory. The map is to be used in con- nection with the tabulated data, plate 12. In the Hudson-Champlain and Connecticut valleys the estuary, sea-level waters have left a record of the submergence in the shore features. The height of those features today is the measure of the postglacial uplift. The lines of equal uplift, isobases, connect points of equal rise in the two valleys; and the lines have been extended westward across the State. Across New York the isobases have nearly direct courses, 20 degrees north of west by south of east. It is recognized that the extended isobases must lie in circles or ovals about the domed area of uplift, and that both east and west they must be given decided curvature. On the east the curvature is determined by study of the land uplift in New England. Westward the curvature is hypothetic. The lines of 300 and 400 feet are located in accordance with the determinations of Professor Emerson (66, 67). The zero isobase should, it is probable, be laid farther south, but as it is an uncertain and elusive element the line is drawn well within the limits of the map. It will be seen that the rate of tilting, or gradient, of the shore line increases toward the north, as indicated by the spacing of the isobases. From present knowledge it appears that the steepest gradient lies over the Champlain district, and that the surface of the dome of uplift has a decreasing slope in Canada. The height of the estuary features in Lake Memphremagog district have located the 800 feet isobase. Plate 10. This profile has been drawn to connect points of clear summit shore features. These stations are numbered on the chart, 10, 22, 24, 50, 54, 58, 78, 89, 138, 144. The fact that nearly all the topmost shore features, even in localities as far away as the Connecticut valley and the east shore by the Green mountains, coincide very closely with this profile is confirmation of its accu- racy. And the vertical relation is greatly exaggerated, as the vertical scale is 528 times the horizontal. Since the isobases are inclined 20 degrees from the latitude parallels and this profile is for a meridian, the proper location of the stations is by the intersection of their isobases, and the results are surprisingly harmonious. In only three localities are summit bars found at heights above this profile. These are at Crown Point, 24 NEW YORK STATE MUSEUM 111; Port Henry, 114; and 131, in the Ausable river embayment near Peru. As these are in decided embayments of the west wall of the valley it is possible that the high features are due to glacial waters, or lakes lateral to the ice lobation in the valley. However, the strength of the bars and their regular spacing does not favor the idea of ephemeral waters like the narrow pondings alongside the ice. It appears probable that the profile does not show the total height of the marine inlet waters in the Champlain lake district. The profile certainly does give the uplifted plane of the sea-level waters in the-Champlain valley at the time those waters passed around into the St Lawrence valley. It therefore seems as if there might have been some little rise of the land in the Champlain region while the ice front lay about Covey hill, and that the superior beaches indicate the amount of such lifting above the datum plane. This has an important bearing on the relation of the land uplift to the withdrawal of the ice cap. It seems quite certain that through the Hudson valley, or to about Glens Falls, number 89 of the profile, the wave uplift did not overtake the retreating. ice front. By the time the ice cap had waned so as to expose the Champlain valley the weight of the ice mass had so diminished that perhaps the northward-progressing wave of land rise did affect the border of the ice-covered territory. This is also suggested by the Iroquois beaches in the St Lawrence valley. The history of the postglacial phenomena is possibly more com- plex than here outlined, and there may be unrecognized factors in the problem. The lower bars along the international boundary are mapped in plate 5. Woodworth’s line A-B in his plate 28 (no. 82 of the list of writings), is nearly coincident with this profile. Plate 11. This diagram should be used in conjunction with the maps, plates 5-7, 9. The shore features are plotted on the profiles according to their isobases. The vertical scale is 264 times the horizontal. The lines for the uplifted Iroquois shore are drawn as straight lines from, Covey outlet to beyond Adams, ignoring any slight curvature. Southwestward from Adams the line is given slight curvature so as to intersect the Iroquois beach at Ontario, Wayne county. 5 The upper of the two lines of Iroquois is regarded as the closing or extinction plane of the lake. If this be true then the lower line TANAT VAIS FANT Laawz~ = Plate ro FEATURES EAST OF MERIDIAN. FEATURES WEST OF MERIDIAN FEATURES NEAR MERIDIAN FEATURES I’ VERMONT ANO MASS. 6) Hinder hook, plains aad cliffs Fas 15 N. line of N.it1,at Greenwood Lake, /o0t 10 Pork Washington, L.h, Sandplain, 60 A Portland, Cr, two heavy bars, 220- 62 Valatre, ee on plain, FOS 20 Wes+Haverstraw sardplains 120 22 Crofon Pointe head of delta, /20 8 Morine plane on Cond. River, &. Ty es 338A 63 NiverviHe sandplains F/T 23 Verplanck, (m,n, bars 1/25 IF Hudson, (ms, bar 2754 S “ ee A a Bim YS tire MB Cle EOD) 67 Schodack plains J4o 29 Vones Point ferrace 130. 72 Loudenvisfe, ch¥f and Ferrace 350+ D Selisbury, Vk cobble plain. 580 800 it Ais 69 Eustr Greenbush, bars, JZ0-320 27 Fort Moatgemery. bar /35 G2 Daeaeag Springs, bars and cliffs 70-360 E Middleburg, Vi Sm. re. cobble plain, 590-595 Ws liar W DefreestWile, bar-chiffs, F40 28 Mighland Falls (plain, (40 89 Glens Falls, 5 m.' Sw, bars oa Hudson delta 440-45 F Brisfol, Vel delra suminit 620 ns ey Buen V7 Schaghticoke, Moosic delta, TIS 29 West Point, plains, /60-/40 143 Cannoa Corners, bars, 730-695 iy nb) \ Ye Grand wich, Battenki// delta, #20 32 Newburg saadpleas, (60 (44 White School, bars 735-70 a) a? 87 Durkecfown, 7 m.$,, bar 425 93 Beacon, sandplains (So “4S Int Boundary, (m.s..channel, 7#o 700 is = | 700 go North Argyle, clif¥s and bars, 450 3S New Hamburg, rerrace, (ms, (75-170 Zscbake of Covey outlet, == | foo Hague, £) George, cliff and terrace 525, 36 Marlboro, Sakdplain 170 146 Paralle/ 4500, bars 740-720; 530-360 ‘il se 3 " / Gpleer fice sdudplain-#$0%; bars 435-37 ° 39 Foagtkespsie sandplatas (Fo 147 Covey ti}! PO. Caa,, Clif¥ 740; bars 530-300 m io = ' “1 Crowa Point, glacial ferraces, 620 4 fig de Fark, rerrace—plara, 200-195 80 Mechanicsvi//e,3 im nw, heavy bar, 3G0 600 m = = = i WA Fort Heury, Glacial bars, 690 42 Hosendale plain 220 (2) Uh 0G fo9 = fae malic WG ElizebelAtowna delpa, 620 46 Hingston platas 220 Hs a i | WE Bouguel; ferraces afd bars, 620 47 Fhinebeck delta platas, 245 S— aye Se i W 124 Clidtonville delta 660 So Mount hiarvoa, glacial chanae/s, 240 _—t = ze, ; wy (26 Harkness, terraces aad bars S60-FES S2 Mount Airy, glacial channel and dé/fa 250 S00 pe as = 2 = <= 00° 155° 150 ME 40 135 730 125 120 USE 410 105 100 IS UPLIFTED WATER PLANES IN THE ONTARIO- ST. LAWRENCE VALLEY ON THE LINE JOINING COVEY, FARR’S, ONTARIO 7o 6s 80 75 LL. Fairchild_1917. TILTED WATER PLANES IN THE ONTARIO-ST LAWRENCE VALLEY Plate 12 MEW YOK LOCATIONS Fresent altitude of the upraised /roguors plane Altitude of /rogvois af time of extinction. Amount of uphkt since extinction of /reglo/s Altitude of the ypratsed marine plane Amount of land uplit? during rogers time Total amount of land uyalitt, by /sobases kise of /roguors fevel We ro Flooang. } 4y excess of ipiitt af Krome liitial height of the /roguo/s plane Fresent a/titide of *he Upra/sed /rogvals plane 38 Splitting 188 566 192 580 of beaches due to uplifr 205 622 3/ £16 CANADA LOCAT/IOWVS Fresent altitude of rhe uprarsed /rogio/s plane Altitude of /roguo/s af time of extinction. Amount of uplift since extinction of /rogvo/s Altitude of +he wpraised marine plane Amount of land iplitt during /raguo/s time Teta! amount of land uplift, by 1s0bases Kise of sroguors leve/ due fo ffoodin. by excess of up/itf at Krome Initial height 0f rhe sroguo's plane Fresent altitude of the yprarsed /rogvo/s plane OD gGLAG/IAL LAND OPAIPT JN SZ ONIATAO, BA S//V Ht lL farrchild 19/7, Figures show altitudes, in feet, above sea /evel Ynderscored tgures are field measurements. Compare with profiles, plate 1. “ TABULATION OF DATA RELATING TO UPLIFT IN THE ONTARIO BASIN PLEISTOCENE MARINE SUBMERGENCE 27° localities were the first to be relieved of the burden of the ice sheet (164, plates 9-17). Other localities between Rome and Hamilton had proportionate movement. It will be seen that Rome was the point of largest rise in glacial time, and the station of lowest initial altitude. From Rome northward the glacial uplift was small, but the postglacial was large. Toward Canada nearly all the rise has taken place since the sea-level waters entered the St Lawrence valley. The low initial height of Rome is in agreement with the facts of the early glacial drainage in central New York; for the escape long before Iroquois time was eastward through Syracuse to the Mohawk-Hudson; and the Syracuse channels are today, after uplifting and some filling, less than 400 feet above tide. In apply- ing the mathematics of the table to any particular locality it must be understood that the figures apply to the precise point used for Iroquois or marine altitude. Taking Rome as example, the altitude, 460 feet, is the crest of beaches southwest of the city. The lowest part of the divide, the channel head or wasteweir of the latest outflow of Iroquois, the Iromohawk river, is about 430 feet. Hence the initial altitude of that point is 30 feet less than 110, or 80 feet. If we add 20 feet for depth of water we have a fall of 100 feet for the river flow between Rome and Schenectady, a distance of g2 miles by the railroad. The initial height of localities can be approximately estimated by comparison with any near-by shore line (latest) of Iroquois, or a summit beach of Gilbert gulf. The profile of the closing Iroquois, plate 11, shows that from Lacona to Chateaugay, or in the area north of the Rome isobase, there are shore features higher than the lake level. This implies that the land rose out of the water; in other words, the rise of the outlet, either at Rome or Covey, did not keep pace with the land uplift in the Watertown-Malone district. The greatest vertical spacing or splitting of the bars is at Farr’s, 3 miles east of Water- town, where the highest beach is 62 feet above the profile. The table shows that Farr’s rose only 69 feet during the whole of Iro- quois time. But Rome rose 180 feet before and 170 feet after the extinction of Iroquois. It does not seem possible that Farr’s could rise 62 feet over Rome in only 69 feet of total rise. The better explanation is that the northern uplift took place rapidly just after the outflow was shifted to Covey, as that outlet, and hence the water level, rose only a small amount before the extinc- tion of the lake. Certainly the land uplift in the Watertown dis- 28 NEW YORK STATE MUSEUM trict exceeded the rise of the water level by the 62 feet of vertical spacing. The relatively stationary attitude of the lake after the Covey outlet became effective gave the wave of land uplift the opportunity of rising out of water. It may be noted, as illustration and proof of the wave movement that during glacial (Iroquois) time Rome was lifted 111 feet more than Farr’s, but that during Post-Iroquois (Postglacial for New York) time Farr’s rose 211 feet more than Rome. In way of summary, it may be stated that south of Rome, which was on the fulcral line for nearly all the life of Iroquois, all the beach phenomena appear to an effect of rising water ; that north of the fulcral line the splitting of beaches declines in amount both toward and beyond Watertown; that the tabulated figures for the Canadian stations show similar relation; and that the splitting of the bars is due to a local uplift of the ice-unloaded territory during the relatively short period that the lake outlet was at Covey pass. The south shore of Lake Iroquois has the characters produced by a rising water level. Evidently the rise of the lake surface was produced by the excessive rise, or differential uplift, at the outlets, especially at Rome. The huge gravel bar at Hamilton is the moat striking feature due to the rise of the lake. This has been described by Coleman (151, pages 351-52), who implied that the flooding by the rise of the lake level was toward 100 feet. Our tabulation shows that while Rome was lifted 180 feet, Hamilton was lifted only 123 feet, and the flooding at that point was 57 feet. It is an inter- esting fact that “unworn Mammoth remains” were found in the Hamilton bar at a depth of 83 feet (151, page 352). By similar calculation the approximate amount of flooding is estimated for other stations. The figures are maximum, and prob- ably slightly excessive, being as much above the fact as the uplift at Rome, after the outflow was shifted to Covey, exceeds the rise at Covey. As this difference is unknown, but probably small, the comparison of stations is made with Rome. The beaches in Canada show relations similar to those in New York. The figures are chiefly Professor Coleman’s. Toronto, on nearly the same isobase as East Gaines with about the same rela- tion to the ice body, has similar figures, the glacial uplift being two-fifths of the total. But Quays, on the same isobase as Rome, but much longer under the weight of the glacier, received less than one-fourth of its rise in glacial time. The district north from Quays shows declining glacial uplift and increasing postglacial, similar to northern New York. PLEISTOCENE MARINE SUBMERGENCE 29 From the data at hand it appears that New York State was not raised as a rigid body but by a progressive wave movement. The south side of the Iroquois basin suffered about one-half of its total rise during Iroquois time. The northern part of the basin was lifted very little until after extinction of Iroquois. The New York City district did not rise at all until the ice was gone, for not until the ice front had withdrawn considerable distance was there any effective reduction in the weight of the ice cap. The question is, Did the wave uplift of the land ever overtake the receding margin of the waning glacier? In a former paper the writer expressed a negative opinion (27, page 250), but with further study and in the light of the accompanying charts it,seems probable that some small rise occurred at Covey hill while the thin ice margin yet lingered against that northern salient. DESCRIPTION OF THE SHORE FEATURES Long Island The amount of Postwisconsin submergence is shown in plate 3. The positive evidences of submergence are abundant and sufficient, the only ones lacking being bars of wave construction and marine fossils. The absence of bars on sand plains has been described in an earlier chapter; and absence of fossils on a shore of abundant drifting sand is probably to be expected. This subject has been recently traversed in a published paper (55), to which the reader is referred for fuller discussion. For this present writing it will be sufficient té enumerate some of the characters which prove the burial in the open sea. 1 The island lies entirely within the area of postglacial depression. 2 Positive proof of the submergence of the near-by valleys of the Hudson and Connecticut. 3 The evident shore lines about the eastern moraines. 4 The admitted wave-eroded origin of the cliff extending from the west end of the island to 6 miles beyond Jamaica. 5 The very smooth, even surface of the lower parts of the area. 6 The materials of the plains and the occurrence of surficial loams over large tracts of the lower plains. | 7 The subdued, wave-smoothed surfaces of the moraines beneath the theoretic plane, and the very rough, harsh, unsubdued surface of the same moraines above that plane. 30 NEW YORK STATE MUSEUM 8 The presence of innumerable kettles in the smooth eastern plains, showing the subjugation by standing waters of the ice-laid or moraine drift. 9 The admitted delta terraces or sand plains on the north side of the island, and on the north side of the latest moraine, at the theoretic altitude of the marine plane. 10 The occurrence of fine, evenly bedded sands containing boul- ders, evidently rafted, in low valleys in the moraines; the valleys opening freely southward. Staten Island District In the region of New York City and southward where the waters were shallow and of diminishing depth, with fluctuating levels, it is to be expected that the amount of submergence can not be easily determined. But the erosional work and smoothing effect of stand- ing water is evident. The writer has not made any study of Staten island or in New - Jersey except along the northern boundary. ‘Confidence has been placed in the published descriptions of Merrill (30-32), Ries (33-36), and Salisbury (41-43). West of the Palisades the low- lands exhibit clear evidence of water action since the ice sheet withdrew. Over the till, colored red by the debris of the Newark ‘beds, lie abundant water-laid, yellow sands. In the Hackensack valley the evidence of standing water is clear up to the theoretic plane of submergence. The silt plains are found to the head of the Hackensack river, near the Short Clove and Long Clove. Pro- fessor Salisbury gives many references to the presence of water as the latest occupant of the territory. Along the Hudson in the district of New York, and in West- chester county, the records of standing water were conclusive to: the earlier students. In the last four decades the great expansion of commerce, business and building operations has obliterated many features. “ Civilization” and “progress” have little care for such “impractical”? matters as the geologic records. It has not been practicable for the writer to use the time that would be necessary to study closely this difficult area, but the testimony of the able men named above is regarded sufficient to prove the fact of recent submergence in the New York City district. Hudson Valley — Tarrytown sheet. South of Ossining close study may find some remnants of deposits left, either by the glacial outwash or the land ‘Jooy} OZ-O9Z apnyy[e JussaIg ‘[AAa] vas }e }Inq SeM YOY elep oy} wory ‘weasjsdn ‘yJ10U Suryooy ‘][lys}yep Jo ysaMyjnos sop Z ‘s][ey Jeary je ‘JouURYD WeI1}s [eIIL[S) €I 93e1q . PLEISTOCENE MARINE SUBMERGENCE 31 _ drainage, in the marine estuary, but the prevailing steep walls of the valley, with absence of heavy tributary drainage, has prevented the construction and preservation of conspicuous deltas. Of course, cliff-cutting and bar construction were negligible in such narrow waters. But northwest of Ossining is one of the best deltas in the valley, and the finest in the present water. Croton Point, projecting 2 mules into the Hudson river, is the remnant of the heavy delta of Croton river. It is incontrovertible proof of high-level water in the Hudson valley since the glacier vacated. Some small remnants of the great delta are found in the level patches north of Ossining, but the greater part of the original delta has been cut away by the same stream that built it, aided by the tides and waves of Tappan Sea. The delta promontory represents the north flank of the original filling, and an evidence of the erosion is seen in the gap across the middle of the promontory. The broad sand plain at the head of the promontory is definitely roo feet altitude, by the topographic map; but this does not give the full height of the Hudson estuary. Ain examination. of the eround in company with Professor Berkey finds that the summit water level is at about 120 feet. The 100-feet plain was under. water, though wave-swept by the lowering (relative to the land) waters. Merrill made the usual mistake of taking the highest . broad and conspicuous plain as marking the water surface. In some cases this may be the fact, but commonly not so. On the west side of Haverstraw bay, at Haverstraw, West Haverstraw (Bensons Corners), and North Haverstraw, are thick clays and capping sands lying in an embayment of the broad valley. The summit altitudes of the sand plans agree closely with the profile in plate Io. : The northern portion of the low ground west of the Palisades, mentioned in the preceding chapter, is shown on this sheet. West Point sheet. North of Verplanck the clay pits of an aban- doned brick factory testify to the deep water of the Hudson estuary, and the capping sands are seen a mile northeast of the village. Here leveled sands and weak bars indicate the full height of the waters, about 125 feet. Southwest of Peekskill for 2 miles the careful observer may see indeterminate inscriptions of the high waters. The state camp, over a mile northwest of Peekskill, is on a delta terrace with an altitude of 105 feet, some 25 feet inferior to the summit level. Across the river from Peekskill is one of the most interesting 32 NEW YORK STATE MUSEUM sand plains, unfortunately now mostly removed. Jones point has been for many years one of the sources of sharp sand and gravel used in New York City construction. Seen from across the river, or from the steamers, it yet shows the line of the gravel terrace banked against the Dunderberg mountain. The map is faulty and does not indicate even the remnant of the original plain. The north end and highest part of the plain is at about 130 feet above the sea. The southward slope of the summit shows clearly when seen from some distance. The structure and location of the gravel terrace, in relation to the mountain and valley, prove that it was a glacial delta. Its position rules out any possible land drainage. It was built by a glacial ice-border stream which flowed along the west edge of the ice lobe and which received the contribution of the land drainage north of the Dunderberg. The lower portion of the deposit is very coarse, containing thousands of boulders. The top and the southern end are finer, with the foreset and topset beds well displayed. The geographical relations of the Jones point gravel terrace rule out, as explanation of the receiving water, any suggestion of glacial ponding alongside the ice lobe. The waters were the open Hudson inlet or estuary. The constricted valley between Peekskill and West Point could not hold any large shore features; but minor features can be seen from the opposite side of the valley, or from the river steamers, and such have been measured at Fort Montgomery and Highland Falls. At West Point the parade ground is the theoretic height for the summit level of the estuary, about 150 feet. But there has been so much grading and interference with the natural surface that precision in this locality is not attempted. The terraces a mile northwest of West Point and across the river east of Cold Spring are contoured at 160 feet. As these lie in embayments of the valley walls they probably were marginal to the shrinking ice lobe, as described by Woodworth (82, pages I1I-13), and were graded somewhat above the open waters to the south. The control of the waters on the West Point side must be the steep slope south of the point; on the Cold Spring side the channels of outflow control will probably be found opposite the point, a mile northeast of Garrison. West Point, Schunnemunk and Newburg sheets. At the junction of these three quadrangles with the Poughkeepsie quadrangle two large and interesting deltas are found, one affording the site for the city of Beacon and the other for part of the city of Newburgh. PLEISTOCENE MARINE SUBMERGENCE 5 33 The southern part of Newburgh lies on the delta of Quassaic creek. The summit plain of the delta is well shown, both on the map and in the field, on both sides of the creek, with an elevation of 160 feet. The broader part of the delta plain is on the south side of the creek, underlain with scores of feet of blue clay. This clay has been extensively excavated along the river south of New- burgh and at New Windsor, and shows the usual succession; glaci- ated rock and compact till at the bottom, then the thick deposit of finely laminated blue clay becoming yellow toward the top, and a capping of sand and gravel. This will serve as an example of the valley deposits and the record of the succession of events since the ice occupation. The occurrence of huge boulders in the clays is evidence of waters laving the receding ice front. Opposite Newburgh is the delta of the Fishkill, the larger part showing on the West Point sheet. The summit plain is on the Poughkeepsie quadrangle and carries the part of Beacon formerly called Fishkill. The altitude of the main street of Beacon is about 150 feet, at the west end. The map is wrong in showing the east end higher. From Newburgh, or from the river steamers, the plain and terraces of the Fishkill delta are plainly seen. South of Beacon the delta stretches for 3 miles, and at Dutchess Junction and below are extensive brick works. Apparently the southward drift of the waters, aided by exposure to the northerly winds, swept the stream detritus southward. Denning point is a little remnant of the delta, a small imitation of Croton point. Poughkeepsie sheet. Northward from Newburgh terraces of gravel and excavations in clay occur at several places. Woodworth indicates them as far as Marlboro (82, plate 5). The terraces have been so mutilated that their original form is uncertain. The ter- race at Roseton, like many that will not be noted, was inferior in altitude, about 100 feet. At New Hamburg is the delta of Wap- pinger creel; but only the lower terraces lie here, for the reason that the summit level of the delta head forms the broad flats extend- ing 2 to 4 miles above Wappinger Falls. A fair terrace and beach along the highway a mile south of New Hamburg, at 175 feet by the map, marks the summit level of the estuary. The smoothing effect of the waves is seen on the weak shales and the silt filling of the hollows west of Wappinger Falls, at about 170 feet. East of Marlboro are flat-topped sand hills not properly shown by the map, but of inferior altitude. Northwest of the village, and north of the creek, by the railroad station, is an extensive gravel my ‘ NEW YORK STATE MUSEUM plain, all in fruit farms. Mr ‘Charles Young owns the point by the station and his house stands on the edge of the plain with altitude about 165 feet. The sand plain is 5 to 10 feet higher. North from Marlboro are terraces and gravel and clay pits, espe- cially on the west side of the valley. Many evidences are seen of the leveling work of waters, many being inferior in height as should -be expected. The eastern part of Paweiiceeae is on a sand plain built by Fallkill and Caspar creeks. The Vassar College campus occupies ‘the southeast portion of the plam, with an aibeuie of 175 to 180 feet. Rhinebeck sheet. Hyde Park stands on ‘the north end of a ter- race plain which stretches south 3 miles. The plain shows clearly on the map, which makes the height 200 feet, about the theoretic summit altitude. Some wave work may be seen along the highway in low, flat bars and swells of sand. Two creeks, one at each end of the plain, contributed material. Rondout creek, the largest tributary of the Hudson south of the Mohawk, enters the Hudson at Kingston. One might expect to find here a large delta, but the deposition took place far up-stream, above Rosendale. However, detached plains and terraces record the summit level, about 220 feet. The broad sand plain at Rosen- ‘dale, contoured at 220 feet, seems too high for its latitude as an estuary deposit, and may represent a distinct water body, glacial waters, or perhaps supergradation by the Rondout creek. The village of Rhinebeck, two and one-half miles east of the Hudson, is located on a delta plain of the Landsmans kill. The plain, one and one-half miles in north and south extent, has been bisected by the creek, the village standing on the north half. The altitude of the flat plain is 210 to 215 feet, only some 15 feet beneath the profile. The existence of the village at this place is evidently wholly due to the plain. The upper left corner of the Rhinebeck sheet shows a part of the plain of the Esopus creek, considered below. Rosendale sheet. This quadrangle does not touch the Hudson river but covers features mmportant in this study. We see here the Rondout river with its large tributary, the Wallkill; and the Esopus creek that joins the Hudson at Saugerties, on the Catskill quadrangle. The Rosendale plains are contoured at 220 feet, over 10 feet above our profile. Assuming that the map is correct, excess in ug PLEISTOCENE MARINE SUBMERGENCE 35 height may not be more than allowance for supergradation of the large Rondout creek. The form and relation of the rolling gravel plain suggest that it was built by the Rondout and not by the Wallkill. The Esopus creek curves across the northern part of this sheet. The mile-wide flood plain in the Kingston district lies much below the marine plain, and is apparently a plain of erosion, graded to the rock channel south of Saugerties (Catskill sheet). The higher plain which carries the main portion of the city of Kingston, with altitude up to 200 feet, represents the marine level. North of Kingston it is apparent that the Esopus has intrenched itself in a plain that was at least 60 feet higher than the stream, now 140 feet. Catskill sheet. The theoretic marine summit along the Hudson on this quadrangle is about 240 feet, rising to 275. Sufficient rec- ords of the deepest waters are found, although no heavy deltas occur at the full height. The village of Saugerties lies on an inferior delta plain of Esopus creek, and Catskill is on a dissected lower plain of the Katskill. The east face of the Catskill highland is a series of bare rock ledges, carved by south-flowing drainage, marginal to the waning ice lobe. The topography is probably the result of repeated glacia- tion with marginal stream work. The lowest channels of the latest glacial drainage must correlate with the estuarine waters. These significant features are found on-the east face of the Mount Marion range of Hamilton sandstone hills, locally called the Hoogeberg. At Dutch Settlement (Ruby P. O.) on the southeast corner of the Kaaterskill quadrangle, the stream channels terminate at some- thing below 240 feet, with a gravel delta at 220 feet. South of Mount Marion P. O. the Plattekill has left a delta at 200 feet. Along the east face of Mount Marion stream cutting is distinct down to about 200 feet, and a delta heads at East Unionville (Veteran) at 220 to 230 feet. It is to be expected that confined streams along the ice margin, having torrential flow, will cut below the surface of the receiving water. f On the lower road to Mount Airy is a small delta at 240 feet, with correlating channel at 260. At Great Falls, near the county line, the Kaaterskill built a delta in the estuary with present altitude about 250 feet. A glacial channel (see plate 13) lies behind the hill at 260 feet, by the map. The delta of the Catskill is on the Coxsackie quadrangle, to be described below. A mile south of Hudson city the marine waters built a heavy _ gravel bar, tailing from the south end of the hill on which the city 36 NEW YORK STATE MUSEUM reservoirs are located. The house of Mr W. Tenbroeck stands on the bar, the head of which was made 275 feet by aneroid. The map contours the bar from 280 down to 240 feet. The profile (plate 10) makes 275 feet the precise altitude for the estuary at this point. The smooth tract 6 miles east of the Hudson, stretching several miles past Livingston, Blue Stone and Manorton, shows the leveling and smoothing effects of standing water. Numerous kettles indi- cate that ice blocks of the glacier margin were buried in the detritus swept in by the land drainage from the east, perhaps aided by glacial outwash. The smooth kettle plain southeast of Livingston is contoured at 240 feet. The full height of the open estuary, 260 _ feet, is registered in the bare shales about the kettle area. At Greendale, 4 miles east by south from Catskill, good bars were seen by the writer and Professor Chadwick at over 240 feet, by the map; and the top of the hill is planed at 260 feet. Coxsackie sheet. ‘This sheet shows the broad clay plains west of Hudson, traversed by the West Shore Railroad. Except for a space west of New Baltimore these plains extend the whole length of the quadrangle. On the north they join the great Mohawk delta, at Ravena and Coeymans. The marine plane is about 280 feet at Athens, and rises to 315 feet at Coeymans. ‘The clay flats are much below the summit plane; the “Athens flat” being contoured at 120, the West Cox- sackie plains at 120 to 140, the New Baltimore at 200, and the Ravena at 200 feet. The deposits were laid in deep, quiet waters, and the material was probably contributed in larger part by the earlier strong glacial drainage through the Mohawk valley (164). The west boundary of the estuary was here the bold face of the rock hills. The drift had been so fully removed from the high- land by the ice-border streams that the later land drainage found little detritus to pile as sand or gravel, as topping for the clays, as we find southward. The land on the west was thoroughly swept by the glacial flow, and the glaciation and stream work, perhaps repeated, has given the decided allineation, north and south, shown by the map. Only two streams were heavy enough to build deltas, and these are not in the open Hudson valley but up stream. One is the Catskill, extending from Leeds to South Cairo. This was years ago the subject of an admirable paper by Davis (37), in which he makes the altitude of the estuary waters at South Cairo about 275 feet. This proves to be the theoretic height, and the delta is PLEISTOCENE MARINE SUBMERGENCE 3v7/ on the same isobase as the gravel bar south of Hudson, 10 miles distant and on the opposite side of the Hudson, with the same altitude. The other and similar delta is that of Hannacrois creek, on the north part of the sheet. This has not been examined, but the map gives the height of the plains as 300 to 320 feet. The west side of the Hudson on this sheet shows only the lower terraces of the detrital deposits in the estuary. Kinderhook sheet. This displays the broad sand plains related to the Kinderhook river and its tributaries. The plain at Stuyvesant Falls is 200 to 220 feet, or some 70 feet inferior to the summit level. At Kinderhook the plain is 260 feet and over, or about 35 feet low. At Valatie, Niverville and Kinderhook lake the roll- ing flats are sandy and have the summit level, 300 feet. Flat, weak bars, characteristic of sand areas, occur northwest of Valatie at 300 to 305 feet. Weak cliffs are seen on the slopes east of Kinder- hook and south of Valatie at the same height. Westward toward the Hudson the detrital plains exhibit the ter- racing produced in the soft deposits by the subsiding waters. ‘This feature is characteristic of the detritus-filled valley from here north- ward to Glens Falls, and very conspicuous in many sections. Albany and Troy sheets. On the Albany map is seen the larger part of the great delta built by the Iromohawk river. The southern plains about Selkirk are 200 feet altitude, and the delta rises stead- ily to 350 or 355 feet at Schenectady. The delta and its genesis has been described by Stoller (87) and the writer (164), and fur- ther description here seems unnecessary. North of Albany is a bold summit shore line. Along the Lou- donville road a strong cliff extends for two and one-half miles in north and south direction, and the terrace facing it has provided a level stretch for a handsome boulevard. This is a favorite subur- ban residence district and popular drive. The south end of the beach is along the east side of a morainal tract, and the cliff curves sharply west about the south end of the hill between the Loudon- ville and the Shaker roads. In altitude the beach is about 340 feet. On the Troy sheet inferior terraced plains are conspicuous along the Boston & Albany Railroad through Schodack town. The higher, rolling plains with irregular surface in the district of Scho- dack Center were probably laid in glacial waters, as noted by Wood- worth (82, plate 8). The altitude of these plains, with kettles and rough surface, is 20 to 30 feet over the estuary level, 330 to 340 38 NEW YORK STATE MUSEUM feet. The difference in the surface and composition of the plains above and below the theoretic plane is noticeable. Shore lines are not conspicuous on the east side of the valley, but some cliffs are found on the slopes and terraces by the streams. A fair gravel beach occurs one-half of a mile northwest of East Greenbush, at 320 to 325 feet; another at the south end of Grand- view hill with similar height. Along the road from a mile south of Defreesville to near South Troy the work of the higher waters is quite evident; 330 to 335 feet at Defreesville and rising to about Bybee arn SOUL Toye Along both sides of the Hudson north and south of Albany the terracing of the valley walls is plainly shown by the map, and is very striking in the field. The history is clear; accumulation of detritus in the marine estuary at all stages from the highest, level- ing and smoothing at all levels by the subsiding waters (land uplift), with later erosion by modern drainage. Schenectady and Cohoes sheets. Besides the profuse estuarine deposits these two quadrangles hold several important special fea- tures. The Cohoes sheet displays in remarkable form the lower terraces on both sides of the river; the extensive delta of the Hoosick river; and a portion of the later filling by the Iromohawk river. The Schenectady sheet exhibits the deserted channels of the diverted Iromohawk, the north-leading one by the present Ballston Lake, and the subsequent one leading east by the Round lake and Anthony kill. A singular feature is the ice-block kettle holding Round lake. The Hoosick delta has been described and mapped by Wood- worth (82, plates 10, 24); and the Schenectady quadrangle by Stoller (87); while the history of the district has been recently described by the present writer, with a large map (93). The summit plains in the Hoosick valley are at Hoosick Junches and North Hoosick at 400 feet. The interesting history of the Round lake district may be briefly epitomized as follows: The delta of the great Iromohawk river, the predecessor of the St Lawrence, headed above Schenectady during the time of maximum submergence, and the current flow was to the southeast. When the land uplift began and the estuary waters retired the river was diverted northward through the Ball- ston Lake channel; then building the sand plains by Saratoga lake. Further uplift with northward tilting eventually diverted the flow eastward through the Round Lake channel. This flow seems to — have continued until the land here had lifted 200 feet of its total rise of 380 feet, as indicated by the stream work in the village, PLEISTOCENE MARINE SUBMERGENCE 39 which was diverted southward by the persistent ice block. Yet further land uplift diverted the river flow into its present channel. If the record is correctly interpreted we have a correlation with Lake Iroquois history. The outflow of Iroquois continued here until the Covey outlet was opened. This implies that 200 feet of land uplift had taken place at Round lake when the ice front reached Covey hill, leaving 180 feet of rise in later time. It also gives an illustration of the persistence of buried ice blocks until exposure to the air. For further discussion the reader is referred to paper 93. On the irregular rocky surface of the east side of the valley the summit shore features are weak; but they are found in the upper terraces of the Hoosick delta at Schaghticoke and Valley Falls, with an altitude of 380 to 385 feet. On the Schenectady sheet the summit levels are seen on the delta plains at East Glenville, at about 380 feet; and in the Mourning Kill delta, south of Ballston Spay at 300 feet. Saratoga and Schuylerville quadrangles. The Hudson river lies on the eastern half of the Schuylerville map but the western border of the estuary is mostly on the Saratoga sheet. On the latter sheet we see the great sand plain north of Ballston Spa, which was built by the glacial Kayaderosseras when it carried the glacial flow of the upper Hudson, the latter being forced south at Corinth (76). The full height of the plain is 400 feet by the map, which indicates that the rolling surface was a few feet over the static waters. Weak beaches and cliffs are found northwest and west of Sara- toga Springs with a height of 400 feet and downward. The Cryptozoan ledge has been laid bare by wave action of the sea-level waters. On the east edge of the Schuylerville sheet the summit plane of the estuary is seen in the highest terraces of the Batten kill delta, at Greenwich, 420 feet, and in cliffs southwest of the village. A splendid gravel bar lies 3 miles south of Durkeetown, at an alti- tude of 425 to 430 feet, only some 10 feet beneath the theoretic level. The bar mapped by Woodworth, 2 miles north (plate 12 of 82), is under 300 feet. Between these two bars are several good shore features, ranging from 4co feet down. Many shore features are found on the hills northeast of Sara- toga lake, which hills stood as a group of islands in the estuary waters. The Batten kill drains a large territory on the east and in Ver- mont. It filled its upper valley with coarse detritus, at Cambridge, 40 NEW YORK STATE MUSEUM Salem and East Greenwich, but the bulk of its finer burden was swept into the estuary and forms the extensive plains stretching for 7 miles along the east side of the Hudson. Fish creek did not come into existence until the Saratoga dis- trict was lifted out of the static waters. With its small volume it made no delta of consequence. As in the Schenectady-Cohoes section of the valley, the sand and silt plains show elegant terracing by the subsiding waters, at all levels from the summit down to 200 feet. The supposed river channels at Quaker Springs and Coveville are only the effect of wave work on the shales and delta stuff. In the northwest corner of the Schuylerville sheet and west of Fortsville are sand plains at 426 feet, which are the delta built in the open estuary by the glacial outflow of the Hudson, past the east face of Palmertown mountain. Further details and a map for this and the Glens Falls area will be found in paper no. 93. Glens Falls and Fort Ann quadrangles. With this area we take leave of the Hudson river and valley proper, and have the col or divide between the Hudson and Champlain sections of the great valley. The divide is a wave-smoothed stretch a mile wide and about 4 miles northeast of Fort Edward, with altitude about 150 feet. It never carried any river flow. The depth of the estuary over this divide was about 300 feet. From the time when the yielding ice front allowed the sea-level waters to pass beyond the divide into the Champlain section, the waters became the Hudson—Champlain estuary. While the ice sheet lay against the Luzerne-Palmertown moun- tain face, southwest of Glens Falls, the upper Hudson and eastern Adirondack drainage was forced south at Corinth, through the Kayaderosseras valley, as described above. During the later phase of this flow the waters in the valley of Lake George were forced over into the upper Hudson by a pass 6 miles northeast of Luzerne, at an elevation of 760 feet (see Luzerne sheet). The delta from the George overflow is found north of Luzerne, the broad sand plain being 660 to 680 feet. Ten miles south, at South Corinth, is the outlet of the Luzerne lake, fed by the upper Hudson and the Sacandaga rivers, with altitude 630 to 640 feet (76). When the ice front weakened on the steep face of Palmertown mountain the Lake Luzerne found lower escape into the estuary through the mountain pass where the Hudson now emerges from PLEISTOCENE MARINE SUBMERGENCE AI the highlands. Here the upper Hudson waters built their delta, the great terraced sand plain covering all the southwestern part of the Glens Falls sheet and some of the Schuylerville. The summit altitude of the marine waters in the Glens Falls district is definitely shown by a series of strong gravel bars on the terrace east of the mountain, with a height of 440 down to 415 feet. The farmhouse of Mrs M. Hall stands on the terrace at 440 feet. The house of Richard Denton is on a broad bar, the third below the summit. As the land slowly lifted the Hudson extended itself to reach the retiring waters, which carved the sand deposits into the cliff and terrace so well shown southwest of Glens Falls, at 400, 380, 340, 320, 300, 280 and 260 feet. The latest deposits of the glacier in this district are found in the moraine and kames north of Glens Falls, at the foot of the highlands. During this phase of the waning ice it was faced by the waters of the George valley, occupying the passes either side of French mountain. The detritus from the land drainage was ‘mingled with the glacial drift and outwash, together forming a morainal tract of cobble and sand, holding kettles and lakes. Glen lake and the neighboring “ponds” occupy the larger ice-block kettles. These sand-cobble tracts were partially leveled by the lowering glacial Lake George waters, down to about 460 feet, and below that more effectively by the sea-level waters. The rolling and knobby gravel tract north of Pattens Mills is typical of the deposit of mixed origin. The coarser, hilly area about Glen lake is more distinctly kame-moraine. The sand plain south of French mountain, at 520 feet; that about Rush Pond, at 500 and lower; and the kettle-plain at Bloody pond, west of French mountain, at 570 feet, represent the glacial George waters. The terraces in the valley southeast of French mountain at 450 feet, and all the lower plains and terraces are products of the estuary waters (Woodworth's plate 14). The estuary, sea-level waters at their higher levels occupied the valley of Lake George, through the pass east of French mountain. Small deltas and other shore features will occur both sides of Lake George at and below the summit marine plane. This plane is about 450 feet at Caldwell and about 540 at Ticonderoga. The features are.mapped in paper 93. The Hudson-Champlain estuary. lay over the western part of the Fort Ann quadrangle. Cliff cuttings in the shales have been noted west of North Argyle. No close study has been made of the rest of the area. Between Smith Basin and Fort Ann we see 42 NEW YORK STATE MUSEUM the north portion of the narrow valley that was the long divide between the Hudson and Champlain; now cut by Wood creek. The only large stream is the Mettewee river. Its delta in the sea- level waters is apparently the filling at and above Granville, on the Vermont line. Whitehall quadrangle. Sufficient examination has not been given to this area to speak with confidence of the features. Good shore phenomena must not be expected in such narrow valleys. The small deltas of the torrential streams will be the best criteria for the water levels. The marine altitudes are about 490 at the south edge of the sheet and about 530 feet at Stony Point, the north edge. The waters occupied the crooked valley of East bay and Poultney river, and passed far east to the Green mountains in Vermont (92). The evidences of standing water are very clear from the trains of the Delaware and Hudson Railroad. Champlain Valley Ticonderoga quadrangle. On this area the estuarine waters were’ very irregular in shape, and the shore features about the hills on the eastern side of the lake have not been examined. The eastern shore of the estuary lies far eastward in Vermont, beyond Bran- don and Middlebury, against the west flank of the Green moun- tains. The Vermont features are described in the Vermont report, paper 92. On the west side of Champlain the shore features are well known, having been described by several authors, though not always with the correct interpretation (75-77, 82, 94). The sand and clay plains representing inferior levels of the Cham- plain waters are conspicuous. ‘They appear along the railroad from Baldwin to Ticonderoga, at 340 to 360 feet; north of Ticon- deroga over a large area between the lake and the highland, at 260 to 280 feet; and especially in the embayment west and south- west of Crown Point, ranging from 200 to 480 feet. The theoretic marine plane lies on the west edge of the sheet at about 525 to 565 feet, or along the meridian of the lake at 530 on the south to 572 on the north. This summit level of the sea-level waters is registered in the Crown Point district by gravel bars. The best series occurs 3 miles northwest of Ticonderoga and a mile north of Street road, on the east face of a kame-moraine, locally known as Sawyer hill. This locality was cited by Baldwin in 1894 (75, page 176); PLEISTOCENE MARINE SUBMERGENCE 43 described by Woodworth (82, pages 154-56,.plate 15) ; and recently by Barker (94, page 12). In passing north from Street road it is seen that the south point of the hill is strongly wave-swept. At the forks of the road is a terrace at 350 feet; then we find a bar- cliff at 370, a good shelf-bar at 430 to 435 feet by the cemetery and house, a strong bar at 460 under the house of W. J. ‘Cross- man, a heavy cobble bar-terrace at 480, the wave-smoothed edge of the summit plain at 530 to 535, and a heavy summit cobble bar at 540 feet. The theoretic summit of the sea-level waters here is something over 550 feet. The rear side of the plain, next the bare rock face of the mountain, is a few feet lower than the front and smoothed by some stream flow past the ice margin that drained the Crown Point embayment. Shallow kettles lie on the plain and strong kettles at the edge. Woodworth gives a map of the district (82, plate 15) and thought that the standing water did not reach above 500 feet because of the unfilled kettles. But we have multitudes of kettles in deltas and river plains, and abundant evidence that drift-buried ice blocks may persist indefinitely as long as the area is under water. The kettles were not produced until the locality was lifted out of the estuary. The front of the plain is capped with cobble beaches which have been made dis- continuous by the slumping in production of the depressions. The kettles have changed the surface as left by the waves, but have not fatally obscured the record. From the edge of the plain, 540 feet, down to the lower silt plain, 340 feet, the front of the kame- moraine is marked with bars and benches. The deep embayment in the mountain wall, west and southwest of Crown Point, was partially filled with drift and stream detritus, largely of fine and clayey material. When the district was lifted these deposits were planed by the lowering waters, producing a conspicuous display of terraces and flat-topped areas. The evi- dence of standing water is found much above the marine plane, and perhaps represents glacial waters held in:the embayment. The shifting outlet or control of the glacial waters is not determined, but probably was along the steep east face of Buck mountain. It is possible that there are unrecognized elements in the history of this region. The high levels are best seen west of Crown Point Center and at White Church, rising up to 610 to 615 feet. Barker’s map (94, no. I) represents approximately the summit level of the marine invasion. His maps are correlated to imaginary outlets or flow-control which did not exist; and they attempt to represent distinct water levels which are not recorded either there 44 NEW YORK STATE MUSEUM or elsewhere. Evidences of wave-work can be found up and down the valley at all levels, but water planes can not be postulated on a few detached features. Bar-building and cliff-erosion are con- trolled by variable factors, and except for strong and continuous beaches or through long distances the inscriptions are not reliable for levels. Of course it is probable that the rise of the land was not perfectly uniform, but there were no pauses long enough to pro- duce distinct shores for any distance in the Hudson and Cham- plain valleys. With reference to the assumed outlet or control of “ Lake Ver- mont” at the divide northeast of Fort Edward, there is something more to be said. It appears that 200 feet of uplift had taken place at Round lake at the time Covey outlet became effective, and the ice front lay on Covey hill (see page 39). The divide is 31 miles farther north than Round lake, by isobases, and it should have been later in its uplifting. But even assuming that it did rise in company with Round lake, the 200 feet of uplift would have left it yet 100 feet under the sea (see page 40). And it is not reason- able to suppose that it rose the other 100 feet during the relatively short time that Covey outlet was effective. It is possible that the divide rose 300 feet and was out of water, or above sea level, when the Champlain waters were permitted to mingle with the salt water of St Lawrence gulf. In the valley of Lake George the shore features have not been seriously examined, but the proofs of standing water at various levels are evident. Theoretically, the highest levels should corre- late with the outlet toward Luzerne, 760 feet. With some allow- ance for depth of water in the outlet it makes the water level at Caldwell about 780 feet, or some 460 feet over the present lake. At Ticonderoga the plane would be about 860 feet, or some 540 over the lake. The pass west of French mountain gave an outlet 185 feet lower. The marine plane is about 115 feet below the second glacial plane. ‘The marine plane is estimated to lie at about 470 feet at Caldwell and 545 at Ticonderoga. It is for future students to verify and correct these three planes in the George valley. Port Henry quadrangle. The most striking feature on the map is the vast clay plain east of the lake, with the Dead creek, repre- senting the later work of the receding marine waters. Snake mountain stood as an island in all the sea-level waters, and distinct summit shore features will doubtless reward careful search. With this wave-beaten height we take leave of shore fea- PLEISTOCENE MARINE SUBMERGENCE 45 tures on the east side of the Champlain valley, as they lie far east in Vermont (92). At Port Henry is a narrow embayment or recess in the west wall -of the Champlain valley which holds some excellent but puzzling records of standing waters. West and northwest of the village good delta terraces occur, related to Mill brook. The fair ground is on a plain at 600 feet, with wave erosion at the road corners. The cemetery is on another plain, the higher terrace being 640 to 650 feet. These levels are seen both sides of the creek valley. North of the fair ground on the east-facing slope are ridges and shelves that appear wave-shaped at 640 to 660 feet. Southwest of the village, by McKenzie brook, a good series of bars occur on both the north and south roads. On the north road the topmost bar is under the house of A. M. Edwards, at 620 feet by the map. Four other close-set ridges carry down to about 550 feet, with terracing on the delta to 530 feet. On the south road the upper bar carries two houses at about 630 feet, with moraine beyond (above) it. In the field toward the brook good . bars occur at 605 down to 560 feet; and terraces to 500 feet. The reason for the above detail is the fact that these features lie much above the theoretic marine plane, which is here about 570 or 575 feet. The lower of the gravel bars falls within the marine level, but the highest is 60 feet too high. The topography of the valley wall and the small width of the embayment do not favor the existence of glacial waters with wave-efficiency to pro- duce the bars; and the vertical succession of the bars through 70 feet rules out any definite outlet or fixed control. The series of close-set, well-developed bars is similar to those positively due to slow rise of the land out of water; and none of several explana- tions in appeal to nonmarine origin are satisfactory. It seems more likely that in this region, the east flank of the Adirondack mass, there has been an excessive uplift of 60 feet, with or with- out Postglacial faulting. The superior height of the Crown Point terraces, coupled with high features in the Peru region, to be noted later, lend force to this view. In such case our theoretic or datum plane does not represent quite the total rise in the Champlain region. The profile, plate 10, is drawn to connect with the summit shore at Covey hill. About Westport are conspicuous lower plains, but the summit features have not been sought. The estuary waters penetrated far inland up the valley of Bou- | quet river, which has a bend on this sheet, and the primary or full- 46 NEW YORK STATE MUSEUM height delta appears at and south of Elizabethtown, 8 miles west of Westport. The village is built on the delta, with altitude 600 to 640 feet, and lies just above the isobase of 600 feet. This delta was the product of several streams uniting at this place. The superior altitude of the delta is due to the aggradation in a narrow valley far from the base level. The “ Pleasant valley” section is graded to a lower level, 560 feet. This locality was made the subject of a paper by Ries (74). _ Willsboro quadrangle. The profile levels along the west side of the lake rise from about 615 to 660 feet. The lower plains of the Bouquet delta are conspicuous on the map, north and south of Willsboro. The coarser detritus of the river was dropped at the junction with the high-level waters far inland, that of the south branch at Elizabethtown, as already noted, and that of thé north branch on the Ausable quadrangle 3 miles north of Towers Forge. The hill 2 miles south of Willsboro carries elegant inferior bars on the summit and east face, from 300 feet down. Northwest of ’ East Bouquet mountain clear evidence of standing water was seen along two roads up to a height of 620 feet. The theoretic height is about 625 feet. Examination of the area will locate many evi- dences of summit wave action. Plattsburg and Dannemora quadrangles. On this area the sum- mit shore features lie inland, with handsome display. The Platts- burg sheet shows the low ground built by the Ausable, Little Ausable, Salmon and Saranac rivers. But the south edge of this sheet covers the north part of the Trembleau mountain, which carries on its northwest slope a fine series of gravel bars below the summit of the marine flood. Woodworth maps these bars in his plate 21. The Trembleau gravel bars lie one and one-half miles south- west of Port Kent, and 2 miles east of Keeseville. An east and west road crosses the plateau which carries the higher good bars. The highest bars, at about 590 feet, lie in weak form close to the steep northwest face of the mountain. This is 70 feet short of the summit plane, but the steep rock face shows its rinsing. On the road bars appear at about 575, 560, 545 and 530 feet. The northwest end of the hill is encircled by a series of bars to. a lower level. The lowest feature is a cliff toward the railroad and near the border of the silt plain. Woodworth indicates shore features on the north and east faces of the mountain. A mile southeast of Keeseville, on the northwest and north slope opminty JsoM SUDIOOT out] UMO} UO _ SBR ME (oNo) SSssoUyIeFT JO JSa9MY}IOU SoTIW OMT, VI 9}e[g ‘ured pues ejjep uo FI[o ra es pee aia MY uOIsOIg, PLEISTOCENE MARINE SUBMERGENCE 47 of Prospect hill (Willsboro sheet) good evidences of wave work appear at 600 feet. About Keeseville the Ausable river has laid down extensive gravel plains at 500 feet altitude, with terraces declining to Lake Champlain. The summit waters extended up the river 10 miles from Keeseville, to Ausable Forks, and broad plains between there and Clintonville, at 660 feet by the map, represent the higher delta. The Dannemora quadrangle carries some of the strongest, hand- somest and most convincing shore features of the marine-level waters of the State. As these are mapped in plate 8, detailed description will be unnecessary. It will be seen on the map that the bars have been plotted on the highways, but have not been traced across country, which gives the beaches on the map a broken and patchy appearance, untrue to fact. Along the meridian of Harkness, Clark School, Beckwith School, and West Plattsburg the summit plane rises from about 660 at Harkness to over 700 feet at the north edge of the map. The deltas, glacial channels, and summit bars agree closely with this plane. The only discrepancy noted is the excessive height of some bars a mile southwest of Clark School which rise to 706 feet by the map, or nearly 40 feet above the profile (plate 10). The Harkness embayment was competent to hold broad glacial waters, but these bars are so closely connected with the marine shore that they are regarded in the same category as the high Port Henry bars. Three classes of features are depicted on the map: (1) the ice- border drainage channels which terminate at or somewhat beneath the static waters; (2) the cobble and gravel bars of wave con- struction; (3) delta plains and terraces which occur at varied levels, from somewhat above the static waters to low levels in the sub- siding waters (plate 14). As is usually the case along all shore lines, the heaviest bars are somewhat below the summit plane, where the waves had suf- ficient accumulation of coarse material. The vertical series of heavy bars are found on stony slopes, usually so rough and stony as to be left uncultivated. Above and below the ground may be tilled. All the strong, close-set bars, not only on the Dannemora quadrangle but elsewhere, are on tracts of cobble or coarse gravel, commonly the deltas of glacial streams. Over ground immersed in sand the waves produce only smooth or rolling surfaces. On the areas of rising land, with open sea and free wave action, the construction of bars required coarse materials, at least for the basis or framework. 48 NEW YORK STATE MUSEUM On the north edge of the sheet, 2 miles north of West Platts- burg, is the termination of an extensive cobble delta tract, built by glacial drainage along the high ground west of West Chazy (plate 5). This carries a remarkably fine series of bars, as depicted on the sheet, ranging from 684 down to 570 feet (plate 15). On this sheet the relative vertical position of the Covey Hill P. O. beaches is a smooth, sandy plain 2 miles northeast of West Platts- burg, with no decided shore forms. It illustrates the fact stated above, the absence of bars on sand plains. The Saranac sand delta illustrates the lack of bars on sands. The Northern Salient. Covey Hill Plate 5 Physiography. The northern promontory of the Adirondack highland is shown in plate 5, made up of the Mooers, Churubusco and Chateaugay sheets, with a strip of the Canadian Chateaugay sheet. This salient, wholly of Potsdam sandstone, terminates a mile north of the international boundary in an oval knob, locally known as Covey. hill. The summit of the hill is given by the map as 1113 feet. It drops off steeply on the north, falling to 300 feet in 2 miles. The depression south of the hill, and one-half of a mile north of the boundary, has an altitude on the long swamp col of 1000 feet plus, by the map. The steep gorge on the east of the divide has been known as the “gulf.” In relation to the glacial history this locality is perhaps the most critical in the State. The first geologist to recognize the significance of the Covey pass as related to the glacial waters was Dr G. K. Gilbert, who was the pioneer in glacial work, especially in New York. The water parting, it will be noted, is on the west side of the promontory, which throws the larger territory into eastward drain- age, the Chazy river. The Chateaugay river gathers the waters of the west slope. This is partial explanation of the larger volume of ice-border drainage on the Mooers quadrangle. Along the boundary a strip 2 miles wide drains into Canada. As the Labradorian ice front backed away on this salient, the glacial outwash flowed freely away, east and west, making no decided channels near the crest of the ridge. On the west all the waters found their way into Lake Iroquois by the channels depicted on the Chateaugay sheet. On the east slope the waters came to rest in the sea-level Champlain estuary. Mooers quadrangle. The drainage and static water features are SI 93eI[¢g 2 ay - | tl 7 ‘ureatjsdi ‘YZIOU Sulyoo'T ‘UMOJULUTYDIG JSO\ JO JSAMYNOS SojitU YJAMOJ-9u0 pue sUuQ “aS VAOq joa} OOL MOU Jado] vas Je yYIMq ‘eIap atqqoD QI 23e1g ‘Joo} OOTI OpPNjIN[W ‘Wreo1suMop 4svo sulyoo] ‘vuoj[y JO Yjnos sop VP [IY JO 9sou UO YOM WI1}s [BIR] Pe eee - eel - Sa Ir Lr 93e1d ‘JOLISIP VUOITY 94} FO ,, JU -oAed peor poAoidun juourwtiod ,, I4si1ojoVIeyY) ‘“YINOsS BUIYOOT ‘IseI][IA eUO][Y ‘au0j}spuvs Wepsjog uo AvMYSIT{ rs ge gt aed e/ fe) ee Pay, ae PLEISTOCENE MARINE SUBMERGENCE 49 shown in a broad way in plate 5. This quadrangle was made the subject of a special paper by Woodworth (81), and was also cov- ered in his more comprehensive Bulletin 84 (82). At the time of Woodworth’s study no territory adjacent to the Mooers quadrangle had been mapped and definite correlation of features could not be made. It becomes necessary to republish the sheet in order to locate the summit shore line of the sea-level waters, to show the relation of features to adjacent territory, and to reveal graphically the sequence of events or the later Pleistocene history — the very latest glacial events of New York State. Much study has been given to this area, long ago by Woodworth and later by the writer. Many visits have been made and some localities have been visited several times. Some of the features are so peculiar or equivocal or unusual in character that they were uncertain, and at first were misinterpreted. Some of the heavy tracts of cobble and boulder delta stuff had been regarded as moraine. The key to the history has been the determination of the summit level of the sea-level water, but much time and travel have been required to verify phenomena at critical points. Even now there are stretches of the summit shore line, rather inacces- sible, far from deltas and of weak development, which are inter- polated on the map. Future study will verify the shore line. The position of the summit shore is determined by (1) wave- built bars; (2) higher terraces on deltas; (3) lowest reach of the ice-border drainage. The last is well displayed. Over large areas the Potsdam sandstone has been stripped of its drift mantle, and in the Altona region conspicuous channels have been cut (see Woodworth’s illustrations). These areas of glacial drainage make the most conspicuous features of the map. The sandstone in this region has an eastward dip and formed a hard floor, declining toward the receding ice front, thus favoring the stripping. our areas of the “stripped rocks” may be dis- criminated on the map (plate 5). First, the Altona rocks, south and southeast of Altona (81, page 18; 82, page 161). This area is some 5 miles long by 1 or 2 miles wide. The upper margin on the east slope of Big Hill must lie under 1100 feet, and the lower limit is at Pine ridge, at the marine plane. Earlier glacial stream flow is indicated at higher levels south of Big hill. The Altona rocks are famous for their production of huckleberries (plate 18). The other bare rock areas are partly on the adjacent Churu- busco quadrangle. The second is the area southwest of Cannon Corners, called the Blackman rocks. The third is the Stafford 50 NEW YORK STATE MUSEUM rocks, west and northwest of Cannon Corners, and traversed by the road from White School to the Rebideau farms. Fourth, Arm- strong’s Bush, an indefinite rocky area on the north edge of the map, which records the latest glacial stream flow in the State. The heavy delta tracts of coarse materials are the product of the copious drainage noted. above, of which two are of special note. The southern and earlier delta tract is the belt of bouldery, cobbly stuff, complicated with moraine piling, lying west of West Beek- mantown and West ‘Chazy, the effects of the Altona drainage. The later large and coarse deposit is on the west edge of the Mooers sheet at the north, and related to the bare rock areas on the west. West Chazy district. In this district, the southern part of the Mooers sheet, is a remarkable display of summit shore features. The copious drainage from the Altona rocks supplied superabund- ance of very coarse material for work of the waves, while the ice built its frontal moraines as a foundation for bar construction. We have here a complex of features which will be misinterpreted and wrongly diagnosed by the geologist who has not had experience with such deposits. Here is the work of powerful torrential waters mingled with morainal material, and then more or less modified or reshaped by the wave-work of the highest static waters. The effects of the three agencies are mingled in varying proportions and it is often difficult or even impossible to discriminate the wave work, especially at the topmost line of the standing waters. In some cases the approximate summit is marked by wave embank- ments, but commonly the unmistakable bars are inferior to the summit level. On the junction of the Mooers and Dannemora sheets the sum- mit beach lies against a steep slope at slightly over 700 feet. Imme- diately west of the four corners, at the bottom edge of the Mooers sheet, is a heavy bar ridge with precise altitude (U. S. G. S.) 684 feet; and just east of the corners is another strong, conspicuous cobble ridge at 660 feet. The south termination of the delta tract is seen on the Dannemora sheet, plate 8. Northward on the north- leading road the delta gravels are shaped into indefinite ridges at about 700 feet. The photograph is plate 16. One-half of a mile west by south from West Beekmantown is an isolated ridge, probably morainal, rising to 700 feet. About the south end of the ridge are heavy bars of boulder and cobble. On the east slope at the north end the ground is so rough that no one would suspect it to have been subjected to centuries of heavy wave action. It is a good example, that can be indefinitely multiplied, of the nonvalue of negative shore-line characters. -007] ‘Yjiou FO jsoM out ‘OSPII OY} FO SSVU OY} SB OUIVIOW JoppMog e& suT[eaAVI ‘odo[S SoA oY} UO Wep d}J919U0D 9Y} JO UOTIONAYs -U0) IOf PdAOWII UD9q Sey YIOM-oAVM Aq Pie] IIqGqoD JO JoOUDA ayy, ‘ZIOI ouUN[ UI ,, [JT eUOIsSaTqQqo),, Jo WwuNs 61 93e[q PERE aes ae FO ee me PLEISTOCENE MARINE SUBMERGENCE 51 Toward and at Shelter’s Corners, northwest of West Beekman- town, the delta stuff is shaped into a fine display of bar ridges. Northeast of the corners the summit ridge is over 700 feet, and between that crest and the three corners below 12 to 15 bars may be counted in the drop to 580 feet. A mile north of Shelter’s Corners is a long ridge carrying a road, and wave action is shown to the summit, 700 feet. Behind this ridge, on the west, is a smooth hollow, over 20 feet deep, which was apparently a channel for the latest flow when the ice front was building the ridge. Such smooth channels somewhat beneath the static water level are to be expected near the summit level where the glacier front was piling coarse moraine stuff in bold ridges, that the waves could not later demolish. Where there was little moraine drift, or drift of finer material, the frontal stream channels might be more or less obliterated. One and one-half miles west of West Chazy on the east-facing slope the cobble bars are well developed. On the highway, the Basset road, 10 to 12 bars are counted in the fall from 500 to 400 feet. This lower series of bars has about the relative vertical position of the Franklin Center series in Canada, previously mentioned. Cobblestone hill. This hill, described and illustrated by Wood- worth (81, pages 32-35), is a good example of a moraine ridge modified in form by wave work. Lying detached, a mile north of the Basset road, and with conspicuous, bare, cobble bars crossed by the road, it was the subject of special notice. The top and east slope were handsomely shaped into bars of well-rounded cobble. The summit bar was 665 feet altitude, the lower bars ranging down to 580 feet. The summit was at least 50 feet beneath the highest stand of the Champlain waters. In recent years a reservoir has been built on the west of the hill and the summit cobble bar has been entirely destroyed for concrete material. This removal shows that the cobbles were only a veneer for a block moraine ridge (see plate 19). Cobblestone hill is not unique, but an example of the moraine ridges more or less modified by wave action. The occurrence of such a large quantity of uniform cobble on the detached hill is, however, a puzzle, and suggests that there may be some unknown factor in the history of the ridge. The character of the Altona channels suggests a larger stream flow than merely that of the local waters, the Chazy rivers and the glacial outflow. The eastward position of the Altona highland seems to make it quite certain that the Altona channels carried the 52 NEW YORK STATE MUSEUM earlier Iroquois, that through the Covey pass. ‘Woodworth seems to have recognized this. This implies that the ice front rested against the Altona-Beekmantown highland after the ice had deserted the notch south of Covey hill. It also requires a glacial lake in the embayment west of Altona. There are evidences of standing water between Altona and Alder Bend, and north of Ellenburg Depot at 900 to 960 feet. We may refer to this water as the Ellenburg lake. The later outflow of Iroquois produced the features in the Can- non Corners district. Cannon Corners district. Here we find another remarkable dis- play of Pleistocene features, fully matching that described in Altona. It includes vast areas of stripped rock, numerous river channels, enormous piling of cobble deltas over large tracts, and splendid development of high-level bars. The areas of stripped rock have been named above. They are essentially a single area; that is, they represent the work of the same drainage, the Iroquois outflow, with falling levels as it washed the retreating ice front. The rocks are Potsdam sandstone, usually in irregular terraces, but sometimes steeply dipping. The inclined beds are well shown at Mitchell Rebideau’s place, 2 miles south- east of Covey gulf. The stripped rocks may be conveniently seen by taking either of three roads: the indefinite and branching rock roads leading west from near the schoolhouse, three-fourths of a mile south of Cannon Corners; the road going west from Cannon Corners; and the road at the White School, a mile north of the Corners, leading to the Rebideau farms. The limits of the bare rocks are not perfectly defined on the map. The rocks are par- tially covered with scrub, bushes and huckleberries, and the pre- cise mapping is not worth present effort. At a rough estimate, they extend some 6 miles north and south, and perhaps average a mile and one-half in width, or 9 square miles in area. The surface in general declines eastward, and the river flow which swept them clean migrated down the slope, clinging to the ice margin as the glacier slowly gave way. The lowest points of bare rock, and the termination of river work, lie along the north and south road from Cannon Corners to Shea’s Lines. One exp ure of rock is seen on the highway one-half mile north of the VCorners, and another three-fourths of a mile south of the international boundary. As the rivers reached the sea-level waters near the north and south line of the highway, it is along this road that we find the — me Se se aS ‘OSLUILIPUMOP SIONDOIT FO 4sv] oy} Suroq YIoX MoN UI oSseUTeIpP [eIoRys jsoje] Off, You suryooy ‘yoy SEZ jnoge opninjy ‘s1ous10D uouue) FO }JsaMyj}IoU of I ‘JoOYyIS AYA AG ‘eIep 2FGqGod uo JouULYD WIeat}s [eIOe]4) Oz 93e[g a Ss ee — a PLEISTOCENE MARINE SUBMERGENCE 53 delta tracts of coarse stuff, formerly mistaken for moraine, and cobble bars in excellent development. Passing south from Shea’s Lines the road lies on a boulder moraine, at 760 feet, shown in plate 21. East and west of the low ridge are shallow scourways, the latest and lowest definite channels of glacial river flow in New York. The altitude of these channels is 740 feet. The road crosses the west channel three-fourths of a mile south of the boundary, and immediately south is seen some of the coarse delta stuff dropped by this, or the preceding flow, when checked by confluence with the marine-level waters. The White School, by the corners leading to Rebideau’s, is in another river channel (plate 20), which has an altitude on the road of 720 feet, IO or 15 feet beneath the marine plane. The delta stuff might be mistaken for moraine. South of the White corners the road rises slightly on the cobble delta, follows it for one-fourth of a mile and crosses another bare rock channel at 720 feet. Strong cobble bars lie east of the road, the highest southeast of the White School at 735 feet. North of Cannon Corners the road CrOssesnasenics, Ol Six pans, the Mishest peme 720) feet and wtie lowest, close to the corners, at 700 feet. This fine series of bars curves about the slope and parallels the road northward. Cannon Corners and the road leading west, up English river, are on very coarse delta. The surface appearance is that of a bouldery moraine, but the banks of the river cutting show its character as torrent deposit. South of Cannon Corners one-third of a mile is another series of cobble bars, in altitude from 720 down to 700 feet, but behind the schoolhouse and at the corners of a west-leading road is evidence of wave work up to 730 feet. These bars swing to southward and continue in good shape for over a mile along the slope of the delta on the east side of the road with an altitude of 720 down to 712 feet. For one and one-half miles southward the road lies on the delta, which suggests the amount of rock-rubbish that the glacial drainage swept off from the Blackman rocks. The sand plain delta of the Chazy river, north branch, heads at 720 feet but declines to 660 feet 3 miles east, as shown by rem- nants. From this locality the marine shore turns southeastward, as shown in the map. The series of lower beaches, the Franklin Center shore line, is very strongly represented on the north edge of the Mooers sheet, in 42 bars of coarse material spaced over one and one-fourth miles. Two miles southeast by English river the level is represented by numerous weak bars. Southwest of Sciota the shore appears in 54. NEW YORK STATE MUSEUM good form, and again west of West Chazy. As already stated (page 19) this level of the lowering waters is not recognized dis- tinctly south of the Mooers quadrangle. The Covey channel. The form, dimensions and relations of the Covey pass are shown on plate 5. The postglacial drainage history of this critical locality is not known in all its details. The locality is difficult to reach, far from highways and farther from any hospitable place of entertainment. It is a wild and romantic place; forest on the north wall of the channel, the roughest kind of rocky and swampy ground on the south side; on the west, at the head of the channel, a wide swamp and lake; and on the east, downstream, steep or precipitous rock cliffs and ledges, dropping down to the exceedingly rough lower ground. Attempts to reach the pass from the south were aban- doned on account of the difficulty and limitation in time. The channel proper is a splendid example of an abandoned river bed, over the hardest of sandstone; but it is unusual in the absence of any correlating delta. Below the normal channel we expect to find the deposited detrital burden of the current. Here is nothing of the sort. The low ground southeast is very rough, with no deposit of ordinary detritus. The only loose material within the grasp of the stream was whatever filling of drift the ice sheet had left in the pass. It is more than possible that the recent history of the pass has been duplicated by glaciation earlier than the Wisconsin (Labra- dorian ice body), and this admission makes it uncertain as to how much of the form and character of the channel are really due to Iroquois outflow, and how much to earlier episodes of river work. It seems probable that the earliest water across the col was tributary to a glacial lake, which we may call the Ellenburg lake, having its control on the Altona rocks. As the Ellenburg waters lowered, the Covey river cascaded over the Potsdam ledges and removed whatever detritus it had dropped in the preceding flow. Its latest cascading must have been the most vigorous and erosive. Another query is whether the rocks on the lower ground are partly glacial, rinsed off by the flood, or blocks plucked from the channel by the latest river, or by more ancient rivers. The ravine or “ gulf” below the upper broad channel, with its lakelets is evidence of plunging flow to low receiving waters, prob- ably at the marine level. The ravine is not correctly contoured, for about midway between the head of the gulf and Covey Hill post office is an extensive filling, with piled rocks, and broad swamps. Yjiou suryooy ‘stonbory oYVT JO MOYINO JsojyeT Aq jdams Ajqeqoid (Arepunog [euoneussjUr) OUI] S ways Je oureIOW YOY IZ 9}€[q PLEISTOCENE MARINE SUBMERGENCE 55 The upper swamp was estimated as one-fourth of a mile long, with aneroid altitude 765 feet. The lower filling was made 740 feet, the marine level. The total length of the swamps and rock piles was thought to be nearly a mile. This may be regarded as the delta of the Covey river at the sea level, during its latest flow. The rock bottom of the river channel is 1010 feet altitude on the divide. The limit of visible water work on both the north and south banks is about 1030 feet. The granite boundary monument on the south side of the ravine has an altitude of 929 feet at the base and 934 feet for the top. The altitudes given on the Churu- busco sheet for the boundary monuments are all for “ top of monu- ment.” On the Chateaugay sheet the altitudes refer to the base of monuments. North slope and shore lines of Covey hill. The steep north and northeast slopes of Covey hill are mostly in forest, with only a few small clearings. A traverse was made down the north slope, but the line of strongest pressure and longest hold by the ice front must have been on the northeast'face. The surface of the north slope is gradual and fairly smooth, such as would be expected of a strongly glaciated surface, down to 1010 feet, corrected aneroid. Below that occur rock ledges, benches and irregular terraces, such as belong to steep slopes cut by rivers held to their work by the forceful glacier. From over 1000 feet down to over 700 feet the slope must have been eroded by the profuse waters of the Iroquois downdraining. Below about 720 feet, allowing 20 or 30 feet of cutting below static water level, the slopes were subjected to wave work of the sea-level water. Below the marine plane the steeper slopes show the ledges and rock piles due to wave action, while the moderate slopes carry embankments of wave construction. The evidence of wave work at 740 feet is clear at all points where the plane has been examined. On the highway leading down the east side of the hill a well-defined cliff occurs at the critical level, and others at lower levels, especially at about 640 to 625 feet. On the north and south road, 2 miles west of the hilltop, the level appears in terraces at the angles in the road. Three miles farther west, by the four road angles, distinct cliffs show on the south, and delta sands by the Outarde river at 725 to 730 feet. The shore line can be traced along the road leading southwest; and on the road leading northwest, 2 miles southwest from Franklin Center, strong bars cross the road from about 725 down to about 660 feet. At Frontier the shore passes back into New York, where 56 NEW YORK STATE MUSEUM good bars lie at 700 to 730 feet. These features are indicated on the map, between which the shore line has been interpolated, being mostly in forest and not examined. Future study will discover many good features. It should be emphasized that this shore line lies with identity of character and altitude on both flanks of the Covey promontory, in both the Champlain and Ontario basins. The Franklin Center-Covey Hill post office beaches. This strong shore line, 215 feet beneath the marine summit, was formerly regarded as the marine summit (81, 82). It carries a splendid set of bars at all points about the Covey salient in Canada. Lying low on the slopes it probably represents an accumulation of coarse detritus by the rinsing down of 200 feet on the higher slopes, and perhaps some kame-moraine at this level. Around the north side of Covey hill the wave work had been mainly erosional from the summit level down to the Franklin Center level. At this lower plane the off-shore depth and other relations were such that the work of the waves became chiefly constructional. The exceptional development of summit bars in the Cannon Corners district was due, as already stated, to the abundance of coarse delta stuff from the inferior downdrainage of Iroquois. The 215 feet interval between the two strong shore lines so prominent on the map is rather misleading. Intermediate features exist, and the scanty representation is due more to lack of observa- tion than to actual absence of beach phenomena. Attention has been chiefly directed to the two series of bars. The unusual development of the Franklin Center bar series might be regarded as the record of an episode of much slower land uplift. But as the shore is not clearly recognized southward beyond the area mapped in plate 5 or southwestward beyond Lawrence- ville, on the Moira quadrangle, it must be explained as due to exceptional local conditions. The possibility is recognized, how- ever, that in the progressive wave uplift of the land this district might have risen at first with relative rapidity, for the 215 feet, and then more slowly. The location and character of this shore is sufficiently shown in the map. Below the upper bars, 525 feet, the beach phenomena are abundant at all declining levels where conditions were favor- able. A fair set of bars lie on the Chateaugay sheet, and a remarkable series on the north edge of the Mooers sheet. The shore also appears along English river, and west of West Chazy; but southward on the Dannemora sheet its place is occupied only by smooth or rolling tracts of sandy soils, with no bars. ‘JOoF OZII OpMIN[Y ‘“Wreoiysdn Ysva suryooy “AvsnvoayeyD FO jsoMyjnos soy € ‘jauueyd wreasys [wry ZZ 9}eIq PLEISTOCENE MARINE SUBMERGENCE 57 Bar Succession : HORIZON- GREATEST LOCALITY NUMBER TAL Beer end men en: SINGLE OF BARS DISTANCE, FEET ia BIE INTERVAL IN MILES IN FEET Bars of the marine summit. Iiversial, Stelmerelle so aie oe. cauoe A 8 4 40 (730-690) 5 | ro (middle) Aiemstroneseausheni een 6 i 20 (730-710) 4 North of Cannon Corners. . 7 4 20 (725-705) 3 | To (at top) Cannon Corners School.... 6 i 25 (730-705) 5 | 10 (at bottom) Shelters Corners.......... I5 3% | 120 (700-580) 8 Beant owitieysare caro oss TSE seal eae ae T15 (684-560) 9 HERG telcltalarecel Wieteys dee hevaueh sict s'adeyisi8ys 9 4 80 (590-510) 9 Bars of the Franklin Center series neice Centenaanae een n. 18 38 | 112 (525-413) 6 StockwellUPNO wy seek to. 13 a | 135 (510-375) To | 12 Covey Hill P. O. north..... 16 I | 210 (530-320) 13 | 23 (at bottom) Covey Enlil 2. O., east. 1... 18 ; I | I3I (523-392) WA |) 13) (Bie OD) DOUbMoOLpotundanyn se se. 42 t+ | 160 (525-365) 4 IBRISSEtr OMG sadn aco coe Boos TP Oaliussattysnaeare IT00 (500-400) 8 i} Bar succession. The above tabulation clearly proves that the production of embankments or bars along shore lines is not wholly a function of duration, or length of time for wave work at a fixed level, but that it depends on a combination of physical shore conditions. Chief of these factors is an abundance of coarse material, as boulders and cobble, which the waves can throw beyond their future grasp. This is proved by the large development of bars on cobble deltas and their absence at the same level, in near localities, on sandy tracts. Other evident conditions must be suffi- cient breadth and depth of water for efficient waves and shore cur- rents, and favorable shore topography for piling the detritus. The succession of bars with close spacing through large vertical range can not be produced in water of fixed level, in relation to the land, nor in rising levels. They are the product of slow and steadily falling levels. Marginal glacial lakes do not have the requisite conditions. The series of bars shown in the accompanying maps, for Lake Iroquois and the sea-level waters, can be constructed only by the slow uplift of the land out of the waters. St Lawrence Valley Chateaugay quadrangle. The striking feature of this map (plate 5.) is the Iroquois shore line with its correlating glacial drainage channels (plate 22). This is well marked by deltas an dweak bars, but fading northeastward on the Churubusco and Canadian sheets toward the second outlet at Covey pass. In this district the marine 58 NEW YORK STATE MUSEUM shore has much stronger development of bars than the Iroquois. The heavy representation on the map of the lower, Franklin Center, series is somewhat misleading, as these bars are only gentle -rolls or swells on the plains away from the stream deltas. Near North Burke, however, is a kame-moraine which has been shaped into bold ridges. Two views of the Chateaugay delta in Lake Iroquois are given in plates 23 and 24. Malone quadrangle. The shore lines and deltas are well shown on the map, and do not require much description. The lower marine deltas lie in position to represent the Franklin Center shore. Below this broad sand and silt plains extend down the Trout and Salmon rivers to Canada; but are not colored on the map. The head of the Salmon river delta in Lake Iroquois is repre- sented in boulder masses some 7 miles up the river ravine at Chasm falls. Remnants of the delta are seen south of Malone in the reservoir and other gravel hills, but the vigorous Post-Iroquois erosion has swept away most of the Iroquois delta and redeposited it downstream at the sea level, making the massive sand plain north of Malone. On this sheet no attempt has been made to map beaches below the marine summit. The marine shore lies across the southeast corner of the Moira quadrangle, which is not included among the maps of this writing. The most conspicuous feature on the Moira quadrangle is a strong shore south of Brushton and Moira and passing through Lawrenceville, in the approximate position of the Franklin Center shore line. So far as observed, this is the last clear representation of that lower shore, going to the southwest. The area south of the Moira and east of the Potsdam quad- rangles has not been mapped, but the shores lie across the north- west corner of this unnamed sheet in strong shape. The Iroquois delta on the Deer river is at Dickinson Center; and on the east branch St Regis, at Nicholville. Northwest of Dickinson Center are good summit bars of Iroquois, and one and one-half miles southeast of Nicholville are strong boulder bars, lying obliquely across the road with moraine surface behind them. This will give a good figure for the Jroquois shore when the topographic survey is made. The marine plane is shown by bars and delta at Fort Jackson, on the St Regis river, east branch. Potsdam quadrangle. This quadrangle has been examined with care, and with the assistance of Prof. George H. Chadwick. Two large rivers cross the area, the west branch of the St Regis, and the Raquette, and they have left heavy deltas at the Iroquois and “00 JYysiIt sy} UO 9s105 IATL YT, “Ytou sur ‘stonbory oye] UI eijop 1oANy AeSneajeyD jo jwuns ‘OSUTTIA Aesnva}eYy) FO JSOMYINOS Sopiur F[ey-auo pur sO €% 93e[q ‘ureyd Surdojs-Yj1ou oY} sso19e 4svoa suIyOOT] ‘asvqIIA AesneajeyD JO JSoMYINOS [IW IUG ‘stOnNbosy oye] ul ejjop JoANY AesneojeyD Jo peoy oy} 1esu urejd s[qqo)D ve 921g PLEISTOCENE MARINE SUBMERGENCE 59 the marine levels. The map (plate 7) shows the standing water features. A good development of bars, with clear relation to the drift sur- faces, gives fairly exact altitudes. One occurrence is a mile northeast of Parishville, where three elegant bars have altitude, 928, 905 and 885 feet. At Colton and the Clafin School the strong shore features have not been measured. The marine shore is well shown by weak bars and points of deltas northeast of Southville, at 600 to 615 feet, and west of Hannawha Falls by cliff and bar. The Franklin Center stage is only suggested; but detached beaches are found at many levels inferior to the summit. The delta at Allens Falls, on the St Regis, appears to have been built during the downdraining of Lake Iroquois. Canton quadrangle. The details on the sheet have been studied, mainly by Professor Chadwick, and as he has projected a paper on the Pleistocene geology, the map is not included here. Now it will be sufficient to say that the Iroquois shore merely touches the south- east corner of the sheet; that the marine shore crosses south of Crarys Mills and Langdon Corners, with construction of weak bars on the northwest face of Waterman hill, and a heavy delta on the Grass river at Pyrites. Russell quadrangle. On this area the Iroquois waters reached far up the Grass River valley, among the Adirondack hills. The plains at Burns Flat and northward, on the east side of the quad- rangle, probably represent the delta of the Grass. Wave erosion of Iroquois is well shown on the hills about West Pierrepont, and on the hill at Stone School, a mile southwest. Cliffs and bars appear on the northwest and the south faces of Kimball hill, north of Russell. An excellent development of beaches is found on the Hatch (Hamilton) hill, over a mile southwest of Russell. These have been measured with sufficient precision. The summit bar of Iroquois is here 850 feet, and bars range down to 815 feet. The vertical range of 35 feet appears to represent the amount of land uplift at this locality during the life of Iroquois. The Oswegatchie river crosses the southwest corner of this quadrangle, and its delta is about South Edwards and Pond Settle- ment. The theoretic altitude here is 780 feet for the closing level, and the features range from 826 down to 780 feet, a vertical range of 46 feet. The marine shore lies on the northwest corner of the area, north 60° NEW YORK STATE MUSEUM and south of the village of Hermon, which is built on a terrace of the Elm creek delta. The summit shore line passes through the east edge of the village, with altitude 520 to 525, the theoretic figure. The extended plain lying for miles along the upper valley of Elm creek, from Fairbanks Corners to Scotland School, appears to be due to waters held in by rock control south of Marshville. The marine delta of the Grass river is at Pyrites, on the Canton quad- rangle. Gouverneur quadrangle. The Iroquois level appears in the south- east part of the area, in the higher sand plains about Fullerville Ironworks, at about 780 feet. These plains are the north part of the delta of the west branch of the Oswegatchie river, which extends 7 miles south to Harrisville, on the Lake Bonaparte quad- rangle. The narrow waters entangled among the hills could not be expected to produce distinct shore features. The lower plains north of Fullerville, 700 feet, and those at Edwards, 660, seem to have been due to pondings of the Oswe- gatchie while it was cutting the rock gorges at Hyatt and Emery- ville. The marine shore lies diagonally across the area from the north- east to the southeast corner, with altitudes of 525 down to 480 feet. The Oswegatchie delta begins at Hailesboro, 2 miles south- east of Gouverneur, and the lower levels are the extensive plains at and above Gouverneur. The delta plains are fine material, as the coarse detritus had been dropped above the rock barrier. The Gouverneur sheet shows strikingly the singular topographic character of that region, a complex of smoothed rock knobs and ridges, with intervening smooth silt plains. The latter are the product of the sea-level waters which rinsed the drift off of the knolls and hills and spread it out evenly in the hollows. The clean- cut horizontal line of contact between the silt plains and the steep rock slopes is characteristic of the submarine silt plains in New York and Vermont. The traveler on the Rome, Watertown and Ogdensburg branch of the New York Central Railroad may see this feature all the way from Canton south to Keenes. Southward through Antwerp the road lies above the marine plane. Five miles northeast of Gouverneur and 2 miles south of Rich- ville, by the Cole School, is a good display of summit marine cobble bars on some drift knolls. The bars are from 516 feet down. Evidences of wave work on the slopes is common in this district. Lake Bonaparte quadrangle. The Iroquois waters passed up the Oswegatchie valley as a deep embayment to Harrisville, where the PLEISTOCENE MARINE SUBMERGENCE 61 delta seems to head. The waters lay here and among the detached hills at an altitude of 745 feet for the closing phase, but the plains recording the earlier and uplifted levels are about 770 feet. No study has been made of this area. The marine waters did not reach this quadrangle. Antwerp quadrangle. On the southern part of this area lies the greater mass of the huge delta of the Black river built in Lake Iroquois. The head of the delta lies south, up stream, on the Carthage quadrangle. The theoretic altitude for closing Iroquois in the district of the Great Bend is 700 feet, and the broader plains are-contoured at 700. The higher plains, about Carthage are up to 740 feet. The history of the waters in this region is told in publications 162 and 163. The marine waters did not reach this area; but had irregular extension among the hills northward, on the Hammond quadrangle. The accompanying map, plate 4, gives the approximate location of the shore lines on the quadrangles which are not reproduced for this writing. Ontario Basin Lake Iroquois. West of the St Lawrence area, above described, the beaches of Lake Iroquois and of thé sea-level waters have been described and mapped in former publications. The beaches of Iroquois were the first of the ancient shore lines to be dis- tinctly recognized as such, and are too well known in the Ontario basin to require extended notice here. The more important papers have been listed in the bibliography. The more recent maps are in the following papers: In 154 of the appended list, plate 19 is a map of the lake south and west from Watertown; with description of the strong shore from Watertown to Richland, pages 104-12, and tabulated details in plates 9 and Io. In 152, a good map by Coleman, with description of the Canadian shore. In 163, a part of the Black river delta is shown in plate 44, and described in pages 136-72. In 164, plate 17 shows the early stage when the lake had reached its full westward extent, as a narrow stretch of water along the south front of the Ontario glacier lobe. Plate 4 in this paper is a detailed map of the shore line in the Watertown region, from Carthage to Adams, with the channels of tributary glacial drainage. Accompanying this paper, plate 1 shows Lake Iroquois at its greatest expansion, just previous to its extinction; plate 4 shows 62 NEW YORK STATE MUSEUM the approximate location of the shore north of Richland; and plates 5, 6 and 7 depict the northern shore in New York in detail. For future mapping there remains only three unpublished sheets, in part; and the short stretch from Rome to Richland. A very brief outline of Lake Iroquois history may appropriately close the description. The lake originated at the margin of the waning Ontarian lobe of the latest ice sheet when the ice uncovered the southeast part of the Ontario basin, the low ground at Rome and Oneida lake. An early stage, when it reached westward only to about Lyons, is mapped in plate 41, paper 160. As the ice lobe gave way the lake extended itself westward until it was a narrow belt of water, laving the south front of the glacier, the whole east and west extent of the Ontario basin, as mapped in plate 42, of 160; and plate 17, of 164. As the Ontarian ice lobe diminished the lake increased, and inserted a tongue of its water northeastward, between the ice margin and the foothills of the Adirondacks. The greatest extent and area of the lake was attained while the lake had its second outlet at Covey pass, above described and mapped in plate 1. The lake came to its extinction when the ice barrier on the north slope of Covey hill weakened, and melted back to a height beneath 1030 feet, or the height of the Covey river. Then the waters were permitted to drain down to sea level, and to become part of the Hudson-Champlain estuary, shown in plate 2. Gilbert gulf. That the low altitude of the northern land at the time of disappearance of the latest ice sheet must have allowed oceanic waters to occupy the St Lawrence and Ontario valleys has been recognized many years. As long ago as 1808 F. B. Taylor mapped the Champlain sea as extending into the Ontario valley (130 pasew/3)) Dr G. K. Gilbert was the first geologist to recognize the beaches produced by this extension of sea-level waters (11, page 59), and called them the Oswego shore line, although they do not quite reach to Oswego. In 1905 the writer briefly described the beaches in the southerly stretch between Oswego and Clayton, and added sketch maps of most of the distance (157, pages 712-18; figures 1-3); and took the liberty of naming these marine-level waters after Doctor Gil- bert, in admiring recognition of his leadership in the study of the New York Pleistocene. In 1910 the writer extended the mapping of the Gilbert gulf Plate 25 Cobble bar on the shore of Lake Iroquois. One-fourth mile north of Farr’s and 3 miles east of Watertown. Upper view looking northeast; lower view looking southwest. PLEISTOCENE MARINE SUBMERGENCE 63 shore as far northward as Alexandria Bay and Redwood, in a partial way, as the beaches are detached and mostly weak (163, plates 44-47; pages 136-72). The most important series of bars is ON a moraine tract 2 miles north of Lafargeville, with summit altitude about 440 feet. In this district of horizontal rocks, low relief and clay plains; or farther north, with glaciated granitic knobs and silted hollows, the waves found little material and poor conditions for leaving their inscriptions. SUMMARY It seems possible that the Pleistocene history of New York State includes more than one ice invasion, or glacial epoch; but this writing deals with only the records of the latest ice sheet, and specifically with the waters that occupied the low valleys as the ice body melted. When the Labradorian ice cap was disappearing, the land which had been beneath the ice sheet was much lower than at present. The amount of the depression seems to bear quite direct proportion to the thickness and weight of the ice burden. The measure of that depression is found in the Hudson-Champlain valley, and about New York City and over Long Island, in the shore phenomena left by the sea-level waters that took possession as the ice vacated. The amount of the land uplift is shown in the maps, and for the Hudson-Champlain valley in the diagram, plate Io. In the St Lawrence-Ontario valley the amount of postglacial rise of the land is found by the amount of deformation, or north- ward up-tilting of glacial lake shore lines, which must have origi- nally been horizontal. The shore line of Lake Iroquois has been deformed 668 feet, and bodily lifted 72 feet more, which gives a total rise at Covey hill of 740 feet, the same as the altitude of the marine beaches at that point. The diagram (plate 11) shows the tilt of the St Lawrence beaches. The records of the sea-level waters in the Hudson-Champlain valley cover all of the long time involved in the wamng and dis- appearance of the ice sheet, from the moment of its greatest extent to the time when it passed entirely off the State. But the glacial records in the St Lawrence valley cover only the latter part of glacial time. For this writing the history of the St Lawrence valley is only that of Iroquois and Post-Iroquois time. The history, in brief, is as follows. The sea-level waters con- tinuously laved the receding front of the glacier as it retreated up the Hudson and Champlain depression. Large glacial boulders in 64 NEW YORK STATE MUSEUM the clays are proof of this. When the margin of the ice sheet receded, on the high ground north of the Adirondacks, to the inter- national boundary, it uncovered a low notch, the Covey pass, which permitted the outflow of the glacial waters of the Ontario-St Lawrence basin, Lake Iroquois; and from this time the St Law- rence waters were tributary to the Champlain valley, instead of, as formerly, to the Mohawk-Hudson. At that time the Covey out- let was 740 feet lower than today, and only 290 feet above the sea. With further recession of the ice barrier on the north slope of Covey hill, Lake Iroquois was drained down to sea level. The Hudson-Champlain estuary then passed westward around the Covey salient and occupied the St Lawrence basin. The altitude relations of Lake Iroquois and the sea-level waters are tabulated: in plate 12. The postglacial rise of the land was by a wave uplift, progress- ive from south to north, following the removal of the ice burden. The rise was laggard or dilatory, and it appears that no appreciable rise occurred at any point in the Hudson valley while the ice lay on that point. But it seems more than possible that the uplift wave overtook the receding ice front in the Champlain valley; and that a relatively small rise took place at Covey hill while the ice held Lake Iroquois to the Covey outlet. This would account for some shore features in the districts of ‘Crown Point, Port Henry and Peru somewhat above the profile shown in plate 10. In such case the bars at Covey hill, 740 feet, do not give the full amount of glacial depression and postglacial uplift. The maps and profiles do show the positive minimum of recent diastrophism. It is recognized that there may be complications in the Pleistocene history, and that the present altitude of the upraised water plane is only the final or average result of any up and down land move- ments, and any variations of the sea level; the arithmetical sum of all the plus and minus elements. But it appears that such com- plicating factors would probably increase the record of land depres- sion and subsequent rise, instead of reducing it. To the degree that the ocean level was lowered by removal of water to build the ice caps, the ancient water plane was so much beneath present ocean level. The present height of the summit plane above the sea must be only the excess of land uplift over any rise of the ocean surface. The gravitational pull on the sea level by the ice body at the attenuated margin of the valley lobe is thought to have been a negligible factor in the New York district; and probably so at all PLEISTOCENE MARINE SUBMERGENCE 65 other localities when the receding and relatively thin ice margin was passing off. The evidences of marine submergence of Long Island and the Hudson-Champlain valley are briefly stated. The lack of marine fossils in the Hudson valley, and of wave-built embankments on the sand plains, are explained. A running description is given of the summit shore phenomena from New York City northward; at and around Covey hill, and through the St Lawrence valley. The summit shore features on the Vermont side of the great estuary has been recently published (92). SIN @ GiRsa wee ' The Pleistocene depression of the land and the postglacial uplift involves wide territory of northeastern America, and a full list of writings would approximate a complete bibliography of the Pleistocene geology. The following list is restricted to writings which contain some reference to the static water phenomena, or have some bearing more or less direct on Pleistocene land deformation. - The literature of the Ontario basin can not be entirely separated from that of the Great Lakes area. A list of papers relating to the glacial waters of the upper Great Lakes, up to the year 1907, is given by Goldthwait in no. 23. In no. 82 Woodworth gives an extended list of the older literature, to 1905, with special reference to eastern and northern New York. Eastern Canada is in its geography and glacial history so closely connected with the Champlain-St Lawrence basin that some papers describing Canadian territory are included. Many papers relating to New England geology have direct bear- ing on the diastrophic problem, but only a few papers concerning the Connecticut valley are here included. For convenient reference the titles are arranged in six groups, with a few cross references. Within each group the order is chronologic by authors. A General; theoretic; land deformation B Lower Hudson district C Long Island | D_ Connecticut valley FE Upper Hudson, Champlain and eastern Canada F Upper St Lawrence, Ottawa valley and Ontario basin 66 NEW YORK STATE MUSEUM A General; Theoretic; Land Deformation 1 H. D. Rogers. On the Origin of the Drift, and of the Lake and River Terraces etc. Proceedings of the American Association for the Advancement of Science, 1849, 2:230-55 2 E. Desor. [Evidences of Marine Deposits in Eastern America.] Pre- sented to the Boston Society of Natural History. Proceedings, v. 3, 4, 1848-52 3 Warren Upham. A Review of the Quaternary Era with Special ‘Reference to the Deposits of Flooded Rivers. American Journal of Science, 18901, 41:33-49 4 Glacial Lakes in Canada. Bulletin of the Geological Society of America, 1891, 2:243-76 5 Relationship of the Glacial Lakes Warren, Algonquin, Iro- quois, and Hudson-Champlain. Bulletin of the Geological Society of America, 1892, 3:484-88 6 The Champlain Submergence. Bulletin of the Geological Society of America, 1892, 3:508-11 D, Deltas of the Hudson and Mohawk Valleys. American Geolo- gist, 1892, 9:410-11 8 Wavelike Progress of an Epeirogenic Uplift. Journal of Geology, 1894, 2:383-95 9 Late Glacial or Champlain Subsidence and Reelevation of the Saint Lawrence Basin. American Journal of Science, 1895, 49:1-18 ie) The Glacial Lake Agassiz. United States Geological Survey, Monograph 25, 1895, p. 255-64 11 G. K. Gilbert. (No title.) United States Geological Survey, 18th Annual Report, 1807, p. 58-590 Recent Earth Movements in the Great Lakes Region. United States Geological Survey, 18th Annual Report, 1898, pt 2, p. 595- 647 13 Gerard de Geer. Isobases of the Postglacial Elevation. American Geologist, 1892, 9:247-49 On Pleistocene Changes of Level in Eastern North America. American Geologist, 1893, 11:22-44; Proceedings of the Boston Society of Natural History, 1892, 25:454-77 15 Frank Taylor. The Limit of Postglacial Submergence in the High- lands East of Georgian Bay. American Geologist, 1894, 14:273-89 12 14 16 Niagara and the Great Lakes. American Journal of Science, 1895, 49:249-70 7 The Second Lake Algonquin. American Geologist, 1895, 15 :100-20, 162-79 18 The Champlain Submergence and Uplift, etcetera. British Association for the Advancement of Science, Report for 1897, 1808, p. 652-53 19 Robert Bell. Proofs of the Rising of the Land Around Hudson Bay. American Journal of Science, 1806, 1:219-28 Evidences of Northeasterly Differential Rising of the Land Along Bell River (\Canada). Bulletin of the Geological Society of America, 1897, 8:241-50 20 PLEISTOCENE MARINE SUBMERGENCE 67 Rising of Land Around Hudson Bay. Smithsonian Institution Annual Report for 1898, p. 359-67 22 J. W. Goldthwait. Correlation of the Raised Beaches on the West Side of Lake Michigan. Journal of Geology, 1906, 14:411-24 21 23 The Abandoned Shore Lines of Eastern Wisconsin. Wis- consin Geological and Natural History Survey, Bulletin 17, 1907 24 A Reconstruction of Water Planes of the Extinct Glacial Lakes in the Lake Michigan Basin. Journal of Geology, 1908, 16:459-76 25 Isobases of the Algonquin and Iroquois Beaches, etcetera. Bulletin of the Geological Society of America, 1910, 21:227-48 26 H. L. Fairchild. Pleistocene Geology of New York State. Bulletin of the Geological Society of America, 1913, 24:133-62; Science, 1913, 37 :237-49, 290-99 27 Pleistocene Uplift of New York and Adjacent Territory. Bulletin of the Geological Society of America, 1916, 27:235-62 27a Pesiglacial Uplift of Northeastern America. Bulletin of the Geological Society of America, 1918, 29 :187-238 See also numbers 92, 108-14, I3i1, 138-41, 144, 152-53, 166-67 B Lower Hudson District 28 W. W. Mather. Geology of New York. Survey of the First Geolog- ical District, 1843, p. 148-58 29 J. S. Newberry. The Geological History of New York Island and Harbor. Popular Science Monthly, 1878, 13:641-60 30 F. J. H. Merrill. Quarternary Geology of the Hudson River. toth Annual Report of the New York State Geologist, 1890, p. 103-9 31 Some Ancient Shore Lines and Their History. ‘Transactions of the New York Academy of Sciences, 1890, 9:78-83 32 On the Postglacial History of the Hudson River Valley. American Journal of Science, 1891, 4:460-66 33 Heinrich Ries. Quaternary Deposits of the Hudson River Valley, etcetera. 10th Annual Report of the New York State Geologist, 1890, p. II0-55 5 34 Notes on the Clays of New York State, etc. Transactions of the New York Academy of Sciences, 1892, 12:44-46 35 Quaternary Clays . . . and the Estuary Clays of the Hud- son and Champlain Valleys. Transactions of the New York Acad- emy of Sciences, 1894, 13:165 36 Clays of New York. New York State Museum Bulletin 35, 1900, 7:576-94 37 W.M. Davis. The Catskill Delta in the Postglacial Hudson Estuary. Proceedings of the Boston Society of Natural History, 1892, 25 :318-35 38 N. H. Darton. Pleistocene Geology of Albany County. 13th Annual ‘Report of the New York State Geologist for 1893, p. 259-61 Pleistocene Geology of Ulster County. 13th Annual Report of the New York State Geologist for 1893, p. 368-72 40 C. C. Jones. A Geologic and Economic Survey of the Clay Deposits of the Lower Hudson River Valley. Transactions Mining Engi- neers, 1890, 29:40-83 39 68 NEW YORK STATE MUSEUM 41 R. D. Salisbury. - Glacial Geology of New Jersey. Geological Survey of New Jersey, 1902, 5:196-203 42 Postglacial Submergence. United States Geoloeiee Suir veue New York City Folio, no. 83, 1902, p. 16 43 Submergence of the Lower Part of the Newark Plain Since the Last Glacial Stage. United States Geological Survey, Passaic Folio, no. 157, 1908, p. 20 See also numbers 80, 82, 92 C Long Island 44 W. C. Watson. The Plains of Long Island. Transactions of the New York State Agricultural Society, 1859, 19:485-505 45 E. Lewis. Evidence of Coast Depression Along the Shores of Long Island. American Naturalist, 1860, 2:334-36 46 On the Water Courses upon Long Island. American Journal of Science, 1877, 13:142-46 . 47 — Certain Features of the Valleys or Water Courses of Southern Long Island. American Journal of Science, 1877, 13 :215-16 48 — Ups and Downs of the Long Island Coast. Popular Science Monthly, 1877, 10:434-46 49 Warren Upham. The Terminal Moraine of ihe North American Ice Sheet. American Journal of Science, 1879, 18:197-209 _ 50 F. J. H. Merrill. Geology of Long Island. Annals, New York Acad- emy of Sciences, 1886, 3:241-64 51 J. B. Woodworth. Pleistocene Geology of Portions of Nassau County and Borough of Queens. New York State Museum Bulletin 48, IQCI, p. 657-63 52 A. C. Veatch & others. Underground Water Resources of Long Island, New York. United States Geological Survey, Professional Paper no. 44, 1906, p. 33-50 53 W. O. Crosby. Outline of the Geology of Long Island, N. Y. Annals of the New York Academy of Sciences, 1908, 18:425-29 54 M. L Fuller. Geology of Long Island. United States Geological Survey, Professional Paper no. 82, 1914, p. 212-19 55 H. L. Fairchild. Postglacial Marine Submergence of Long Island. Bulletin of the Geological Society of America, 1917, 20:279-308 D Connecticut Valley 56 James D. Dana. On the Quaternary or Post-Tertiary of the New Haven Region. American Journal of Science, gat series, 187%, I:I-5, 125-26 57 On the Glacial ce Champlain Brae in New England. Autor ican Journal of Science, 1873, 5:198-2I11, 217-18, 219 58 On the Submergence During the Gee! Peron. American Journal of Science, 1875, 9:315-16 50 On Southern New England During the Melting of the Great Glacier. American Journal of Science, 1875, 10:168-83, 280-82, 353-57, 409-38, 497-508; ee IT :151; e187, 12:125+28> PLEISTOCENE MARINE SUBMERGENCE 69 160 The Flood of the Connecticut River Valley from the Melting of the Quaternary Glacier. American Journal of Science, 23:87-97, : 179-202, 360-73; 1882, 24 :98-104 : - 61 On the Western Discharge of the Flooded Connecticut, etcetera. American Journal of Science, 1883, 25:440-48 . 62 Phenomena of the Glacial and Champlain Periods about the Mouth of the Connecticut Valley, etcetera. American Journal of Science, 26:341-61; 1883, 27:113-30 63 Manual of Geology, 4th edition, 1895, p. 981-93 ‘64 Warren Upham. Northern Part of the Connecticut Valley in the Champlain and Terrace Periods. American: Journal of Science, series 3, 1877, 14:459-70 Changes in the Relative Heights of Land and Sea During the Glacial and Champlain Periods. Geology of New Hampshire, 1878, Vv. 3, Pt 3, D. 329°33 66 B. K. Emerson. Geology of Old Hampshire County, Massachusetts. U. S. Geological Survey, monograph 29, 1808 67 Holyoke Folio, U. S. Geological Survey, Folio no. 50, 1898 68 C. H. Hitchcock. The Glacial Flood in the Connecticut River Valley. Proceedings of the American Association for the Advancement of Science, 1883, 31:325-29 69 H. L. Fairchild. Pleistocence Marine Submergence of the Connecticut and Hudson Valleys. Bulletin of the Geological Society of America, IOI4, 25:219-42 E Upper Hudson, Champlain and eastern Canada 70 Ebenezer Emmons. Geology of New York. Survey of the Second Geological District, 1842, p. 422-27 71 C. H. Hitchcock. Geology of Vermont, 1861, 1:93-I101 72 The Champlain Deposits of Northern Vermont. Report of the State Geologist of Vermont for 1905-6, p. 236-53 73 J. W. Dawson. The Canadian Ice Age, 1893 74 Heinrich Ries. A Pleistocene Lake-bed at Elizabethtown, Essex County, New York. Transactions of the New York Academy of Sciences, 1893, 13:107-9 75 S. P. Baldwin. Pleistocence History of the Champlain Valley. Amer- ican Geologist, 1894, 13:170-84 76 G. F. Wright. Glacial Phenomena Between Lake Champlain, Lake George, and Hudson River. Science, 1895, 2:673-78 Glacial Observations in the Champlain-Saint Lawrence Valley. American Geologist, 1898, 22:333-34 78 F. B. Taylor. Lake Adirondack. American Geologist, 1897, 19:392-96 79 R. Chalmers. Pleistocene Marine Shore Lines on the South Side of the Saint Lawrence Valley. American Journal of Science, 1896, 1:307-8 80 C. E. Peet. Glacial and Postglacial History of the Hudson and Champlain Valleys. Journal of Geology, 1904, 12:415-60, 617-60 81 J. B. Woodworth. Pleistocene Geology of the Mooers Quadrangle. New York State Museum Bulletin 83, 1905 77 70 NEW YORK STATE MUSEUM Ancient Water Levels of the Champlain and Hudson Valleys. New York State Museum Bulletin 84, 1905 83 J. W. Goldthwait. Twenty-foot Terrace and Sea Cliff of the Lower Saint Lawrence. Bulletin of the Geological Society of America, LOMMpe2 ees 84 R. A. Daly. The Geology of the Northeast Coast of Labrador. Bul- letin of the Museum of Comparative Zoology, 1902, 38:205-70 85 I. H. Ogilvie. Glacial Phenomena in the Adirondacks and Cham- plain Valley. Journal of Geology, 1902, 10:397-412 86 H. E. Merwin. Some Late Wisconsin and Post-Wisconsin Shore Lines of Northwestern Vermont. Report of State Geologist of Vermont, 1907-1908, p. 113-38 87 J. H. Stoller. Glacial Geology of ‘the Schenectady Quadrangle, New York State Museum Bulletin 154, 1011 88 G. H. Perkins. Geological History of Lake Champlain. Report of the State Geologist of Vermont for 1911-1912, p. 38-53, I913 89 H. L. Fairchild. Report of Field-work (no title). In Report of Director of the Science Division, New York State Museum Bul- letin 158, 1912, p. 32-35 82 — 90 The same, Bulletin 164, 1913, p. 21-25 QI The same, Bulletin 173, 1914, p. 67-69 92 — Postglacial Marine Waters in Vermont. Report of the Ver- mont State Geologist for 1915-16, p. I-42 93 ——— Postglacial Features of the Upper Hudson Valley. New York State Museum Bulletin 195, 1917 o4 E. E. Barker. Ancient Water Levels of the Crown Point Embay- ment. 12th Report of the Director of the Science Division, New York State Museum Bulletin 187, 1916, p. 165-90 95 H. L. Alling. Glacial Lakes and Other Glacial Features of the Cen- tral Adirondacks. Bulletin of the Geological Society of America, 19160, 27:645-72 See also number 142 F Upper St Lawrence, Ottawa Valley and Ontario Basin 96 Amos Eaton. Geological and Agricultural Survey of the District Adjoining the Erie Canal, 1824, p. 105-6 97 Thomas Roy. In Proceedings of the Geological Society of London, 1837, 2:537-38 98 James Hall. Lake Ridge. In Report of Governor Marcy, 1838, Pp. 310-14, 348-50 © 99 ——— Physical: Geography of Western New York. In Report of Governor Seward, 1840, p. 431-44 100 ——— Geology of New York. Survey of the Fourth Geological Dis- trict, 1843, p. 348-54 101 G. E. Hayes. Remarks on the Geology and Topography of Western New York. American Journal of Science, 1830, 35 :86—105 102 James Lyell. Travels in North America, 1845, v. 2, ch. 20, p. 71-95 103 E. Desor. On the Ridge Road front Rochester to Lewiston, etcetera. Proceedings of the Boston Society of Natural History, 1851, 3:358-50 PLEISTOCENE MARINE SUBMERGENCE 71 104 E. J. Chapman. Notes on the Drift Deposits of Western Canada, etcetera. Canadian Journal, 1861, 6:221-29 105 Sandford Fleming. Notes on the Davenport Gravel. Canadian Jour- nal, 1861, 6:247-53 106 W. E. Logan. Geological Survey of Canada, Report for 1863, p. 910-15 107 G. J. Hinde. The Glacial and Interglacial Strata of Scarboro Heights and Other Localities near Toronto, Ontario. Canadian Journal, 1878, 15:388-413 1o8 G. K. Gilbert. Old Shore Line of Lake Ontario. Science, 1885, 6:222 —(see number II) 109 The Place of Niagara alts in Geologic History. Proceedings American Association for the Advancement of Science, 1887, 35 :222- 23; American Journal of Science, 1886, 32:322-23 IIO Old Shore Lines in Ontario Basin. Proceedings of the Cana- dian Institute, 3rd series, 1888, 6:2-4 III Changes of Level in the Great Lakes. Forum, 1888, 5:417-28 112 History of Niagara River. 6th Annual Report, Commissioners of State Reservation at Niagara, 1880, p. 61-84; Smithsonian Insti- tution Annual Report, 1890 113 (Iroquois shore line discussion.) Bulletin of the Geological Society of America, 1892, 3492-93 114 Niagara Falls and Their History. National Geographic Mono- graph 1, no. 7, 18905, p. 203-6 115 J. W. Spencer. Terraces and Beaches about Lake Ontario. Trans- actions of the American Association for the Advancement of Science, 1883, 31:359-63 116 Notes on the Origin and History of the Great Lakes of North America. Proceedings of the American Association for the Advancement of Science, 1888, 37:197-09; American Geologist, 1888, 2:340-48 Tey, The Iroquois Beach; a Chapter in the Geological History of ‘Lake Ontario. Transactions of the Royal Society of Canada, 1880, v. 7, sec. 4, p. 121-34; Review in American Geologist, 1890, 6:311-12 118 On the Focus of Regional Postglacial Uplift. Transactions of the Royal Society of Canada, 1880, 7:129 ime) The Deformation of eee Beach and Birth of Lake Ontario. American Journal of Science, 1890, 40:443-51 120 The Northeastern Extension of the Iroquois Beach in New York. American Geologist, 1890, 6:294-95 121 High Level Shores in the Region of the Great Lakes and Their Deformation. American Journal of Science, 1891, 41:20I-I1 122 Prof. W. M. Davis on the baguitions Beach. American Geolo- gist, 1891, 7:68-69; 2606-67 123 Post-Pleistocene Subsidence Versus Glacial Dams. Bulletin of the Geological Society of America, 1891, 2:465-76 124 Channels over Divides not Evidence per se of Glacial Lakes. Bulletin of the Geological Society of America, 1892, 3:491-93, 404 125 The Iroquois Shore North of the Adirondacks. Bulletin of the Geological Society of America, 1892, 3:488-91 126 A Review of the History of the Great Lakes. American Geologist, 1894, 14:289-301 72 NEW. YORK STATE MUSEUM 127 The Geological Survey of the Great Lakes. Proceedings of the American Association for the Advancement of Science, 1895, 43 :237-43 | if 128 How the Great Lakes Were Built. Popular Science Monthly, 1896, 49:157-72 129 An Account of the Researches Relating to the Great, Lakes. American Geologist, 1898, 21:110-23 130 The Falls of Niagara, etcetera. Geological Survey of Canada, 1907 131 Postglacial Earth-movements about Lake Ontario and the Saint Lawrence River. Bulletin of the Geological Society of America, 1913, 24:217-28 132 W. M. Davis.. The Iroquois Beach. American Geologist, 1890, 6:400 133 Was Lake Iroquois an Arm of the Sea? American Geologist, 1891, 7:139-40 134 F. B. Taylor. Notes on the Quaternary Geology of the Mattawa and Ottawa Vialleys. American Geologist, 1896, 18:108-20 Origin of the Gorge of the Whirlpool Rapids at Niagara. 135 Bulletin of the Geological ‘Society of America, 1808, 9:59-84 136 A Short History of the Great Lakes. Studies in Indiana geography, 1907, p. 90-III 137 A Review of the Great Lakes History, etcetera. Science, 1908, 27 :725-26 138 Isobases of the Algonquin and Iroquois Beaches and Their Significance. Science, 1910, 32:187 139 The Glacial and Postglacial Lakes in the Great Lakes Region. Smithsonian Institution, Annual Report for 1912, p. 201-327 140 Later Glacial Lakes. United States Geological Survey, Niagara Folio, no. 190, 19173, p. 18-24 141 (With Frank Leverett). The Pleistocene of Indiana and Michigan and the History of the Great Lakes. United States Geological Survey, Monograph 53, 1915 142 A. P. Low. Notes on the Glacial Geology of Western Labrador and Northern Quebec. Bulletin of the Geological Society of America, 1892, 4:419-21 143 R. W. Ells. Sands and Clays of the Ottawa Basin. Bulletin of ithe Geological Society of America, 1808, 9:211-22 144 Frank Leverett. Glacial Formations and Drainage Features of the Erie and Ohio Basins. United States Geological Survey, Mono- graph 41, 1902 (See number 141) : 145 Robert Chalmers. Ancient Shore Lines of the Great Lakes. Geolog- ical Survey of Canada, Annual Report, v. 15, 1902-3, p. 274-76 A. The Geomorphic Origin and Development of the Raised Shore Lines of the Saint Lawrence Valley and the Great Lakes. Amer- ican Journal of Science, 1904, 18:175-79 147 A. P. Brigham. Topography and Glacial Deposits of the Mohawk Valley. Bulletin of the Geological Society of America, 1808, 9:183-210 148 A. P. Coleman. Lake Iroquois and Its Predecessor at Toronto. Bul- letin of the Geological Society of America, 1890, 10:165-76 146 PLEISTOCENE MARINE SUBMERGENCE WS 149 The Iroquois Beach. Transactions of the Canadian Institute, 1899, 6:20-44 , 150 Marine and Fresh Water Beaches of Ontario. Bulletin of the Geological Society of America, 1901, 12:129-46 I51 Sea Beaches of Eastern Ontario. Bureau of Mines of Canada, Report for 1901, p. 215-27 152 Iroquois Beach in Ontario. Bulletin of the Geological Society of America, 1904, 15:347-68; Ontario Bureau of Mines, Report for 1904, pt I, p. 192-222 153 Glacial Lakes and Pleistocene ‘(Changes in the Saint Lawrence Valley. International Geological Congress, 8th Report for 1905, p. 480-86 154 H. L. Fairchild. Pleistocene Geology of Western New York. 20th Annual Report of New York State Geologist for 1900, p. 105-12 155 Latest and Lowest Pre-Iroquois Channels between Syracuse and Rome. 21st Annual Report of New York State Géologist for IQOT, PD. 33-47 156 Glacial Waters, Oneida to Little Falls. 22nd Annual Report of New York State Geologist for 1902, p. 17-41 157 Gilbert Gulf (marine waters in the Ontario basin). Bulletin of the Geological Society of America, 1905, 17:712-18 158 Glacial Waters in the Lake Erie Basin. New York State Museum Bulletin 106, 1907 159 Iroquois Extinction (abstract), Science, 1907, 26:398-099 160 Glacial Waters in Central New York. New York State Museum Bulletin 127, 1900 : 161 Report of field work (no title). In Report of Director of the Science Division. New York State Museum Bulletin 121, 1908, p. 19-21 162 The same, Bulletin 149, I911, p. 17-18 163 Geology of the Thousand Islands Region (with H. P. Cushing and others). New York State Museum Bulletin 145, 1910, p. 136-72 164 Glacial Waters of the. Black and Mohawk Valleys. New York State Museum Bulletin 160, 1912 165 G. H. Chadwick. Fossil Lake Shores. Saint Lawrence Plaindealer (Canton, New York), July 19, 1910; Watertown Daily Times, July 25, I9I0 166 W. A. Johnson. The Trent Valley Outlet of Lake Algonquin and the Deformation of the Algonquin Water-plane in Lake Simcoe Dis- trict, Ontario, Canada. Geological Survey, Bulletin 23, 1916 Late Pleistocene Oscillations of Sea-level in the Ottawa Val- ley, Canada. Geological Survey, Bulletin 24, 1916 167 Dyer fae aha i INDEX Albany sheet, 37 Antwerp quadrangle, 61 Beaches, absence of in Staten Island region, 17-20 Bell, Robert, cited, 14 Bibliography, 65-73 Canada, postglacial submergence, 13 Cannon Corners district, 52-54 (Canton quadrangle, 22, 59 Catskill, clays, 10 Catskill delta, 15 Catskill sheet, 35 Chadwick, Prof. G. H., 5 Chalmers, Robert, cited, 14 Champlain section, I5 Champlain valley, shore features, 42-48 Chateaugay. quadrangle, 57 Clay deposits, 9 Cobblestone hill, 51 Cohoes sheet, 38 Coleman, A. P., cited, 14 Connecticut valley, clay deposits, 10; evidence from, 13; deposits, 15 Covey channel, 54 Covey Hill, 6, 55; shore features, 48-57 Coxsackie sheet, 36 Dannemora quadrangle, 22, 46-48 Darton, N. H., cited, 15 Davis, W. M., cited, 15 Dawson, J. W., cited, .14 Diagrams, explanation of, 20-26 Ells, R. W., cited, 14 Emerson, B. K., cited, 15 Fort Ann quadrangle, 40 Franklin Center-Covey Hill, beaches, 56 Fuller, cited, 18 Gilbert gulf, 62 Glens Falls quadrangle, 40 Gouverneur quadrangle, 60 Hudson Valley, shore features, 30— 42 Iroquois, Lake, 61; uplift from, 12 Jones, C. C., cited, 10 Kinderhook sheet, 37 Kingston, clays, 10 Lake Bonaparte quadrangle, 60 Lake Iroquois, see Iroquois, Lake Lakes, absence of, 7 Long Island, evidence from, 13; shore features, 29 Low, A. P., cited, 14 Malone quadrangle, 22, 58 Maps, explanation of, 20-26 Marine life, absence of, 16 Mather, cited, 14 Merrill, F. J. H., cited, 14, 17 Mooers quadrangle, 21, 48-50 New England, postglacial submerg- ence, 13 Newburg sheet, 32 Newburgh, clays, 10 Ontario basin, deformation and alti- tudes, 26-29; shore features, 61-63 Plattsburg quadrangle, 46-48 Port Henry quadrangle, 44-46 Potsdam quadrangle, 22, 58 Poughkeepsie sheet, 33 Rhinebeck sheet, 34 Ries, Heinrich, cited, 10, 15 76 NEW YORK STATE MUSEUM Rosendale sheet, 34 Russell quadrangle, 50 St-Lawrence Valley, shore features, 57-61 Salisbury, R. D., cited, 11, 15 Saratoga quadrangle, 39 Schenectady sheet, 38 Schunnemunk sheet, 32 Schuylerville quadrangle, 39 Shaler, Professor, cited, 18 Shore features, description of, 29-63 Shore line, marine, differential up- lift of, 11 Shore lines, location, 21 Staten Island region, absence of beaches, 17; shore features, 30 Summit shore phenomena, 10 Tarrytown sheet, 30 Ticonderoga. quadrangle, 42-44 Troy sheet, 37 West Chazy district, 50 West Point sheet, 31, 32 Whitehall quadrangle, 42 Willsboro quadrangle, 46 Woodworth, cited, 10, 21 atl . } } | ; } a[sueIpenO eioUIeuUeEC ey} UO Seulje10yg °8 9eI1d ajueipend wepsjog ey} wo seuyesoyg “4 are] q[sueipenO suojeyl 24} UO seuTpe10yS “9 Id WIOK MAN UIOYWON UI S19zVAM\ BUI003S19Iq “S 7d 294 9d]I oy} JO Suruepy oy} Ul seBeig “z ‘T saieIq ge ee \ Fe. fe E State: OF ae YORK 2 naa MUSEUM : “> fETIN 209-10 PLATE 4 | | i . : | | { | a | | | | | { JOHN M. CLARKE STATE GEOLOGIST i 5 UNIVERSITY OF THE STATE OF NEW ¥ STATE MUSEUM SRK y Gf ft? + ML: SEE > Cah ie i STAGES IN T a WANING OF THE ICE SHEET IN | NEW YORK ST, H. L, FAIRCHIL ATE STAGE 14.5) LAKE IROQUOIS AT ITS GREATEST HXTENT With continued shrinking of the glacier, Lakelpoquois extended northeast along the northwest slope of the Adirondack highland and finally found an outlet at the Internationa! Boundary, south of Covey Hill ch at that time was lower than the Rome outlet. This stage, here mapped, shows Lake Iroquois at its greatest ex- tent; with altitude 290 feet above the sea. A slightly further retreat of the ice margin on the north face of Covey Hill will allow the lake waters to fall to sea-level and blend with the Hudson-Champlain Estuary, as shown in Stage 1b. The progressive wave uplift of the land has estricted the sea-level waters in the Hudson Valley. Scdleen tan ‘ 9 oH none NAT f 6 a OK 4 Wie r ee BULLETIN 209-10 PLATE 1 BR \ | CNTF ds UW ors Ys r era =i : \ A BrOnrHeS Warr 4 et a Gorge § | i Weville | Gloversville as Johnstown : AW Hoasick Falls 12) ¥ 17 HW We OHN M. CLARKE . STADE GZOLOGIST a UNIVERSITY OF THE STATE OF NEW YORK STATE MUSEUM a” BULLETIN 209-10 PLATE 2 kia SaaS a Ir | ila | BP Cake Pllc ! ol Paull Ee | Lo ALON | EXizabettt ony Me gee | a 1 | { . at ‘ } | eS se 15 aan TG wie Y s ‘ sat eae a | S = ; rate. ee <= Toronto : . . SS SS UTiceelery [schroor” 5G | - \ ae pA A} | : ol Wilshéan 7 Wake Pleasant { Ranville | es | Neritiun \ \ | \ ie \ ee on | i a Satta eS Yo! | {omen | QN } t 3 | es ‘i ts | \ lal fr oe Blodmyille = ae = 5 = ; : Rae ae Hancoo £0. Kingsto’ af Rosendale {) / | Ge. A ) Ltherty ‘ 4 j ~ —~ 9 4 wou bv A Sle Monticello YS ATE. - J At this latest stage the Labrado’ York State and the United States. i below present level, and the ocean-level wate: Ontario Valley. The broad waters, ees ab - gonnected with the Gulf of St marine life. enter the St. Lawrence and Oham The part of the Champlain Sea lying in Gulf, ; < = . UiThe continued land uplift has caused fa in the Hudson Va) ey. plain Valleys. in is called the Gilbert Sea-level waters UNIVERSITY OF THE STATE OF NEW YORK BULLETIN 209-10, PLATE 5 STATE MUSEUM - = ees / = _ Siok —\\\ ( LEN TPIT PII) Lyi} Towareicourt SCNNADA -y, eT Siren STMES haa “Wine Shuck. tc eenue — 5 - — 2 a —— Ft") sy) a sys (A Opis | \: ich ¢ Workls Fills pe ABH Seat — We = 5 RS Gos cS, alt Tah Siren Seioow Roumen Point) rm GLACIAL STREAM ~ (CHANNELS: —~ =| WEEE 4 7 i { if 7 oe . 77 > U Te = Y x 6S MALONE QUADRANGLE : E =e Cee aaTRSGuAE YORK BULLETIN 209-10 PLATE 6 Ss . MALONE QUADRANGLE JOHN M.OLARKE BTATE GEOLOGIST SHORELINES ON THE = H. L. FAIRCHILD 1919 LEGEND GLACIAL STREAM CHANNELS Channel with both banks preserved Channel with south bonk i only, the north bank [Sass] naretng been the toe as Channel hypethatical, or with indefinite borders DELTAS Deltax of tox-borler ss drainage SHORELINES a Gravel bars me 8d Interpolated NOTE: Thix map Joins the Chateaugay Sheet, Plate 6 E i _oMARBONT {Bya 730) _ “ Contour interval 20 fret Potem tm mean sou lave’. 3 a Se: eA; 1p) AR: ieee Jee ee atl : Oo ——S ee SS —— as == crn Ny) Wy, WW Dee ; . Ww Ke: ce UNIVERSITY OF THE STATE OF NEW YORK BULLETIN 9 STATE MUSEUM si SHORELINES ON THE DAM QUADRANGLE H. L. FAIRCHILD 1919 LEGEND GLACIAL STREAM CHANNELS fess] Channel with both pease ty ks preserved [Y =] Channel with south bank Ds) “only, tte north bank [zee] “nituing been the ice Channel hypotratinal or with indefimte borders DELTAS Deltas of toe-border [tn EN SHORELINES Gravel bare Bis The as! Contour interval 20 ter: Datum ix mean see taret. rc enn caiianemmnecmeanmedneeiaintaaenietnmninenent: ieieiattiel ~ a ~ - - UNIVERSITY OP THE STATE OF NEW YORE STATE MUSEUM Mi AN MARINE SHORE __ ON THE ae DANNEMORA QUADRANGLE | ——+ 02 ——_ I. L. FAIRCHILD 1919 LEGEND GLACIAL STREAM CHANNELS se Channel with both . vi Contour interval 20 feet. Datu a rear woe level. ved he U University af the State of New York New: York State Museum JOHN ou CLARKE, Director GATE.OF Fak Charles Dees oLocy OF THE LAKE PLACID QUADRANGLE By WILLIAM J. MILLER By HAROLD. I,, ALLING eek c PAGE Pleistocene geology. nL L. Alling 74 Introduction tee tural geology Gy ALBANY THE. “UNIVERSITY OF THE STATE OF NEW YORK ronD e as Braue NG EENesaip M. ih ‘Ph. es io De nee ABRAM i Es ELxus LL.B. LEDAD, CL. 5 1928 Saute: Guest Rees B a Ui D. age “43020: JAMEs Byrne B.A, LEB. LL.D. ~~ --- ea 1929 HERBERT L. BripcMan M.A. - - - - - - Br x 1931 THOMAS J. Mancan M.A. - - - - - - ' President of ‘the University and Commissioner of Saueion _ Joun H. Fintey M.A. LL.D. L.H.D. Deputy Commissioner and Counsel ; Frank B. Gisert B.A. (eee Assistant Commissioner and Director of Professional Education “Avcustus S. Downie M.A. L.H.D. LL.D. Pane 9 et - Assistant Commissioner for Secondary Education CHARLES F. WHEELOcK B. S. LL.D. Acting Assistant Commissioner for Wiemefitaey Education GerorcE M. Witey M.A. Director of State Library a 2g eS James I. Wyer, Jr, M.LS. Pd.D. Pins Director of Science and State Mjseuia os Joun M. Crarxke D.Sc. LL.D. a Chiefs and Directors of Divisions ersten Hiram C. Case a ae _ Agricultural and Industrial Education, Lewis A. Wi1son ae Chaaives and History, James Suttrvan M.A. Ph. D. 0m _ Attendance, James D. SULLIVAN f cee Educational Extension, Witt1am R. Watson B.S. et a _. Examinations and Inspections, GEORGE M. Witey M.A. aa - Law, Frank B. Giipert B.A., Counsel Library School, Frank K. WaLtterR M.A.M.L.S. School Buildings and Grounds, Frank H. Woop M.A. — School Libraries, SHERMAN WILLIAMS Pd.D. _ Visual Instruction, ALFRED W. Aprams Ph.B. 4 Oe The University of the State of New York Science Department, November 16, 1918 Dr John H. Finley President of the University oe the Lake Placid Ouaarangle ea has been prepared, at my quest, by Prof. Wiliam J. Miller. With this manuscript are alse transmitted the necessary me and illustrations. ‘Very respectfully yours Joun M. CLARKE Director ee ived for publication, November 16, 1918 President of the University i New York State Museum Bulletin Entered as second-class matter November 27, 1915, at the Post Office at Albany, New York, under the act of August 24, 1912 Published monthly by The University of the State of New York No. 211, 212 ALBANY, N. Y. July-August, 1918 The University of the State of New York New York State Museum JoHN M. CLARKE, Director GEOLOGY OF THE LAKE PLACID QUADRANGLE By WILi1aAM J. MILLER WITH A CHAPTER ON THE PLEISTOCENE GEOLOGY By HAROLD L. ALLING INTRODUCTION The Lake Placid quadrangle: comprises a territory of approxi- mately 214 square miles in the northeastern portion of the Adiron- dack mountains. It is bounded by latitude lines 44° 15’ and 44° 30’, and by longitude lines 73° 45’ and 74°. More than two-thirds of the area of the quadrangle lies in Essex county, while the remaining (northern) portion lies in Franklin and Clinton counties. Lake Placid, Newman, Keene, Upper Jay, and Wilmington are the principal villages. Haselton has but a few houses, and Franklin Falls, once a village of 30 or 40 houses, now has but two resi- dences and an electric power plant. Only one railroad enters the map limits, this being the Adirondack branch of the Delaware and Hudson, which reaches I mile into the quadrangle to Newman near Lake Placid. A new state road crosses the quadrangle from west of Newman, through the Wilmington notch, the village of Wil- mington, and thence eastward. Another state road passes through Keene and Upper Jay. Lake Placid and immediate vicinity is one of the greatest of all _ Adirondack summer resorts. There are several large hotels and many smaller hotels and boarding houses which accommodate 1See map in pocket of back cover of this bulletin. 6 NEW YORK STATE MUSEUM thousands of people during the summer season. Of late years Lake Placid has enjoyed considerable popularity as a winter resort. Thirty-five or forty years ago there was great activity at East, Middle and West Kilns where charcoal was made for use in iron furnaces at Black Brook a few miles to the east. In 1842 Prof. E. Emmons published his Survey of the Second Geological District, including Essex county. This report, how- ever, contains almost nothing on the geology of the Lake Placid region. | | To Prof. J. F. Kemp belongs the credit of first having done extensive field work which las resulted in solving many important problems in the geology of Essex county. He published reports, based upon reconnaissance field work, on the geology of the county _ in 1893 and 1895. These reports contain important data pertaining to the geology of that portion of the Lake Placid quadrangle which lies in Essex county. Based upon this reconnaissance work, Pro- fessor Kemp also published a report, accompanied by a geologic map, on the vicinity of Lake Placid. At one time it was planned that Professor Kemp and the writer should prepare-a joint report and map based upon a detailed study of the Lake Placid quad- rangle. Soon after entering the field in 1915, however, Professor Kemp was obliged, on account of health, to abandon the work. He generously allowed the use of certain data on his field map. The writer gratefully acknowledges his indebtedness to Professor Kemp. Prof. H. P. Cushing, in his Preliminary Report on the Geology of Franklin County, makes a number of references to the rock formations in the vicinity of Franklin Falls, in the northwestern part of the quadrangle. Professor Cushing also briefly refers to some of the formations in that part of the quadrangle which lies in Clinton county in his Report on the Geology of Clinton County. Mr H. L. Alling, who contributes the chapter on the Pleistocene of the quadrangle in this bulletin, has kindly furnished data, more especially the location of several diabase dikes and Grenville lime- stone outcrops, and the use of some thin sections of rocks. Mr Herbert Insley, a former student in the writer’s classes, assisted in the survey around Keene and on the rough Sentinel range. For this service the writer is sincerely grateful. Prof. D. W. Johnson has kindly permitted the use of two photo- graphs. Fotlowing are the principal publications which bear more or less upon the geology of the quadrangle: ‘F927 OY} UO TY VJGqo) ‘spunois qnyD por OAL] OY} WOTF pIVAjsed SUIYOO, ISuvI [OUTUOS IY} JO MOA TOJUIM VY AaMoq [LATS Jo Asequnop ojoyd ‘uvuIpeIs “IT T I 238] gq Neen Te ini ean) GEOLOGY OF THE LAKE PLACID QUADRANGLE 7 1842 E. Emmons. Survey of the Second Geological District (Adiron- dack mountains), pt 2 of The Geology of New York. 1895 J. F. Kemp. Preliminary Report on the Geology of Essex County. 13th Annual Rep’t N. P. State Geologist, p. 431-72. 1895 J. F. Kemp. Preliminary Report on the Geology of Essex County. 15th Annual Rep’t N. Y. State Geologist, p. 575+614. 1895 H. P. Cushing. Report on the Geology of Clinton County. 15th Annual Rep’t N. P. State Geologist, p. 499-573, especially p. 543-44. 1898 J. F. Kemp. Geology of the Lake Placid Region. iN. Y. State Mus. Bul. 21. p. 51-64. 1899 H. P. Cushing. Preliminary Report on the Geology of Franklin County. 18th Annual Rep’t N. Y. State Geologist, p. 73-128. 1900 J. F. Kemp. Precambrian Sediments in the Adirondacks. Science, 12 :81-08. 1905 H. P. Cushing. Geology of the Northern Adirondack Region. N. P. State Mus. Bul. 95, p. 271-453. 1914 W. J. Miller. The Geological History of New York State. N. Y. State Mus. Bul. 168, 130 pages, especially chapter 3. 1916 W. J. Miller. Origin of Foliation in the Precambrian Rocks of Northern New York. Jour. Geol., 24:587-610. 1917 W. J. Miller. The Adirondack Mountains. N. Y. State Mus. Bul. 193, 97 pages. A somewhat untechnical guide to the geology and physiography of the Adirondack mountain region. ; 1917 N. L. Bowen. The Problem of the Anorthosites. Jour. Geol., 25 :200-43. 1918 W. J. Miller. Adirondack Anorthosite. Geol. Soc. Amer. Bul. 27 :309-462. ‘JYstIt oy} UO UIeJUNOUW osIIuUNg puke Yo}Jou ssuuNG ‘ayK] 24} JO dIVJAINS dy} DAOGL JooF OOOL ULY} IIOW SOSII UIeJUNOW IY, “plor[_d Ie] Woy preMYJIou Suryoo] ‘seypoyA\\ IV SOUIT [eijJUeD HIOX MON oy} JO Asaqun0g Z 93e1d GEOLOGY OF THE LAKE PLACID QUADRANGLE 9 GENERAL GEOGRAPHY AND GEOLOGY The Lake Placid quadrangle lies immediately north of the great group of highest mountains in the Adirondack region. Altitudes range from 660 feet where the East Branch Ausable river leaves the quadrangle on the east, to 4872 feet at the summit of Mt White- face near the center of the quadrangle. Mt Whiteface rises majes- tically as a great mass culminating in a sharp peak from 2500 to 3800 feet above the immediately surrounding country. Around the nearly circular base of the mountain the distance is approximately 16 miles. Eight or ten sharp, rugged spurs with deep intervening vaileys radiate from near the summit. The great bowllike depres- sion just east of the summit of Whiteface was formerly occupied by a local glacier, and its remarkable shape is due to the action of the glacier in plucking out the rock. The valley between Esther mountain and Marble mountain was also formerly occupied by a local glacier. Sentinel range, some 8 miles long, has several peaks rising from 3600 to 3902 feet above the level of the sea. This, too, is a very rugged, steep mountain mass. Just north of Sentinel peak is another fine example of a bowllike depression cut out by a local valley glacier. A local glacier also lay in the valley next to the north. i Pitch-off mountain, with altitude 3340 feet at the southern edge of the map area, is the northern slope of the still higher mountain within the Mount Marcy quadrangle. St Armand mountain is an irregular mass with several points from 3100 to 3250 feet above sea level. It lies just northeast of Moose mountain, whose altitude is 3921 feet in the Saranac quad- rangle. Wilmington mountain is a relatively narrow ridge 7 miles long with a number of points 2800 to 3450 feet above sea level. It is a very rugged, densely wooded mountain rising 1500 feet above the narrow valley on the west and more than 2000 feet above the broad valley on the east. Catamount mountain ridge, in the north-central portion of the map area, is about 3% miles long and relatively broad with its summit (Catamount) 3168 feet above the sea. Its western end rises abruptly 1500 feet and, viewed from the broad valley on the west, it is a very impressive sight (see plate 19). On a large scale, Mt Whiteface and Wilmington mountain taken se) NEW YORK STATE MUSEUM together, and, on a small scale, Catamount mountain, show a north- east-southwest trend which is common in the eastern half of the Adirondack region. The other mountains of the quadrangle are, however, very irregularly distributed. There are three large, broad valleys. One of these with the vil- lages of Wilmington, Haselton, and East Kilns in the northeastern part of the quadrangle, is approximately 10 miles long and from 2 to 4 miles wide, with altitudes from 660 to 1400 feet. This valley was once occupied by an extensive glacial lake (see chapter on the Pleistocene geology). A prominent valley, 7 miles long and 3 to 5 miles wide, lies in the northeastern part of the map area. Its alti- tudes vary from 1400 to 1700 feet, and most of it is the site of a former glacial lake. The third large valley lies in the southeast. It is 7 miles long and from 1% to 3% miles wide. Altitudes range from 1640 to 1900 feet. A former glacial lake also covered this area. Lake Placid now occupies the northern end of this valley. Three large streams flow across the quadrangle, namely, Saranac river for about 8 miles across the northwestern corner, East Branch Ausable river for 9 miles across the southeastern portion, and West Branch Ausable river for about 20 miles from southwest to northeast almost across the middle of the map area. All the drain- age of the quadrangle passes into these three rivers and north- eastward into Lake Champlain. The West Branch Ausable river drains Lake Placid and, after pursuing a winding course for some miles through a broad valley in the vicinity of Newman, passes through a deep, narrow pass known as Wilmington notch, the rocky sides of which rise precipitously to a maximum height of 700 feet above the river on the east side, and 1700 feet on the west side (see plates 4 and 20). The explanation of this remarkable course may be found on a subsequent page. A mile beyond the Wilmington notch, the river descends more than 100 feet by waterfall (High fall, see plate 5) and cascades in a small gorge (see plates 13 and 14) cut in granite. Two miles beyond the High fall gorge the river flows through a narrow gorge known as The Flume (see plate 8), and then enters the broad valley in which are located the villages of Wilmington and Haselton. There are twenty-four lakes and ponds within the quadrangle in addition to portions of two large reservoirs along the Saranac river... Lake Placid, over 4 miles long and from 1 to 1% miles *These reservoirs are not shown on the accompanying geologic map, but they occupy the swamp areas above and below Franklin Falls. ‘OMA Ose JO JIUWNSs 94} WOIF ‘plov[d o94V TY sso1ov ‘AON ‘plovld eyed ‘uvupayg I 1 Aq ojoyd € aed Ynos suryoo Ty GEOLOGY OF THE LAKE PLACID QUADRANGLE II wide, lies 1859 feet above sea level.1. By many it is regarded as the gem of Adirondack lakes. Mt Whiteface rises majestically more than 3000 feet above the surface of the lake on the north- east, and Moose mountain rises over 2000 feet above the lake on the west. The lake contains two large, high rugged islands and one small one. | Morgan pond on Wilmington mountain has a remarkable situa- tion at an altitude of 3020 feet. The Lake Placid quadrangle contains a wonderful variety of rock formations, including most of the familiar Adirondack types as well as several others described in this bulletin for the first time. Excepting the Pleistocene deposits, all the rocks are of Precam- brian age. Oldest of all is the Grenville series which takes rank among the very oldest rock formations of the earth. It consists of gneisses, quartzites, and crystalline limestones. These are sedimentary rocks which have been thoroughly crystallized. There are no large areas, but many small masses are scattered throughout the quadrangle. Next in age, definitely proved, is the Marcy type of anorthosite with its extensively developed facies known as the Whiteface anorthosite. These rocks, which are igneous in origin, are intru- sive into, and therefore younger than, the Grenville rocks. Anor- thosite is the most abundant rock of the quadrangle. The syenite-granite series, with its several variations, is intrusive into both the Grenville and the anorthosite. It ranks next to the anorthosite in areal extent. Of particular interest is a peculiar rock, called the Keene gneiss, occurring as a border zone between the anorthosite and the syenite- granite. There is strong evidence that this rock has resulted from the assimilation of anorthosite by the molten syenite or granite. At several places in the northern portion of the quadrangle there are series of parallel, gneissoid, basic, usually badly weathered dikes cutting the granite. They are different from any rocks hitherto observed by the writer in the Adirondacks. It is probable that they are older than the gabbro below mientioned. | A number of gabbro bodies of the usual Adirondack kind occur within the quadrangle. These are seen to cut both the Grenville and the syenite-granite series. 1The altitude number 1864 printed on the accompanying map was determined by an older survey. I2 NEW YORK STATE MUSEUM Pegmatite dikes of wholly nonmetamorphosed material are occasionally present throughout the quadrangle. Diabase, in the form of numerous nonmetamorphosed dikes, is the latest of the Precambrian rocks. Paleozoic and Mesozoic rocks are entirely absent, but glacial deposits are widespread and varied, especially in the valleys. Faulting appears to have played a much less important part than usual in the eastern Adirondacks, only a few fault zones having been observed, the principal one passing through the Wilmington notch. THE PRECAMBRIAN ROCKS Grenville Series General statements. Among all the rocks of the quadrangle, those which comprise the (Grenville? series are the most ancient. They rank among the very oldest known rocks of the earth’s crust. It is certain that by far most of the Grenville rocks are of sedi- mentary origin, though all are now metamorphosed and thoroughly crystalline. In most cases the stratification surfaces are still plainly visible and these often separate rock layers of sharply varying com- position. Various bedded gneisses, schists, quartzites and crystal- line limestones almost, if not entirely, constitute the Grenville series, the original rocks having been shales, sandstones and lime- stones of the usual kinds. The presence of numerous flakes of graphite (so-called “black lead”’) scattered through many of the Grenville rocks also strongly indicates their sedimentary origin. Grenville strata are common throughout the Adirondack moun- tain region and also in eastern Ontario. Their thickness is known to be very great —a few miles at the very least — with neither top nor bottom of the series definitely known. Since the Grenville strata throughout the Adirondacks have been all cut to pieces by vast intrusions of igneous rocks, their present distribution is very patchy, and the irregular scattering areas now visible are merely remnants of what was once a continuous body of strata covering not only all of northern New York, but also large adjacent areas, particularly eastern Ontario. Within the Lake Placid quadrangle the Grenville strata are less abundant than usual throughout the Adirondacks. As shown on the accompanying geologic map, definitely known areas of Gren- *This name has been given from the town of Grenville in the St Law- rence valley. Plate 4 W. J. Miller, photo, 1916 Sunrise mountain with its precipitous eastern face rising 1700 feet above the river at the lower end of Wilmington notch. Viewed from the top of the gorge on the east side of the river. The rock is syenite. GEOLOGY OF THE LAKE PLACID QUADRANGLE 13 ville, not one of them more than a few square miles in extent, are rather widely scattered over the quadrangle, but they make up only a small percentage of its area. They are mere fragments of the formerly continuous Grenville series which has been cut to pieces by vast intrusions of plutonic igneous rocks, especially the anortho- site and the syenite-granite series. The actual extent of Grenville strata is somewhat greater than indicated directly as such on the geologic map. Thus, in the vicinity of Newman, the bedrock, probably mostly Grenville, is largely concealed under glacial deposits. Similar conditions prob- ably also obtain in the areas of unknown bedrock west of the river between Keene and Upper Jay, and between Franklin Falls and West Kilns. Again, the areas of Grenville-anorthosite mixed gneisses, and of syenite or granite and Grenville mixed gneisses, contain much Grenville. Finally, there are occasional small unmappable masses of Grenville which occur as inclusions in the great intrusives. But, after making every reasonable allowance, it is believed that Grenville rocks do not actually occupy more than 8 or 10 per cent of the area of the quadrangle. Compared with the Adirondacks in general, the Grenville rocks of the Lake Placid quadrangle are mostly of quite the usual sorts, namely, graphitic crystalline limestones, pyroxene gneisses, horn- blende gneisses and quartzites. Areas in the vicinity of Lake Placid. In the extreme south- western corner of the quadrangle an area of about I square mile shows some good outcrops of Grenville. Dark hornblende-feldspar gneiss, hornblende-feldspar-garnet gneiss, together with some light- gray garnetiferous feldspar gneisses and a little quartzite, make up the main bulk of the rock.’ At one locality (near the diabase dike) the dark gneiss contains large red garnets with hornblende rims. The area which extends from Pulpit mountain to Connery pond and southward several miles contains various Grenville rock types. The eastern portion of Pulpit mountain consists mostly of dark hornblende-feldspar-garnet gneiss with scattering red garnets up to 4 inches in diameter enveloped in rims of black hornblende. The hill south of Tom Peck pond contains mostly hornblende- feldspar gneisses (often garnetiferous) interbedded with con- siderable well-stratified pyroxene gneiss and a little biotite gneiss. On the ridge for 2 miles south from Big Cherrypatch pond the Grenville is mostly hornblende-feldspar gneiss, usually garnetifer- ous and with a little interbedded pyroxene gneiss. The southern 14. NEW YORK STATE MUSEUM part of the area shows a number of exposures of dark hornblende- feldspar-garnet gneiss with red garnets up to one-half of an inch in diameter. A little quartzite was noted at one place. About one-half of a mile east of the southern end of Mirror lake there is a large outcrop of dark, very gneissoid, but not banded, hornblende-feldspar-garnet gneiss with garnets up to an inch or more in diameter often inclosed in envelops of hornblende. ‘ The small Grenville masses on and near Cobble hill, and 1 mile west of Coldspring pond, are hornblende gneisses, two of these masses being distinct inclusions in the syenite. On the mountainside 114 miles north of Eagle Eyrie (a few rods above the trail) there is an interesting exposure, several hun- dred feet long, of white, rather coarse-crystalline calcite marble with scattering small crystals of phlogopite, pyroxene and green apatite. On the east side it is in contact with syenite, while on the west it seems to overlie, in part at least, gray feldspar-quartz-garnet gneiss (presumably Grenville). / In the bed of a small brook one-half of a mile south of Owen pond there is a small exposure, clearly an inclusion, of Grenville limestone — some pure white and some rich in mica, pyroxene and pyrite — associated with Grenville gray feldspar-pyroxene gneiss. Near Winch pond the inclusion of Grenville (see map) in the syenite is a light-gray feldspar-quartz gneiss. In the Wilmington notch a good exposure at the edge of the river (see map) shows well-bedded Grenville green pyroxene- feldspar gneiss and light-gray calcareous pyroxene-quartz gneiss, each about 20 feet thick. The small area in Sunrise notch consists of quartzitic and pyroxenic gneisses. Areas in the vicinity of Keene village. On the western side of the gorge of Ausable river (close to the map limits) there is an outcrop of Grenville limestone and close by it an outcrop of Gren- ville quartz-biotite gneiss or schist. The Grenville which constitutes the hill from one-half to 1% miles north of Keene is quite variabie. At the south, hornblende- feldspar gneisses and quartzites are interbedded with some light- gray feldspar-graphite gneisses. The middle portion of the hill is mostly hornblende-feldspar gneiss. In the northern portion of the hill the rock is mostly green pyroxene-garnet gneiss with some interbedded hornblende gneiss and limestone, the limestone con- taining graphite and green pyroxene. The western of the two limestone outcrops shown on the map is the larger. ) W. J. Miller, photo, 1916 High fall of the West branch, Ausable river GEOLOGY OF THE LAKE PLACID QUADRANGLE 15 In the Grenville area about 1% miles a little east of north of Keene, well-bedded quartzites and hornblende gneisses are prom- inently developed. The area between 2 and 3 miles north of Keene shows a number of large exposures of typical hornblende-feldspar gneiss with one small limestone outcrop in the southeast. On Styles brook, just above the falls, well-stratified Grenville . hornblende gneiss and hornblende-garnet gneiss with some inter- bedded green pyroxene gneiss form the walls of a small gorge. The Red Rock area shows very fine big exposures of variable well-stratified quartzite, some sharply defined beds being rich in green pyroxene, others in red garnets, and still others in phlogo- pite. Most of the rock contains flakes of graphite. The small area 114 miles northwest of Keene shows light-gray feldspar-mica-graphite gneiss. According to Kemp’s 1898 map, limestone occurs here, but this was not seen by the writer. The small Grenville areas east of Keene show green pyroxene gneiss and quartzite. Area near Upper Jay. In this area, southwest of the village, the main body of Grenville appears to be dark hornblende-feldspar gneiss with quartzite or green pyroxene gneiss sometimes locally developed. Crystalline limestone and gneiss outcrop in the eastern corner of this area. Wilmington mountain areas. In the area at the southern end of Wilmington mountain there are many fine big outcrops of well- stratified Grenville. The rocks are mostly green pyroxene-feldspar gneisses, biotite-feldspar gneisses, and some hornblende gneisses interbedded. In and about the graphite mines in the central-eastern part of the area there is considerable crystalline limestone associated with some pyroxene-garnet rocks. _ The large West Kilns-Middle Kilns area shows a considerable number of good outcrops. On the side of Wilmington mountain the principal rocks are hornblende-feldspar gneisses and green pyroxene gneisses, both of these at times carrying garnets. Quartz- feldspar-mica gneiss and almost pure quartzite are there more locally developed. Within one-half of a mile east of West Kilns there are several ledges of clearly bedded quartz-feldspar-phlogo- pite-graphite gneisses, considerably weathered and rusty looking. Near the road three-fourths of a mile east of West Kilns, Gren- ville limestone and quartzite are poorly exposed, and one-fourth of a mile east of this, by the road, pyroxene-feldspar-quartz gneiss 16 NEW YORK STATE MUSEUM outcrops. Parts of the latter rock are porous, probably due to weathering out of calcareous material. Just west of Middle Kilns, by the road, well-banded hornblende-feldspar gneiss shows in a good ledge. The Grenville at the base of Catamount mountain is mostly dark hornblende-feldspar gneiss, often garnetiferous. In the quarry (see map) in this area there is a fine big exposure of _ very coarse crystalline limestone with some portions containing large irregular masses of clear quartz and one-fourth to one-half inch crystals of dark-green pyroxene and pale bluish green apatite. Other portions of this limestone contain considerable titanite. Areas near Franklin Falls. The Grenville area east and north of Franklin Falls shows very fine outcrops. By the roadside, one- third of a mile north of the village, there is a large exposure of distinctly bedded, impure, badly weathered limestone containing quartz, graphite and pale-green pyroxene. It is associated with some hornblende-feldspar gneiss and calcareous quartzite with flakes of graphite and phlogopite and specks of pyrrhotite. On the road just east of Franklin Falls there are good ledges of greenish gray quartz-pyroxene gneiss, some of which contain graphite. Steep ledges forming the north bank of the river just opposite are of similar rock. On the road one-half of a mile east of the village there are small exposures of rotten graphitic limestone and quartzitic gneiss with graphite. The southern part of the area consists of hornblende gneiss and quartzite interbedded. The small area 14% miles east of Franklin Falls shows greenish gray quartz-pyroxene gneiss not certainly in situ. At Woodruff fall coarse crystalline limestone containing graphite and green pyroxene shows in an old quarry. A few rods to the south there are ledges of hornblende-feldspar gneiss. The other two limestone outcrops indicated on the map are associated with pyroxene gneiss. In an old prospect hole, one-half of a mile south of Franklin Falls, coarse crystalline limestone with much graphite is exposed. The small area 1 mile east of Franklin Falls shows hornblende gneiss and quartz-pyroxene gneiss interbedded. Anorthosite Series General statements. So far as now known, the anorthosite was the first of the great intrusive bodies which broke through the Grenville strata. This rock is almost wholly confined to an area of about 1200 square miles mostly in Essex and Franklin counties. GEOLOGY OF THE LAKE PLACID QUADRANGLE 17 It is prominently: developed in the Lake Placid quadrangle. The typical rock, known as the Marcy anorthosite, is very coarse grained, bluish gray in color, and consists principally of basic plagioclase feldspar. A widely developed facies, known as the Whiteface anorthosite, is usually medium grained and character- ized by a preponderance of milky white to light, greenish gray, basic plagioclase feldspar with small amounts of dark minerals. both of the types locally contain considerable quantities of dark minerals. For most part the molten anorthosite appears to have pushed aside or displaced the Grenville rocks, though in many cases masses of Grenville, from small fragments to large bodies, were enveloped by the anorthosite, and in still other cases there appears to have been intimate injection of the Grenville by the molten anorthosite. Marcy type of anorthosite. Distribution. This type of the anorthosite is named from Mt Marcy where the rock is so well developed. When the whole great body of Adirondack anorthosite is considered, this Marcy type is the most commonly and typically developed. Within the Lake Placid quadrangle, however, a special phase, known as the Whiteface anorthosite (see below) is actually somewhat more abundant in the known areas of outcrop. The areas colored to show the extent of the Marcy anorthosite represent about 35 square miles wholly confined to the southern two-thirds of the quadrangle. There are ten areas in all. By far the largest exposed body of Marcy anorthosite in the quadrangle extends from the northern portion of the Sentinel range north- eastward to the village of Haselton. Next to the largest body extends northwestward from Lake Placid for several miles. Two small bodies occur on the large islands in Lake Placid. Other small masses are located as follows: on Marble mountain; west of Wilmington village; and four small ones in the vicinity of Keene village. In addition to these definitely known areas, some Marcy anorthosite quite certainly lies concealed under Pleistocene deposits in the areas mapped as occupied by heavy glacial and postglacial deposits. Megascopic features. The most common phase of Marcy anor- thosite is a very coarse-grained, light to dark bluish gray rock con- sisting very largely of basic plagioclase feldspar, mainly labradorite. The dark bluish gray labradorite crystals usually vary in length from one-fourth of an inch to several inches, with crystals an inch long very common. Occasionally the labradorites exhibit the beautiful play of colors (chiefly green and blue) so characteristic 18 NEW YORK STATE MUSEUM of this species of feldspar, but this phenomenon is neither so strik- ing nor so common in the Marcy anorthosite as in labradorite from certain other regions. Twinning striations are usually evident on the shiny cleavage faces of the labradorite. Accessory minerals visible to the naked eye are large individuals of pyroxene and hornblende, and small individuals of biotite, ilmenite, pyrite, garnet, and more rarely chalcopyrite and pyr- rhotite. Due to decomposition of the dark minerals, the weathered anorthosite is usually light brown, but such rock is not common. Locally the amount of dark-colored minerals rises to 15 to 25 per cent when the rock should really be called anorthosite-gabbro. In many places such anorthosite-gabbro and typical anorthosite exhibit perfect gradations from one into the other, often within a few rods. © The gabbroic facies is, however, decidedly subordinate in amount, and it has not seemed feasible to represent it separately on the geologic map. An important facies of the Marcy anorthosite is one in which dark bluish gray labradorite individuals, from a few millimeters to an inch or more across, stand out conspicuously in a distinctly granulated groundmass of feldspar. In the fresh rock the granu- lated material varies from light gray to pale greenish gray. The granules usually vary in size from microscopic to I or 2 millimeters across. Even a glance at a hand specimen of such a rock makes it clear that the large labradorites are roughly rounded, uncrushed cores of what were considerably larger individuals before the rock was subjected to the process of granulation. In this type of rock, therefore, the labradorites stand out like phenocrysts, thus giving the rock a distinctly porphyritic appearance, though of course crystal boundaries are seldom if ever present. All degrees of granulation are shown, from rocks’ in which there is little or no evidence of crushing, to others in which relatively large, dark lab- radorites are scattered through a granulated groundmass, to extreme cases where the whole rock has been so thoroughly granu- lated that few, if any, labradorite cores remain. In spite of exces- sive granulation, the fresh rock is very firm and hard. The extremely granulated types, especially. where somewhat weathered to light brown, bear a close resemblance to normal weathered syenite (see below) and may be readily mistaken for such in small outcrops in the woods. Careful examination of a number of speci- mens from an outcrop will, however, almost invariably yield at least a few small uncrushed cores of labradorite to furnish the clew to the nature of the rock. In connection with the granulation W. J. Miller, photo Upper figure. Photcgraph of a hand specimen of typical Marcy anorthosite. About natural size. Large dark patches are “augen” of labradorite whose natural color is very dark bluish gray. Matrix is mostly granu- lated plagioclase whose natural color is light greenish gray. A few of the small black patches represent chalcopyrite and pyrite whose natural colors are dark and light brass-yellow. Lower figure. Photograph of a hand specimen of typical moderately gabbroid and gneissoid Whiteface anorthosite, About natural size, and almost natural color. White material is plagioclase, and dark ma- terial is mostly hornblende and pyroxene. oN ey GEOLOGY OF THE LAKE PLACID QUADRANGLE 19 of this rock it is important to note that extreme degrees of crushing may often be observed in single outcrops of ordinary dimensions. A striking example of such phenomena is in the big ledge on the shore of Lake Placid at the southwestern end of Moose island where coarse-grained, nongneissoid anorthosite, with labradorite crystals up to 4 inches across, has in it a zone of much finer grained and moderately gneissoid anorthosite, the one grading into the other. Another illustration is in the road metal quarry near the road 1% (4 Fig. 1 Sketch of a large crystal of labradorite from the anorthosite quarry 14% miles northeast of Upper Jay. Natural size. Note the large amount of granulated feldspar irregularly distributed through the crystal. Due to deformation during the process of granulation, the twinning bands are distinctly curved in the middle right portion and sharply shifted in position in the lower portion. Dark patches are pyroxene. Dotted rim on left is granulated garnet. 20 NEW YORK STATE MUSEUM miles northeast of Upper Jay where is to be found one type of anorthosite made up of crystals of labradorite from one to several inches across with evidence of only moderate crushing, along with another type in which only occasional large rounded cores are leit, and still other types in which practically all the feldspar has been granulated into a fine to medium-grained rock. These types are in zones which show perfect gradations from one extreme to the other. Most of the typical Marcy anorthosite is practically devoid of foliation, hence the general absence of dip and strike signs from these areas on the geologic map. In some places, where the rock is only moderately coarse grained, there is a noticeable tendency for the feldspars to show a crude parallelism. It is usually impos- sible to determine satisfactorily the dip and strike of such foliation in ordinary outcrops in the woods. The more gabbroic phases of the rock do, however, often exhibit a fair to well-defined foliation due to the parallel arrangement of the dark-colored minerals. An important consideration is the frequent gradation from well- foliated to slightly or nonfoliated anorthosites or anorthosite- gabbros within short distances, often not more than a few rods. The causes of the foliation and granulation of the anorthosite are evidently closely related and this matter is considered below in the chapter on Structural Geology. Microscopic features. In accompanying table 1, the six thin sections were selected to illustrate the usual mineralogical varia- tions of the Marcy anorthosite. About a dozen mineral species in all were noted. By far most of the feldspar is seen, under the microscope, to be striated labradorite, to possibly bytownite in some cases. Where more acidic plagioclase is present, it is always in subordinate amount. In thin section, with a low power of the microscope, the larger labradorites are usually seen to be more or . less filled with very dark dustlike particles. With a higher power these are seen to be practically opaque, slender prismatic, or some- times tabular, forms with parallel arrangement often strung out parallel to the twinning bands of the feldspar. Professors Cushing and Kemp, who have noted such inclusions, think they are most likely ilmenite. They no doubt give the dark color to the labra- dorite. Monoclinic greenish gray pyroxene with good cleavage — usually augite but sometimes diallage — appears in all the slides. The chlorite in slide 5 was quite certainly derived from pyroxene. The hornblende exhibits good cleavages and pleochroism from ‘DOVFOMY AA WA JO do} oy} yo oovy u1oyynos JY} SWAOF YIM o}IsOy}1ouv ddVJoHYM JO Ispo] Jeois oY, AoMOC [fATeI Jo Asozano0p ojoyd ‘uBvUuIpaIS “TI ‘TL L a3zIg GEOLOGY OF THE LAKE PLACID QUADRANGLE 21 Table 1 Thin sections of anorthosite = a 2) £2 l 2 2 g| 25 2 l2s| 2] o& 2 oes s=) |/e@teil| Gel || oS 3 Oeil! ‘eno ol/2 S é BAGH BE |) a |) ee a= Bel ; o 2 | #ls 2) a se | SB BP Si) Se Si) Seal se es her |e 4) SSIS o as} a |S is =} = gs rs =| &0 =°0 =] ° iS) 5 g|2 5 5 Salo | aS SS | SS si 2 iS eee Ss 2 = | BEE wa ll fer (Sy feet ee 1 tSy || feet] eal Gi ep tS 2a2'o) 8 | ea | Heals e@ {| 1) 583 Fu ere Ves i oan 2|, @ol |} Bec) Bl Blecsaiceel] Al) Sl eee cllooecllawe calle = Peewee cht | 98...) Qo... Sh-.3f 3] 8 al) Sfidittlel 2) 7. little ue SE) Sl) CO) bs Bia ae |e Ce a ee eee ores eae . B || 35} 73 little} 13). fi om eeaersasi tc) SOS) RE ane Pcie! dle woalloce a. Le Oran [ease Belle 6| 1k2 little] 5] little] little]...) 4 Gal) Wc) GE A) ey ieaae lee il eee Zee Ticitles| oreene elite | ere eee ee 2 7| Gel GOOG lin Pelee dice 22 Tittle} $/.- Uae fe Cuuna | eamenltAe g g| 4d1 CYA} no) (0) Col lettin [eet eal fates a SIE Ge gallon little: FY e) = 9| 5gl Cid | il | Men ee (Epa Te Lee ert | ea ae litthel! WF AN. S{] 13] 9f38 | 98 rh eae lo aie cule taualhy eee git Iie teet si] 14] sf | 88 4a} 7]. ADE little| little little meee Mee PMN CSe lesions sO [Lae i Weal og 5 il | Sica a 2B || ly) Ol BG lsead) Stes oil eee nein HS | Poor ts soll opcallarwsel| ae seit PMN ISN PeOeTS |e) 75a 25 [esce| eo Neca ee ae BE so olloascsllodoslloo sll JAMMIE sc ollo- Feit) || 1L8)|) 95} ....|.... COW OA, callascloece eon | Rigas Beit Irae Me le 30) || Ra) OAc Dl Blocecllesdle ee Tittle | eee | ee eR lie nilteullpes a! || @al ||...) a) Sl nO. SO) 2) TES) 8) taal] | I] Tease oe olfolle al] 8 No. 1, five-sixths of a mile east-southeast of Owen pond; no. 2, south- western end of Moose island in Lake Placid; no. 4, same; no. 5, Under- cliff, on Lake Placid; no. 35, three-fifths of a mile north of Undercliff; no. 44, five-sixths of a mile north of Loch Bonnie; nos. 6 and 6a, river gorge one-half of a mile south of Keene; no. 7, by the river two-thirds of a mile southwest of Copperas pond; no. 8, one-half of a mile northwest of Malcom pond; no. 9, one-half of a mile east of Owen pond; no. 13, one- third of a mile northwest of the summit of Mt Whiteface; no. 14, summit of Mt Whiteface; no. 15, just above bridge at The Flume; no. 17, The Flume; no. 18, between the tongues of granite 14% miles northeast of the summit of Little Whiteface mountain; no. 19, by the road three-fourths of a mile east-northeast of Keene; no. 20, two-thirds of a mile northeast of the summit of Sunrise mountain; no. 34, same locality as no. 7 above. yellowish green to deep green. Garnet is quite certainly of second- ary origin, having developed along the contact between feldspar and pyroxene, or as rims around the pyroxene. The other minerals require no special comment. Under the microscope, the granula- tion is often a striking feature. Whiteface type of anorthosite. Distribution. Of the defi- nitely known areas of outcrop of anorthosite within the quadrangle, the Whiteface type, where practically free from mixture with other rocks, occupies about 40 square miles. It is, therefore, some- what more extensive than the Marcy anorthosite. There must be added some 2 or 3 square miles of Whiteface anorthosite more or less intimately mixed with other rocks and mapped as such. An unknown, though considerable, amount of this anorthosite also 22 NEW YORK STATE MUSEUM extends under cover of glacial drift where such deposits effectually conceal the underlying rocks, this being particularly true east and southeast of Franklin Falls, west and north of Wilmington, and north of Clifford Falls. So far as known at present, this White- face type of anorthosite appears to be relatively more abundant in the Lake Placid quadrangle than in any other portion of the Adi- rondacks. Professor Kemp has described similar rocks as occur- ring in smaller amount in the Elizabethtown quadrangle. The Whiteface anorthosite is most irregularly distributed with reference to the other rocks. One reason for this is that the later syenite-granite intruded it so very irregularly. Although the Whiteface anorthosite is quite certainly a differentiation phase of the Marcy anorthosite, and, in a broad sense, may be regarded as a border facies of that rock, nevertheless it does not form well-. defined borders about the Marcy anorthosite as the gabbroic facies do about the anorthosite of the Long Lake and Elizabethtown quadrangles mapped by Professors Cushing and Kemp respectively. The largest area of Marcy anorthosite is, to a considerable extent at least, flanked on either side by Whiteface anorthosite. On the north, however, the Whiteface rock is more extensively developed than the Marcy rock. Also, some small mappable bodies of both Whiteface and Marcy anorthosite are isolated from the larger bodies. It is by no means uncommon to find within the areas of Marcy anorthosite small local developments of rocks which greatly resemble the Whiteface type and vice versa. In short, the differen- tiation of the anorthosite magma was asymmetric and this, com- bined with the very irregular intrusion of the later syenite-granite body, accounts for the very uneven distribution of the anorthosite. By far the largest area occupies much of Wilmington, White- face and Esther mountains, Knapp hill and vicinity, and the vicinity of Franklin Falls. An area several miles long mostly occu- pies the valley of the West Branch Ausable river from The Flume to near Connery pond. Several square miles of the Whiteface anorthosite occur in the vicinity of Keene, and a little over 1 square mile in the vicinity of Upper Jay. Areas of less than 1 square mile are located as follows: the southern base of Catamount mountain; 1 mile north of Middle Kilns; 114 miles northeast of Wilmington; southern slope of Little Whiteface mountain; on Hawk island, and on a portion of Moose island in Lake Placid; along the river west of Malcom pond; 2% miles northeast of Keene; one-half of a mile south of Keene; and 1% miles southwest of Upper Jay. Plate 8 W. J. Miller, photo, 1916 The Flume, through which flows the West branch, Ausable river, 2 miles southwest of Wilmington. The rock is pinkish gray Whiteface anorthosite. i GEOLOGY OF THE LAKE PLACID QUADRANGLE | 23 - Megascopic features. A glance at 35 or 40 specimens of White- face anorthosite shows the usual rock to be medium grained and white, light gray, pale greenish gray, or, more rarely, pinkish gray, depending upon the color of the plagioclase feldspar. In most cases the greenish tint seems to be due to stains of chlorite or serpentine which have resulted from the decomposition of the dark minerals. A few specimens contain no large uncrushed cores of lab- radorite, but the outcrops from which such specimens come show these large labradorites to be sporadically present. Nearly all the specimens contain from I to 10 or 12 per cent of dark minerals, these being principally pyroxene and hornblende, with garnet and biotite less common, and tiny grains of oxides and sulphides of iron in most specimens. A gneissoid structure is generally well enough developed to be readily noticeable in the hand specimens, this being particularly true of the rocks relatively richer in dark minerals. Many of the rocks show more or less evidence of granulation, sometimes to an excessive degree, but many others appear not to have been notice- ably granulated. The most typical Whiteface anorthosite, so well exposed at the top of Mt Whiteface, is medium grained, and consists of white plagioclase (all or nearly all labradorite) with 5 to 12 per cent of dark minerals scattered through the mass parallel to a crude foli- ated structure. Such a rock stands out in marked contrast against the most typical Marcy anorthosite which has nearly the same com- position, but which is very coarse grained, light to dark bluish gray, and rarely foliated. Since both types are differentiates of the same cooling magma, they are not sharply separated, and it is often diffi- cult in the field to draw other than arbitrary lines between them. This matter is more fully discussed below. - Local variations of the more typical Whiteface anorthosite are richer in dark minerals, which may make up from 15 to 30 per cent of the rock. In short, they are nearly always clearly foliated gabbroic anorthosites with white or light-gray feldspar. Such rocks are not abundant and they do not exist as rather definite borders about the anorthosite like the gabbroic border phase of anorthosite in the Long Lake quadrangle, as described by Cushing. Rather, these gabbroic phases occur very locally as zones or belts here and there throughout the areas of Whiteface anorthosite. So far as could be made out, they are not different from the typical Whiteface rock except for the higher content of dark 24 NEW YORK STATE MUSEUM minerals, including garnet. \A few examples follow. On the southern side of Hawk island in Lake Placid, big ledges show typical nearly white anorthosite and a gray anorthosite with 20 to 25 per cent of dark minerals, these two facies not being sharply separated. Along the river two-thirds of a mile ‘west-northwest of Owen pond there are big ledges of Whiteface anorthosite with zones of very gneissoid, dark, gabbroic anorthosite. On the moun- tain spur two-thirds of a mile southeast of Morgan pond there is locally developed in the Whiteface anorthosite a strongly gneissoid facies. In the little area of mixed gneisses one-half of a mile east of Keene village the Whiteface anorthosite shows a local develop- ment rich in black minerals and garnet. By the river three-fifths of a mile west of Owen pond a single outcrop exhibits quite typical Whiteface anorthosite and a very gabbroic facies (no. 34 of table 1) in fairly sharp contact but without one cutting the other. Local variations of the sort here described are believed to have been produced as a result of differential flowage under moderate pressure in the cooling and differentiating anorthosite magma, this matter being rather fully considered beyond. Certain exceptional types of very limited extent deserve men- tion. One of these forms the walls of The Flume through which flows the West Branch Ausable river. It is medium to moderately coarse grained, consists very largely of pink labradorite together with 2 to 15 per cent of hornblende and pyroxene scattered through the mass, and is at times slightly gneissoid. This is no. 17 of table 1. It contains no large blue labradorite crystals. Some small drawnout or lenslike inclusions of (Grenville pyroxene gneiss occur, a careful study of these in the field having led to the suggestion that most of the much smaller (one-fourth to one-half of an inch) lenslike masses which make up 5 to 15 per cent of considerable portions of the rock are really very small fragments of Grenville gneiss which were caught up in the intruding magma and roughly arranged parallel to the magmatic lines of flowage. The only other similar pink anorthosite found, occurs in the small area on the mountain side 1 mile east-southeast of Owen‘ pond. This rock never shows over 2 per cent of dark minerals, and it contains no inclusions of Grenville. Another exceptional type is medium grained and almost pure white, with about 1 per cent of green pyroxene and very few scattering grains of ilmenite and titanite. In thin section it shows fully 24 per cent of colorless monoclinic pyroxene with good cleavages. This is no. 18 of table 1. It is finely exposed in bare 1916 photo, J. Miller, Mio Lower end of The Flume, 2 miles southwest of Wilm‘ngton. GEOLOGY OF THE LAKE PLACID QUADRANGLE 25 ledges on top of the mountain spur 114 miles northeast of the summit of Little Whiteface mountain. Microscopic features. The thirteen thin sections listed in table 1 are from specimens chosen to illustrate the usual range in mineral composition of the Whiteface anorthosite of the quadrangle. Altogether some sixteen or seventeen mineral species were noted. Plagioclase feldspar, chiefly labradorite, always makes up the main bulk of the rock, being seldom less than 85 per cent. Oligoclase and andesine commonly occur in small amounts. So far as observed, the feldspar never shows the black dustlike inclusions so common in the labradorite of the Marcy anorthosite. Some of the large phenocrysts probably would show them, but none of these appear in the thin sections examined. Greenish gray, or less commonly a nearly colorless, monoclinic pyroxene (in one case some diallage) appears in all the sections except no. 6, in which slide the chlorite was evidently largely derived from pyroxene. In no. 18 all but 1 per cent of the pyroxene is nearly colorless and the large amount is very exceptional. Pyroxene is the second most abundant constituent of the rock. Next in amount comes the hornblende, never more than 5 or 6 per cent. Its pleochroism is usually greenish yellow to deep green or brownish green, and the cleavages are good. Biotite was noted in only one slide, but it was occasionally noted in the field. Red garnet occurs in several slides, but it is present as scattering grains through the Whiteface anorthosite in many localities. Ilmenite (or magnetite) is generally present in tiny grains. Tiny prisms or rounded grains of apatite, zircon or titanite often occur in very slight amounts. Hematite, muscovite and quartz (probably secondary) are rare. So far as can be judged by a study of hand specimens and thin sections, it seems to be quite the rule that the Whiteface anorthosite is less granulated than the Marcy anorthosite. Only exceptionally does the Whiteface type appear to have been severely crushed. A possible explanation will be offered beyond under the caption “ Foliation.” Chemical composition of the anorthosite. Analyses of the Marcy type of anorthosite from the summit of Mt Marcy, and of the Whiteface type from the summit of Mt Whiteface, have been made for, and described by, Professor Kemp. They are as follows: 1N. Y. State Mus. Bul. 138, p. 32-34 and 36-37. 1010. 26 NEW YORK STATE MUSEUM I 2 Si Oho, pbava lee ed lelace nse la a cevole lores Soave eens ae a enero 54.47) Hanae PN © MURA Pam E RS rs conn A Sens oA oS icnty ooo 26.45) 923025 Pie Oy oo. dike yd Gib aN aw, Sette Ree 1530! 153 ik: O eee Pane PE INO tlseYtS AN Ars SOG cAcc 67. SEae2 A Fs © ear men eG MmEnpe Neb nite Aik ora ie of a5 oa .69 2.60 CY O Rare MN Mie Men eR ea cee chil c(h ad a PRS A 10.80 11.18 INaRONIEE Fone es ee Pe re Pays Ai ohne 4.627 NEZROT, 1 AO nee re rer aren HO MMA AG cieMhig Genie. < .92 .86 1 BA © os re ee ees aA yi Asoka unon oes eectin cel 53ers COR ei DEINE RUE, SSE eee A a ee 34 i Gi @ OMe ent aty a iam Ate AL is Us 6a ins 6 0,0" -45 SA en Perm AeA dina Gucie, deri ato ee Ries 6 tr. PO wo) h Sa Be RS STON Tee Ae nen eg aaa ae .O9 Ii 6 O Mr ere ee MO Se ALIA RRO ing Oa 6 3 ait! No. I represents the analysis by A. R. Leeds of the rock from Mt Marcy, and no. 2 represents the analysis by George Steiger of the rock from Mt Whiteface. According to Kemp, no. I, in the Quantitative Classification of Cross Iddings, Pirsson, and Wash- ington, belongs in class 1 (Persalane), order 5 (Canadare), rang 4 (Labradorase), subrang 3 (Labradorose); and no. 2 falls in class 2 (Dosalane), order 5 (Germanare), rang 4 (Hessase), sub- rang 3 (Hessose). The mineral composition of a thin section of rock from the summit of Mt Whiteface is shown by no. 14 of table 1 on page 21. These two analyses are doubtless very repre- sentative of the more common Marcy and Whiteface types of anorthosites in the Lake Placid quadrangle, as judged by the micro- scopic examination of various thin sections. The analyses show a close similarity in the chemical composition of these two rock types. Order, rang and subrang are the same for both, the dif- ference in class no doubt being due to the somewhat greater per- centage of ferro-magnesian minerals in the Whiteface rock which happened to be chosen for analysis. Such close similarity of chem- ical composition strongly supports the idea that the Marcy and Whiteface types of anorthosite represent differentiates of the same magma. The rather high percentage of potash in rocks of this character calls for explanation. The lack of such dark-colored minerals as would furnish enough potash causes Kemp?’ to think that orthoclase *N. Y. State Mus, Bul. 138, p. 30. 1910, Plate 10 W. J. Miller, photo, 1916 Gorge and falls (over dam) of Saranac river at Franklin Falls. The rock is Whiteface anorthosite. GEOLOGY OF THE LAKE PLACID QUADRANGLE 27 must be present up to 5 per cent or more as untwinned feldspar. Cushing, however, says: ‘‘ The potash is in the labradorite (or other plagioclase), replacing a certain amount of soda”’ and “ that analyses of this feldspar always show it.” If orthoclase is present in the typical anorthosites, the writer has been unable to demon- strate it in the thin sections examined. Usually the plagioclase is beautifully and completely twinned, but many of them are much less so, some of the slices showing only a little very local, very faint twinning. Still other feldspar slices, which show no twinning but which have apparently similar index of refraction and double refraction, are quite certainly untwinned plagioclase. It seems most probable, therefore, that much, if not all, of the potash is in the plagioclase, with possibly a little in the dark minerals pyroxene and hornblende. Certain border phases of the anorthosite (below described) do contain orthoclase and microperthite, but these are believed to be due to mixing with the later syenite-granite magma. Graphite in the anorthosite. Professor Kemp has in a letter furnished the following information regarding some interesting occurrences of graphite in the anorthosite. “‘ Below the dam across the Saranac river at Franklin Falls, in the ledge on which it rests, there is a streak of graphite traceable for some yards. In several places on Knapp hill, 2 miles to the south, I found the graphite again in the Whiteface type. I have also found it in the Marcy type of anorthosite where exposed near the Grenville at the Red Rocks (near Keene). Probably the hydrocarbons which yielded the graphite were stewed out of the neighboring or included Grenville. This mineral is unusual in intrusive rocks.” The anorthosite an intrusive body. Until very recently, the Adirondack anorthosite has been regarded by the several workers in the region as an intrusive in the ordinary sense of that term. N. L. Bowen has, however, seriously questioned whether the anor- thosite ever had been a truly molten mass. His reasons for think- ing that it was never hot enough to have been really molten are based upon certain chemical considerations. His study of the literature led him to believe that his conception is not opposed by — field facts. He stresses the simple mineral composition of the anor- thosite and says in part: ‘‘ Normally rocks are made up of several minerals, and when considering their magmas, we have to regard the various minerals as existing therein in mutual solution. . What, then, of the solution theory as applied to the anorthosites which typically consist almost exciusively of the single mineral plagioclase? Were they ever hot enough to be molten per se? 28 NEW YORK STATE MUSEUM Chemical considerations and field facts both indicate that this latter question is probably to be answered in the negative. The chem- ical considerations bring out the improbability of the formation of anorthosite in any manner other than by the accumulation of plagioclase crystals precipitated from solution in a mixed magma.” He therefore conceives of “the Adirondack anorthosite-syenite complex as essentially a stratified mass with syenite above and anorthosite below.” + Bowen’s arguments from the theoretical standpoint, at least, are not to be lightly brushed aside. But after months of detailed field work in a region like the Lake Placid quadrangle where anorthosite is so prominently developed in all its phases, the writer believes that certain field facts are most decidedly opposed to Bowen’s conception.2 The main facts of this sort will be here briefly men- tioned, actual examples and detailed descriptions being given else- where in this bulletin. 1 Sharply defined inclusions (small and large) of Grenville rocks occur in many portions of the anorthosite. These certainly bear every evidence of having been enveloped in an active magma. According to Bowen’s hypothesis, how can such inclusions be accounted for? 2 In a number of places, clearly defined inclusions of anorthosite have been found in the syenite-granite series. Could fragments of the anorthosite, if formed by the settling of plagioclase crystals, have been forced upward by some process into the syenite-granite magma? Is it not much more plausible to regard these inclusions as indicating the envelopment of previously solidified anorthosite in an active syenite-granite magma? 3 Tongues or dikes of syenite and granite, as off-shoots of large masses of similar rocks, are known definitely to cut the anorthosite. Must we assume that tonguelike masses of overlying molten syenite or granite were forced downward into the anorthosite? 4 In a number of areas there is clear evidence that anorthosite has not only cut to pieces, but also intimately injected, Grenville gneiss. Could such injection gneisses have developed except by forcible and intimate intrusion of a highly molten mass into the Grenville? 1 These quotations are from an abstract of Bowen’s paper in Bul. Geol. Soc. Amer. 28:154. I917. 2'The interested reader should consult Bowen’s paper “The Problem of the Anorthosites” in Jour. Geol. 25:209-43, 1917, and the writer’s paper “Adirondack Anorthosite” in Geol. Soc. Amer. Bul. 29:399-462, 1918. GEOLOGY OF THE LAKE PLACID QUADRANGLE 29 5 Certain areas of mixed gneisses are anorthosite literally cut to pieces by syenite, often with fairly sharp contacts visible. Such a relationship is anything but stratiform as conceived by Bowen. 6 The anorthosite is by no means an almost perfect homogeneous mass of plagioclase. Most of the rock contains from 2 to 5 per cent of minerals other than plagioclase; portions with 5 to 10 per cent are not uncommon; and sometimes the rock contains 10 to 20 per cent, or even more, of dark minerals. Such gabbroic facies exist locally throughout the anorthosite body, sometimes as narrow zones or belts. On the basis of the origin of the anorthosite by the settling of plagioclase crystals, how are such variations to be accounted for? Also, since so much of the rock contains very appreciable amounts of ferro-magnesian minerals, is the mutual solution theory necessarily precluded? 7 Foliation, particularly of the Whiteface anorthosite, is by no means rare, and the writer has repeatedly seen highly gneissoid facies and facies with little or no foliation in close proximity. The writer believes that the alternations of gabbroic and nongabbroic facies, and gneissoid and nongneissoid facies, of the anorthosite are not results of regional compression, but that they were devel- oped essentially by forced differential flowage in a congealing magma. This matter is explained at some length beyond under the caption “ Foliation.” Some of the phenomena above described might possibly be har- monized with Bowen’s hypothesis that the anorthosite originated by the “accumulation of plagioclase crystals precipitated from solution in a mixed magma,” but, taken altogether, the writer believes that they render such an hypothesis untenable. Relation of Whiteface anorthosite to Marcy anorthosite. As above stated, it is often a matter of judgment as to where the bound- ary lines between the Whiteface and Marcy anorthosites should be drawn. As a result of the field studies, the best evidence points to the conclusion that the two types are merely differentiates of the same cooling magma. On the one hand, in spite of many careful observations in the field in passing from one type across to the other, no evidence was obtained to show that one type cuts the other, while, on the other hand, one type of the rock grades into the other in many places. Transition rocks in some places form zones only some rods in width, while in other places they may be one-fourth of a mile across, and then any accurate delimitation of the Whiteface and Marcy types on the geologic map is impos- sible. Among many localities where intermediate facies are well 30 NEW YORK STATE MUSEUM exhibited are one-fourth of a mile southeast of The Flume; on the mountain side one-fourth of a mile northwest of High fall; a long wide belt one-half to 1 mile west of Upper Jay; and along the northwestern base of the Sentinel range. In some places there are locally developed, without sharp boundaries, within the Marcy anorthosite masses of rock which are quite certainly to be classed with the Whiteface type and vice versa. Only two such masses are represented on the geologic map, one on the Mt Whiteface trail near Marble mountain, and the other on the mountainside 1% miles east-southeast of Owen pond. As already shown, the Marcy and Whiteface types are very closely related in chemical composition, which strongly supports the view that the two are differentiates of the same magma. In the writer’s paper? already referred to evidence is presented in support of the view that the whole body of Adirondack anortho- site is best to be regarded as a direct derivative of a laccolithic mass not much greater across than the area of its present outcrop; that the anorthosite differentiated practically im situ from an intruded gabbroid magma; that the anorthosite crystallized from the upper or residual portion of the magma during and after the sinking of many of the femic constituents; and that the Whiteface anorthosite developed both as an outer and an upper, somewhat more gabbroid, marginal facies of the anorthosite. Cushing? maintains that the gabbroid (Whiteface) facies developed as an outer chilled border of the anorthosite. His argument seems so conclusive that it is unnecessary to repeat it here. But, in this connection, it should be noted that the borders of the anorthosite body have in some dis- tricts, like the Lake Placid and the Schroon Lake quadrangles, been so cut out or cut to pieces by the later syenite-granite intrusions that the full original extent of the anorthosite is not now shown. The writer believes further that the chilled gabbroid (Whiteface) border facies also developed as an upper limit which formerly existed as a cover resting directly on the whole great mass of anorthosite rather than merely as an outer limit, as Cushing suggests. Thus, the Whiteface anorthosite of the Lake Placid quadrangle does not exist merely as a definite fringe around the outer margin of the Marcy anorthosite. Typical Whiteface anorthosite occurs fully I4 or 15 miles within the present border of the anorthosite area, and inclusions in the syenite-granite series outside the general anorthosite area show that the Whiteface anorthosite formerly 1 Geol. Soc. Amer. Bul., 29 :399-462, 2 Jour, Geol., 1917, 25 :506. GEOLOGY OF THE LAKE PLACID QUADRANGLE 31 extended at least a few miles farther out than the present boundary. One area of Marcy anorthosite, 12 miles long within the Lake Placid quadrangle and extending an unknown distance into the Ausable quadrangle, is flanked on either side by Whiteface anortho- site. It is hard to resist the suggestion that the Whiteface rock formerly covered this whole mass of Marcy anorthosite. There is thus a distinct difficulty in the way of considering this Whiteface anorthosite merely an outer border facies. But if we do so regard this border facies, we are forced to conclude that it is exceedingly thick — that is to say, fully 10 or 12 miles — the width of the area containing Whiteface anorthosite representing practically the thick- ness of the border phase. This is scarcely possible. If, however, we consider the Whiteface anorthosite of the quadrangle to mark an upper limit of the great anorthosite body, but now partially removed by erosion and partly cut into by the syenite-granite series, not nearly so great thickness need be assumed. On this view a vertical thickness of fully 3000 feet is actually exposed in Mt Whiteface, and how much more should be added to make up for the upper portion removed by erosion is of course unknown. Prob- ably little or none is to be added to the bottom, because Marcy anorthosite outcrops near the base of the mountain. The anorthosite younger than the Grenville. There is two- fold evidence that the anorthosite is younger than the Grenville series, namely, distinct inclusions of Grenville rocks in the anortho- site, and the more or less intimate penetration of the Grenville by the anorthosite, particularly by the Whiteface anorthosite. Inclusions of Grenville in the Marcy anorthosite seem to be uncommon, having been noted in only one locality, namely, one- fourth to one-half of a mile north of Red rock in the vicinity of Keene, where a number of sharply defined, small inclusions of Grenville quartz-pyroxene gneiss and quartzite, and one 2-foot inclusion of limestone, are plainly imbedded in the typical Marcy anorthosite. The writer recalls having seen a 10-foot inclusion of limestone in anorthosite on the shore of Long lake in the Blue Mountain quadrangle (see Museum Bulletin 192). In the Whiteface anorthosite, however, inclusions of Grenville occur in many places. Only a few of the better, more accessible localities will be cited. A 20-foot inclusion of nearly white Gren- ville quartz-feldspar-garnet gneiss clearly shows in a big ledge just east of Keene. Others, including quartzite and green pyroxene gneiss, occur for a mile eastward on the way up the hill east of Keene and along its summit. 32 NEW YORK STATE MUSEUM In the quarry by the road 3 miles north of Keene, and also in ledges by or near the road one-half to two-thirds of a mile north of the quarry, the Whiteface anorthosite contains numerous bunches or lenses of Grenville, usually less than a foot long, as distinct inclusions. Near the southeastern end of the Grenville area 2 miles due north of Keene, and also by the road in the mixed gneiss area 1% miles southwest of Upper Jay, the anorthosite contains numerous sharply defined inclusions of Grenville gneiss and some of lime- stone. Most of these are less than 2 or 3 feet across. In The Flume southwest of Wilmington, and also in the mixed gneiss area 21% to 314 miles west-northwest of ‘Wilmington, por- tions of the anorthosite contain small lenses or Hee masses of Grenville green pyroxene gneiss. » Just west of the bridge at Franklin Falls the big ledges of White- face anorthosite contain a number of clearly defined bands or lenses of Grenville gneisses from a few inches wide and long, to 7 or 8 feet wide and 10 or 20 feet long (see plate 11). These inclusions are mostly gray quartz-feldspar-biotite gneiss, white feldspar- quartz-garnet gneiss, and quartzitic gneisses. A big ledge of Grenville hornblende gneiss on the western shore of the river I mile south of Upper Jay is clearly intruded by a dike of Whiteface anorthosite 20 feet wide, this doubtless being an off-shoot from the anorthosite body just to the north. In the areas of Grenville-anorthosite mixed gneisses, the Gren- ville rocks are literally cut to pieces by, and often injected with, much anorthosite, so that a separate mapping of the two forma- tions 1s rendered impossible. Areas of this sort are considered below. The above phenomena, mentioned somewhat in detail, strongly support the view that the anorthosite is, in the strict sense of the term, an intrusive body. Such evidence is directly opposed to the hypothesis of origin of the anorthosite as advocated by Bowen (see above). The anorthosite older than the syenite-granite series. That the anorthosite is older than the syenite-granite series (described beyond) is conclusively proved both by tongues or dikes of syenite and granite cutting the anorthosite, and by inclusions of anorthosite in the syenite and granite. Several excellent examples of tongues of syenite and granite cutting anorthosite have been discovered by the writer within the quadrangle. These are of particular inter- est and importance because they constitute the only known evi- Plate 11 W. J. Miller, photo, 1916 A ledge of Wh’'teface anorthosite by the road just across the river from Franklin Falls. The anorthosite contains a long, narrow inclusion of Grenville, gray, gneissoid feldspar-quartz-garnet gneiss. Width of the in- clusion, 1% to 2 feet. GEOLOGY OF THE LAKE PLACID QUADRANGLE 33 dence of the sort in the northern portion of the great body of anorthosite demonstrating that the syenite-granite series is younger than the anorthosite. In fact the only other evidence of this kind thus far published is the important discovery by Professor Cushing of dikes of syenite cutting the western margin of the anorthosite in the Long Lake quadrangle.* One mile south of Morgan pond, on a prominent spur of Wil- mington mountain, two tongues or dikes of quartz syenite, clearly exposed for 50 or 60 feet, cut through a big bare ledge of White- face anorthosite (see map). The dikes are from 10 to 20 feet wide, and they are quite certainly off-shoots from the considerable body of quartz syenite which lies to the west. As would be expected in such narrow dikelike masses, the syenite is somewhat finer grained than usual, but otherwise it is quite normal. No. 39 of table 2 gives the mineral composition of a thin section from one of the dikes. The dike rock has weathered moderately to a light brown. It is very slightly gneissoid. The contacts against the anorthosite are not perfectly sharp and there may have been very slight assimilation along the borders. Along the brook three-fourths of a mile west of The Flume, a tongue of quite normal quartz syenite 20 feet wide cuts typical Marcy anorthosite. This dike is an off-shoot from the considerable body of similar syenite extending southwestward (see map). On the mountain spur 1% miles northeast of the summit of Little Whiteface mountain, a number of tongues of granite cut the Whiteface anorthosite. The relations are very clear in the big bare ledges. Of the three tongues of granite, shown on the map in somewhat exaggerated form, the middle one is only 20 feet wide, while the other two are some rods in width. The dike granite contains several per cent of hornblende, is clearly gneissoid, and weathers to pink or brown. South of the dikes just mentioned, several tongues of granitic syenite, none over 2 or 3 feet wide, cut the typical Whiteface anorthosite. Inclusions of Whiteface anorthosite in syenite and granite, fur- nishing decisive evidence that the syenite-granite series is the younger, were observed at a number of localities. A few of these will be cited. Ledges of syenite by the river one-fourth of a mile east of High fall contain inclusions of Whiteface anorthosite arranged parallel to the foliation of the syenite. Near the base of Little High fall three-fourths of a mile northeast of High fall, *N. Y. State Mus. Bul. 115, p. 479-82. 1907. 2 34 NEW YORK STATE MUSEUM an 8-foot boulder of syenite has in it several distinct inclusions of Whiteface anorthosite, these usually not showing very sharp con- tacts against the syenite. On top of the hill in the area of syenite- granite and Grenville mixed gneisses, there are some small lenses of Whiteface anorthosite in the syenite parallel to its foliation. Near the middle of the northern boundary of the area of Keene gneiss 1144 miles west of East Kilns, a big ledge of typical syenite has many inclusions of Whiteface anorthosite which are bunches, lenses or bands from 2 or 3 inches to several yards long. Their borders are not always sharp against the syenite. This is one of the finest exhibitions of such phenomena observed by the writer within the quadrangle. In the area of Whiteface anorthosite and syenite mixed gneisses ~ from one-half to 2 miles east of High fall, the anorthosite has been much cut up by intrusions of syenite, good contacts having been noted at several places, but neither definite dikes of syenite nor inclusions of anorthosite were observed in this rough-wooded area. The Syenite-granite Series The syenite-granite series, prominently developed in the Lake Placid quadrangle, comprises a variable lot of rocks all of which, with one possible exception, are, apparently, facies of a single great cooling magma. Most common is a quartz syenite which grades into a basic (dioritic or gabbroic) facies on one side, and through granitic syenite to medium-grained granite or coarse-grained (usually porphyritic) granite on the other. Since such rocks, which are very abundant in the Adirondack region, have been described in detail in various State Museum bulletins and in other publica- tions on Adirondack geology, no omy Oy) descriptions will be given in this bulletin. That the syenite-granite series is younger shen the anorthosite series has already been shown in the discussion of the anorthosite. Quartz syenite. This is the most common and typical facies of the syenite-granite series. It is known to occupy approximately 35 square miles in very irregular areas mostly in the southern half of the quadrangle. In areal extent it is, therefore, about the same as the Marcy anorthosite but not so great as the Whiteface anorthosite. As usual in the Adirondacks, this typical syenite is a medium- grained rock, dark greenish gray where fresh, and it weathers to a light brown. In some places a pinkish gray weathering was noted. GEOLOGY OF THE LAKE ‘PLACID QUADRANGLE 35 Outcrops seldom show a depth of weathering greater than a few inches. Immediate surfaces are sometimes light gray due to leach- ing out of the iron oxides by waters rich in decomposing organic matter. 5 The granularity varies considerably, in some places being rather fine grained, and in other places being slightly porphyritic. Granu- lation of the rock is often a notable feature, particularly when viewed in thin section under the microscope. The feldspars show the greatest effects of the crushing of the mineral grains. Notable differences in coarseness of grain or degree of granulation are sometimes very locally exhibited. The degree of foliation of the syenite varies extremely. Very commonly the rock clearly displays a streaked or lenticular gneissoid ‘structure which is accentuated by the arrangement of the dark minerals with their long axes parallel to the foliation as, for example, in the quarry at the extreme southern end of Lake Placid. In other places it is excessively gneissoid as near the road one-half of a mile north of Keene village, on the mountainside one- half of a mile southeast of the mouth of Styles brook, and on the mountain 1% miles south-southeast of Upper Jay. Notable varia- tions in degree of foliation are often very local, sometimes showing in single outcrops. The problem of the origin of the foliation is discussed beyond under the caption “ Foliation:” The usual range in the mineralogical composition of the normal quartz syenite of the quadrangle is well shown in accompanying table 2. Microperthite is the most abundant constituent, and it occurs with orthoclase in about one-half of the slides examined. Oligoclase and quartz in moderate amounts never fail. » Horn- blende, pyroxene and garnet usually occur in small amounts. Some tiny grains or crystals of magnetite, apatite, and zircon. almost invariably occur. A few other minerals are sporadically present. 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ORCC RCNCED Duca Sr Spootal| aq S ¢ I S00G006 ITI UIT S S Teel OT peewee aT ese ee see £T eee eee epeammenreiey | mein (msgiene) | eG: Ce encery g g CeCnOnOnCs (eacecr arcs Ciena ary see eee SI settee £1 se eeee . . eee a4 I 9 Sooo oa @ — — |voouKD see 8 . eee . o. t z P2005) arming apyouse yy youre TELO TT) apus[quioyyT auayysied AT asel[erd OIUT[IOUO PT a suexorAd (e) E p 2 oe wD pn fone} Ot 5.0 oo oO 9SE[IOBIIO ase[s0uIO ayy yledororyAy ‘ou Plsld ‘ou 9PiS ayueigs pue oqruaAs dIPIUBIL a aytuaAs Jo seseyd ose [eulIoN ayiuedAs zyrenb SO1I9S 9}TULIZ-9}1UEAS OY} JO SUOT}IOS UIT, 2 2IqGeZ Plate 12 Photomicrographs by W. J. Miller Upper left figure. Part of slice of coarse granite from upper end of gorge one-half of a mile south of Keene. All is sliced (or sheared) and granulated quartz except a little scattering ilmenite and microperthite. Polarized light. Magnified 23 diameters. Upper right figure. Part of slice of syenite from roadside at southeastern base of Ccbble hill. Diallage crystal almost surrounded with a rim of granulated hypersthene. Embedded in microperthite and quartz. Ordinary light. Magnified 23 diameters. Lower left figure. Part of slice of rather gabbroid Whiteface anortho- site from shore of river two-thirds of a mile southwest of Copperas pond. Magnetite or ilmenite surrounded with a rim of granulated garnet. Large somewhat rounded prisms above and below are apatite. Large white areas are mostly plagioclase. Ordinary light. Magnified 30 diameters. Lower right figure. Part of slice of Keene gneiss from 1 mile east- northeast of Malcom pond. In the center, remarkable vermicular quartz intergrown with plag’oclase. Ilmenite (black) above; orthoclase (gray) on right; plagioclase below; and quartz and orthoclase on left. Polarized light. Magnified 30 diameters. GEOLOGY OF THE LAKE PLACID QUADRANGLE 37 No. 24, from Keene gneiss area just north of Keene; no. 25, by the road at southeastern base of Cobble hill; no. 27, quarry at southeastern end of Lake Placid; no. 28, by the road one-half of a mile north-northeast of Keene; no. 29, near the road one-half of a mile north of Keene; no. 30, by the road one-half of a mile west of Big Cherrypatch pond; no. 33, by the road one-third of a mile west of Copperas pond; no. 36, White- face brook, 1 mile from the lake; no. 38, 1% miles north-northeast of Keene; no. 30, from tongue of syenite cutting Whiteface anorthosite 1 mile south of Morgan pond; no. 43, 1 mile west of High fall; no. 32, quarry by the road five-sixths of a mile north of Malcom pond; no. 40, by the river three-fourths of a mile west-southwest of Owen pond; no. 31, granitic syenite from middle eastern shore of Buck island in Lake Placid; no. 47, granite from the small area in Wilmington notch; no. 48, granite from the gorge at High fall of Ausable river; no. 46, granite porphyry from side of new road one-half of a mile southwest of Franklin ~ Falls; no. 40, granite porphyry from the gorge one-half of a mile south of Keene. There is no evidence that the syenite cuts the granite of the quadrangle, or vice versa, but a gradation from one into the other seems to be clearly shown in many places as, for example, on Catamount mountain ridge, on Wilmington mountain, and on the southern slope of Mt Whiteface. In a few cases the change from syenite to granite occurs within such short distances that the inter- mediate granitic syenite can not be mapped. Proof that the syenite is younger than the anorthosite has already been given. As usual in the Adirondacks, this syenite is definitely known to be younger than the Grenville series. In certain localities the syenite contains masses of Grenville rocks as inclusions, this being particularly true near its borders with the Grenville. Such inclusions are nearly always arranged with their long axes parallel to the foliation of the syenite. Some of these inclusions are to be measured in inches, others in yards or rods, and still others are large enough to be separately indicated on the geologic map. Good examples of small inclusions may be observed on Cobble hill (east of Lake Placid village), and in Styles brook on the western border cf the Grenville area. Some of the areas of mixed gneisses show Grenville rocks all cut to pieces by, and intimately associated with, svenite as, for example, 2 miles north-northeast of Keene, and 1 mile northeast of Keene. Basic phase of the syenite. But one mass of rock of this kind has been separately represented on the accompanying geologic map. It lies in the valley of West Branch Ausable river east of Connery pond. The area is 134 miles long, with a maximum width of nearly 38 NEW YORK STATE MUSEUM one-half of a mile. The origin and relations of this rock are not clear to the writer. The main bulk of the rock is decidedly like the syenite in appear- ance, being medium grained nonporphyritic, moderately to very eneissoid, greenish gray where fresh, and weathering to brown. In the small quarry by the road near the southern end of the area, this type of rock is finely exposed. No. 32 of table 2 represents a thin section of rock from the quarry. No. 40, which represents a thin section of similar rock from the shore of the river 1% miles farther north, is exceptional in being pinkish gray, probably due to weathering. ‘Compared with the normal syenite, the average amount of plagioclase in this so-called basic phase of the syenite is seen to be higher. Thus the rock is more basic, being more like diorite than syenite. In every other way, however, the rock shows strong syenitic affinities. Whether this so-called basic phase of the syenite is merely a differentiation phase of the adjacent normal syenite, or is a product of assimilation of some anorthosite by the syenite magma, the writer can not say. Its situation between the Keene gneiss (below described) and syenite strongly suggests the latter possibility. If the rock is an assimilation product it may be regarded as a sort of nonporphyritic outer zone of the Keene gneiss where the latter shades off into the normal syenite. In the field the relation of the rock to the Keene gneiss could not be positively determined because of lack of exposures along the border. Very similar rocks, usually regarded as basic differentiation phases of the normal syenite, are, however, known from various parts of the Adirondacks. Granitic syenite. This rock is clearly intermediate between the normal quartz syenite and the granite or granite porphyry. It is an acidic facies of the syenite in which the quartz content is about 20 to 25 per cent. Since nothing like sharp boundaries exist, this percentage of quartz is only approximately represented in the twelve areas indicated on the geologic map. These areas, well scattered over the quadrangle, do not occupy more than 5 or 6 square miles. The rock 1s in every way much like the normal quartz syenite except for higher quartz content and frequent tendency to weather pink or pinkish gray. On the eastern shore of Buck island in Lake Placid, where the pegmatite dikes cut the granitic syenite, the latter contains as much as I per cent of graphite in small flakes (see no. 31 of table 2). Since this granitic syenite is here closely associated with small Photograph loaned by J. D. Washer, keeper of High fall and gorge Looking upstream through the lower portion of the gorge of the West branch, Ausable river below High fall. The rock is pink granite intersected by dikes of diabase. GEOLOGY OF THE LAKE PLACID QUADRANGLE 39 amounts of dark Grenville gneiss, it seems probable that the gran- itic syenite magma took up the graphite from the Grenville. A fine big ledge, known as Pulpit rock, on the eastern shore of Lake Placid contains some inclusions of Grenville. The hill just east of Connery pond is mostly a great barren ledge of quite homogeneous granitic syenite. Granitic syenite as a transition rock between syenite and granite is well exhibited on the southern side of Mt Whiteface, and also on Catamount mountain ridge. Granite. As already stated, this rock is, so far as could be determined, an acidic differentiation phase of the normal quartz syenite. Rather arbitrarily, when a rock of the syenite-granite series contains more than 25 per cent of quartz it is classed as granite. In a few instances the transition from syenite to granite takes place within too short a distance to permit mapping of the intermediate granitic syenite. Like the normal syenite, the granite is more or less clearly gneissoid, medium grained, and often con- siderably granulated. It is, however, nearly always pink or pinkish gray instead of greenish gray like the syenite. The mineralogical compositions of two typical granites are shown by nos. 47 and 48 of table 2. Ten areas of this granite appear on the accompanying gealogic map. Altogether they occupy only 8 or 9 square miles, and they are confined to the western half of the quadrangle. The wide belt of granite on the southern side of Mt White- face is very typical medium to moderately coarse grained, pink to red, and distinctly gneissoid. Transition through granitic syenite to syenite is well shown, but on the north it appears to come sharply against the Whiteface anorthosite. A number of tongues of the granite sharply cut the Whiteface anorthosite at the eastern end, as already explained (see map). At High fall and in the gorge just below the granite is pinkish, medium to moderately coarse grained, and very gneissoid. The granite of the southern end of Wilmington mountain grades through granitic syenite into syenite. About Silver lake, and also just west of Still brook, the granite clearly grades into the coarse granite porphyry. Several outcrops of granite south-southwest of Woodruff fall, and also 1 mile southwest of Malcom pond, contain small, distinct inclusions of Grenville hornblende gneiss as lenses or irregular masses mostly parallel to the foliation of the granite. 40 NEW YORK STATE MUSEUM Granite porphyry. A body of coarse, usually porphyritic, granite occupies about 25 square miles of the northern portion of the quadrangle. Feldspar crystals nearly always range in length from one-fourth to 1 inch, and usually these stand out conspicu- ously as phenocrysts. Quartz individuals are often one-fourth to three-fourths of an inch long. Dark minerals seldom make up more than 10 or 12 per cent of the rock. Most of the granite porphyry is more or less gneissoid, but locally there are considerable bodies of the rock which are practically devoid of foliation and not ‘much granulated. Such nonfoliated rocks occur in big exposures on the hills in several square miles of the northwestern corner of the map area, on Fremont hill, and on the two hills respectively 2 and 3 miles east of Fremont hill. At the other extreme there are considerable developments of highly gneissoid coarse granite and granite porphyry. In these facies the feldspars are generally highly granulated, with the larger ones more or less flattened out into lenselike eyes or so-called “augen.” The quartz crystals in these very gneissoid phases are remarkably flattened out into thin lenses, sometimes nearly an inch long. Fine examples of flattened quartz may be seen in the ledges from one- half to 1 mile southwest of Franklin Falls, 114 miles north of Woodruff fall, and three-fourths of a mile north-northwest of West Kilns. The flattened quartz crystals are always arranged with long axes parallel to the foliation. In some localities the degree of foliation varies greatly within small areas. Thus, on the hillock 1% miles southeast of Fremont hill, nonfoliated, moderately foli- ated, and highly foliated coarse granites are associated. Similar variations in foliation occur on the hilltop 1 mile east of the south end of Silver lake. The coarse granite very commonly weathers to a pink or pinkish gray, and more seldom to light brown. Fresh rock was obtained in but few localities as, for example, from a ledge recently blasted open by the roadside one-half of a mile southwest of Franklin Falls. Such rock is greenish gray. Whether or not much, if any, of the fresh granite is pink could not be determined. The mineralogical composition of the granite porphyry is well illustrated by no. 46 of table 2, which represents a thin section of the typical, fresh, very gneissoid rock with large granulated “augen”’ of feldspar and highly flattened quartz individuals. This rock differs from the granite porphyries described by the writer from the central and southern Adirondacks by the absence of micro- cline, though possibly this mineral does occur in other portions of Plate 14 W. J. Miller, photo, 1916 Looking down the gorge of the West branch, Ausable river from the foot- bridge just below High fall. The rock is pink granite intersected by several dikes of diabase parallel to the course of the stream. GEOLOGY OF THE LAKE PLACID QUADRANGLE 4I the large area of granite porphyry. Hornblende appears to be a constant constituent, while pyroxene often fails. No. 49 of table 2 is from the small area of mixed rock in the gorge one-half of a mile south of Keene. Like the other members of the syenite-granite series, inclusions of Grenville gneiss sometimes occur in this coarse granite as, for instance, on Catamount mountain, and on top of the hill 1 mile east of the south end of Silver lake. It seems very clear, as a result of both field and laboratory studies, that the granite and granite porphyry are both only facies of a single great cooling magma. The perfect gradations from syenite through granitic syenite to granite and granite porphyry strongly support the view that the members of the syenite-granite series (except possibly the basic phase of the syenite) are differ- entiation products of a single great cooling magma. Possibly some of the granite may be distinctly older or younger than the syenite but, except for the small granitic dikes below described, no such rock could be proved to be present. Granite, Aplite, and Pegmatite Dikes The various acidic dikes which have been definitely located are represented on the geologic map (each dike by a number) there being twenty-one in all. There must be many others concealed under glacial drift, or hidden in the woods, or not discovered where actually outcropping. In some cases the age relations are not altogether clear. Granite dikes. At dike localities 1 and 2 there are several pink granite dikes cutting anorthosite. No. 3 is a dike of pink granite 75 feet long cutting Whiteface anorthosite, but not with very sharply defined contacts. No. 4 is a dike 4 feet wide clearly cut- ting Grenville gneiss. Dike no. 11 is pink granite cutting Marcy anorthosite. At locality no. 12 several dikelike masses of granite are involved with syenite and Whiteface anorthosite. Most of these dikes may be merely off-shoots from the great syenite-granite intrusive body, but some may possibly be consider- ably later in age. Aplite dikes. Interesting dikes of aplite were observed. At no. 9, in the bed of the river east of Copperas pond, a dike of pink aplite, with several small tongues, clearly cuts a gabbroic, very gneissoid facies of the Whiteface anorthosite. A thin section of this aplite shows 20 per cent orthoclase, 20 per cent microperthite, 42 NEW YORK STATE MUSEUM I5 per cent albite, 44 per cent quartz, I per cent magnetite, and a little zircon. The rock is moderately gneissoid and variable in grain from medium to coarse. Possibly it is an acidic off-shoot from the neighboring syenite. On the southern side of the top of Catamount mountain, a num- ber of small nonfoliated aplite dikes lie parallel to the foliation of the coarse granite. Whether these are younger or older than the neighboring gabbro-diorite dikes was not definitely determined, but the aplites are probably the older. At number 17, t mile west of East Kilns, a fine aplite dike 3 feet wide cuts a big ledge of coarse granite. A thin section shows the following mineral percentages: Microperthite, 58; microcline, 1; albite, 5; quartz, 35; biotite, 1; and very littl sarnetaapanic and zircon. The rock is not gneissoid. The fact that the contact against the granite is not very sharp strongly suggests that the aplite was intruded while the granite was still fairly hot. At dike locality no. 18 several small aplite dikes cut granite. Granite-pegmatite dikes. Nos. 5, 6, 7, 8, 10, 13, 14 and 16, indi- cated on the geologic map, are pegmatite dikes of the usual sort. They are nonfoliated and cut the Grenville, anorthosite, and syenite- granite series. No. 8 lies in contact with a diabase dike, and these two. clearly cut syenite. No. 16 is a pegmatite dike 3 feet wide very sharply cutting across the foliation of one of the gabbro- diorite dikes below described. Within the Lake Placid quadrangle no pegmatite was observed cutting the gabbro stocks (below described), but in various portions of the Adirondacks dikes of such have been found to be intrusive into the gabbro. It is quite possible that these pegmatite dikes are not all of the same age, but all are. doubtless younger than the syenite-granite series, most of them probably representing a late stage in the intrusion and cooling of the syenite-granite magma. Syenite-pegmatite dikes. A much more unusual type of pegma- tite dike was noted at several localities, namely, near Franklin Falls (dike no. 19); 1% miles south of Wilmington (dike no. 20) ; and 1 mile southwest of Haselton (dike no. 21). These are very coarse- grained rocks consisting chiefly of irregular masses of microperthite and black hornblende (or pyroxene) up to several inches across. No quartz occurs. Dike no. 19 is 2 feet wide, cuts Whiteface anor- thosite, and contains masses of magnetite I or 2. inches across. The contact against the country rock is not sharp. At no: 20 a number of pegmatite dikes from 1 to several feet wide cut Marcy anor- thosite usually without sharp contacts. GEOLOGY OF THE LAKE PLACID QUADRANGLE 43 these dikes consist almost wholly of microperthite and horn- blende in large masses. It seems very clear that the pegmatites of this sort were intruded very soon after the intrusion of the anortho- site and that they are, therefore, distinctly older than the ordinary granite-pegmatites above described. Keene Gneiss General statements. One of the most interesting rocks of the quadrangle is locally developed as belts or irregular bodies along portions of the borders between the anorthosite and syenite-granite. Both the Marey and the Whiteface types of anorthosite show such border rocks. There is very strong evidence, based upon field work and a study of thin sections, that this is really a transition rock between the anorthosite and the syenite or granite due to actual digestion or assimilation of anorthosite along its border by the invading syenite-granite magma. It is here proposed that this rock be called the Keene gneiss because a fine exposure of the typical! fresh rock occurs by the road at the northern edge of the village of Keene. In view of the fact that many geologists maintain that there are no definitely proved cases of magmatic assimilation on considerable scales at least, the evidence furnished by these rocks of the Lake Placid quadrangle has been very carefully considered by the writer who is convinced that actual assimilation has taken place. In other words, the Keene gneiss seems to be quite cer- tainly a good example of a “hybrid” rock, to use the term sug- gested by Harker, the English geologist, who has maintained that such rocks have been produced either by the mixing of two distinct magmas, or by the assimilation of solid rock by magmas. Fifteen areas of Keene gneiss are represented on the geologic map which accompanies this bulletin. Others probably exist but were not located owing to scarcity of outcrops or roughness of country in some places. The typical Keene gneiss presents a different appearance from any of the other rocks of the region, and it is usually readily recog- nizable. The main body of the typical rock is medium grained, gneissoid, notably granulated, and looks much like a rather basic phase of syenite, but it contains scattering phenocrysts of bluish gray labradorite up to an inch in length. These phenocrysts, which are rounded and usually elongated parallel to the foliation of the rock, doubtless represent cores of crystals which survived the process of granulation. Locally the phenocrysts of labradorite are 44 NEW YORK STATE MUSEUM absent or only sparingly present, ledges of such rock being very difficult to distinguish from a) basic phase of syenite. Under the microscope, however, the distinction may generally be made. Where fresh the rock is greenish gray, and it weathers to brown. The mineralogical compositions of selected samples of various phases of the rock are shown in table 3. Labradorite and andesine are always present, and oligoclase usually. Microperthite occurs in most of the specimens in varying amounts up to 30 per cent, and orthoclase in most specimens in varying amounts to over 50 per cent. A little quartz is generally present. All the thin sections examined show greenish gray monoclinic pyroxene, sometimes diallage. A little green hornblende nearly always occurs up to 14 per cent. Garnet varies from none to 12 per cent. Ilmenite (or magnetite) up to a few per cent never fails. Apatite and pyrite in small amounts always occur. N. L. Bowen, in a recent paper, states that he has observed, in the transition rock from anorthosite to syenite, inclusions of potash feldspar which are small patches, uniformly oriented, and, in some cases, surrounded by areas of plagioclase differing from the crystal as a whole. A few slight suggestions of this sort of thing were noted by the writer, but certainly this is not a characteristic feature of the Keene gneiss thin sections examined. Table 3. Thin sections of Keene gneiss o oO o o a | = = x © | ,o = G S) 1A a 2 #/ 2 ee oe eaes Bic fe) 9° 3 o| Ss Say || 2) Sei) 2 x 2i|s a 5 } Sl Ss | Ss sy || SHS) @ 5) q ® = © o ‘re “ = ia] h ¢q = = oO q p fe) he 5 5 ue! 2 S 2 8 | S88 (Se) es loa [eh ela ee eas a ea a SloOleals | 4 i VS oO < N A | & lo 3 4£8 |ol.—-Lab. 80] ro].... Al enens 3 I 4| little Dl 1ittle| little} eyes |(eres ro | 7£7 a |ol.—Lab. 28] 25) 20] 64 OIF ares listo 2 Wea Pe rdigacoalicocclls> = - II 14 ¢4 |An.-Lab.66]...| 20 2 4|. heise reve ve little} little].....].. s8-[h 30 - I2} 14b4 ol.-An. 48] 20].... 9 Bilooacl| wh Tih aioe little 3|.....| little 2 41 TO) 9) 7) | Anisvabss0|h eal 50 5 Bloc 5 3 5 Blea aeas Little | sere ees 42 |1kz10a/An.-Lab.70] 20].... I 3 2 2 I 4 a eatin: ir llonoso}(o.0 c 45 |}1k10b| ol.-Lab.40] 32] 1o}.... 2 8] 6% Tiaras Bltescves little||ie alee No. 3, 1 mile east-northeast of Malcom pond; no. 10, 1 mile a little south of west of High fall; no. 11, one-half of a mile south of the summit of Catamount mountain; no. 12, one-half of a mile north of Franklin Falls; no. 41, in the brook 134 miles due west of East Kilns; nos. 42 and 45, by the main road at northern edge of the village of Keene. 1Jour. Geol, 25:221. I917. GEOLOGY OF THE LAKE PLACID QUADRANGLE 45 Areas in the vicinity of Keene village. The type locality of the Keene gneiss is a ledge by the side of the state road at the north- ern edge of the village of Keene where an excellent opportunity is afforded for the study of the rock and its relations to both anor- thosite and syenite. All three of these rocks show as unweathered material in this one ledge which has been recently blasted open. The anorthosite, which occurs in minor amount, is the typical Marcy facies consisting mostly of dark, bluish gray labradorite up to an inch across embedded in some granulated feldspar, and associated with 10 to 20 per cent of ferro-magnesian minerals. The syenite is quite normal in every respect except that it is a little finer grained than usual. No. 24 of table 2 gives its mineral content. Most of the rock of the ledge, however, is clearly an assimilation product of syenite and anorthosite. This assimila- tion rock (Keene gneiss) exhibits at least three distinguishable facies. One of these is highly gneissoid with elongate cores of labradorite crystals as phenocrysts up to an inch long arranged parallel to a distinct foliation. Its mineral content is given as no. 42 of table 3. A second facies is only faintly gneissoid, with labra- dorite phenocrysts only roughly parallel to the foliation. Its com- position is given as no. 45 of table 3, the presence of orthoclase and a greater amount of microperthite making this rock much more syenitic than the first facies. In the two facies just described, the phenocrysts of labradorite not only finely exhibit polysynthetic twinning, but they are also perfectly twinned according to the albite law, thus giving the freshly broken surface a striking appear- ance. Both of the facies are notably granulated, and the rounded phenocrysts are the uncrushed portions of what were once still larger crystals. A third facies, in minor quantity, is nonfoliated ‘and contains no labradorite phenocrysts, but it does contain a few rounded red garnets up to an inch across. This third facies is the most syenitic of the three. All three facies just described grade into one another and they are quite certainly only differentiates of a single cooling magma. Also it is important to note that the Keene gneiss is not sharply separated from the true syenite on one hand, and the true anortho- site on the other, but rather by narrow transition zones. All three facies of the Keene gneiss are certainly intermediate in composi- tion between the syenite and anorthosite, the first one described having decided anorthosite affinities, the third having decided syenite affinities, and the second being very clearly intermediate 46 NEW YORK STATE MUSEUM between the syenite and anorthosite. The conclusion, therefore, based upon the field relations and composition of the rocks is that we have here a true magmatic assimilation product, the invading syenite magma having actually incorporated and assimilated more or less of the anorthosite material. The close juxtaposition of sye- nite and Keene gneiss may be reasonably explained if we consider the syenite to have been an intrusion as an off-shoot of the great body of syenite magma into previously formed and cooling (or possibly solidified) Keene gneiss magma, the temperature then having been high enough only to permit fusion along a narrow border zone between the intruded and intrusive masses, thus accounting for the narrow transition zone between the two in the ledge. The foliation of the Keene gneiss is quite certainly an orig- inal structure due to magmatic flowage under pressure, and accord- ingly the marked differences in degree of foliation within this one outcrop are regarded as the result of differential magmatic flowage according to the principles explained beyond under the caption’ Soliattonhe : Professor Kemp has informed the writer that rock similar to that just described was formerly visible in outcrop at the present sawmill site in Keene village, and the area of Keene gneiss is accordingly extended that far south on the geologic map. The little area one-half of a mile east of Keene shows a variable lot of rocks, some being apparently Whiteface anorthosite, some rich in black minerals and garnet, and much containing large bluish gray labradorites in a very syenitic looking, crudely gneissoid, brownish-weathered rock like the typical Keene gneiss above described except for its brown weathering. Oak ridge shows fine big exposures of a rock which, in the field, would be taken for a rather basic phase of syenite except for the large scattering bluish gray labradorites. It is, without doubt, a large scale mass of the Keene gneiss. Good outcrops of typical Keene gneiss also occur in the small areas respectively I mile northeast; 2 miles west-northwest; and 4¥%4 miles west of the village of Keene. Areas near Upper Jay. In the area of over one-half of a square mile just east of Upper Jay, there are many very good exposures, certain of them of particular interest because they throw important light upon the origin and relations of the Keene gneiss. Near the top of the hill at the northeastern border of the area, Whiteface anorthosite and syenite in big exposures are separated by a zone, a few feet wide, of basic syenitelike rock with scattering bluish GEOLOGY OF THE LAKE PLACID QUADRANGLE ‘47 gray labradorites. This is very clearly a transition zone of typical Keene gneiss produced by the assimilation of Whiteface anortho- site by syenite magma. On the little hill just south of the center of the area, several outcrops of quite typical Keene gneiss contain bands or lenslike inclusions of Whiteface anorthosite, the Keene gneiss magma, moving from a lower level where it was formed, evidently having penetrated or caught up inclusions of unchanged Whiteface anorthosite at the higher level. The Keene gneiss here contains many tiny red garnets, and the labradorite phenocrysts are very conspicuous on the weathered surfaces. A little area, shown on the map 1% miles west of Upper Jay, is thought to be Keene gneiss, but the matrix of this rock is finer grained and more gneissoid than usual. Sentinel range area. This long, narrow area extends east-west across the middle of the Sentinel range. . It is about 4 miles long and nowhere over one-fourth of a mile wide. It is all in a rough, densely wooded country, but a good many outcrops make the mapping fairly satisfactory. Perhaps the most instructive ledges are on the little hill 1 mile northeast of Malcom pond. The top of this hill is quite typical Marcy anorthosite. On the southern side the rocks are variable, being mostly fine to medium grained, gneissoid.and gabbroic in appearance with some closely involved basic syenitelike rock containing a few small, scattering labradorite phenocrysts, this latter being presumably Keene gneiss. Near the top of the hill, on the west side, the rock is coarser grained with few dark minerals, and this appears to be quite like typical Keene gneiss. All the types mentioned grade into one another. On the hillside one-half of a mile southeast of the hill just described, there are outcrops of a moderately coarse-grained, rather gabbroic rock with some labradorite phenocrysts. Its mineralogical composition, given as no. 3 of table 3, shows that it should be classed as Keene gneiss with strong anorthosite affinities. Good exposures of Keene gneiss may be seen in other portions of the areas mapped, particularly for a mile eastward from the summit of Sentinel range, where the typical rock forms a wide transition zone between the Marcy anorthosite on the north and the quartz syenite on the south. Sunrise notch area. This, the largest area of Keene gneiss within the quadrangle, is about 3% miles long and from one-half to two-thirds of a mile wide. It is a rock distinctly intermediate between Whiteface anorthosite and syenite. Most of the outcrops are quite typical Keene gneiss, though usually not strongly foliated. 48 NEW YORK STATE MUSEUM It is generally medium grained with scattering labradorite pheno- crysts, and weathered brown. A locality of special interest is a cliff on the southern border of the area three-fourths of a mile east of the summit of Sunrise notch. Most of this rock is very gneissoid and only moderately gabbroic Whiteface anorthosite, a little finer grained than usual. Its mineral content is given as no. 20 of table 1. Within this rock there is a wide band of fine-grained, very gneissoid, gray rock with a reddish tinge due to numerous tiny garnets. The composition of this local band, given as no. 10 of table 3, causes it to be classed with the Keene gneiss, the high content of microperthite and ortho- clase showing it to have strong syenite affinities. Its contact against the anorthosite is not very sharp. Evidently a dike or tongue of the Keene gneiss magma here intruded the Whiteface anorthosite near its border, and the temperature was high enough to cause fusion of the anorthosite walls of the dike or tongue. The small area of Whiteface anorthosite one-third of a mile north of the locality just described, presumably represents a body of anorthosite which failed to become assimilated by the syenite magma. Area west of East Kilns. This area, ‘between 1 and 2 miles west of East Kilns, shows certain interesting and important fea- tures. Much of the rock, whose composition is given as no. 41 of table 3, has strong syenite affinities because of its high orthoclase content. Near the middle of the northern boundary, syenite contains Whiteface anorthosite inclusions as bunches, lenses and bands from 2 or 3 inches to several yards long, the boundaries of the inclusions usually not being very sharp. [Evidently very little assimilation of the anorthosite took place here. Along the northwestern side several ledges are very gabbroic in appearance, in some places very gneissoid and in others not. Locally there is intimately associated syenite and Whiteface anor- thosite. Apparently these ledges show the effects of partial diges- tion or assimilation of anorthosite by the syenite magma. Along the main brook, for one-fourth of a mile after it enters the area, there are good exposures of homogeneous, scarcely gneis- soid Keene gneiss, with the phenocrysts of labradorite not so large as usual. This rock, whose composition is given as no. 41 of table 3, has strong syenite affinities because of its high ortho- clase content. In this portion of the area, syenite magma quite certainly completely assimilated more or less anorthosite. GEOLOGY OF THE LAKE PLACID QUADRANGLE 49 The little hill in the eastern portion of the area consists of rather mixed rocks, but it is mostly Keene gneiss with large labradorites. At one place fairly coarse granite is intimately associated with gabbroic Whiteface anorthosite with local development of what appears to be an assimilation product of the two containing some quartz. Small masses of Grenville gneiss are also commonly involved with the rocks of this hill. Other areas. [he narrow band of Keene gneiss at the southern base of Catamount mountain contains large labradorites but it is scarcely gneissoid. No. 11 of table 3 gives its mineral content. In the small area one-half of a mile north of Franklin Falls, a medium-grained, rather gabbroic, gneissoid rock, without pheno- crysts, has the composition of Keene gneiss as shown by no. 12 of table 3. This rock grades into gabbroic Whiteface anorthosite, but its relation to the nearby granite could not be determined. The area just north of Owen pond shows big ledges of homo- geneous, typical Keene gneiss. The small area 1144 miles south-southeast of The Flume shows Keene gneiss closely associated with much syenite and some White- face anorthosite. Significance of the distribution of the Keene gneiss. That the Keene gneiss is actually an assimilation product of the fusion and digestion of anorthosite by syenite or granite magma is regarded as proved by the evidence above presented. But such rock is not universally present,as a transition or border rock between anor- thosite and syenite or granite. For instance, the long boundaries between the Whiteface anorthosite and granite of Mt Whiteface, and between the Whiteface anorthosite and syenite from the southern side of Mt Whiteface to west of Knapp hill, were crossed at many places without noting any rock like the Keene gneiss. As seen on the map, other areas also show an absence of Keene gneiss as a border rock. It is possible that some masses of Keene gneiss may have been overlooked in the rough, densely wooded country, or that some may exist under cover of glacial and postglacial deposits, but, in view of the detailed survey, it is certain that any such masses of Keene gneiss are relatively small. How is this difference in distribution of the Keene gneiss to be accounted for? Also why do the borders between the Grenville and syenite-granite series, as well as in the mixed eneiss areas of Grenville and syenite- granite, show little or no evidence of magmatic assimilation? The writer believes that the answer to these questions may be found in the temperature relations of the rocks at the time of the intrusion 50 NEW YORK STATE MUSEUM of the syenite-granite series. If we consider that the great mass of anorthosite was still at a relatively high temperature, though not necessarily molten, at the time of the syenite-granite intrusion, it would have been only necessary for the syenite-granite magma to have raised the temperature of the borders of the intruded anor- thosite comparatively little to have effected actual assimilation. The tongues of syenite cutting Whiteface anorthosite on Wil- mington mountain, and the tongues of granite cutting Whiteface anorthosite on Mt Whiteface (described on page 33), furnish important evidence in support of this view, because these tongues or dikes, instead of being in real sharp contact with the anortho- site, show very narrow transition zones due to slight fusion of the anorthosite. Now, it does not seem at all probable that even smal! amounts of relatively cold anorthosite could have been fused and assimilated by such small masses of intrusive magma, but with the anorthosite at a high temperature, though not really molten, its — borders might very conceivably have been fused. Thus, if we make the very simple and plausible assumption that the anorthosite was still very hot (though not necessarily molten) when the syenite-granite magma was intruded, or, in other words, that this latter magma was forced up comparatively soon after that of the anorthosite, the usual strong objection to magmatic assimilation, namely, that a magma does not possess a sufficiently high temperature to raise relatively cold country rock to the point of fusion, is distinctly obviated. Where no Keene gneiss occurs along the borders, it may be plausibly conceived that either the anorthosite, or the syenite- granite, or both, may not have been hot enough to permit assimila- tion. Also, in harmony with this hypothesis, the failure to find any considerable assimilation of Grenville either along its borders with, or where involved with, the syenite-granite series may be explained on the basis of a temperature of the Grenville too low to have per- mitted any more than comparatively slight assimilation by the invading syenite-granite magma. It should be borne in mind, how- ever, as pointed out in a recent paper by the writer, that local assimilation of Grenville was not uncommon in the Adirondack region.+ . to In the mixed rock areas near the center of the quadrangle, where anorthosite has been cut to pieces by intrusions of syenite, the few contacts observed are not very sharp. Apparently, in these areas *Geol. Soc. Amer. Bul. 25 :254-63. 1914. GEOLOGY OF THE LAKE PLACID QUADRANGLE 51 either the syenite magma or the anorthosite, or both, were not hot enough, or the syenite was not in sufficient bulk, to effect more than slight fusion of the immediate borders of the invaded anor- thosite. Another important fact is that, in the field, the Keene gneiss by no means universally forms a narrow zone or belt with syenite- granite directly adjacent on one side and anorthosite on the other. A fine case in point is the eastern part of the Sunrise notch area where the Keene gneiss for 1% miles lies between granitic syenite on one side and syenite on the other. A different case is the Oak ridge area which is bordered on the south by Whiteface anortho- site, and on the north by Grenville, Marcy anorthosite and syenite. How can areas of this sort possibly be explained by Bowen's hypothesis, which assumes that the anorthosite was never an active magma but that it was formed by sinking of plagioclase crystals with the development of a transition rock (called Keene gneiss in this bulletin) occupying a position distinctly intermediate between the syenite-granite and the anorthosite? Is it not much more in harmony with the field relations to conceive that Keene gneiss magma was produced by assimilation at a lower level and then rose to invade previously formed Grenville and anorthosite, or moved upward flanked on either side by syenite or granite? Also are not elliptical areas like those just east of Upper Jay and 1% miles west of East Kilns much more satisfactorily accounted for by the latter hypothesis than by Bowen’s hypothesis? Again, do not the inclusions of anorthosite in the Keene gneiss (see above descriptions) strongly support the writer’s view that the Keene gneiss, in some places at least, moved upward as a true magma? Finally, it should be noted that the Keene gneiss accompanies both the Marcy and the Whiteface types of anorthosite, being about as common with one as with the other. Within the Lake Placid quadrangle, then, the temperature relations between the syenite- granite and Marcy anorthosite on the one hand, and the Whiteface anorthosite on the other, do not seem to have been notably different during the syenite-granite intrusion. The presence or absence of the Keene gneiss appears to be irrespective of whether the syenite- granite borders the Marcy or the Whiteface anorthosite. Comparison with Cushing’s southwestern Franklin county basic syenite. In Cushing’s report on the geology of the Long Lake quadrangle, he describes a basic phase of the syenite which grades into a rather fine-grained, even granular, gneissoid rock with few feldspar phenocrysts, and dark minerals often equaling or 52 NEW YORK STATE MUSEUM exceeding the feldspar in quantity. Some of the feldspar is micro- perthite and some oligoclase-andesine. “‘ The most of the basic syenite, and all of the more gabbroic of it, is in close association with the anorthosite border. . . . Now the syenite is unques- tionably younger than the anorthosite, and the observed relations seem to point to the conclusion that the change (in the syenite) is due to the actual digestion, by the molten syenite, of material from the (anorthosite) gabbro.”* The Keene gneiss of the Lake Placid region differs in being coarser grained, distinctly porphyritic, and not so rich in dark minerals, but both Cushing’s basic syenite and the Keene gneiss are intermediate in position and composition between the anorthosite and the syenite-granite series in their respective regions, and the writer believes that Cushing’s suggested explanation is the correct one. Another rock, earlier described by Cushing? from a railroad cut nearly 5 miles north of Tupper Lake Junction, is regarded by him as intermediate between the syenite and the anorthosite. Judging by the description, this rock is, in almost all respects, similar to the typical Keene gneiss except that the labradorite phenocrysts are not so large. This work of Cushing, therefore, strongly supports the idea that the Keene gneiss is a magmatic assimilation product. Mixed Rocks Grenville or amphibolite and Whiteface anorthosite mixed gneisses. Under this caption there are described several areas in which Grenville rocks and probably some ortho-amphibolite have been cut to pieces by, and are more or less intimately associated with, the Whiteface type of anorthosite. In some places the Gren- ville or amphibolite predominates, and in others the anorthosite, but the two rocks are too closely associated to be satisfactorily separated on the geologic map. During the writer’s recent survey of the Lyon Mountain quadrangle next to the north much gabbro-amphibolite older than the syenite-granite and probably older than the anorthosite was encountered. Quite likely then at least some of the amphibolite of the Lake Placid quadrangle is to be placed in the same category. The largest area, over 3 miles long, lies between Keene and Upper Jay. It is traversed by the East Branch Ausable river. For most part, the rocks of this area are Grenville hornblende gneiss TNE YM. State) Mus Bulkeris ss par47osoo7. “N.Y. State Mus, Rept 545 t:r43and 168. 1902: GEOLOGY OF THE LAKE PLACID QUADRANGLE 53 and pyroxene gneiss which have been cut to pieces by intrusions of Whiteface anorthosite, the Grenville and the anorthosite nearly always being clearly recognizable as such. Very distinct small inclusions of Grenville gneiss in the anorthosite’ were noted in various ledges, particularly along the road between 1 and 2 miles south of Upper Jay; by the road 144 miles southwest of Upper Jay; and 2% miles due north of Keene in the western corner of the large area. Another type of mixed gneiss from the above-mentioned area is of particular interest. This rock shows in good outcrops west of the river between 2 and 3 miles north of Keene; in the quarry by the road 314 miles north of Keene; and by, or close to, the road between one-half and three-fourths of a mile north of the quarry (see map). The best place to study this rock is in and around the quarry. In the quarry the rocks are Grenville hornblende and pyroxene gneisses, more or less intimately involved with White- face anorthosite. Much of the rock is a true injection gneiss, the Grenville gneiss having been so intimately penetrated by the anor- thosite magma that the small hornblende and pyroxene crystals were mostly separated from each other and enveloped in the molten mass parallel to the magmatic currents, thus giving to the resulting gray, medium-grained rock a clearly defined foliation. Some por- tions of this rock are richer in dark minerals than others, and some portions show lenselike masses or bunches of dark minerals as dis- tinct inclusions I or 2 inches long which were enveloped in the magma without being broken up. This rock contains occasional light bluish gray labradorite crystals up to an inch in length, and numerous tiny grains of titanite. A thin section of this injection gneiss reveals the following mineral percentages: andesine to labra- dorite feldspar, 58; green monoclinic pyroxene, 30; green horn- blende, 10; titanite, 114; biotite in tiny flakes, 12; and very little zircon. Another slide is similar, but it has several per cent of quartz in one narrow band. Locally, where the anorthosite greatly predominates, the rock is much coarser grained and the dark minerals are more irregularly arranged so that the foliation is not ° so pronounced. It is very evident that Grenville gneiss has here been more or less intimately injected by Whiteface anorthosite magma, but there is no indication whatever of actual digestion or assimilation of the Grenville by the magma, the crystals and frag- ments of the Grenville always showing sharp contacts against the enveloping anorthosite. 54 NEW YORK STATE MUSEUM In the small area one-half of a mile east of Keene, the Grenville gneiss occurs as bands or inclusions in the anorthosite. The area 2 miles long on the southern end of Wilmington moun- tain shows mostly Whiteface anorthosite, but nearly every outcrop contains so many inclusions of Grenville, chiefly green pyroxene gneiss, that it has seemed advisable to map this as an area of mixed rocks. Injection gneisses like those just described above were not noted. The small area just to the north contains similar rock. Along the road just east of Franklin Falls there are some instruc- tive ledges of Grenville and Whiteface anorthosite mixed gneisses. One phase of this rock is white, medium-grained Whiteface anor- thosite (practically all andesine to labradorite) containing approxi- mately 20 per cent of irregular lenslike masses and bunches of dark monoclinic pyroxene crystals, these masses ranging in size from mere specks to an inch or two long and roughly parallel, causing the rock to have a crude foliated structure. A thin section shows a little ilmenite and apatite. Closely associated with this rock is a true injection gneiss which is gray, medium grained and clearly foliated. In thin section it reveals the following mineral percent- ages: andesine to labradorite, 82; hornblende, 9; green and color- less monoclinic pyroxene, 7%; biotite, 1; and ilmenite, %. Stilt another phase of the rock from the same ledge is very similar in . mineral composition to the last phase described, but it is finer grained and contains several per cent of pale-red garnets in small, scattering grains. It is very evident that this rock, with its several facies, is a border phase of the considerable body of Grenville just to the east (see map) where it has been penetrated more or less intimately by the Whiteface anorthosite magma. The small area bordering the Grenville one-half of a mile north of Franklin Falls has a big ledge of gray, medium-grained, well- foliated injection gneiss, similar to those above described, with scattering light bluish gray labradorites up to nearly an inch long. By the road 1% miles north-northeast of Franklin Falls a single outcrop exhibits streaks and narrow bands of Grenville rusty biotite gneiss closely involved with Whiteface anorthosite parallel to the foliation of both. At the edge of the quadrangle just east of Silver lake good exposures show dark Grenville gneisses all shot through by White- face anorthosite. Along the border between the Whiteface anorthosite and dark Grenville gneiss east of the gabbro at the southern base of Cata- mount mountain, the anorthosite contains streaks and bands of the ‘aseqeip JO oYIp oy} uodn oly, S1owlUeY possor) ‘o}TULIS Aq Jo opsoyJoue dovFoyIY\\ ApJSoU st Yor oy], ‘presses suryoo'y ‘ooo y FO YIos oI v JO Jyey-ouo ‘JOATI apqesny oy} JO Youesrq isey oy} Jo 28103 oy} Jo pua saddn oy} Ur MoIA 916 ‘OJoyd ‘uosuyor “AM “Cd GEOLOGY OF THE LAKE PLACID QUADRANGLE 55 Grenville due to cutting to pieces of the Grenville by the anor- thosite magma along the border. This rock is not separately repre- sented on the geologic map. In the area of Whiteface anorthosite along the river west of Malcom pond several ledges exhibit Grenville closely involved with the anorthosite. Grenville or amphibolite and syenite-granite mixed gneisses. In five areas shown on the map, the Grenville or amphibolite and syenite or granite are so closely associated that the delimitation of these rocks was not found to be practicable. The area bordering Lake Placid on the east shows, along the lake shore, some ledges of pink granitic syenite with many long, narrow inclusions of dark hornblende gneiss roughly parallel to the foliation. Toward the interior of the area, there are some outcrops of nearly pure granite syenite, and others which are very gneissoid, rather basic looking, almost banded syenitic rocks which have resulted from more or less fusion of layers of dark gneiss by the syenitic or granitic magma. In some of these ledges there exist rather well-defined bands or layers of dark gneiss not over a foot thick where fusion has not been so effective. At the map edge southwest of Keene, the area of mixed gneiss seems to show a predominance of syenite, but there are a good many outcrops of light and dark-gray Grenville gneisses. In some exposures the syenite and Grenville are rather closely associated, but, as a rule, the relationships of the rocks are not well exhibited. One mile northeast of Keene the small area of mixed gneisses well exhibits intimately associated Grenville light and dark gneisses and syenite. Streaks and bands of Grenville are in some places more or less fused in. In the area 2 miles a little west of north of Keene, syenite pre- dominates, but considerable quantities of Grenville are involved with it, often having been more or less fused in. On top of the hill there seems to be a little Whiteface anorthosite as bands or inclu- sions parallel to foliation of the syenite. The whole hill north of Cranberry pond is a mixture of fine to medium-grained, gneissoid, pink granite and hornblende gneiss, sometimes one and sometimes the other predominating. The horn- blende gneiss (or amphibolite) occurs as bands in the granite par- allel to the foliation. This dark gneiss is either Grenville or meta- gabbro, probably the latter. Whiteface anorthosite and syenite-granite mixed gneisses. Four areas of mixed rocks of this sort are shown on the geologic 56 NEW YORK STATE MUSEUM map. ‘They represent masses of Whiteface anorthosite which have been more or less shot through, and cut to pieces, by syenite or granite. Individual outcrops within these areas are usually either good anorthosite or good syenite or granite, but they are too much involved to be separately mapped. The largest area, extending from 1 to 3 miles east of Wilmington notch, is quite typical. There are many outcrops of clearly recog- nizable Whiteface anorthosite and of syenite with contacts visible at several places. Such contacts as, for example, on the ridge at the northwestern border of the area, are usually not perfectly sharp as though some fusion of the anorthosite by the syenite magma took place along the immediate borders between the two rocks. Actual fusion on a considerable scale did take place on the eastern side of the area as shown by the small body of assimilation rock (Keene gneiss) on the map. This whole area is a fine illustration of a mass (about 1% square miles) of Whiteface anorthosite cut through by many intrusions of syenite of considerable size, but where apparently the temperature of one or the other, or both, of the rocks was not high enough to permit more than slight fusion of the anorthosite along the contacts. The long, narrow area traversed by the river between High fall and The Flume contains a number of interesting exposures along the river. The Whiteface anorthosite has been badly cut through by intrusions of syenite, such phenomena being well exhibited in ledges by the river within one-third of a mile east of High fall. Small inclusions of Whiteface anorthosite in the syenite and par- allel to its foliation occur in a ledge by the river one-half of a mile southwest of The Flume. An 8-foot boulder of syenite near the base of Little High fall, one-third of a mile east of High fall, con- tains several distinct inclusions of Whiteface anorthosite without very sharp contacts against the syenite. The little area near the eastern end of Wilmington notch con- tains mostly good syenite with considerable Whiteface anortho- site as bandlike inclusions through it. In the gorge of the river one-half of a mile south of Keene, there are excellent outcrops of Whiteface anorthosite cut by a consider- able mass of coarse, rather porphyritic granite, with small tongues of the granite extending into the anorthosite. The anorthosite is the quite normal Whiteface type and clearly gneissoid. The granite is pinkish brown, gneissoid, and medium grained with scattering phenocrysts of feldspar. Much of the mixed rock here is badly broken up due to crushing in a fault zone (see plate 21). These Plate 16 waren xe W. J. Miller, photo, 1915 The gorge of the East branch, Ausable river, one-third of a mile south of Keene. Looking south upstream. The rock is mostly Whiteface anorthosite. GEOLOGY OF THE LAKE PLACID QUADRANGLE 57 crushed rocks are notably granulated, and in thin section the crushed granite shows very interesting examples of sliced and granulated quartz (see plate 12). Gabbro-diorite Dikes These very interesting dikes show considerable variation in mineralogical composition, but all of them may be classed as ortho- clase gabbro-diorites. No rocks of this sort have ever been observed by the writer elsewhere in the Adirondack region. Alto- gether ten or twelve dikes were found, eight or nine on Catamount mountain, and two on the mountain 1%4 miles north-northeast of East Kilns. These dikes are certainly younger than the coarse granite of the syenite-granite series, and older than the diabase, and some, at least, of the pegmatite, dikes. Whether they are older or younger than the gabbro stocks could not be determined. Five or six of these dikes at or near the summit of Catamount very clearly cut the great bare ledges of granite for distances up to one-fourth of a mile. They vary in width from 2 to 30 feet, those toward the very summit all being over 20 feet wide. The strike of the dikes is roughly parallel to the foliation of the granite but it varies from N 10° E to N s0° E, the latter being the strike of the large dike which lies just below the summit and reaches one-fourth of the way down the mountain. The dikes are badly weathered (much more so than the granite) to brownish gray, so it is impos- sible to obtain good specimens of fresh rock. Contacts against the granite are rather sharp, and the dikes stand in practically vertical position. Two wide dikes just below the summit are weathered and eroded out leaving clear-cut trenches in the granite, these trenches being visible from the base of the mountain. All the rock is somewhat gneissoid, but the larger dikes are usually clearly finer grained and more gneissoid to almost schistoid at the borders. The most common facies of the dike rock is tine to medium even grained with mineralogical composition shown by no. 57 of table 4. Another facies is almost medium, even grained, and looks something like a basic phase of the syenite. Its mineral content is given as no. 56 of table 4. Least common is a fine-grained facies with scattering flakes of biotite each several millimeters across. Its mineral con- tent is shown by no. 59 of table 4. As already stated, it was not positively determined whether the small aplite dikes in the immedi- 58 NEW YORK STATE MUSEUM ate vicinity are younger or older than the gabbro-diorite dikes but, since the aplites are more strictly parallel to the foliation of the granite and not so sharply separated from it, it is probable that they are the older. Since the granite is only moderately foliated and the aplite not at all, it seems evident that the foliation of the gabbro-diorite dikes, especially near the borders, is the result of magmatic flowage rather than of regional pressure. At the top of the ridge one-half of a mile northeast of the summit - of Catamount mountain, there are three more of the gabbro-diorite dikes. The middle one is fully 40 feet wide and distinctly gneis- soid. All three strike about N 20° E. A diabase dike 3% feet wide, and a pegmatite dike 3 feet wide, each cuts obliquely across the largest of the gabbro-diorite dikes. On the mountain 1% miles north-northwest of East Kilns, two more gabbro-diorite dikes, presumably of the same age as those above described, show good contacts against the coarse granite. Each dike is about one-third of a mile long. The larger one is fully 100 yards wide, and the other is much narrower, being reduced to a width of only 1 foot at the western end where it very sharply cuts the granite. Fresh rock from the larger dike is dark greenish gray, and it weathers to a brownish gray. It is fine to medium grained and moderately gneissoid. It looks very much like a very basic facies of syenite, but its high content of albite and pyroxene (see no. 58 of table 4) makes it distinctly different. It differs from the Catamount gabbro-diorite pe its high percentage of monoclinic pyroxene. Table 4. Thin sections of gabbro-diorite oO o = 5 zs © a a o% £ | 8 4 af @ [esol oe ely Ge &| 3 S aai|a|s|e] 2 2 2 2 a rahe a 3 e S S| a 1s ise 5S Fe = E Me} S| is q = oF raf SI pe) a) = 9 zy 3 es a 5 SO Ae Sh 8 2 E a = a fea = || Oo ay = A | a | a ee oa) a < N 56]15¢5a] 50 OANA AR Hosnscclleasallocc. ra) 12 I 1} 3 | little 59 |15g@5b]. 18 y allo pyee el [lie ofl leoyrcra | Iioves 24 (o) 4 14 LHe Kedah eee Sop || seis ep Aball acts} |) in} PAU sasT77 een | peepee 4 Yel lig MO lis gin a I 2 pve Pectin SOauzukces | 10 Alb. 50 28 6 2 I 2 1} 5 a Nos. 56, 59 and 57, from the top of Catamount mountain; no. 58, from top of mountain 1% miles north-northwest of East Kilns. ‘SeoyJNOS SUIyYOOT ‘aUIay, FO Yjnos QyIl B JO F[VYy-auo ‘TIAIT s[qesny ‘YourIq jsey oY} JO Poq oY} UTSassToUS PoXTlU o}1UvIS PUL d}ISOYJIOUL DIVYA 916— ‘ojoyd ‘uosuyof “M ‘a ZI 93eIqg 4) ee GEOLOGY OF THE LAKE PLACID QUADRANGLE 59 Gabbro and Metagabbro Seven gabbro masses are represented on the accompanying geo- logic map. These are in most respects quite like the usual gabbro of this age throughout the Adirondacks. A rather full account of the typical gabbro is given in the writer’s State Museum report on “The Geology of the North Creek Quadrangle.” Most of the gab- bro masses of the Lake Placid quadrangle appear to occur as true stocks rather than as dikes. No tongues or branches from them were observed to extend into the country rocks. The stocks all have rounded or elliptical ground plans, and range in size from one-eighth of a mile across to 1 mile across. Most of the gabbro bodies are certainly intrusive into, and therefore, younger than, the syenite-granite series, but, judging by experience in the Lyon Moun- tain quadrangle some may be older than the syenite-granite. They are clearly older than the diabase dikes. Whether they are older or younger than the gabbro-diorite dikes above described could not be positively determined, but they are probably younger. The gabbro bodies nearly all consist of nongneissoid interior facies with more or less well-developed diabasic texture, and very gneissoid (amphibolitic) border facies without diabasic texture. The nongneissoid diabasic textured gabbro is generally easily dis- tinguished from the other Adirondack rocks, but the amphibolitic border facies often greatly resemble certain of the Grenville horn- blende gneisses. The fresh rock is dark gray, which, on weathering changes to deep brown. Most of the rock is medium grained. About equal amounts of plagioclase (chiefly labradorite) and dark minerals make up the main bulk of the rock. Portions or all of the labra- dorite crystals are often filled with tiny dark specks of some unknown mineral arranged parallel to the twinning bands. Most prominent of the dark minerals are monoclinic pyroxene, hyper- sthene and hornblende. Garnet seldom fails, and it often consti- tutes 10 or 15 per cent of the rock. The pyroxene and garnet are commonly much granulated, the crushed garnet generally either forming rims around feldspar or granulated pyroxene, or borders between feldspar and granulated pyroxene. Olivine occurs in at least two of the masses, this mineral being rather uncommon in Adirondack gabbros. Slide 52 of table 5 shows olivine with suc- cessive rims of granulated hypersthene, feldspar and garnet (see lower right figure of plate 18). Table 5 gives the mineralogical compositions of several typical gabbro bodies. 60 NEW YORK STATE MUSEUM Table 5 Thin sections of gabbro Oo o (| ~P g 2 ° a ok Slept 3 ae 3 ie 86 o S| oO ABW Siw a j| aS 23 ® Ss Re} 8 a i | el |S 2 2) aac » 2 I Y ag} bp S| = | & | a | & 3 q 5 = Bey 9 eo a Sy EE aap is |e a | & 5 & | 8 a ca ay =} S) i) el |) Sl tae |} a Oo | t= Ay < N 26 5 cL O].—Lab. 50 Bi [ha scd ame a2 OP || eeuete)| 25a [aaa I I | little 3 | little 53 4c9 | An.—Lab. 50 HF) We oaal) LA |loncal| 2S || lore Io Gy || RE oso cblleacas 54 4c3 |An.—Lab. 50 Giilooe nll a2) Ne oooll || litle Whig a oc » 14 | little | little |..... 52 | 4ma2 | An.—Lab. 50 20 SH cues [aes I a> LA! I WE loaocn cllacdos 55 | 14¢2 Lab. 50 H@ loool i677 I 7 4 TOPs little. |e, eee tereraees Nos. 26, 53 and 54, from Pulpit mountain gabbro mass; no. 52, from southern side of gabbro 2%4 miles south-southeast of Upper Jay; no. 55, from gabbro at southern base of Catamount mountain. Most of the Pulpit mountain gabbro mass is gneissoid, only a relatively small portion of the interior being nonfoliated and with a diabasic texture. Nos. 26, 53 and 54 of table 5 are from this stock. The largest body, from 2 to 214 miles south-southeast of Upper Jay, lies only partly within the limits of the quadrangle. Most of the rock is medium to moderately coarse grained with good dia- basic texture, and a gneissoid border facies is more or less well developed. It is an olivine gabbro (see no. 52 of table 5). A small diabase dike, with nearly north-south strike and dip 60 degrees east, sharply cuts the gabbro near the southern margin. A small diabase dike sharply cuts the small gabbro mass 1 mile west of East Kilns. The other gabbro masses are quite typical in every way. The gabbro at the southern base of Catamount mountain clearly exhibits its relations to Whiteface anorthosite, Keene gneiss, and granite, all three of which it sharply cuts. Diabase Dikes General features. Without counting two or more dikes close together within practically single outcrops, sixty-one diabase dikes were found within the quadrangle. These are all located and num- bered on the accompanying geologic map. Without question still others exist, but they are either effectually concealed or they escaped detection in the rough wooded country. Such diabase dikes are known to occur throughout the Adirondack region. They are the youngest of the Precambrian rocks, and they always sharply Plate 18 Photomicrographs by W. J. Miller Upper left figure. Part of slice of gabbro from dike no. 5, one-half of a mile south-southwest of Owen pond. Shows very fine diabasic texture. Toward top, a large phenocryst of olivine with a thin rim of magnetite or ilmenite. Dark gray angular patches, brown augite; black patches, magnetite or ilmenite; white material, plagioclase. Ordinary light. Magnified 23 diameters. Upper right figure. Part of slice of diabase from quarry at southern base of Hamlin mountain. Toward top, augite phenocryst with inclusions black patches) of pyrite. White laths are labradorite crystals embedded in a black glassy groundmass. Ordinary light. Magnified 30 diameters. Lower left figure. Part of slice of diabase from dike at south end of gorge one-half of a mile south of Keene. Toward upper right, a large idiomorphic phenocryst of olivine with a thin magnetite or ilmenite rim and much decomposed to chlorite. On left, a large idiomorphic phenocryst of augite with zonal structure. Dark laths, biotite; black specks, magnetite or ilmenite; white material of matrix, plagioclase. Ordinary light. Magnified 23 diameters. Lower right figure. Part of slice of gabbro from southern side of stock, 214 miles south-southeast of Upper Jay. Toward top, two large rounded grains of olivine (with black streaks of secondary magnetite) surrounded by successive rims of granulated hypersthene, plagioclase, and garnet. Dark patches, hornblende. Part of large labradorite crystal at bottom, Ord'nary light. Magnified 23 diameters. ” GEOLOGY OF THE LAKE PLACID QUADRANGLE 61 cut all the other types of Adirondack rocks as narrow bands of slight areal extent. They are wholly nonmetamorphosed. The fresh rock is dark bluish gray and generally fine grained, though a few of the larger dikes are medium grained toward the middle. Many of the dikes are distinctly finer grained toward their margins. A glassy groundmass occurs in a few cases. Many of the rocks contain small phenocrysts of augite or olivine, or both, and a few contain phenocrysts of plagioclase feldspar. A good diabasic texture is often clearly discernible with the naked eye in the relatively coarser grained rocks, and with the microscope in the finer grained ones, though some of the dikes apparently fail alto- gether to exhibit this texture. In width most of the dikes range from less than an inch to 25 or 30 feet, and in length up to at least one-half of a mile. Most of the dikes show a general northeast-southwest strike, this being parallel to certain prominent structure (fracture) lines of the region. Some of the dikes strike nearly east-west, but not one was Table 6 Thin sections of. diabase ig 3 ; 2 ae 3 a S 5 | sae 53 2 i=} uo] o o ® oS) ‘ore a o ee 2 xs ~ =] ~ iD ¢ 53 A a= vo MS) 5 7) i ee) fe) tev) = 3) n 3 x £ 3 SS] = 2 fe S SS “’ a a, a ea 4 < Oo fe ©) = of O. ©) < 61 723 OSt eee it Mel Wastcseer Uae hetceeneat tic DOW er sienceaelltereeretectets 62 17j6 60 20 5 3 7 ARI rcsaceete ts TO (eee ctl eeenenit cians 63 IOmtr 60 ES iil eee onremes| ass cusaet| eel arshe Sil apaevaortcveal| fess tearcnene BOW lle ievsedlors 64 5fr 58 21 I 7 A |loosc oer (OM Wicicoteensl cress 0 8 65 2k14 65 T'S in | eeoeeSenus TOM Rene See He liGtle urs seen lin eye ots little 66 1k2 30 40 4 ZOU tac snciee Ova rev oreeioral | Peareesrciesst| fopeeet caren lege ceerene No. 61, dike no. 33, High fall of West Branch Ausable river; no. 62, dike no. 48, 1% miles southeast of Fremont hill; no. 63, dike no. 24, quarry at southern base of Hamlin mountain; no. 64, dike no. 5, one-half of a mile south-southwest of Owen pond; no. 65, dike no. 14, 1 mile north-northwest of Keene; no. 66, dike no. 9, one-half of a mile south of Keene in the gorge. observed to strike northwest-southeast. Many of the intrusions quite certainly took place along zones of faulting of excessive jointing, but tn some such cases, at least, renewed earth move- ments occurred after the intrusion of dike material because the dike rocks themselves, in such cases, are either brecciated or exces- sively jointed. As seen in table 6, the chief minerals are labradorite and augite. 62 NEW YORK STATE MUSEUM Special descriptions. No. 65 of table 6 is very typical of a medium-grained diabase without olivine from a dike 30 feet wide with fine-grained margins. The diabasic texture is plainly visible to the naked eye. Under the microscope the labradorite is seen to be in distinct laths, the biotite pale yellow to deep brown, and the augite pale brown with good cleavages. This rock is lighter gray than the usual diabase of the quadrangle. In the southern part of the gorge of the river one-half of a mile south of Keene, a dike (no. 9) fully 5 feet wide cuts the mixture of granite and anorthosite. It stands in a vertical position, is trace- able for fully 100 yards, and shows a fairly good columnar struc- ture. The rock is really an olivine basalt porphyry. It is repre- sented by no. 66 of table 6. Two generations of crystals are evi- dent, all of the olivine and some of the augite belonging to an earlier period of crystallization, these two minerals clearly standing out as phenocrysts (black and pale yellowish green respectively ) up to nearly a centimeter across. The groundmass is very fine grained, dull black, and without a diabasic texture. Under the microscope the olivine is colorless with crystal boundaries fairly well defined, and it shows some alteration to serpentine and hema- tite along the fractures. In thin section the augite is pale brown, mostly as rather idiomorphic crystals with good cleavages, and often with excellent zonal structures. The biotite is in the form of slender prisms with light to dark-brown pleochroism. The biotite evidently crystallized before the feldspar because the latter fills spaces between the biotite crystals. Much of the labradorite is in the form of small lath-shaped crystals. In the gorge of West Branch Ausable river at High fall, there are several dikes (probably branches of a single large one) sharply cutting the granite parallel to its jointing. They are traceable for fully 100 yards in the walls of the gorge, the largest dike being about 5 feet wide. Just above High fall one of the dikes is brec- ciated. No. 61 of table 6 gives its mineral content. The rock under the microscope, is seen to be badly decomposed, which accounts for the large amount of secondary calcite. On top of the ridge 1 mile east of Upper Jay there are seven or eight short dikes from 1 inch to 1 foot wide and roughly parallel, as indicated on the map. The largest is exposed for 75 feet. The middle ones are slightly faulted in a number of places. A dike 4 or 5 feet wide is beautifully exposed at the lower end of The Flume where it cuts the Whiteface anorthosite vertically. It contains some inclusions of the anorthosite. GEOLOGY OF THE LAKE PLACID QUADRANGLE 63 About one-half of a mile northeast of the summit of Catamount mountain, a diabase dike 3% feet wide sharply cuts the largest gabbro-diorite dike obliquely and the granite parallel to its folia- tion. A few rods farther east there are five dikes, none over a few feet wide, and roughly parallel. Near the summit of Catamount, a dike (no. 52) 6 feet wide may be clearly seen cutting the granite for several hundred feet. This may be a continuation of the large dike (no. 51) one-half of a mile to the northeast. On the mountain top 14 miles northeast of Catamount summit, there are several dikes from 2 to 6 feet wide, nearly parallel, and close together. Dikes nos. 13 and 53, each about a foot wide, sharply cut gabbro stocks. Dikes nos. 3, 30 and 35 show various branches or tongues extend- ing into the country rocks. No. 3 is in contact with a pegmatite dike, and it is considerably brecciated due to faulting. Dike no. 55, one-half of a mile north of Franklin Falls, is 2 feet wide. It contains fresh labradorite crystals as phenocrysts up to an inch long with very evident twinning bands. Very instructive dikes may be seen at locality no. 28 where sev- eral dikes (one 10 feet wide) sharply cut Whiteface anorthosite. There were very plainly two injections of diabase magma here. The earlier injected mass was the larger, and it solidified into a dark bluish gray rock with a very fine-grained diabasic texture. The second injected masses are only a few inches wide, in sharp con- tact with the first; black and almost glassy with very small pheno- crysts of labradorite whose long axes are approximately parallel thus causing this second intrusive to have a fairly good flow-struc- ture. A similar combination of diabase cutting diabase was observed in a glacial boulder 1 mile southeast of Wilmington. Dike no. 42 (see no. 63 of table 6) is only 4 inches wide, but it exhibits a very fine diabasic texture in the middle portion, and black glass at the margins. At locality no. 18 several dikes from 5 inches to over 5 feet wide are close together and sharply cut Grenville quartzite. In the old limestone quarry at dike locality no. 16, a good diabase dike with several small branches sharply cuts the limestone. The Rocks of Catamount Mountain A remarkable assemblage of rocks occurs within an area of less than 1 square mile, including the summit and southern base of 64 NEW YORK STATE MUSEUM Catamount. Fully fourteen kinds of rocks are represented, most of them having been formed at different times. Oldest of all are the Grenville hornblende gneiss and crystalline limestone well shown in, and just west of, the quarry at the base of the mountain. In contact with this Grenville gneiss there are good outcrops of typical Whiteface anorthosite. On the southeastern slope of the mountain, syenite grades into granitic syenite, and this, in turn, into coarse granite. A narrow band of Keene gneiss, formed by assimilation of anorthosite by the granite magma, lies between the granite and anorthosite near the southern base of the mountain. Numerous small aplite dikes cut the granite parallel to the foliation toward the top of the mountain. In the vicinity of the aplite dikes, quartz veins lie across the foliation of the granite. Dikes of gabbro-diorite cut the granite roughly parallel to its foliation at and near the summit, and one-half of a mile to the northeast. A small stock of typical gabbro cuts anorthosite, Keene gneiss and granite near the base of the mountain. A diabase dike 6 feet wide sharply cuts the granite just. south of the summit. A diabase dike and a small pegmatite dike cut obliquely across the larger of the gabbro- diorite dikes one-half of a mile northeast of the summit, Glacial - deposits are extensively developed around the foot of the mountain. SHURE TURAL, (Gi OQLOG Ww Tilting and Folding of the Grenville Series It has been generally assumed that the Adirondack Grenville strata have been severely compressed and folded as well as thor- oughly metamorphosed and foliated by the compression. Recently, however, the writer has presented strong evidence! that the Gren- ville strata have neither been highly folded nor severely com- pressed, while many broad belts of Grenville are known to be prac- tically undisturbed or only very moderately folded, and many masses, large and small, are merely tilted or domed at various angles. Very locally the strata are sometimes contorted. Paral- lelism of Grenville and syenite-granite rock belts is common with a general tendency toward northeast-southwest strike, but there are so many notable exceptions (some, for example, in the Lake Placid quadrangle) that any generalization, regarding such a strike of the rock belts as due to severe lateral compression, is of little signifi- cance. 1 Jour. Geol., 24:588-96. 1916. ‘ay1ueis Ae13 ysryuid osivoo Ayjsow st UleyuNOU ay} JO YOOI oy, “A1jUNOD Surpunosins AjJoJeIpswtut oy} oAoqe JO9} OOSI A][N}F sastx (Goof QOIe opnynye) ureyuNoU sy, ‘SUPP IS9A\ WoIF Jsvoyjsou Suryoo] ‘U1e}UNOW jJUNOWe}L) 916r ‘oJoyd “JOTITIN “£ ‘MA 61 93e1d 66 NEW YORK STATE MUSEUM preserved. Parallelism of Grenville foliation and _ stratification appears to be universal. The Grenville has, for a long time, been regarded as essentially a result of severe regional compression after the great igneous intrusions had taken place. Recently, however, the writer has seriously questioned this view. If the Grenville and accompanying great intrusives had been sub- jected to compression severe enough to develop the foliation, is it not remarkable that the stratification surfaces have never been obliterated and cleavage developed instead, and also that stratifica- tion and foliation are always parallel? Also, unless we assume intense isoclinal folding, so that mineral elongation could every- where have taken place essentially at right angles to the direction of lateral pressure, the parallelism of stratification and foliation can not be accounted for by crystallization under severe lateral pressure. But the Grenville strata were never highly folded. We are thus forced to the only alternative conclusion, namely, that the Grenville foliation was developed during the crystallization of essentially horizontal strata under a heavy load of overlying material, or, in other words, under conditions of static metamorphism. Those minerals which cause the foliation were elongated during crystal- lization under the heavy load of overlying material. According to this view, the parallelism of foliation and stratification is pre- cisely what would be expected. This also explains the important fact that the Grenville rocks are notably less foliated and granu- lated than the great intrusives, particularly the syenite-granite series. Foliation of the anorthosite and syenite-granite series.” By far most of the great intrusive rocks exhibit more or less well-developed foliation, ranging from very faintly gneissoid to very distinctly gneissoid, the structure usually being accentuated by the roughly parallel arrangement of the dark-colored minerals. Some masses, particularly of the Marcy anorthosite, are practically devoid of foliation. Granulation of minerals, especially feldspar, is common, the more highly foliated rocks generally being most granulated. The writer considers these intrusives to be so-called “ primary gneisses’ whose foliation was developed as a sort of magmatic flow-structure under moderate compression rather than by severe lateral pressure brought to bear upon them after the cooling of the magmas. * Jour. Geol., 24:596-600. 1916. _2For a rather full treatment of this subject, see the writer’s paper in Jour. Geol., 24:600-16. 1016. GEOLOGY OF THE LAKE PLACID QUADRANGLE 67 A brief summary of the writer’s views may be stated as follows. During the processes of intrusion, which were long continued, the great magmatic masses were under only enough lateral pressure to control the general strike of the uprising magmas with conse- quent tendency toward parallel arrangement of intrusives and invaded Grenville masses; the foliation is essentially a flow-struc- ture produced by magmatic currents under moderate pressure dur- ing the intrusions; the sharp variations of strike on large and small scales, and rapid variations in degree of foliation, are essentially | the result of varying magmatic currents under differentiated pressure, principally during, a late stage of magma consolidation ; the almost universal, but varied, granulation of these rocks was produced mostly by movements in the partially solidified magma, and possibly to some extent by moderate pressure after complete consolidation; and the mineral flattening or elongation was caused by crystallization under differential pressure in the cooling magma. It would seem, therefore, that the general absence of foliation from so much of the Marcy anorthosite is best explained as the result of much more uniform intrusion of this single great body which was probably a stiffer or less fluid magma and which is less involved with Grenville masses, or, in other words, to much less forced differential flowage. Foliation of the gabbro and gabbro-diorite. As already stated, the interior portions of most of the gabbro bodies are nonfoliated and they possess a diabasic texture, while the outer portions are highly foliated rocks, often true amphibolites. In many places the degree of foliation varies considerably within single stocks. More or less granulation is very common. This foliation and granulation have been quite generally regarded as secondary features produced by severe regional compression. But it is very difficult to imagine a process of development of foliation, which boxes the compass around the borders of the gabbro masses, by regional compression. Such foliation often of course strikes directly across the foliation of the older adjacent rocks. If due essentially to regional com- pression of the solidified gabbro, should not the foliation every- where strike at least approximately at right angles to the direction of application of the pressure? Also how are such notable varia- tions in foliation and granulation to be explained ? According to the writer’s view, the foliation and granulation of the gabbro stocks are largely, if not wholly, primary features due to movements in the magma béfore final consolidation. Consider- able pressures must have obtained within the stock chambers while 68. NEW YORK STATE MUSEUM the magmas were being intruded under deep-seated conditions. Such pressure against the country rock, combined with the usual development of differential flowage, particularly in the magmatic borders, would readily account for the peripheral foliated zones which were produced, no doubt, during a late stage of magma con- solidation. But the conditions for magmatic pressure and flowage must often have varied considerably, and thus the local variations in degree of foliation and granulation are accounted for. The gabbro-diorite dikes are also more or less foliated, their borders particularly so. As in the gabbro stocks,’so here, the folia- tion is considered to have been due to differential magmatic flow- age under moderate pressure during a late stage of magma con- solidation. In these dikes, however, the foliation was developed parallel to the strike of the dikes because cross-sections of the magma chambers were long and narrow rather than rounded or elliptical as in the gabbro stocks. Faults General features. Faults are neither so numerous nor so promi- nently developed as is usually the case in the eastern and south- eastern Adirondack region. Within the Lake Placid quadrangle the faults are not sharply defined earth-fractures, but rather they are zones of excessive jointing in which more or less crushing and faulting of the rocks have taken place. These broken-rock zones are relatively straight for considerable distances, in some cases for some miles. It seems clear that such alignments of crushed-rock zones are due primarily to faulting, probably multiple faulting. The width of the fault zones is commonly from 25 to 100 feet or more. Most of them strike from northeast-southwest to north- south as usual in the eastern half of the Adirondack area. Because the rocks are broken up into numerous small blocks, the crushed zones form belts of weakness along which valleys (sometimes deep and narrow) have been developed. Little or. no positive evidence regarding the positions of. upthrow and downthrow sides could be obtained. Wilmington notch fault. This is the finest example of a shat- tered-rock zone definitely known within the quadrangle. Its length, as indicated on the geologic map, is about 5 miles. The deep, nar- row Wilmington notch, the gorge at High fall, and the gorge at The Flume, all owe their existence to rapid erosion along this prominent zone of weakness. In preglacial time the river did not ‘ouoz j[Ney & Ut SuTjUTOL DAISSaOxXa 0} ONP oINjonIJs LeUWINTODS spn4sd wv SMOYS YOTYM I}1UVAS ST YOOI YT “opsue ysty ve ye pavMdn poyurod sem viowed Of “Opis JSAM OY} UO JOATI DY} AOS JooF OOOE AT[NF OSIT YOIYM YJOU UO}SUTLUIAA OY} JO ST[VM snojydD91g 9TGI ojyoyd “1811 “£ MM oz 9381 GEOLOGY OF THE LAKE PLACID QUADRANGLE 69 flow through this deep, narrow valley, the site of the present Wil- mington notch having then been a division of drainage or col which has been cut through by the West Branch Ausable river, the latter having taken this course as a result of the glaciation of the region (see chapter on the pleistocene geology). In fact the position of the whole valley of the river between Mt Whiteface and the Sen- tinel range has been primarily determined by the presence of the great zone of weakness in the rocks. In the bed of the river three-fourths of a mile west-southwest of Owen pond, there is a big ledge of crushed rocks, especially pegmatite and diabase, which are distinctly brecciated. Some frag- ments of diabase have been mingled with the pegmatite. This zone strikes N 20° E. Along the river within the granite area in the notch, the rock is badly broken up in a wide zone parallel to the stream. Just northeast of this along the river, the Grenville gneiss is faulted with slickensides visible. At High fall the granite of the gorge is highly jointed, the joint surfaces being from one to several feet apart, forming a zone of weakness which has determined the stream course. The joints strike N 40° E and dip 65° E. Slickensided joint faces are com- mon. Just above High fall a diabase dike in the stream bed is brecciated, and close by is a distinctly slickensided scarp 4 feet high. At the so-called Little High fall, about one-half of a mile below High fall, there is a very prominent crushed zone as wide as the river bed with a strike N 30° E. In the river bed about half way between High fall and The Flume, there are two well-developed crushed-rock, or highly jointed, zones with strike parallel to the river. In The Flume the rock is considerably jointed, but just above the bridge there is an exces- sively jointed zone parallel to the course of the stream. Evidently the gorge development here has been greatly aided by the rock structure. Faults in the town of Keene. At the southern end of the gorge one-half of a mile south of Keene, the rocks are badly broken up and somewhat slickensided, indicating a prominent crushed-rock zone here with strike about east-northeast by west-southwest. By the roadside at the edge of the gorge, this fault zone is well exposed (see plate 21). The topography strongly suggests the continua- tion of this fault zone some distance northeastward as indicated on the map, but this is not verified by actual outcrops. By the roadside nearly 2 miles north of Keene, the Whiteface anorthosite and Grenville mixed rocks are much broken up, some- 7O NEW YORK STATE MUSEUM what slickensided, and considerably weathered. The strike of this crushed-rock zone is about north-south, but no other crushed rocks are exposed along this fault zone as mapped. The Grenville gneiss in the small gorge of Styles brook is excessively jointed, forming a zone of weakness with strike east- west or parallel to the stream course (see map). Tracing this zone eastward was impossible because of lack of outcrops. A fault zone of weakness has almost certainly determined the position of the deep, narrow valley between Pitchoff mountain and the southern end of the Sentinel range as indicated on the geologic map, though actual exposures of faulted or excessively jointed rocks are lacking at the critical localities. Other faults. Several nearly vertical faulted joints pass across the small quarry at the southern end of Lake Placid. They strike N 30° E and probably represent a fault zone which extends through the long, narrow, eastern portion of Lake Placid, but, if so, it is everywhere under water. The long, narrow, western side of the lake basin also strongly suggests its origin along a fault zone of weakness, but positive evidence is lacking. The group of diabase dikes about a mile east-northeast of Upper Jay are slightly faulted in a number of places. Possibly a fault zone has determined the position of the promi- nent valley which separates Catamount and Wilmington mountains, but positive evidence is entirely lacking because of heavy drift covering, and it is possible that simple removal of a large mass of relatively weak Grenville rock by erosion has caused this valley. The notch between Mt Whiteface and St Armand mountain suggests a development along a north-south fault zone, but out- crops in the notch do not appear to have been faulted. W. J. Miller, phcto, 1915 Crushed-rock zone due to faulting by the road, one-half a mile south of Keene GEOLOGY OF THE LAKE PLACID QUADRANGLE WA PERRIS TOCHNE GEOLOGY BY HAROLD L. ALLING INTRODUCTION In the detailed mapping of the quadrangles in the Adirondack region more attention has usually been given to the crystalline rocks than to the Pleistocene geology. The glacial phenomena, however, are clearly discernible and promise to add materially to the knowledge of the Pleistocene history of the State of New York when fully worked out. Besides the usual types of glacial deposits the Lake Placid quadrangle exhibits deltas, terraces and shore-line features of a succession of extinct glacial lakes whose history can be traced with a fair degree of accuracy. Unfortunately for con- cise description, the lakes were not confined entirely to the quad- rangle so it is necessary in many cases to examine adjacent topographic sheets in order to appreciate the extent and history of each during its initiation, life and extinction. Nevertheless only those lakes which formerly covered some portion of the Lake Placid quadrangle will be described. Although positive evidence of multiple glaciation in the Adiron- dacks is not, as yet, forthcoming, Prewisconsin glaciation in Penn- sylvania, New Jersey and on Long Island’ has been established so as to lead us to the conclusion that this area has been subjected to continental ice bodies more than once. In some of the stream valleys the depth of the drift is enormous and a difference in the character of different levels can often be detected. If evidence is to be found of Prewisconsin ice action in the Adirondacks, it is in such deposits. But as the surface deposits are chiefly due to the last or Lauren- tian lobe of the Wisconsin ice, we shall confine ourselves to its effects. Wisconsin Glaciation Without much doubt the entire Adirondack region was com- pletely buried by the ice, which has been estimated to have been gooo to 12,000 feet in altitude over the central Adirondacks.? To this enormous load upon the land surface is attributed the well- observed phenomenon of deformation, to which we will return later. * Fairchild, H. L. Bul. Geol. Soc. Amer., 24:134. © ? Fairchi iId, H. L. Geol. Soc. Am. Bul., 24: 136. After Shackleton. SSE 72 NEW YORK STATE MUSEUM Movement Seventeen occurrences of glacial striae have been noted in the quadrangle; they are especially numerous beside the highways in the valley of the East branch of the Ausable river. The majority of them have been observed by Doctor Miller, who has indicated them upon the accompanying map. The striae in the valleys were made by the waning stages of the glacial lobes, for their direction has been influenced very largely by the topography of the country. The more general direction of the ice flow would be shown by striae on the mountain summits, but their records have been destroyed by weathering agencies. Nevertheless it can be stated that the ice that covered the quadrangle flowed southward with a slight deviation to the west. ; Table of Glacial Striae STRIAE . TOWNSHIP LOCATION OBSERVER reas 5 ooo oc 4+ mile north of Franklin Falls............. W. J. Miller Bramiclinieerseee 2? mile northeast of Franklin Falls......... W. J. Miller Black Brook....] 1 mile northwest of East Kilns............ H. L. Alling Wilmington..... 2 miles east of Wilmington............... W. J. Miller Wilmington..... 3 miles southeast of Wilmington........... J. F. Kemp UeIeiRa rai opera oes Southeast of Upper Jay......... 5 J. F. Kemp Wayescserecte sree 2 mile south of Upper Jay....... ae . J. Miller Wats wate eee 2 miles southwest of Upper Jay........... W. J. Miller KEEN a terce ene 22 mMilesmornbnor: WMeene ner arn aeeerae W. J. Miller ISGENGS Sood hasan) et saat morn Ot IKEEIO, so c5nnneconnaoos W. J. Miller Keenet asa cero: Tey TaMIKSS) TaVCHeEl A Chi IMINO, 555600000 ancecbo- W. J. Miller Keene nnenn soe sia aniles morthvon INecenenere ah ener H. L. Alling Keene sci. t t Ty miles northiot Keeneseereaceeeeeoe aeee H. L. Alling Keene..........]| 1+ miles north northwest of Keene......... W. J. Miller WKGGn eink reps acces ti miles northeast of Keene.............. W. J. Miller J. Miller KEG cists ace 1 mile southwest of Keene................ W. Erosional Work The residual soil resulting from weathering during interglacial periods was completely removed by the ice, the mountains smoothed and their contours subdued. The extent of ice action is recorded in the comparatively fresh condition of the rocks on exposed ledges, as is shown on the bare slopes of Pitchoff mountain, on the southern edge of the map. The many amphitheaters and little rocky pockets on the moun- tainsides are due, in all probability, to the erosive action of the ice. These cirques have been attributed to the combined work of the continental ice bodies and to local glaciers.1 They are visible on * Ogilvie, I. H. Glacial Phenomena in the Adirondacks, Jour. Geol., 10:406. 1902. Johnson, D. W. Date of Local Glaciation in the White, Adirondack, and Catskill Mountains, Geol. Soc. Amer. Bul. 28:543-52. 1917. GEOLOGY OF THE LAKE PLACID QUADRANGLE WS the slopes of Whiteface, Sentinel’ and especially Esther mountain. The origin of rocky pockets, now occupied by ponds, on the south- western slopes of some of the mountains is not clearly understood, but plucking action of the ice may be regarded as a contributing cause. In pushing through the major fault-line valleys, such as the Pitchoff “pass,” the Wilmington Notch, and also the Middle Kilns valley, the ice carried with it the talus material that had accumu- lated during interglacial periods, freshened out the valley walls and left U-shaped valleys, blocking both ends with crescent-shaped moraines as it retreated. The occurrence of glacial boulders is quite common, some of which appear to have been transported from great distances while others can be traced to parent ledges in the neighborhood. Rounded boulders of Potsdam quartzite have been noted all over the quad- rangle. Large irregular slabs of Potsdam sandstone and quartzite are encountered in some of the brook valleys where the drift is abnormally thick. To the north of the road running from Upper Jay to Wilmington, some 2 miles directly south of the latter, irregu- lar nonglaciated flagstones were encountered in such numbers as strongly to suggest that a ledge of the Potsdam existed here before the ice invasion broke it up. Similar occurrences in the Elizabeth- town” and Mt Marcy quadrangles,* together with outliers,* point to the conclusion that the Adirondacks were submerged in the Potsdam sea to a much greater extent than was formerly considered to be the case. Moraines There is but little true morainal material to be found in the Lake Placid quadrangle, for most of it has been modified by water ;° the movement of the ice during the maximum advance having evidently been too vigorous for deposition and the material that was deposited as the ice retreated having been sorted by the waters of the glacial lakes. The recessional moraines appear to be largely confined to the fault-line valleys, being formed by the ice-tongues as they with- drew from the narrow defiles. At the southern ends, in the broa¢ *Kemp, J. F. The Geology of the Lake Placid Region, N. Y. State ise Bul. 27; p. 2T * Rudemann, Rudolf, N. Y. State Mus. Bul. 138, p. 62. * Alling, H. L., Bul. Geol. Soc. Amer. 27 :650. *Miller, W. J., N. Y. State Mus. Bul. 182, p. 44. *Cushing, H. P., N. Y. State Mus. Bul. 115, p. 496. Ogilvie, I. H., Jour. Geol., 10:406. 74 NEW YORK STATE MUSEUM valleys, the rate of retreat was slow and moraines were formed; but in the narrow valleys the melting of an equal amount of ice would produce a much more rapid recession, giving but little oppor- tunity for the deposition of material. Again at the northeastern ends of the passes the ice-tongues paused long enough to deposit another series of moraines. ‘The damming of such valleys by recessional moraines has resulted in the Cascade lakes, located in the Mt Marcy sheet; and in Silver lake and Taylor pond on the northern edge of the Lake Placid quadrangle. A very striking example of morainal damming is Lake Placid, formed by the blockading of twa parallel (fault-line?) valleys which have been joined by valleys, producing the islands, thus forming a ladder-shaped body of water. In a depression in the dam Mirror lake now lies. Just south of Mirror lake Doctor Miller found, beside the road, an exposure 20 feet thick, which showed glacial till with large boulders in the upper half resting upon distinctly stratified sands.t. The writer would infer that dur- ing slight variations in the advance and retreat of the ice lobe, glacial debris was deposited on top of a glacial lake bottom (see page 83. Glacial Lake Upper Newman). A similar phenomenon is known in the Cobb’s hill kame-moraine at Rochester, N. Y. The preglacial drainage has been modified by glacial material of one kind or another in several localities. A good example was found south of the town of Keene in the East branch of the Ausable river. In this comparatively broad valley on the northern edge of the Mt Marcy sheet we note an unnamed hill, around the two sides of which the two highways leading to Keene Valley circle. To the west of this hill the present river rushes between steep walls of syenite and mixed rocks (southern edge of the Lake Placid quadrangle), experiencing rapids and ‘falls. It is clearly a post- glacial channel and is one of the beauty spots in the quadrangle. On the other side of this hill the preglacial channel is plainly per- ceptible, although now blocked by sands of a lateral delta.” Local Moraines; Local Glaciation The writer’s work in the central Adirondacks would lead him to suspect that local glaciers existed on the slopes of the higher moun- tains. This conclusion has been reached through the study of *Miller, W. J., Personal communication, Jan. 17, I917. ? Alling, H. L., Glacial Geology of the Mt Marcy Quadrangle, in The Geology of the Mt Marcy Quadrangle, Kemp, J. F., in preparation; N. Y. State Mus. Bul. ‘JadF OOQE Jnoqe JO UOeAIa UL WOIF YOU SuLyoo'T ‘UIeJUNOU ToyIsy Jo ado[s Jsvayj10u oy} UO onda oY} OJUT UMOP SsuULPOOT gI6k ‘ojoyd ‘uosuyor “A ZZ 9g | ‘SUO] OI ev JO SYJINojJ-d91Y J, ‘Joo} COOL Jnoqe opnyt ‘UreJUNOW ToyISy FO odoys jsvoyjs0U oy} UO oNbsTD UL oUTeIOW JeD07] 916 ‘ojoyd ‘uosuyor “MM — Li EPMO t oe ay: wt! €z 93e]q GEOLOGY OF THE LAKE PLACID QUADRANGLE 75 lateral moraines, usually modified and dissected by streams in the brook valleys, often of perplexing character, but suggesting local origin; and through the presence of poorly developed cirques, on the mountain slopes; and hanging tributary valleys. In 1916 the writer, under the leadership of D. W. Johnson, found in the incipient cirque on the eastern slope of Esther mountain (a portion of the Whiteface massif) a narrow ridge of debris at an altitude of about 3000 feet, some three-fourths of a mile in length. Its form is that of a glacial moraine rather than that of a landslide. This cirque valley slopes northeast, which offered a favorable opportunity for the continental ice to force a tongue into it and to deposit a recessional moraine; but this would have a crest declining south- west, while the moraine found has the opposite inclination. Fur- thermore the northeastern end points slightly toward the axis of the valley. The moraine is very well preserved and it is incon- ceivable that this ridge of unconsolidated material could have with- stood the destructive forces of the ice sheet. We must, therefore, conclude that local glaciation took place after the withdrawal of the main ice body from the region.* It is sometimes argued that if local glaciers occupied the cirque valleys, small terminal moraines should, in every case, be found at their lower extremities ; their absence being taken as evidence for dating such action before the continental ice invasion, which caused their destruction. The studies of de Martonne in the Alps and the Carpathians show that in regions now undergoing Alpine glacia- tion, where the complications of continental ice bodies are absent, local moraines are seldom prominent features, for the glacial streams destroy them. Thus as a rule only one or two moraines are found in every ten cases examined. It is reasonable to expect that local glaciation could not have been limited to the Catskill mountains (which is a region unlikely to support local glaciers) without the Adirondacks likewise experi- encing it; hence, since local glaciation has been established there,’ it lends weight to the above conclusion. *Johnson, D. W., Date of Local Glaciation in the White, Adirondack and Catskill Mountains. 29th Annual Meeting Geol. Soc. Amer., Bul. 28:545- 52.8 I917. * Rich, John L., Notes on the Physiography and Glacial Geology of the Northern Catskill Mountains, Am. Jour. Sci., 39:154. Feb. 1015. Local Glaciation in the Catskill Mountains, Jour. Geol. 14:113-21. 1906. Local Glaciation in the Catskill Mountains, Geol. Soc. Amer. Bul. 28:133 (abstract) 1917. 76 NEW YORK STATE MUSEUM Eskers are infrequent on this quadrangle, although a number have been located in the Mt Marcy, Ausable, Saranac.and St Regis sheets. The writer has seen within the present limits no glacial deposits as undoubted eskers, but Doctor Miller considers to be such an east-west ridge some 200 yards long and 30 to 50 feet high, observed by him, one-half of a mile directly east of the cross roads at Keene. Kames are likewise uncommon. In the vicinity of the south- western end of the Middle Kilns valley a number of irregular hills are strongly suggestive of kame topography. Outwash Plains Outwash plains can generally be distinguished from deltas and glacial lake bottoms by ice blocks, kettle holes, and the lack of shore- line features. Frequently, however, in the field such distinctions are difficult, if not impossible, to make unless accompanied by other positive evidence. Some of the sand plains in the quadrangle are rather perplexing and their origin may be complicated, although it is believed that the majority of them were formed in connection with the glacial lakes described here. Extinct Glacial Lakes Conditions Favorable for Glacial Lakes in the Region. A number of important factors were favorable for the formation of several series of local glacial lakes in the east central Adiron- dacks, and some of these bodies of water existed im the area cov- ered by this bulletin. Among the conditions we note: (1) north-~ ward-draining valleys, sloping toward and blocked by ice lobes; (2) the complete isolation of such valleys by mountain ranges; and (3) the presence of a huge ice ring that completely surrounded the highlands, impounding vast quantities of water. This area was situated close to the northeast rim of the ring. The large amount of available material for the formation of deltas, terraces and beaches, makes recognition possible. The cause of the great quantities of sand is discussed later on. A number of glacial lakes in the quadrangle have been noted in the past by Taylor,* although he did not attempt to separate and correlate the different levels, and by Kemp who has noted* two or * Taylor, F. B., Lake Adirondack, Amer, Geol., 19:392-66. June 1807. 7Kemp, J. F., Geology of the Lake Placid Region, New York State Muse Buls2ns palo: « GEOLOGY OF THE LAKE PLACID QUADRANGLE FG), three sets of deltas in the Keene valley. It has fallen to the writer to attack the problems of the glacial lakes of the east central Adirondacks, and to attempt to translate something of the wonder- ful history. In such pioneer work mistakes and faulty interpre- tations are apt to appear, for it is impossible to avoid errors. In dealing with the glacial lakes the writer has, for convenience, classified them into three sections: (1) the western section, that is, the region around Lake Placid, to the west of the Wilmington notch; (2) the eastern section, or the Keene valley division in the valley of the East branch of the Ausable river; and (3) the Eliza- bethtown valley group. The last section does not come under dis- cussion here. Upper series: western section. As the ice sheet began to wane, the highest peaks of the Adirondacks were the first to be uncovered, playing the role of islands in a sea of ice.* Slowly these islands became larger, surrounded by a growing accumulation of water impounded by the ice. These waters found escape over the ice to the south and eventually passed to Susquehanna drainage. This process of melting was continued until entire mountain ranges were exposed. The South Meadows lake. The highest definite level recog- nized by the writer in the Adirondacks, as shown by sand plains, terraces and beaches, is one ranging from 1940 to 2210 feet in altitude. When this level was first appreciated some hesitation was felt in describing it as glacial, for no shore-line features or outlets had been noted. It was considered as outwash plains formed by aggrading glacial streams that flowed from the melting ice, but as extended field work was undertaken these lake phenomena were discovered, or strongly suspected, and hence the true nature of the plains was established. The best development of the glacial deposits of this lake is in the northwest corner of the Mt Marcy sheet in the South Meadows country ; hence the name — South Meadows lake. As can be seen in figure 2, the writer conceives that it covered the southwest por- tion of the Lake Placid quadrangle and the corners of the adjacent sheets. The ice consisted of three lobes: one covered the greater portion of the Saranac sheet; the second lobe was fed through the narrow passes to the east and west of the Whiteface-Esther- Wilmington massif and covered the territory where Lake Placid Paccwi Gein le Nie Ne state Mins, Bulyr6oi pl. 11. 78 NEW YORK STATE MUSEUM ‘now lies; the third and the most eastern lobe, here considered, completely filled the valley of the East branch of the Ausable river and Keene valley. ICE SHEET NS GLACIAL LAKE SCALE OF MILES N SOUTH MERDOWS . ~ KEW: ; AANRC [PLACID oo EARLY OUTLET;<-’ 4 a MT i i U ‘ LATER OUTLET! Abul ter ' Fig. 2 The Glacial Lake succession in the Lake Placid quadrangle. Stage one. The South Meadows lake, altitude 1¢40 to 2210 feet. The South Meadows lake was of irregular shape, some 10 miles long and wide, containing a number of islands. Its outlet has not, as yet, been definitely established, but a very probable one is offered as follows. It begins at the swamp just south of Alford moun- tain in the Santanoni quadrangle, on the Essex-Franklin county boundary line (altitude 2105% feet), and passes westward through the narrow pass (altitude 1980 feet) directly south of Van Dorrien mountain to Blueberry pond. Continuing westward into the Long Lake quadrangle, on the boundary. between the two maps, it turns to the southwest and passes three-fourths of a mile south of Palmer brook. When within a mile of the Raquette river, the course turns directly south over Brueyer pond. This river course is a mere sug- gestion as actual field work has not been undertaken in the rugged GEOLOGY OF THE LAKE PLACID QUADRANGLE 79 and inaccessible Santanoni quadrangle. Probably the waters flow- ing through this channel did not form a single river but consisted - of a chain of lakes and ponds. Just where the ice control was located for each successive level is not known. The glacial sands, gravels etc. form a filling in the South Mead- ows country that is estimated to be at least 300 feet thick. This matter will be referred to again in another connection. A number of unmistakable beaches exist on the shoulders of the Sentinel range and on Scott’s cobble, northern edge of the Mt Marcy sheet. The altitude of a series of them ranges from 2146 to 2209 feet.1 These figures, in all probability, represent the water levels during the early stages of the lake. Sand plains with alti- tudes close to 1960 feet strongly suggest that the lake was under- going constant lowering, perhaps as the small ice lobe 3 miles east of the highest peak of Ampersand mountain retreated and allowed escape through the channel of the East branch of Cold brook and then south, lowering the level to 1960 feet as set by the Van Dor- rien pass mentioned above. (See figure 2 as indicated by the “later outlet.” ) The fault-line valley containing the Cascade lakes (Mt Marcy quadrangle) was probably filled by morainal material and by a glacial lobe, preventing escape to the east; thus the outlet was to the west as suggested above. Western portion of Upper Lake Newman. With the gradual _ retreat of the ice and its constant shifting of position, new and lower outlets were exposed. Succeeding the South Meadows lake, the western portion of Upper Lake Newman, as the writer pro- posed to call it,? was ushered in. As the remnants are rather indef- inite in character and the range is considerable, 1800 to 1895 feet, the writer is not unmindful that stream filling forming an outwash plain from the glacier may be an alternative explanation; but in ‘view of the fact that sand plains are found over a considerable area confined within definite limits of range of altitude, they are assumed to represent a series of lake bottoms formed by a lake whose level was experiencing periodic lowering due to the down- cutting of the controlling spillways.. These spillways may have been over the ice itself or a series of outlets which were over rock. Unfortunately, however, the outlets of the lake are not positively *Determined by a surveying aneroid barometer and checked against a barograph, hence as accurate as this method permits. 2 Alling, H. L., “Geology of the Lake Clear Region.” N. Y. State Mus. Bul! 207, 208, p. 133. 8o NEW YORK STATE MUSEUM known but in all probability the drainage was to the west, similar to that of the South Meadows lake. This lake was even more extensive than the South Meadows lake if the writer’s conception is correct. It covered the area nowia™ occupied by the southern end of Lake Placid, the western end of the Wilmington notch, and sent a four-fingered bay into the South Meadows country and flooded the southern edge of the Saranac quadrangle. The valley of the East branch of the Ausable river was occupied by an ice lobe, preventing any connection between the eastern and western portions of the Lake Placid quadrangle. oo — VY EF jf FS wisconsin ICE {EARLY STAGE OF SUAS TIL LAKE KEENE WA ern CRAKE NEWMAN IM |EXISTING LAKES Fig. 3 The Glacial Lake succession in the Lake Placid quadrangle. Stage two. ; The South Meadows lake was succeeded by the western section of Upper Lake Newman, altitude 1800 to 1895 feet. The ice lobe in the valley of the East branch of the Atssable river had retreated since stage one: to allow the Keene lake to accumulate. GEOLOGY OF THE LAKE PLACID QUADRANGLE 81 The best preserved terraces of the Upper Lake Newman were found in the extreme southwest corner of the quadrangle in the neighborhood of John Brown’s grave and along the West branch of the Ausable river. The name of the lake is derived from the town of Newman, the terminus of the Delaware and Hudson Rail- road, where well-preserved levels occur on the north, south and more especially at the point where the Lake Placid-Keene highway crosses the river. Here a striking view of them may be obtained. As may be inferred from figure 3, the present theory is that a portion of the ice body that was responsible for the existence of Upper Lake Newman, was situated for a time near the southern edge of what is now Lake Placid, and it is believed that the morainal dam that later brought about Lake Placid was formed during this period. The ice experiencing minor advances and retreats pro- duced the exposure above mentioned, showing drift on top of the stratined sands of Upper Lake Newman. In the vicinity of John Brown’s grave, well-preserved benches show a complete separation of Upper Newman from the succeeding lake, Lower Newman; the upper series ranging from 1800 to 1820 (one well-marked level at 1806.5 feet) while the lower group vary from 1740 to 1780 feet. The same difference in levels was found in the Saranac quadrangle one-half of a mile north of Harrietstown, where a corresponding group of benches occurs.+ Upper series: eastern section. The Keene lake. During the greater portion of the life of the western portion of Upper Lake Newman, the ice lobe in the valley of the East branch of the Ausable river was retreating northward and allowed a growing body of water to accumulate in the Keene valley. This body of water, named the Keene lake, left terraces high up on the valley walls, especially in the brook valleys where the present streams have bisected them. The sands on East hill at 2000 feet altitude, in the southeast corner of the Lake Placid map, were probably deposited at this time. The greater portion of the lake, however, filled Keene valley and thus was largely located within the confines of the Mt Marcy sheet. The outlet is regarded to have been to the south through the double fault-line valley, in which the famous Ausable lakes are now located, into standing waters in the northern half of the Schroon lake sheet. The two passes to the east, namely, the Spruce hill _ tAlling, H. 1 Geology of the Lake Clear Region, N. Y. State Mus. Bul. 207, 208, p. 133. 82 NEW YORK STATE MUSEUM | | : | pass and the Chapel pond pass on the western edge of the Eliza- | bethtown sheet, although much lower than the surface of the water, | were effectively blocked by side ice lobes from the glacial tongue that occupied the Elizabethtown valley, preventing eastward escape. _ It seems quite likely that as the lobe, which prevented northward escape of the Keene lake, gradually retreated, it at last uncovered the eastern end of the Wilmington notch which furnished connec- tion with the western portion of the area, and then the waters in the valley of the East branch fell to the level of Upper Lake Niewman. Gan Y TA 1] } Z £4 by © Le, FE wisconsin Ice ff] GLACIAL. LAKE A LOWER NEWMAN [P| EXISTING LAKES [= | Towns Fig. 4 The Glacial Lake succession in the Lake Placid quadrangle. Stage three. The Keene lake was succeéded by the eastern section of Upper Lake Newman when the ice lobe in the valley of the Ausable river had retreated to uncover the Wilmington notch, allowing discharge to the west. Both eastern and western sections of Upper Lake Newman were succeeded by Lower Lake Newman, altitude 1740 to 1780 feet. SCALE QF MILES ' 4 re x iy GEOLOGY OF THE LAKE PLACID QUADRANGLE 83 Eastern portion of Upper Lake Newman. The life of the east- ern portion of Upper Lake Newman was probably relatively short compared with that of the western area, for the terraces are very indefinite and the separation of the benches into an upper and a lower series does not exist, or at least can not be demonstrated. Thus soon after the establishment of greater Upper Newman, the outlet was changed, perhaps rapidly deepened by the additional volume of water from the eastern section, so that the waters fell to the level of Lower Lake Newman. Upper series: eastern and western sections. Lower Lake Newman. This lake was of still greater extent than any of the above-described bodies of water. Its northern, and especially the northwestern, extent and boundaries are still to be studied and worked out. Our present knowledge would lead us to conclude, however, that the valleys occupied by the West and East branches of the Ausable river were flooded, the connecting link between the two being the Wilmington notch. This is inferred by the fact that deltas and terraces at similar heights were found to the east and west of the Notch; how else could the waters of the two areas have been confluent? These waters thus flooded the area covered by Lake Placid and the greater portion of the Saranac quadrangle. As the ice barrier retreated the area around Franklin Falls was covered by the later stages of Lower Lake Newman. The outlet is assumed to have been west, although its location is at present unknown. It is possible, though exceedingly unlikely, that the Chapel pond pass may have been an outlet toward the close of this period, changing the drainage to the east. The South Meadows, and the two Newman lakes, probably had outlets to the west; the Keene lake drained south; but the suc- ceeding lake (or group of lakes) had drainage to the east. Saranac glacial waters. The series of sand plains, terraces etc. that come under this head were recognized and described by H. P. Cushing,* in the Saranac region, in what is generally known as the “lake belt.’ These levels have such a wide range, 1450 to 1660 feet, that they must have been produced by a series of glacial lakes, or have been deposited by aggrading streams which no longer exist, or by a combination of both. Doctor Cushing is of the opinion that “ these sands were prob- ably deposited as deltas in a large irregular, shallow, lake formed * Cushing, H. P., Recent Geological Work in Franklin and St Lawrence Counties, N. Y., State Mus. Annual Rep’t. 1900, p. 29. 84 NEW YORK STATE MUSEUM back of the ice tongue which occupied the ‘lake belt’ during its slow retreat north, the material being furnished by the subglacial and englacial streams flowing into the lake at the ice margin.” As nearly two-thirds of the Saranac sheet exhibits terraces and sand plains of the higher levels, it was proposed that the name “Saranac glacial waters” be applied to the standing waters that built these levels, although the waters covered portions of the Lake Placid, Mt Marcy and Ausable quadrangles. Extensive levels are preserved within the area in the brook val- leys such as Clifford, Styles, Brown’s and New Bridge brooks and to the east and west of the town of Wilmington. The general character of the terraces is that of gently sloping plains on the mountain slopes without any prominent shore-line features. An exception to the last statement is a wave-cut cliff on the south side of the Styles Brook valley. The indefinite nature of nearly all the sand plains strongly impressed the writer and thus he was inclined to view them as having been formed by aggrad- ing glacial streams, the remnants now existing being merely por- tions left undisturbed by the present streams. But field work revealed a remarkable series of outlets in the center of the Ausable quadrangle that furnish evidence for regarding them as glacial lake features. Outlets. Here again we must depart from the confines of the Lake Placid quadrangle to understand the nature of these conspicu- ous levels. Although a detailed description of the outlets will not be given, a short summary of them is indispensable.* iBeginning on the southern slopes of Ellis mountain, in the town- ship of Jay, a long glacial channel extends south for a distance of some 9g miles with a dozen side outlets to the east. The lake entrance to this channel was at the northern end, south of Ellis mountain. The controlling spillways were regulated by an ice lobe that lay to the east. Thus it is the writer’s opinion that as the ice retreated it permitted escape first by the most southern side outlets which represents the outlet of the early stages of the Saranac glacial waters; while as the ice continued to retreat, lower spill- ways were opened farther north with a consequent lowering of the waters. In several of these side-outlet channels “fossil” or dried-up falls and cataracts are found. The channels are very impressive For a fuller account, see Alling, H. L., The Glacial Lakes and Other Glacial Features of the ‘Central Adirondacks, Bul. Geol. Soc. Amer., 27:658 and fig. I. GEOLOGY OF THE LAKE PLACID QUADRANGLE 85 and, together with the correlation of the elevations of the outiets and minor breaks in the. sand plains, furnish positive evidence of the nature of these levels. i Yi y, Ve KLIN QO FALLS LAKE PLACID WISCONSIN LATE STAGE OF SARANRAC WATERS [TL ON MT PANNEMORA] KES LAKE 1 TOWNS MT > || ty [ee SCRLE OF MILES Fig. 5 The Glacial Lake succession in the Lake Placid quadrangle. Stage four. With the opening of the glacial channels in the Ausable sheet the Lower Newman Lake was succeeded by the Saranac glacial waters, the late stage of which is indicated on the map. ‘The altitude of this series of lakes range from 1440 to 1660 feet, although the level shown is that at 1500 feet. There is a decided “ gap” in the sand plains in the Saranac levels at about 1550 feet, and thus it would be proper to subdivide the lake into upper and lower phases, but as the lake had a succession 86 NEW YORK STATE MUSEUM of outlets such a simple division is insufficient, so we shall regard the Saranac waters as a series of lakes. The chief cause for the indefiniteness of the levels and the lack of shore-line features must be attributed to the fact that the ice was the barrier in many cases. Many one-bank channels exist, showing that the spillways were constantly being lowered by the melting ice. The lower stages of the Saranac waters were chiefly confined to the eastern section, as can be seen from figure 5. Eastern section. St Huberts lake. At a lower altitude than the Saranac water levels there are scattered over the area sloping ter- races of indefinite character that remind the writer of the preceding plains. They are regarded as subordinate in interest to the preceding levels and to those which are described below. There is a small but finely developed terrace at thé head of Keene valley at 1300 feet. This level surface is now used as a baseball diamond. Taking this as a starting point the other terraces seem to fit in with the general scheme, and hence there is a possibility of a lake level in the series that once flooded portions of the Lake Placid quadrangle. The most prominent remnant left of this level is on the northeast slopes of Owls Head now traversed by the Keene-Cascade highway. Its outlet was, without much doubt, through the gulf, south of Ellis and Black mountains in the Ausable sheet to the east, the spillways being controlled by one-bank channels which are beautifully shown on the southeast slopes of Black mountain. Lower series: confined entirely to the eastern section. In descending from the higher lake levels to the lower ones, the character of the terraces changes from indefinite levels of consid- erable range to neat, clear-cut deltas, wave-cut cliffs and beaches confined within concise limits. No question can be raised as to the origin of many of them. They represent remains of true glacial lakes. Wilmington lake. The history of the Wilmington lake is, per- haps, the best understood of all these local lakes. It was chiefly confined to the Lake Placid sheet, to the East branch of the Ausable river, and to the territory around the town of Wilmington; and stretches northward to Lower Jay. (See figure 6.) The altitude is 1100 feet at the foot of Johns brook in Keene valley where a typical delta was developed. One and one-half miles southeast of the town of Keene, on the state road at Norton cemetery, there is an excellent display of a bisected delta. Around — ‘YNos Sulyooy ‘uo}SsurU JIM JO JsoM out Be JO J[eY-aUO “UOJSUTUTIA\ OCT [eIOV[X) JO dovII0] OY} Jo uoTAod VW e16L “ojoyd “BuyTV “I “H vz 93e1G GEOLOGY OF THE LAKE PLACID QUADRANGLE 87 the town of Wilmington the development of the terraces is excep- tionally fine and thus the name is not inappropriate. As one investigates the terraces of the Wilmington lake from south to north in this area and in the Ausable quadrangle, the altitude rises at a rate of approximately 3 feet a mile and clearly illustrates postlacustrine deformation. The subject of uplift and tilting will be more fully treated beyond.. A number of beaches of the lake are beautifully shown on a hill a mile directly north of LOBE OF WISCONSIN ICE SHEET GLACIAL LAKE WIL- MINGTON. ALT.1100 FT. GLACIAL OUTLET CHANNEL CATARACT PLUNGE BRSIN SCALE OF MILES QUADRANGLES WAL AMin ev Fig.6 The Glacial Lake succession in the Lake Placid quadrangle. Stage five. St Huberts lake that succeeded the Saranac glacial waters is not shown in this series of maps. The lake that followed, the Wilmington lake, with an altitude of 1100 feet is given here. The outlet was to the east, through the gulf. *Kemp, J. F., N. Y. State Mus. Bul. 21, p. 60. 88 NEW YORK STATE MUSEUM Keene, called by the writer “ Keene hill.” Here the altitude is 1113 feet. Farther north we find the outlet channel spillway at 1155 feet. This level, compared with the r10o-foot delta above mentioned, gives on calculation a deformation of 2.94 feet a mile. Outlet. Once more we must depart from the Lake Placid quad- rangle and consult the Ausable sheet to find the outlet. As can be inferred from figure 6 an ice lobe lay in the valley of the East branch of the Ausable river with its southern wall at Lower Jay. Another body of ice blocked the narrow valley now occupied by Trout pond. Thus northward escape was prevented. The waters of the lake found outlet to the east through the gulf, a narrow and deep faultline valley, south of Ellis and Black mountains. In this interesting channel there are a number of Pleistocene cataracts, but unfortunately the topography is incorrectly drawn and they fail to appear on the survey map. At the eastern end of the gulf, on the - boundary between the townships of Jay and Chesterfield, the river turns to the southeast making a series of little ponds, which are really plunge basin lakes at the base of former cataracts. Of the group the remarkably beautiful Copperas pond is the most striking example. Beaches versus stream terraces. Below the Wilmington lake level, on the mountain slopes, in the Ausable valley, a number either of benches or stream terraces have been found and their altitudes measured. The question of origin arises, naturally, in individual cases. Many of them are probably shore-line features formed by glacial lakes, while others are stream meander terraces formed by the postglacial Ausable in cutting its way through the glacial sands. A discrimination between the two is often impossible, thus leaving the identification of succeeding lake levels extremely unsatisfactory. Typical examples are the levels on the “ Keene hill,” a mile directly north of Keene (see plate 25). The following are the altitudes the writer has obtained by the use of two aneroid barometers checked against a barograph and spirit leveling: 1146, 1113 (Wilmington beach), 1037, 1017.7, 993.9, 985.7, 925.7 feet. The mean height of the river at this point is 816 feet. The origin of the lower ones is a disputed question. D. W. Johnson regards them as stream terraces, while Fairchild and Chadwick attribute them to glacial lakes. Another series, in the Ausable sheet, 114 miles northeast of Lower Jay on a similar hill (the “Lower Jay hill”), has been recorded as follows: 1046, 1043, 1024, 997, 917.5, 908 (wave-cut cliff), 880 and 857 feet. The river is a mile distant to the west, Plate 25 H. L. Alling, photo, 1916 Probable glacial lake beaches 1 mile north of Keene, looking north. Altitudes: 925.7, 985.7, 993.9, and 1017.7 feet. ‘Jooy YLVL pue YgeZ sopnynpy AeAYsiy o}e]s oy} WOT, seo sUIyYOOT “IOATI o[qesny oY} JO Opts jsva “Aef taddy, sAoqe soypvosd YL] [eIe[S 10 SoovIID} WeIAG 916 “ojoyd “Sully “I “H 9% eq Pasay Joo} YALvL opnyyyy ‘Yyytou suryooyT “Aef todd) jo jsvo yoroq oye] [eIOe[S 10 99¥110} WRIIS 916E “ojoyd ‘Sully “I ‘H lz d3®1d ay een eras GEOLOGY OF THE LAKE PLACID QUADRANGLE 89 while the best development of the levels is on the east side of the hill. Here glacial lake origin seems certain. To the writer they have exactly the same appearance as those on the hill near Keene.* Other groups of benches in the Lake Placid quadrangle are impor- tant. On the hill north of the junction of Clifford brook (the “Clifford hill”) and the Ausable, a series shows the following figures: 1074, 1070, 1020, 967 and 964. These are perhaps lacus- trine in character, especially the 964-foot level which Johnson admits is a wave-cut cliff. On the east bank of the river 3% miles north of Keene (“ Quarry point”) a series of probable stream terraces ranges as follows: 1028, 970, 921, 912.5, 903, 879 and 859. Doctor Johnson examined them carefully with the writer and pronounced them the work of the river; he likewise so regarded the terraces east of Upper Jay (See plates 26 and 27). ‘Following the lead of Woodworth,” the writer has plotted upon a north and south plane the above data of beaches, terraces and sand plains to see how they correlate among themselves and with the proposed spillways (see figure 8), taking into account the post- lacustrine deformation and the 20° inclination of the isobases. This was done on the basis of Fairchild’s recent studies which furnish the approximate total uplift and amount of differential tilting for the area by means of isobases. It is interesting to note that a large number of these disputed levels fit into the general scheme and thus strongly suggest glacial lake origin. The writer is not, however, unmindful that pure coincidence may bring into line a group of stream terraces that really have no relation to one another. After lining up all available data there remained isolated figures that are impossible to pigeon hole. It is quite possible that with more careful examination in the field corresponding levels will be found, but as the matter now stands there is some doubt as to the character of some of the levels. With this uncertainty in mind we shall, however, now discuss the next level, which probably represents a glacial lake. Upper phase of the Upper Jay lake. The Upper Jay lake, like its predecessor, the Wilmington lake, has left terraces and beaches that are very definite in character. One of the beaches on the “ Keene hill” is 1017.7 feet in altitude, while a similar one on the *Compare pl. 22, fig. 2, facing p. 658 in Bul. Geol. Soc. Amer., v. 27. ? Woodworth, J. B., Ancient Water Levels of the Champlain and Hud- son Valleys, N. Y. State Mus. Bul. 84, pl. 28. go NEW YORK STATE MUSEUM “Lower Jay hill” presents a beach at 1046 feet. This gives upon calculation an uptilt to the shore line of 2.80 feet a mile. The out- let of the lake is not definitely known, but a pass one-half of a mile directly south of Haystack mountain in the Ausable quadrangle (not the mountain of the same name in the Marcy range) has an altitude (1153 feet) that gives the proper figure when the tilting is calculated. When visited, however, this pass did not show evi- dences of stream action. The area is entirely fine sand, but farther north a possible channel, 114 miles north of Bald mountain, is sug- gested as a more probable control. LOBE OF WISCONSIN ICE SHEET 3 GLA LAKE, UPPE CG JAY. ALTITUDE 1000 Er GLACIAL OUTLET CHANNEL Fig. 7 The Glacial Lake succession in the Lake Placid quadrangle. Stage six. Following the Wilmington lake, the Upper Jay lake formed in the valley of the East Branch of the Ausable river. The lower levels are not shown in this series. Lower phase of the Upper Jay lake. A lower phase of the Upper Jay lake is indicated by beaches on the “ Keene hill” at 993.9 feet and a beach at 999.5 feet on the slopes of Oak ridge and a level at 1024 feet on the “ Lower Jay hill.” These figures give the value, 2.75 feet a mile for the tilt. Haselton lake. A possible lake with an altitude of 967 feet around the town of Keene has left terraces, wave-cut cliffs and Joo} QeOI pure ‘€Z6 ‘YOO :sopnqynyy “AdAIL afqesny oy} fo Youeiq jsey oY} pue Yoo1q paso Jo uotounfl oy} 1vou soovtie} divos topuvow wes14S IGT ‘ojoud ‘ZunTy “I “H Bz 211d Wy, i Le yoo} 940 eplyny{y “IOAII opqesny JO opts jsom ‘yoo1q plop YD JO Y}10u ojIw e JO Y}InOoF-3u0 ‘QUIeIOU JND-IAV N\A 9T6E ‘oJoyd ‘sully “I “H 62 2321 OI GEOLOGY OF THE LAKE PLACID QUADRANGLE ‘g]8ueipenb oqesny ‘Aef JomoT $0 jseoyjiou jjey e& pue afIM e—, [IF Aef iaMoT,, ‘QUI0y JO Y}IOU soap zjey & pue 9914} —,, JUIOg Aisien/ . “FOAL opqesny ay} YM Yoorg psoy yO Fo uorounf ay} Jo yjsou ysnf—, IH PIM ,, ‘sud0xy JO YIsJou Fey & pue aim e—, ospry ARO, ‘QUd0y JO YOU AIW e—, [[IP}{ VUs2y, ,, ‘SOpnyyye O} Joyo stoquinu [jews sy ‘g]sueIpenD proe[q sxe] 9Y} Ul S[aAa7] ayeyT [ees ay} JO WBYOIg g ‘Sly == ze LV BQ ] SAUMTUdS SSOWYUGL YU SSHOWIE = CN a | Ls > 6S8 OEE ah OID ae = HONYYHa A008 11 = Es 2 et al eine | sag = losses JINR tet MO 1 a ca ; 16 = < 196 1s86 ae) ase 15:666 6-€66 20) sey porn AUP USddN| | ozo = NOLDNIATM Spiel fl ee > a O00c! AW oes key 9 yyoS aW 2/1 a8Pi seg WW!H BUae)) Kempds aw Fer dn syrosaqy———|— ue} Au ser} Bee OSD g2 NEW YORK STATE MUSEUM beaches. The amount of tilt based upon the wave-cut cliff on the “ Clifford hill” at 964 and a level on the “ Lower Jay hill” with a figure of 997 is 2.71 feet a mile. Relatively. small sand plains of this lake are well shown about the town of Haselton village in the Lake Placid sheet. The controlling outlet is unknown, but the writer offers the sug- gestion that it may have been a one-bank channel on the north side of Haystack mountain (Ausable sheet) carrying the waters east, for there is some evidence of water action in that region. Lower Jay lake. This lake level is very definite and no ques- tion seems to exist as to its nature, although the “ Lower Jay hill” does not show a corresponding level. About Keene there are wave- cut terraces at 930 and 930.5 feet. A well-preserved terrace bottom is located 1%4 miles south of Upper Jay with an average height of 930 feet (see plate 30), and likewise a fine sandy plain on the western edge of the Lake Placid quadrangle which continues on to the Ausable sheet where we find Otis brook flowing on the east- ern edge. Here the altitude is about 940 feet. We have not sufficient data to calculate the amount of tilt. Otis lake. The level called the Otis lake is one of the more doubtful levels, as sufficient data are not at hand to determine whether it is a lake feature or a system of stream terraces. If we take a level that Johnson regards as a stream terrace 144 miles north of Keene at 903 feet and a beach on the “ Lower Jay hill” at 917.5 feet, we obtain an unsatisfactory value of 2 feet a mile for the tilt, which of itself seems to cast some doubt upon the glacial lake origin of the level. Errors in the measurements may, how- ever, be a contributing cause for the discrepancy. | Rocky Branch lake. Rocky Branch lake is recognized on the basis of three terraces around the villages of Upper and Lower Jay, and upon some of the disputed levels. The latter are 114 miles north of Keene, 858 feet, and on the “Lower Jay hill” at 880 feet, giving a tilt of about 3 feet a mile, which is approximately the expected value. Although the outlet is unknown, the terraces are definite in character and thus this level should rank as definitely settled. Clifford lake. This is the last and lowest of the levels definitely recognized within the confines of the Lake Placid quadrangle. Its origin is still in doubt, although a warp of 2.70 feet to the mile is indicated by a beach or stream-terrace a mile south of Upper Jay Jo} O£LO OpNIn[yY “You Ssuryoo'yT ‘Av({ toddy JO YNos sop Jpey-ouo0 pue ou— “Avf JOMOT ONL] [eIOR]D) JO Wo}0q oyeT §16L “ojoyd ‘sully “I “H Of 9}e[g + iy} Somat Ba) od ie GEOLOGY OF THE LAKE PLACID QUADRANGLE 93 at an altitude of 833.5, and another one on “‘ Lower Jay hill” at 857 feet: Lower lake levels. At still lower altitudes several more of these perplexing levels were found, but as they are largely outside the Lake Placid quadrangle they will not be discussed. Suffice to say, the most prominent level in the lower Ausable valley is the marine plain in the vicinity of Ausable Forks. Here the measured altitudes agreed within a foot of the value called for by Fairchild’s figures. Cause of the large amount of material available for the formation of terraces. One of the striking features of the glacial geology of the Adirondacks is the small amount of true morainal material* unmodified by water” as contrasted with the vast quanti- ties of sand and gravel in deltas, terraces etc., when compared with other districts, such as the Catskill mountains. The following hypo- thesis is offered to account for this. It is generally conceded that with the return of warmer climate the Adirondacks were completely - surrounded by a vast ring of ice that isolated the Adirondack high- land from the rest of the state.* It was during this stage that the glacial lakes here described existed. The great ice sheet undoubtedly destroyed all vegetable life in both the Adirondacks and the Catskills, but in the latter case the ice retreated northward as an irregular edge which allowed vegetable life to follow the ice in its withdrawal. This condition was not possible in the Adirondacks where the ice ring prevented much if any encroachment on the part of plants into the ice-deforested area. In the Catskill region the glacial drift was anchored by the roots of newly growing shrubs etc. and thus it was not easily washed by the streams into the standing waters in the valleys below, so a large amount of the drift still remains on the slopes. On the contrary, the glacial debris in the A’dirondacks was not anchored and most of it has been carried down into the valley bottoms and there worked over into lake deposits. Postlacustrine deformation and tilting. It has been pointed out that at the maximum extent of the Wisconsin ice-body, the load upon the land surface must have been tremendous and must have compressed the land below its former level.* Since the ice was PCushins, HH. Py IN. Y: State Mus.) Bul, 115, p.- 405. 2 Ogilvie, I. H., Jour. Geol., 10:3907—412. 1902. witainehid da lee, Ni Y. State Mus. Bul. 160"pl. 1 #This subject of deformation has not received the attention of struc- tural geologists in the light of isostasy. Q4 NEW YORK STATE MUSEUM thicker in the north than in the south, the amount of deformation was greater in the northern part of the State. With the removal of the load by the melting of the ice the land has “ sprung” back, thus elevating the surface, tilting the shore-line features of the glacial lakes. It has been shown by Fairchild’ that the character of the postlacustrine uplift was a lifting in the form of a warped plane with the amount of warping greater to the north. The lines of equal uplift since the marine level are inclined west-northwest to the east south-east (20° from the latitude parallels). The zero isobase passes far south of New York City. The 600-foot isobase enters the Lake Placid quadrangle at the very southeast corner of the map. The northeast corner is cut by the 648-foot isobase. These figures give the total uplift for the region since the marine waters occupied the Hudson-Champlain strait. The figure for the amount of tilting for this datum plane in this region, is 2.71 feet a mile taken along a north and south line, or 2.83 feet perpendicular to the isobases. Although Fairchild’s papers form a very valuable contribution to this subject, there exists some uncertainty as to the character of the uplift. (1) Was the upward movement gradual and uni- form or (2) was it in the nature of a wave or a series of sudden uplifts? The writer believes that the problem will be clarified by the measurement of beaches, deltas etc. situated at higher levels than the marine plain to supplement those mapped at the lower altitudes. The shore phenomena of the lakes above described afford an opportunity to determine the amount of tilt of the land surface, for they furnish a series of datum planes higher than those in the Champlain valley, which was occupied by ice during the entire period that the lakes existed. Fairchild believes that his figures give the total uplift since glacial time. The writer feels, however, that this conclusion is based upon the state of affairs that prevailed during and after the marine stage and overlooks the shore phenomena of higher lake levels. Although accurate meas- urement of the amount of tilt of the lake levels of the Lake Placid quadrangle is an extremely difficult matter (for the chance of error is great), the table given below would indicate that the uplift was taking place while the ice was melting from the area. 1 Fairchild, H. L., Pleistocene Uplift of New York and Adjacent Ter- ritory, Bul. Geol. Soc. Amer., 27:235-62. Post-glacial Marine Waters in Vermont, Rep’t of Vt. State Geol. for 1915-1916, p. I-41. 1917. fa 800 igo ST HUBERTS 100 NFeet WILMINGTON Saie UPPER JAY [.24|967 *jFee' HASELTON 903 ro) Feet LOWER URY 860 feet ROCKY BRANCH Boge 24 | BERCHESRBENCHES SCALE oF MILES SSSR Fig. 9 Remains of the glacial lakes in the Lake Placid quadrangle. Some of the doubtful “lower levels” are included under the head of the Rocky Branch lake. GEOLOGY OF THE LAKE PLACID QUADRANGLE 95 Deformation table for the lower series oj lakes in the quadrangle Altitude Calculated tilt, Lake in feet feet a mile WV MbIMITASIOM so00sc0d0ccccod 90a dgoDDODOOODODDUC 1100 2.94 Wnper phase of Wipper Jay. sc. 6 ie. cre6 soi. soe 1016 2.80 Wower phase, or lower Jaye ees «cece a 994 2.75 SAS Grae Go aro tele ols clGNB LS One ROLER TORO CRO nS Da EIAs ne 967 2.71 iLower Jaw concocsoucccmc0 po dpe0cnDOUKgGKadaC 930 COVES, os Siete BL BONA gee re eae ae eri UPR 903 ody iyeiGh, sosanccvsccadenboonaoucoccmp sae 860 sikaens (CIRO! eB Ws eI CRO CoRR eRe a eas ere des 835 2.70 WNifaarirte melee li ters: ctccersncyois ates « ci) cia-s vie ohare wtereiereloreieae 648 2.71 The writer came to the same conclusion in 1916 although at that time his data ‘were not so accurate as those now available, and hence the figures are slightly different. It will be noticed that the rate of tilt decreases as one passes from Lake Wilmington to Lake Haselton; the tilt of the latter appears to be the same as that of the marine plain. If any con- fidence can be placed in the figures, it would seem that the lakes below and including Haselton drained directly-into the marine waters. Since warping is a function of uplift, it would appear that the total amount of uplift for the quadrangle since glacial times is greater than the amount, 600 feet (for the southeast cor- ner), proposed by Fairchild. ACKNOWLEDGMENT The writer is indebted to Professors James F. Kemp, Herman L. Fairchild, George H. Chadwick and D. W. Johnson for advice and counsel in the field and in the laboratory. 96 NEW YORK STATE MUSEUM HISTORICAL GEOLOGY? Precambrian History The oldest records of the Lake Placid quadrangle are written in the rocks of the Grenville series. .A most conservative estimate by geologists gives the age of the Grenville strata as no less than 25 or 30 million years, but it must be admitted that we have no means of accurately measuring geologic time in years. Since the Grenville rocks are distinctly stratified, very thick (many thousands of feet), and of wide areal extent not only throughout the Adiron- dacks, but also in eastern Canada, we may be sure that the earliest known condition of the area of the quadrangle was a sea in which the Grenville sediments were accumulated layer upon layer on the bottom. After the deposition of the Grenville strata came vast intrusions of molten masses, including first the upwelling of the great body of anorthosite in Essex and Franklin counties, and second the still greater syenite-granite body, these two igneous series being by far more extensively developed than any other rocks of the quad- rangle.2 During the processes of intrusion and cooling of the magmas, the anorthosite differentiated into the Marcy and White- face types, and the syenite-granite split up-into various types rang- ing from rather basic (dioritic) phases, through quartz syenite, granitic syenite, and granite to even granite porphyry. The syenite- granite intrusion appears to have taken place not long (geologi- cally) after the anorthosite intrusion so that the latter was still hot, though probably not molten, and it was locally assimilated along the borders of the invading syenite-granite magma, thus giving rise to the rock called the. Keene gneiss. The whole Adirondack region was raised well above sea level most likely at or near the time of the great intrusions. There are strong reasons for believing that none of the rocks were ever highly folded by orogenic movements, but that the breaking up and tilting of the Grenville strata resulted from the upwelling of the great bodies of magma; that the metamorphism of the Grenville *A treatise dealing with the geography and geological history of the Adirondack region in somewhat untechnical language was prepared by the writer and was published as Bulletin 193 of the State Museum under the title “The Adirondack Mountains.” 2 As already suggested, possibly some gabbro now represented by amphib- olite, was intruded before the anorthosite. GEOLOGY OF THE LAKE PLACID QUADRANGLE Q7 strata preceded, or possibly was in part at least concomitant with, the great intrusions; and that the foliated character of the intrusive rocks is essentially a flow-structure developed under moderate pressure during late stages in the consolidation of the magmas. The great Precambrian land mass just referred to was above sea level, and underwent weathering and erosion for some millions of years at least, extending through later Precambrian time and into the early Paleozoic era, as proved by the facts that the oldest rocks deposited upon the Precambrian floor are of late Cambrian age, and that the rocks of this Precambrian floor immediately below the Cambrian strata exhibit textures and structures which could not possibly have been produced except at very considerable depths below the earth’s surface. Following the anorthosite and syenite-granite intrusions and, for most part at least, during the long time of erosion above men- tioned, came the minor intrusions of gabbro-diorite, gabbro, peg- matite and diabase. Of these, the diabase is the youngest with the finest grained texture showing a cooling of the rock comparatively near the surface of the earth. In the Adirondack region, pegmatite dikes commonly cut the gabbro and hence are younger. Whether the gabbro bedies are younger or older than the gabbro-diorite dikes of the Lake Placid quadrangle could not be positively determined but they are probably younger. Paleozoic History By late Cambrian time the profound erosion above referred to had worn down the whole Adirondack region to a comparatively smooth, low-lying (peneplain) surface. This is proved by the fact that the late Cambrian strata (particularly the Potsdam sandstone), which are the oldest to have been deposited upon the Precambrian rocks, everywhere rest upon a peneplain surface of the latter. In the northeastern Adirondacks, including the Lake Placid quad- rangle, this peneplain was moderately rough with some hills rising probably several hundred feet above the general level, but of course this was not at all comparable to the high, rugged relief of the present day. The best available evidence indicates that the ancient peneplain became sufficiently submerged during late Cambrian time to allow the sea to cover all but a considerable part of the central Adiron- dack area, and that the maximum submergence occurred during nud-Ordovician time when a still smaller part of the central Adi- rondack region remained as a low island. Judging by the marine 4 98 NEW YORK STATE MUSEUM character, thickness and present-day distribution of the Cambrian and Ordovician strata, the late Cambrian sea probably covered some of the area of the Lake Placid quadrangle, and the mid- Ordovician sea quite certainly covered some, or possibly most, or all, of the area of the quadrangle. However extensive the Cam- brian and Ordovician rocks may once have been, they have since been completely removed by erosion from the area of the quadrangle. At some time or times during the middle or late Paleozoic era the whole Adirondack region, then largely mantled with Paleozoic sediments, was raised well above sea level. Some of this upward movement may have taken place at the time of the Taconic revolu- tion (at the close of the Ordovician), though it is generally con- sidered that the major uplift occurred at the time of the Appa- lachian revolution (toward the close of the Paleozoic). In north- ern New York this upward movement was not accompanied by folding of the rocks, but there was a general tilting of the strata downward toward the south or southwest. Mesozoic History The erosion cycle inaugurated by the Paleozoic elevation of northern New York continued for a vast length of time, or till late in the Mesozoic era or early in the Cenozoic era, when the Paleozoic strata were largely removed from the Adirondack area and another eroded surface approaching the condition of a pene- plain was produced. This is commonly referred to as the Cre- taceous peneplain. Apparently this peneplain was least perfectly developed in the central and east-central Adirondack area, including the area of the Lake Placid quadrangle, where various hard rock masses (monadnocks) stood out more or less prominently above the general level. This peneplain was upraised late in the Mesozoic era or early in the Cenozoic era, and distinct remnants of it in northern and central New York now lie at altitudes of from 2000 to 3000 feet or possibly more in some places. Within the quad- rangle, however, no very accurate idea of this peneplain or its remnants can be gained because it was only imperfectly developed there. It is quite certain that much of the faulting which has so largely influenced the major topographic features of the eastern and southern Adirondacks took place after the production of the so-called Cretaceous peneplain, and probably at the time of its uplift. Some zones of fracture, however, like the Wilmington GEOLOGY OF THE LAKE PLACID QUADRANGLE 99 notch fault, whose displacements show little, if any, in the existing topography, are probably much older, and they may in part at ’ least be of Precambrian age. Some of the fracturing is certainly of later age than the diabase dikes because several of these in the Lake Placid quadrangle have been crushed by the faulting. Cenozoic History The major existing relief features of the Lake Placid quadrangle have been produced chiefly by the dissection of the upraised late Mesozoic or early ‘Cenozoic peneplain. As a result of the uplift the streams were greatly revived as erosive agents, and they pro- ceeded to carve out channels and valleys principally along the com- paratively weak belts of Grenville rocks and the fault zones of weakness. Late in the Cenozoic era the area of the quadrangle, in common with most of the State, was deeply buried under the great ice sheet of the Glacial epoch.t The continental ice body in passing across the quadrangle, in a south-southwesterly direction, removed the residual soil of interglacial periods and subdued the contours of the mountains. The tongues of the waning ice were influenced by the topography, as is shown by the striae and the ice action in the narrow valleys. In retreating from such valleys both ends were blocked by moraines, usually forming basins between for the accumulation of lakes. Many other, but more open, valleys were dammed, producing lakes such as Lake Placid. The preglacial stream valleys were likewise blocked and in some localities, as in the case of the Ausable river near Keene, were forced to seek new channels. The ice sheet left a mantle of till all over the area but much of it has been washed into the valley bottoms where it was worked over by the glacial lakes that were brought about by the ice damming the normal drainage lines. Continuing after the with- drawal of the ice body local glaciers persisted for a time on the slopes of the higher mountains, as is indicated by the moraine in the cirque on Esther mountain. _ It is the belief of the writer that the Lake Placid quadrangle was situated near the northeast rim of the ring of ice that sur- rounded and isolated the Adirondack highland from the rest of the State during the retreat of the great ice sheet, and thus the north- ward-draining valleys were blocked, preventing the escape of the 1The summary of the Glacial and Postglacial history was written by Mr H. L. Alling. I0O NEW YORK STATE MUSEUM vast quantities of waters which flooded the district with lakes. These bodies of water, especially at the higher levels, did not leave distinct shore-line features, for their outlets were controlled by ice lobes which caused constant or periodic lowering of their surfaces. The district covered by the glacial lakes here described can be divided into two sections, the western and the eastern. It is con- tended that the western section was the first to be relieved of ice, thus giving birth to the South Meadows lake. The uncovering of lower outlets to the west extinguished this lake which was suc- ceeded by Upper Lake Newman. During this stage the ice lobe that lay in the East branch of the Ausable river, eastern section, retreated to allow the Keene lake to form, with its drainage to the south. Further withdrawal of the lobe uncovered the Wilmington notch and thus the waters of the Keene lake fell to the level of Upper Newman, bringing about a union of the two sections. Suc- ceeding Upper Newman, Lower Newman held the stage until the lobe in the Elizabethtown valley opened the side-outlet channels in the center of the Ausable sheet, then the Saranac glacial waters held dominion, draining east. During the lower stages the western section was drained and only the eastern section was flooded. On leaving the higher levels we descend to the better defined shore lines and levels left by lakes whose outlets were over rock. The Wilmington lake, drained through the gulf, and the Upper Jay lake, both upper and lower phases, likewise drained to the east. The impossibility of distinguishing beaches and stream terraces in certain cases leaves in doubt the exact nature of some of the lower levels; the marine plain around Ausable Forks being the mast important of the lower series. The nature of the postlacustrine uptilting, which inclined the shore lines of the lakes northward, points to the conclusion that the land was experiencing uplift and warping while the ice was retreating from the region. The total amount of uplift since glacial times for the quadrangle was greater than 600 feet. STONE QUARRIES AND MINES The accompanying geologic map shows the locations of nineteen stone quarries and mines or prospect holes. Road Metal Excellent rocks for use in the construction of macadamized roads occur in inexhaustible quantities within the quadrangle. GEOLOGY OF THE LAKE PLACID QUADRANGLE IOI Most of the rocks actually used for such purposes are from the anorthosite and the syenite-granite series. These make a good grade of road metal. Quarries have been opened in Marcy anor- thosite 114 miles northeast of Upper Jay, and at the southern base of Hamlin mountain; in Whiteface anorthosite just south of The Flume; in normal syenite at the eastern base of Cobble hill, and near High fall; in a basic phase of syenite by the road 1 mile north of Malcom pond; in Grenville and Whiteface anorthosite mixed rocks by the road 3% miles north of Keene; and in weathered Grenville limestone by the road one-half of a mile north of Frank- lin Falls. Building Stone Fresh rock from most any portion of the great intrusive masses of anorthosite or syenite-granite would yield excellent building stone of great strength and durability, and often of unusual beauty. Two small quarries have been opened at the southern margin of the Pulpit mountain gabbro stock to furnish stone for the construc- tion of a nearby reservoir. No other building stone quarries worthy of special representation on the map were found within the quadrangle. Limestone for Lime There are several quarries from which Grenville limestone was obtained many years ago and burned to lime in nearby kilns. ‘Tlu:se are indicated on the map 1% miles north-northwest of Keene; on the hillside 314 miles north of Keene; near Woodruff fall; und just west of Middle Kilns. Iron Ore There are two localities from which a little magnetic iron ore was obtained many years ago. One of these is a small opening on the hillside 1 mile west-southwest of Keene. The ore occurs in small, irregular masses in the syenite and Grenville mixed gneiss area apparently as segregation masses in the syenite. The other locality is near the eastern base of Marble mountain about 144 miles southwest of Wilmington. There are two small openings in a rather coarse phase of Whiteface anorthosite, the magnetite occurring as irregular masses up to an inch across in a pegmatite dike. Graphite As above stated, graphite (so-called “black lead”) often occurs in small flakes in the Grenville limestone and certain of the schists and gneisses. So far as the writer could learn, there have been only 102 NEW YORK STATE MUSEUM two attempts to mine this mineral within the quadrangle, this having been in a small opening in the little area of Grenville limestone one-half of a mile south-southeast of Franklin Falls. The lime- stone contains numerous flakes of graphite, but apparently a vein of fibrous graphite less than an inch wide in the limestone was the center of interest. Mr Alling has described a recent attempt to develop a graphite mine 24% miles west-northwest of Wilmington on the side of Wilmington mountain.’ This work has been done since the writer’s survey of the region. According to Alling the last operations were in the spring of 1917. Several prospect pits or small shafts were sunk. The main rock is a coarsely crystalline Grenville limestone with large flakes of graphite. Associated with this limestone are some green pyroxene and red garnet rocks, and some basic peg- matite. 1N. Y. State Mus. Bul. 199. 1918, p. 36-37. Alford mountain, 78 Alling, Harold L., cited, 6, 73, 74, 79, 81, 84, 99, 102; Pleistocene geology, © 71-95 Ampersand mountain, 79 Amphibolite, 52-55 Anorthosite, 11, 13, 45, 50, 51, 52, 53, | 56, 96; chemical composition ot, | 25; an intrusive body, 27; younger | than Grenville, 31; foliation of, 66. anorthosite; | See also Marcy Whiteface anorthosite Anorthosite series, 16-34, 101; older | than syenite-granite series, 32 Aplite dikes, 41 Ausable Forks, 93, 100 Ausable lakes, 81 Ausable river, 14, 37, 82, 80, 91, 99. ; West - See also East branch; branch Ausable sheet, 31, 76, 84, 86, 88, 90, QI, 92, 100 Bald mountain, 90 Beaches, 88 Big Cherrypatch pond, 13, 37 Black Brook, 6 Black lead, 12, 101 Black Mountain, 86, 88 Blue Mountain quadrangle, 31 Blueberry pond, 78 Bowen, N. L., cited, 7, 27, 28, 32, 44, 5I Brown’s brook, 84 Brueyer pond, 78 Buck island, 37, 38 Building stone, 101 Cascade lakes, 74, 79 Catamount mountain, 16, 22, 41, 42, 44, 49, 54, 57, 58, 60, 63, 70; rocks. of, 63 Catamount mountain ridge, 9, 10, 37, 39° Catskill mountains, 75 Catskill region, 93 Cenozoic history, 99 Chadwick, George H., cited, 88, 95, Champlain valley, 94 Chapel pond pass, 82, 83 Chesterfield, 88 Clifford brook, 84, 89, 91 Clifford Falls, 22 Clifford hill, 89, 91, 92 Clifford lake, 92, 95 Cobble hill, 14, 37, 101 Cobb’s hill, 74 Cold brook, 79 Coldspring pond, 14 Connery pond, 13, 22, 37, 30 Copperas pond, 21, 37, 41, 88 Cranberry pond, 55 Crystalline limestones, 11, 12, 13 Cushing, H. P., cited, 6, 7, 20, 22, 23, 27.30; 33; 547) 733 (03: 93 Deformation, postlacustrine, 93; table for lower series of lakes, 95 De Martonne, cited, 75 Diabase dikes, 12, 60-63 Dikes, diabase, 12, 60-63; granite, 41; aplite, 41; pegmatite, 42; gab- bro-diorite, 57 Eagle Eyrie, 14 East Branch Ausable river, 10, 52, TGA. 77, 78, 80; 88, 82), 83,180 88, 90, 100 East hill, 81 Elizabethtown valley, 77, 100 Ellis mountain, 84, 86, 88 Emmons, E., cited, 6, 7 Fast Kilns, 6, 10, 34, 42, 44, 51, 57, 58, 60; area west of, 48 Elizabethtown quadrangle, 22, 73, 82 Erosional work, 72 Esther mountain, 9, 22, 73, 75, 99 [103] 104 Fairchild, Herman L., cited, 71, 77, 88, 89, 93, 94, 95 Faults, 68-70 Flume, The, 10, 21, 22, 24, 30, 32, 33, 49, 50, 62, 68, 69, 101 Foliation, 65-68 Franklin county basic syenite, 51 Franklin Falls, 5, 6, 10, 13, 16, 22, 27, 32, 37, 40, 42, 44, 49, 54, 63, 83, IOI, 102 Fremont hill, 40, 61 Gabbro-diorite dikes, 57 Gabbro masses, II, 59, 101; foliation of, 67 Garnets, 13, 14 Geography, general, 9-12 Geology, general, 9-12; structural, 64-70; pleistocene, 71-95; histori- cal, 96-100 Glacial lakes, extinct, 76-95 Glaciation, Wisconsin, 71; local, 74- 76 Gneisses, II, 12, 13, 52-57, I01 Granite, 13, 32, 33, 34, 39 Granite dikes, 41, 42 Granite porphyry, 40 Graphite, 12, 15, 27, 38, 101 Grenville gneiss, 24, 41, 49, 51, 52-55, 64, 60, 70, 101 Grenville hornblende gneisses, 32, 59 Grenville limestone, 6, 14, IOI, 102 Grenville mixed gneisses, 34, 55, 101 Grenville rocks, 15, 17, 28, 67, 69 Grenville series, 11, 12-16, 37, 49, 96; older than anorthosite, 31; tilting and folding of, 64; foliation of, 65 Hamlin mountain, 61, 101 Harker, cited, 43 Haselton, 5, 10, 17, 42, 92 Haselton lake, 90, 95 Hawk island, 22, 24 Haystack mountain, go, 92 High fall, 10, 30, 33, 34, 37, 39, 44, 56, 61, 62, 68, 69, 101 Historical geology, 96-100 Hornblende gneisses, 13 Hudson-Champlain strait, 94 NEW YORK STATE MUSEUM Insley, Herbert, cited, 6 Iron ore, 101 Jay, 88 Johns brook, 86 Johnson, D, W., cited, O7720 75 os 89, 92, 95 Keene; 5; 6, 13, 15) 17, 2s 27, 31,32, 35, 41, 43) 44,u52n stones 61, 62, 74, 76, 86, 88, 80, 90, 91, 92, 99, IOI; areas in vicinity of, 14- 16, 45; faults in the town of, 69 Keene-Cascade highway, 86 Keene gneiss, II, 34, 37, 38, 43-52, 56, 60, 64, 96; significance of distribu- tion of, 49; comparison with Cush- ing’s southwestern Franklin county basic syenite, 51 Keene hill, 88, 89, 90, 91 Keene Lake, 80, 81, 82, 83, 100 Keene valley, 77, 78, 81, 86 Keene Valley circle, 74 Kemp, James F., cited, 6, 7, 15, 20, 22, 25, 20, 27, 46, 73, 76, 87, 95 Knapp hill, 22, 27, 49 Labradorite, sketch of large crystal of, 19 Lake Champlain, 10 Lake Placid, 10, 19, 21, 22, 24, 35, 37, 38, 30, 55, 70, 74, 77, 80, 81, 83, 99; areas in vicinity of, 13 Lake Placid village, 5 Lakes, glacial, extinct, 76-95 Limestone for lime, Io1 Little High fall, 33, 56, 60 Little Whiteface mountain, 21, 22, 25, 33 Loch Bonnie, 21 Long Lake, 31 Long Lake quadrangle, 22, 78 ‘Lower Jay, 86, 88, 91, 92 Lower Jay hill, 88, 90, 91, 92, 93 Lower Jay lake, 92, 95 Lower Lake Newman, 81, 82, 83, 85, 100 Lyon Mountain quadrangle, 52, 590 INDEX TO GEOLOGY OF THE LAKE PLACID QUADRANGLE Malcom pond, 21, 22, 37, 39, 44, S101 Marble mountain, 9, 17, 30, I01 Marcy anorthosite, II, 17-21, 22, 27720) 131, 33) 415 42.43, 45,147, 65, 66, 67, 96, 101 Mesozoic history, 98 Middle Kilns, 6, 16, 22, 73, 76, IOI © Miller, W. J., cited, 7, 72, 73, 74, 76 Mines, 100-2 Mirror lake, 14, 74 Mixed rocks, 52-57 Moose island, 19, 21, 22 Moose mountain, II Moraines, 73-76; local, 74-76 Morgan pond, II, 24, 33, 37 Mt Marcy, 17, 26 Mt Marcy sheet, 73, 74, 76, 77, 79, 81, 84 Mt Whiteface, 9, II, 21, 22, 23, 26, 30, 37, 39, 49, 50, 69, 70, 73 25, 5I, New Bridge brook, 84 Newman, 5, 10, 13 North Creek quadrangle, 59 Norton cemetery, 86 Oak ridge, 46, 51, 91 Ogilvie, I. H., cited, 72, 73, 93 Ontario, 12 Otis brook, 92 Otis lake, 92, 95 Outwash plains, 76 Owen pond, 14, 21, 24, 30, 37, 49, 61, 69 Owls Head, 86 Paleozoic history, 97 Palmer brook, 78 Pegmatite dikes, 12, 41, 101 Pitch-off mountain, 9, 70, 72 Pitchoff pass, 73 Pleistocene geology, 71-95 Potsdam sandstone, 07 Precambrian history, 96 Precambrian rocks, 12-64 Pulpit mountain, 13, 60, 101 Pulpit rock, 39 Pyroxene gneisses, 13, 53, 102 47, 105 Quarries, 100-2 Quarry point, 89, 91 Quartz syenite, 34-37 Quartzites, 11, 12, 13 Raquette river, 78 Red Rocks, 15, 27, 31 Rich, John L., cited 75 Road metal, 100 Rochester, 74 Recky Branch lake, 92, 95 Ruedemann, Rudolf, cited, 73 St Armand mountain, 9, 70 St Huberts lake, 86, 87 St Regis sheet, 76 Sandstones, 12, 97 Santanoni quadrangle, 78, 79 Saranac glacial waters, 83, 84, 85, 87 Saranac quadrangle, 76, 80, 81, 83 Saranac river, 10, 27 Schists, 12, 101 Schroon lake sheet, 30, 81 Scott’s cobble, 79 Sentinel range, 6, 9, 17, 30, 47, 69, 70, 73, 79 Shales, 12 Silver lake, 39, 40, 41, 54, 74 South Meadows lake, 77-79, 80, 83, 100. Spruce hill pass, 81 Still brook, 39 — Structural geology, 64-70 Styles brook, 15, 35, 70, 84 Sunrise mountain, 21 Sunrise notch area, 47, 48, 51 Syenite, 13, 32, 33, 45, 101; basic phase of, 37, 101; granitic, 38 Syenite-granite mixed gneisses, 55- SY Syenite-granite series, II, 13, 34-41, 49, 101; foliation of, 66 Syenite-pegmatite dikes, 42 Taylor, F. B., cited, 76 Taylor pond, 74 Terraces, 88; causes of amount of material available for, 93 Tilting, postlacustrine, 93 4 106 Tom Peck pond, 13 Trout pond, 8&8 Tupper Lake Junction, 52 Undercliff, 21 Upper Jay, 5, 13, 20, 22, 30, 32, 35; 52, 53, 60, 62, 70, 73, 89, 92, 101; | area near, 15, 46, 51 Upper Jay lake, 80, 90, 95, 100 Upper Lake Newman, 79-81 82, 83, 100 Van Dorrien pass, 78, 79 West Branch Ausable river, Io, 22, 24, 37, O61, 62, 81; 83 West Kiln, 6, 13, 15, 40 West Kilns-Middle Kilns area, 15 27, 29, 31, 32, 33, 34, 37, 39, 41, 42, NEW YORK STATE MUSEUM 43, 46, 47, 48, 49, 50, 51, 52-55; 55- ;. 57, 60, 62, 63, 64, 60, 75, 96, IOI Whiteface brook, 37 Whiteface-Esther-Wilmington mas- Sit, 77 Wilmington, 5, 10, 17, 22, 32, 42, 63, 84, 86, 87, IOI, 102 Wilmington beach, 88 Wilmington lake, 86-88, 89, 90, 95, 100 ’ Wilmington mountain, 9, II, 15, 33, 37, 39, 50, 54, 70, 102 Wilmington notch, 10, 12, 14, 37, 56, 73, 77, 80, 82, 83, 100 Wilmington notch fault, 68, 98 Winch pond, 14 2255 | Wisconsin glaciation, 71 Whiteface anorthosite, 11, 17, 21-25, | Woodruff fall, 16, 39, 40, Io1 Woodworth, J. B., cited, 89 a ee ee ee JOHN M. GLARKE STATE GEOLOGIST UNIVERSITY OF THE STATE OF NEW YORK STATE MUSEUM BULLETIN 211-12 LAKE PLACID QUADRANGLE [Me Maroy) Geology by W. J. Miller, 1915-1916. (Ausable LEGEND > a] and post-glacial GapGatts errectualTy con: ceuling areas of Pre- cambric rocks. Igneous Rocks Ea Diabase dikes. | and metagabbro Sethare possibly older than the syenite-granite JE Gabbro—diorite dikes, more or less goeissoid, intrusive {nto the coarse granite but robably Sider than the post-) syenite gabbro. + Aplite, granite and peg- matite dikes, the per~ matite, In part at least, being younger than the gabbro. bs ‘e ee Keone gneiss. A border rock, usually porphyritio, Detween fAnorbhositeand syenite- anite produce! v Thagmatic assimilation. ras] | Bsuiy Basic syentte. A basic border phase of Gp Granite porphyry. A gneissoid coarse grained, usually por phyritié phase of the granite. Granite. A pmeissold, medium rained. very quartzose phase of the syenite, = Granitic syenite. Intermediate becween the syenite and granite Sy Quartz syentte. Distinctly gneissotd, moderately quartsose, and voupker than thé thosite. , anor! Whiteface anorthosite. A light gray or white phase of the Marcy anor thosite. Usually Medium grained and foliated. Marcy anorthosite. Light to dark bluish- gray and usually very coarse grained and non- folintet Mixed Rocks Whiteface anorthosite and syenite-granite mixed gneisses. Grenville or amphibo- Nite and syenite-granice mixed gooisses. i Grenville or amphibo- Jite and Whireface anor thosite mixed gneirsex. 7 Sedimentary Rocks Grenville limestone out- erops: Grenville, Various nelsses and schists and orystalline limestones, mostly dis- tinctly stratified. Ee Fault zones. Ae Dip and strike of Tollation. Glacial striae. R Stone quarries and mies, SURFICIAL SERIES PLEISTOCENE LATER INTRUSIVE SERIES EARLIER INTRUSIVE SERIES MIXED SERIES GRENVILLE SERIES PRECAMBRIAN Pe LS | | | J -class matter Mosertes B71. 1015, at. the Post Ofice at Albany, New York, vunder the act of August 24, 1912 ~ 2 Published monthly by The University of the State of New York s ALBANY, N. Y. - SEPTEMBER AND OCTOBER, i918 ¢ The University of the State of New York New York State Museum- ee Joun M. CLARKE, DIRECTOR ‘GEOLOGY OF THE SCHROON LAKE QUADRANGLE By WILLIAM J. MILLER PAGE PAGE General geographic features..... 5 | Structural geology..... Vane aagen ee geologic features and Pleistocene geology........ Cems Bae -publications..... Marae ora: . 7 | Summary of geological history... 93 tniefeee. 5% .... 10 | Mines and quarries..... eee e cee wee UG |. LLU MN ea wae eee eee eeae \ 3 ALBANY THE UNIVERSITY OF THE STATE OF NEW YORK dopa) THE UNIVERSITY OF THE STATE OF NEW YORK , Regents of the University With years when terms expire (Revised to September 1, 1919) 1926 PLINY T.Sexran LL.B. LL.D. Chancellor - = Palmyra 1927 ALBERT VANDER VEER M.D. M.A. Ph.D. LL.D. Vice Chancellor Albany 1922 CHESTER S. Lorp M.A. LL.D.. —_- -- - - Brooklyn 1930 WiLL1AM NottincHaM M.A. Ph.D.LL.D. —- —- Syracuse 1923 ABram I. Erxus LL.B. LL.D. D.C.L. = - - New York 1924 ADELBERT Moot LL.D. - - - - - - - Buffalo 1925 CHARLES B. ALEXANDER M.A. LL.B.- LL.D. Litt.D. - - - - —- -—- — — — — = Tuxedo 1928 WaLTER Guest Ketitocc B.A. LL.D. - - —- Ogdensburg 1920 JAMES ByRNE B.A.LL.B. LL.D. —- - —- — New York 1929 Herpert L. BripcMaNn M.A. - - - - - Brooklyn 1931 THomas J. Mancan M.A.- - - - - - -=— Binghamton President of the University and Commissioner of Education Joun H. Fintey M.A. LL.D. L.H.D. Deputy Commissioner and Counsel FRANK B. GILBERT B.A. Assistant Commissioner and Director of Professional Education Aucustus S. Downinc M.A. L.H.D LL.D. Pd.D. Assistant Commissioner for Secondary Education CHARLES F. WHEELOCK B.S. LL.D. Acting Assistant Commissioner for Elementary Education Greorce M Witey M.A. Director of State Library James I. Wykr, Jr, M.L.S. Pd.D. Director of Science and State Museum Joun M. CrarkeE D.Sc. LL.D: Chiefs and Directors of Divisions Administration, Hiram C. Case Agricultural and Industrial Education, Lewis A. WILSON Archives and History, JAMES SULLIVAN M.A. Ph.D. Attendance, JAMES D. SULLIVAN Educational Extension, WiLL1IAM R. Watson B.S. Examinations and Inspections, GEORGE M. WILEy M.A. Law, FRANK B. GitBert B.A., Counsel Library School, Frank K. WALTER M.A. M.L.S. School Buildings and Grounds, Frank H. Woop M.A. School Libraries, SHERMAN WILLIAMS Pd.D. Visual Instruction, ALFRED W. ABrams Ph.B. Se a a The University of the State of New York — aS Science Department, November 12, 1918 — — Dr John H. Finley hy President of the University Sie | vs [ transmit to you herewith and recommend for publication as a Bulletin of the State Museum, a manuscript entitled Geology of — the Schroon Lake Quadrangle which has been prepared, at my request, by Prof. William J. Miller. fone his ep ates is accompanied by necessary maps. Very respectfully yours Joun M. CLaRKE Director "Approved for publication this 13th day of November, 1918. President of the University is iy i New York State Museum Bulletin Entered as second-class matter November 27, 1915, at the Post Office at Albany, New York under the act of August 24, 1912 Published monthly by The University of the State of New York Nos. 213, 214 JNILIBAUNDYZ, INT, Ve. SEPTEMBER—OCTOBER, I9IS8 The University of the State of New York New York State Museum Joun M. CrarKke, DirEcTOR GEOLOGY OF THE SCHROON LAKE QUADRANGLE By WILLIAM J. MILLER GENERAL GEOGRAPHIC. FEATURES The Schroon Lake quadrangle? represents an area of approxi- mately 215 square miles in the central-eastern portion of the Adi- rondack mountain region. The territory is all in Essex county except the southern margin, which lies in Warren county. All the quadrangle is rugged, moderately mountainous, and mostly a wilderness, in these respects being quite typical of the 10,000 square miles of the Adirondack region. ’ The southern half of the quadrangle is less rugged than the northern and contains several farms, roads and villages. Schroon Lake, the largest village, is a well-known summer resort situated near the northern end of the lake of the same name. The other principal villages are Minerva, Olmstedville, South Schroon and Adirondack. No railroad enters the quadrangle, the nearest being the Adi- rondack branch of the Delaware and Hudson with stations at Riverside and North Creek in the northern portion of the quad- rangle next to the south. The northern half of the quadrangle is notably more mountain- ous and less settled, there being but one traveled highway (the Newcomb and Port Henry road) across it. All the permanent settlements of the northern portion of the quadrangle, including the little village of Blue Ridge, are located on this road. *See map in pocket of back cover of this bulletin. ee 6 NEW YORK STATE MUSEUM Both the highest and most rugged mountains are in the north- eastern one-fourth of the quadrangle. Hoffman mountain is the highest with an altitude of 3715 feet, but it does not stand out as a conspicuous peak because it is simply the loftiest of a considerable group of mountain summits in this vicinity. In this northeastern quarter, no other mountain rises to 3500 feet, but several lie between 3000 and 3500 feet, like Wolf Pond mountain (3473), Ragged mountain (3290), Sand Pond mountain (3040), Texas ridge (3212), and several unnamed points on Blue ridge. In the northwestern quarter of the quadrangle the country is notably less mountainous, the highest summits being Bailey hill (3115), the western peak of Sand Pond mountain (2970), and Hewitt Pond hill (2480-+-). In the southern half of the quadrangle no peak rises to 3000 feet, and only three rise to 2500 feet or more, these being Ore Bed mountain (2856), a peak 1 mile northeast of Ore Bed moun- tain (2584), and Hayes mountain (2822). A number of others have altitudes between 2200 and 2500 feet, among them being Cobble hill, Oliver hill, Beech hill, Pine hill, Green hill, Moxham mountain, and a group of points around Barnes pond. There is a marked tendency for the mountains and valleys to show a north-northeast by south-southwest trend. Among the more. or less well-defined ridges are the following: from Bailey hill, through Hayes and Ore Bed mountains, to Moxham mountain (12 miles) ; from north of Ragged mountain, through Sand Pond moun- tain, Washburn ridge, and Bigsby hill, to south of Oliver hill (14 miles) ; Texas ridge (3 miles); Blue ridge (7 miles); Beech hill to south of Pat pond (6 miles); and from Dirgylot hill, through Severance hill, Hedgehog hill, and Merrills hill, to Ledge hill (10 miles). For the most part these ridges are separated by narrow, nearly straight valleys. The most notable exception is the fairly well-defined east-west valley which the road follows across the northern part of the quadrangle. Schroon river, by means of a network of tributaries, drains all the area of the quadrangle except most of the northeastern por- tion, which is drained by Boreas river. Both the Schroon and the Boreas pass into the Hudson river. Altogether, there are about 30 lakes and ponds, the largest being Schroon lake with 7 miles of its length within the quadrangle. Next largest are Cheney pond nearly 2 miles long, and Hewitt pond about 1 mile long. i }Jo] OY} UO YOJOU URUTOPT_ pue jYsI4t oY} UO Idprit sexoy, ‘puod Aayreq JO JsvoyjNOs JIU I ‘JoJOY SUstIeAA WOT JSvOYJIOU PUe Y}IOU SUIYOO] sulejUNnOU oY} JO MoIA [e1OUOT) 916 “OyOUd “AeTITIN “£ “AN I 93¥I1q i fire WA 1 GEOLOGY OF THE SCHROON LAKE QUADRANGLE Wn GENERAL GEOLOGIC FEATURES AND PUBLICATIONS Most of the more common and well-known rock formations of: the Adirondack region, as well as certain unusual ones, are abund- antly represented in the Schroon Lake quadrangle. In the regular order of their geologic ages the principal rocks are as follows: Pleistocene Glacial and Postglacial deposits Paleozoic (Cambrian ) Little Falls (?) dolomite Potsdam sandstone Precambrian Diabase dikes Aplite and pegmatite dikes Gabbro stocks and dikes Keene gneiss, and assimilation product of the anorthosite and syenite-granite series Syenite-granite series Anorthosite series Grenville series of metamorphosed strata - ~The Precambrian formations constitute the foundation rocks of the entire quadrangle. Oldest of all are the Grenville strata, prob- ably of Archeozoic age, which are thoroughly crystalline. Gren- ville strata are well developed in the southern half of the quad- rangle, but their distribution is very “‘ patchy’ because they were invaded and cut to pieces by great masses of intrusive rocks. Next to the oldest known is the anorthosite series which occupies most of the northeastern half of the area. The great bulk of this rock is very coarse grained and highly feldspathic (Marcy anor- thosite), but it has a more or less well-defined border development (Whiteface anorthosite). . The syenite-granite series, so common throughout the Adiron- dack region, is next in order of age, being clearly intrusive into both the Grenville and the anorthosite. This series, more particu- larly its granite facies, is wholly confined to the southwestern half of the quadrangle where it is the most prominent rock formation. Several considerable areas of Keene gneiss lie in general between the anorthosite and syenite or granite areas. This rock is regarded by the writer as an assimilation- product which resulted from the incorporation and digestion of anorthosite by the molten syenite- granite, 8 NEW YORK STATE MUSEUM Gabbro stocks and dikes of the usual Adirondack sort are pronii- nently developed in the southwestern half of the quadrangle, each of two of the stocks occupying several square miles. Pegmatite and diabase dikes of the usual kinds, both later than the gabbro, are well represented. A few small dikes of aplite were also observed cutting the gabbro. Two small areas of Paleozoic strata are known in and near Schroon Lake village. One of these is Potsdam sandstone and the other is Little Falls (?) dolomite. Fifteen faults and zones of excessive jointing have been located and these have notably influenced the topographic development. Pleistocene deposits are very widespread, being especially thick in the mare prominent valleys where the underlying rocks are in - many places effectually concealed by them. The following list includes the principal publications which con- tain statements regarding the Schroon Lake quadrangle itself and the adjoining districts, as well as certain other papers which aid in understanding the geologic features of the quadrangle: 1842 Emmons, E. Geology of the Second District. Pt 2 of The Geology of New York 1879 Hall, C. E. Laurentian Magnetic Iron Ore Deposits of Northern New York. N. Y. State Mus. Rep’t 32, 1870; p. 133-40 1895 Kemp, J. F. Preliminary Report on the Geology of Essex County. 15th Annual Rep’t N. Y. State Geol., p. 590-604 1897 Kemp, J. F. & Newland, D. H. Preliminary Report on the Geology of Washington, Warren, and Parts of Essex and Hamilton Coun- ties. 17th Annual Rep’t N. Y. State Geol., p. 547-48 18907 Kemp, J. F. Physiography of the Eastern Adirondack Region in the Cambrian and Ordovician Periods. Geol. Soc. Amer. Bul. 8, p. 408-12 1902 Finlay, G. I. Preliminary Report of Field Work in the Town of Minerva, Essex County. 20th Annual Rept N. Y. State Geol, Pp. ro6-102. 1905 Cushing, H. P. Geology of the Northern Adirondack Region. N. Y. State Mus. Bul. 95 1905 Ogilvie, I. H. Geology of the Paradox Lake Quadrangle. N. Y. State Mus. Bul. 96 1906 Kemp, J. F. The Physiography of the Adirondacks. The Popular Science Monthly, March 1906 1910 Kemp, J. F. & Ruedemann, R. Geology of the Elizabethtown and Port Henry Quadrangles. N. Y. State Mus. Bul. 138 1912 Miller, W. J. Early Paleozoic Physiography of the Southern Adi- rondacks. .N. Y. State Mus. Bul. 164, p. 80-94 1913 Miller, W. J. The Geological History of New York State. N. Y. State Mus. Bul. 168 1914 Miller, W. J. Magmatic Differentiation and Assimilation in the Adirondack Region. Geol. Soc. Amer. Bul. 25, p. 243-61 ‘QOURISIP OY} UL UTeJUNOU Pog 20 pure WYsI1 sy} UO urejyunow sokepy ‘o[ppitu oy} Jeou puod Aopreq ‘puod Aapeg JO yseayjsouU apm Jyey-ouo julod eB wWoTy JseotINOS Mors Vv zZ aield GEOLOGY OF THE SCHROON LAKE QUADRANGLE 9 1914 Miller, W J. Geology of the North Creek Quadrangle. N. Y. State Mus. Bul. 170 1916 Miller, W. J. Origin of Foliation in the Precambrian Rocks of Northern New York. Jour. Geol., 24:578-619 1917 Miller, W. J. The Adirondack Mountains. N. Y. State Mus. Bul. 193 1918 Miller, W. J. Adirondack Anorthosite. Geol. Soc. Amer. Bul. vol. 20, no. 4 IO NEW YORK STATE MUSEUM PRECAMBRIAN ROCKS Grenville Series General character. The Grenville series of strata, including possibly some contemporaneous igneous rocks, are considered to belong among the oldest known, or Archeozoic, rocks of the earth. These strata represent original shales, sandstones and limestones which have become thoroughly crystallized into various schists and gneisses, quartzites and crystalline limestone or marble. The stratification is usually rather distinctly preserved though not with its original sharpness. A more or less well-developed foliation is always parallel to the stratification. Grenville rocks are not very prominent in the Schroon Jake quadrangle, the combined definitely known areas totaling not over 12 square miles. It is quite certain, however, that Grenville strata of great thickness once spread over not only the whole area of the quadrangle and the 10,000 square miles of the Adirondack region, but also over much of eastern Canada. They were, no doubt, mostly deposited under marine waters much like the typical sedi- ments of later ages. Within the quadrangle no positive proof for great thickness has been obtained, but in other districts a thickness of at least several miles has been demonstrated. Regarding the lands from which the Grenville sediments were derived, and the floor upon which they were deposited, we know nothing at present. That organisms lived in the waters while Grenville deposition took place those many millions of years ago seems evident from the dissemination of graphite (crystallized carbon) through much of the limestone as well as through certain of the schists and gneisses. A glance at the accompanying geologic map will show the very “patchy ” distribution of the Grenville rocks, this being due to the fact that the original body of thick strata, which was the universal country rock of the quadrangle, has been badly broken up, lifted or tilted in masses great and small, more or less engulfed and, in some cases, injected or even partially assimilated by the great intrusive bodies of the region. The entire absence of Grenville strata from the anorthosite area is doubtless due to a laccolithic structure of the anorthosite whereby the Grenville was notably lifted or domed over the rising magma, and completely removed sa ro BD) | ioe sane Se re eee cee HM Aay[eA UOOTYIS sy, ‘ddUeISIP oy} UT “uTod jsoysiy sir ‘UeWOTT ner Ree one aa q velosy J 9SR][IA 94} pue OV] UOOIYIC ssO19e JSOMY}IOU SUTYOO] SUIeJUNOW dy} JO MoIA VV € 93eI[dq GEOLOGY OF THE SCHROON LAKE QUADRANGLE Wit by subsequent erosion. The later syenite-granite magma, however, had a much greater tendency to more or less intimately break up, penetrate, and even engulf the Grenville strata. All except pos- sibly the few largest areas of the quadrangle may well be regarded as true inclusions in the syenite-granite series. Since nearly all the various types of Grenville rocks below men- tioned in the descriptions of the Grenville areas have been described in the writer’s report on the Geology of the North Creek Quad- rangle,’ it seems needless to repeat the details here. Description of Grenville areas. The rocks of the various - Grenville areas are described somewhat in detail, in order to have on record the more important data which may possibly aid in work- ing out at least the broader stratigraphic relations of the Adiron- dack Grenville series. The structural features of the Grenville are discussed in the chapter on Structural Geology. Dips and strikes are shown on the accompanying geologic map. Minerva area. ‘This is the largest area of the quadrangle (see map) and, although there are many excellent exposures, never- theless they are not numerous enough to make it possible to gain anything like an accurate idea of the stratigraphy and structure of the area. The best exposures are north, northwest and west of Minerva. South and southeast of that village there are very few outcrops so that the southern boundary of the area is mostly rather uncertain. Practically all the Grenville rocks of the area show a northwest strike (see map). The little hill just west of Minerva consists of well-bedded quartzitic, biotitic and hornblendic gneisses, all very typical of the usual Grenville series. Just back of the hotel a small mass of twisted crystalline limestone lies in contact with the granite there mapped. On the steep hillside one-half of a mile farther west the rock is mostly hornblende gneiss, some with garnets, and with some bands of biotite gneiss and quartzite interbedded. Northwest of Minerva, in and near the garnet mine, crystalline limestone associated with much red garnet and green pyroxene is closely involved with granite, this being separately mapped as mixed rocks. Just south of the mine there is a vertical ledge, nearly 100 feet high, of well-bedded granitic-looking gneiss, impure quartzite, and some limestone. *N, Y. State Mus. Bul. 170, I2 NEW YORK STATE MUSEUM On the hillside north of the road, from Calahan pond southeast for 1 mile, there are many fine exposures of crystalline limestone with some closely involved pyroxene and hornblende gneisses — toward the north. Toward the south this limestone contains yellow quartz and graphite. That portion of the area near the map edge from Calahan pond northward shows a number of fine exposures of crystalline lime- stone mostly containing graphite associated with some pyroxene and hornblende gneisses, and exhibiting local foldings or contor- tions. Just north of the small gabbro stock at the map edge the Grenville consists of hornblende, hornblende-garnet and pyroxene gneisses, and some quartzite. A very fine outcrop of Grenville was observed a few rods west of the quadrangle boundary on the southern side of the small gabbro stock 1 mile southwest of Sherman pond, the ledge being clearly visible from the road. In a section fully 100 feet thick pyroxene gneiss and biotite gneiss and quartzite are beautifully stratified in thin beds. In the lower half of the section a dike of granite several feet thick has been intruded, both the dike and its foliation being perfectly parallel to the stratification of the Grenville. Most of the ridge 1 mile east of Calahan pond appears to be quartzite with hornblende and pyroxene gneisses and some lme- stone at its eastern base, and hornblende gneiss at its western base, but the outcrops are not very good. On and near the road 1 mile a little north of east of Minerva there are several ledges of rather coarse graphitic limestone associated with some thin-bedded, gray, rusty graphitic gneiss and quartzite. Exposures showing contorted limestone with pyroxene and horn- blende gneisses occur three-fifths of a mile west of the mouth of Kelso brook. The hill 1 mile west of Irishtown consists of hornblende and biotite gneisses on the south side of the small gabbro stock, and quartzite underlain by some limestone on the north side. On the slope northwest of the hill just mentioned, several expos- ures of well-bedded hornblende-garnet gneiss, and one of lime- stone, were observed. From Falls brook northward the Grenville nearly all appears to be typical hornblende-garnet gneiss in good exposures. Limestone shows in a small exposure on the trail one- half of a mile northwest of Irishtown. JE DAOGe jodF OOLT SOSII UIe}UNOCU 9} puke joojf OOTI FO ophyye uv ye sol] Spy ONE] AV] [VIOP[S JOUuTJXO oY} JO poq dy} ST Ory At ‘punois -910f OY} Ul AoT[eA oY T, [[IY poomAeg jo oseq oy} 4e Julod & WO, MODS Sse OSp's onl jo pues UtoyIIOU oY |, LI6T “oJoyd “ASTIN “£ “AA er - v 23e1q GEOLOGY OF THE SCHROON LAKE QUADRANGLE 13 Olmstedville-Irishtown area. This area of Grenville is almost certainly connected, under the Pleistocene of Minerva stream val- ley, with the Minerva area. In Olmstedville, by the stream one-fifth of a mile east of the mill, there is a big ledge of typical limestone. At the bridge just east of Olmstedville, limestone underlying hornblende gneiss forms a ledge 100 feet long. By and near the road one-third of a mile east of the bridge just mentioned, there are several outcrops, includ- ing hornblende gneiss, rusty mica quartzitic gneiss and limestone. Two small outcrops of limestone occur by the road about a mile east of Olmstedville. In a field 114 miles northeast of Olmstedville, there is a large exposure of typical graphitic limestone with some small masses of rusty gneiss twisted into it. Nearby is an outcrop of horn- blende gneiss. Near the road one-half and three-fourths of a mile, respectively, southwest of the village, there are several small exposures of graphitic limestone with some small masses of closely involved pyroxene gneiss. The one nearest the village is weathered to a friable mass and is used for repairing roads. Near the road corners one-half of a mile northwest of Olmsted- ville there are several outcrops of limestone, some containing graphite and green pyroxene and associated with hornblende gneiss. From this locality northward for a mile, by and near the road, there are other good exposures of similar rocks. From one-half to 1 mile east-southeast of Irishtown there are interesting exposures of Grenville. Coming against the syenite on the south side (see map) there are several good exposures of limestone arranged along a strike N 70° W. Just within the syenite _there is a long, narrow inclusion of quartzite. Where the limestone belt comes to the road, hornblende gneiss outcrops. Just north of the tongue of syenite there are large exposures of quartzite with a little associated limestone arranged along a N 70° W strike. One mile north-northwest of Olmstedville, and extending from the road eastward for 200 yards, there are good outcrops of. rusty biotite gneiss, hornblende gneiss and quartzite. Along the road from one-half to 1 mile north of Irishtown, there are several exposures of hornblende gneiss (some garnetiferous) and a little associated limestone. The tongue of Grenville which forms part of the mountain spur 1 mile north-northeast of Irishtown consists of hornblende and 14 NEW YORK STATE MUSEUM hornblende-garnet gneisses with a little interbedded quartzite and biotite gneiss. Catamount hill area. Catamount hill itself is a practically solid mass of well-bedded biotite-graphite schist or gneiss with some belts of quartzitic rock toward the summit. ; At the old graphite mine by the road west of Catamount hill, the rock which was mined is a rusty looking biotite-graphite schist in very thin layers. Most of this rock, forming a belt 30 to 40 feet wide, contains tiny flakes of graphite, but one zone in it only a few feet wide is very rich in large flakes of graphite. In contact with this graphite-rich rock there is a narrow band of limestone containing green pyroxene and graphite. Near the road one-fifth of a mile north of the mine there occurs a ledge of quartzitic to granitic looking gneiss with one two-foot wide band containing lenslike garnets up to an inch long. Adirondack village area. This small area shows only a few out- crops. A small exposure of limestone just east of the village con- tains some graphite and green pyroxene. By the road one-half of a mile south of the village, there occurs a ledge of bedded horn- blende-biotite gneiss. At the southern end of the area there are several good exposures of variable rocks, mostly hornblende gneiss, biotite gneiss and pyroxene-garnet gneiss. These are mostly well bedded but shot through with some coarse granite. No outcrops occur along, or just east of, the map boundary here, but, judging by Doctor Ogilvie’s Paradox lake map, this Adirondack village area of Grenville probably extends across the boundary. Areas on the shores of Schroon Lake. At the southern end of Isola Bella there is a mass of limestone 20 feet long, really an inclusion in the granite. This limestone contains pyroxene, quartz and some graphite. At Grove Point there are two exposures by the lake shore, one being limestone with bunches and strips of green pyroxene gneiss kneaded into the mass, and the other pyroxenic and hornblendic gneisses with a little associated limestone. A few rods south of the Grove Point Grenville, syenite con- tains a long, narrow inclusion of Grenville limestone. On the lake shore one-half of a mile east of South Schroon, limestone with patches of green pyroxene gneiss twisted into it shows in a good exposure. Areas northwest of Schroon Lake village. The small lens- shaped area shown on the map 1 mile northwest of the village con- GEOLOGY Of THE SCHROON LAKE QUADRANGLE 15 sists of interbedded quartzite (some garnetiferous), quartz-pyrox- ene gneiss, and quartz-feldspar gneiss with several thin layers of limestone containing green pyroxene. The area just east of North pond shows a number of good exposures of well-bedded hornblende-garnet gneiss and hornblende gneiss with one two-foot thick layer of limestone in the horn- blende gneiss. Near the western corner oi the area there are many large reddish brown garnets up to 4 or 5 inches in diameter, but without hornblende rims as is often the case with such large garnets in the Grenville hornblende-garnet gneiss elsewhere in the Adirondacks. Other areas of Grenville. In the small area on the west face of Wilson mountain, pyroxenic, hornblendic and quartzitic gneisses are well exposed, some of these being locally contorted. Along the eastern side of this area the Grenville rocks are more or less inti- mately charged with granite. At the western end of the area just southwest of Oliver pond there is a big exposure of hornblende-garnet gneiss interstratified with thin-bedded, fine grained, pinkish gray, quartz-biotite schist. A few rods farther east there occurs a ledge of limestone con- taining green pyroxene, quartz and a little graphite. Toward the eastern end of the area the rock is hornblende-garnet gneiss. A small lenslike inclusion of hornblende-garnet gneiss with gar- nets up to an inch across occurs in the granite one-half of a mile west of Oliver pond. One mile northeast of Loch Muller, in the small area mapped, there is a single large outcrop of hornblende gneiss, somewhat garnetiferous. On the southern slope of Hayes mountain, three-fourths of a mile from its summit, a small lenslike body of typical hornblende- garnet gneiss with garnets up to an inch across occurs as an inclusion in granite. A similar small inclusion occurs in the syenite 2 miles north-northwest of Irishtown, and still another in granite 1% miles west-southwest of the summit of Hayes mountain. *This is the place printed on the map accompanying this bulletin, but since the map was printed the post office has been moved 2 miles to the northwest to Warren’s hotel. 16 NEW YORK STATE MUSEUM Some interesting exposures occur in the small area 1% miles — northwest of the summit of Hayes mountain. In the old stone quarry the rock is greenish limestone containing serpentinized green pyroxene and some graphite. This is associated with some horn- blendic and quartzitic gneisses. Similar rocks outcrop on the west bank of the stream, but there the pyroxene is less serpentinized. Undoubtedly this mass of Grenville is a fairly large inclusion in the granite which outcrops close by on all sides. In the Hewitt Pond brook area there are several good outcrops of Grenville hornblende gneiss and hornblende-garnet gneiss. A conspicuous lenslike mappable inclusion of hornblendic and quartzitic well-bedded gneisses occurs in the granite 114 miles east- southeast of Boreas river. Still other masses of Grenville occur within the aval but these are so closely associated with other rocks that they are mapped and described as “ mixed rocks.” Anorthosite Series General considerations. Recently the writer has published a rather elaborate paper’ on the whole problem of the age, relations, and origin of the Adirondack anorthosite. The interested reader is referred to that paper for much more material than is pre- sented in this bulletin. Some years ago, Professor Cushing, in his report? on the Geology of the Long Lake Quadrangle, presented evidence to show that the anorthosite is a great intrusive body dis- tinctly younger than the great syenite-granite series of the Adiron- dacks. The writer heartily agrees with this view, and in his own field studies, particularly in the Lake Placid and Schroon Lake quadrangles, he has found much more evidence in support of Cush- ing’s view. Recently, however, Dr N. L. Bowen® has offered quite a different explanation of the origin and relations of the anor- thosite. His hypothesis and the writer’s objections to it are briefly stated below, but a fuller criticism is presented in the paper above cited. The anorthosite occupies a largely unbroken area of about 1200 square miles of the central-eastern Adirondack region. It is promi- nently developed with nearly all its facies in the Schroon Lake 1Geol. Soc. Amer. Bul. 29 No. 4, 1918, p. 399-462. 7N Y. State Mus. Bul 115, p. 479-82. 10907. *Jour. Geol., 25:209-43. 1017. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 17 quadrangle where, as a result of its careful study, important light has been thrown upon the age, relations, structure, and origin of the great anorthosite body. Most of the northeastern half of the quadrangle, or an area of over 80 square miles, is occupied by anorthosite to the exclusion of all other formations except Pleis- tocene deposits and a few small basic dikes. Marcy type of the anorthosite. By far the most abundant general facies of the rock may be called Marcy anorthosite because of its great exposures on Mount Marcy in the quadrangle next to the north. The most typical portions of the Marcy anorthosite are coarse grained, light to dark bluish gray, and consist largely of basic plagioclase feldspar, mainly labradorite. The dark bluish gray labradorite crystals usually vary in length from a fraction of an inch to several inches, crystals about an inch long being very common. Among other places, labradorites from 5 inches to I foot long were observed on the western of the three Peaked hills, and on the ridge 1 mile north-northwest of Blue Ridge village. Only occasionally do these labradorites exhibit the play of colors so characteristic of this species of feldspar. Twinning striations are often evident to the naked eye on the cleavage faces. Accessory minerals visible to the naked eye are large individuals of pyroxene and hornblende, and small individuals of biotite, ilmenite, pyrite, garnet, and more rarely chalcopyrite or pyrrhotite. These accessory minerals ordinarily constitute 5 to 10 per cent of the typical coarse anorthosite, but there are local developments of the rock which are made up almost entirely of plagioclase, and still others, rather abundantly developed as zones, bands and irregular masses, which contain from 10 to 25 or more per cent dark minerals, these last named types being really anorthosite-gabbros. Such gabbroid facies are more fully described below. An important facies of the anorthosite is one in which the dark labradorites, from a few millimeters to an inch or more across, stand out conspicuously in a distinctly granulated groundmass of feldspar. The granulated material varies from light gray to pale greenish gray. It is very evident that the large labradorites are roughly rounded uncrushed cores of what were considerably larger individuals before the rock was subjected to the process of granu- lation. All degrees of granulation are exhibited to extreme cases where the rock has been so thoroughly granulated that few, if any, labradorite cores remain. 18 NEW YORK STATE MUSEUM Much of the typical Marcy anorthosite is devoid of foliation, though in some local zones of almost perfectly pure plagioclase rock there is a notable tendency for the feldspars to show a crude parallelism (plate 6). The more gabbroid facies of the rock, how- ever, often exhibit a fair to well-defined foliation accentuated by the crudely parallel arrangement of the dark minerals. In thin section, with a low power of the microscope, the larger labradorites are usually seen to be filled more or less with myriads of very dark dustlike particles, probably ilmenite. The minerals contained in several thin sections of the Marcy anorthosite are shown in table 1 below. Chilled border facies of the anorthorsite (Whiteface anortho- site). Around the borders of the great body of Adirondack anorthosite, and in some places a number of miles within it, there is quite generally a notable development of white or very light-gray labradorite and an increase in the femic minerals causing such rocks to be anorthosite-gabbro or even gabbro. Such rocks, well devel- oped in the Schroon Lake quadrangle, are almost invariably finer grained and lighter colored than the typical Marcy anorthosite, though in some localities a few large, scattering labradorite indi- viduals occur. A foliated structure is generally evident. Although they are more or less variable in general appearance and composition, the writer has proposed that these border phases of the anorthosite be classed as Whiteface anorthosite, a name given by Professor Kemp to the type which occurs abundantly on Mount Whiteface near Lake Placid. At the summit of Mount Whiteface the rock is medium grained and consists of white plagio- clase (chiefly labradorite) with 10 to 15 per cent of dark minerals scattered through the mass parallel to a crude foliated structure. Such rock, which is quite typical of the Schroon Lake quadrangle Whiteface anorthosite, stands out in marked contrast against the typical Marcy anorthosite which is not so gabbroid, very coarse grained, light to dark bluish gray, and generally not so well foli- ated. More exceptionally the Whiteface anorthosite is nearly pure white, being quite free from femic minerals. Much of the rock, however, is locally richer in dark minerals, which may constitute 15 to 30 per cent of the whole. The minerals other than the feldspar are practically the same as in the Marcy anorthosite. Table 1 gives a good idea of the mineral content of the Whiteface anorthosite of the quadrangle. ISET[IA ISPIY ING JO som ou & FO PaAryj-9u0 YOoI1d yourig IY] FO poaq oY} Ul o}ISsSoY}IOUL ADIVIN LIGE ‘oJoyd “ASTI “£ M a = GS o23°Ig GEOLOGY OF THE SCHROON LAKE QUADRANGLE ~- 19 Table 1 Thin sections of anorthosite fe} = g o 2 Soleus 3g a 2 5 6 SVs g [4 = 2 eee Bf WS See I ey | SY) eh Ae irae Ste ee eee) Gee Wrasse o ue} b ojlm| 4 i= a|p|s bb a} ° p fe) = o| oO Mesh al Sue Sales csr ni seen es ssi | BU | el es ae Es rl lees ta |) He PSA Wf (EV Sy tose Wty ay esy pes | ra a < N & |HOlO q : Somer CT MOO eal clic cilies leds calles elie as oe| Line URAIG ona HIE So alle Ge oc > B Za Gls) “lens! UA al) te lleoseollecdiines eee eI HetPaearenpel att. Maes toe eonemrd 1, ee sti P= PANT Sit Olt Owe S| cr oe UG fin) ie) K=N eee al Feet etal [ep recy Ieicren cc S HO) | NA Le | Cte coy eel ecm ted oes [Petce, elyeal saved) Lil morons lleremeyf svenetsce teats all ois Sa eollacie ¢ = II] 5d .1| 75] Io 12 nO tert tcl leche little} little)..... 6 HA” ONG) CAlecllogc 4 3 RHO oo Bolla nc oe little} little sg i] 7) We Cs olla oe 5 TO} meh lic tle ae oil Wee. 2 oo e|fe flo after B 14; 7e9| &5' RA aio olle Pele Enbstees tel Pee ec, little) little)..... als le q I5| 7h1| 81 Slleao 5| 14 Bh et ce little] little}.....].. 2 : 16| 7g1| 68 10| 23 Rel aire 5 ise lie stssetail ine sstae (ieee tota| el | eel 5) 7 Sem SS) ase ge aerate 9| 14 a ee ciacs it lel een GDN 5 2l]o o{lo 6 s 18} ges] 78 4 1%] 14) 4 oo ariel se gal] Minds ols ella S|] EO) Ob ag) ES Bolle de Ti Sif WWII) no odlloomoc little} little}. .|..].. ae} || Quill Ges} fee Ih OV alae 6 itech Ly Gio oo coll WUE! cob elloocaslloossellsolor 5 ce || 2a) mie Apes toa aclooe TO} Mera |Wlittle| eee BS obo beaalieslloclise 37| 8 £25 67, O}] Ye alle i llevcecel [hevateats fei Rosucyeve 4| little callers No. 20, three-fourths of a mile southeast of summit of Hoffman moun- tain; no. 23, by the road 1 mile northeast of Boreas river; no. 24, by the stream I mile east-southeast of summit of Ragged mountain; no. 10, 1 mile southeast of summit of Oliver hill; no. 11, 1% miles a little west of north of Irishtown; no. 12, lake shore just north of Grove Point; nos. 13 and 14, one-half of a mile west-northwest of Bigsby hill; no. 15, by road at Loch Muller; no. 16, one-third of a mile west of Loch Muller; no. 17, one-half of a mile south-southeast of summit of Severance hill; no. 18, top of Hayes mountain; no. 19, by the brook southwest of Smith hill; no. 21, near western summit of Sand Pond mountain; no. 22, near cross-roads at Boreas river; no. 37, southern brow of Cobble hill. _ No. 17 of table 1 exhibits very fine reaction rims as follows: (1) magnetite with rims of garnet; (2) pyrite with rims of garnet; and (3) magnetite with successive rims of hypersthene and garnet. Both the Marcy and Whiteface types of anorthosite are quite certainly differentiation phases of the same cooling magma, the latter representing a chilled border or marginal portion. The one type grades into the other, and nowhere has one been found definitely to intrude the other. _ Special descriptions of Whiteface anorthosite occurrences. In the Boreas river area the Whiteface anorthosite is mostly rather uniformly moderately gabbroid and foliated with scattering bluish labradorites, but some local variations from this composition and structure were observed. Near the cross-roads at Boreas river (no. 22 of table 1) a ledge is unusually rich in pyroxene and quartz. 0S SS eee 20 NEW YORK STATE MUSEUM In the eastern portion of the Sand Pond mountain area the rock is nearly white and free from femic minerals, nonfoliated, and with only a few scattering blue labradorites (no. 21 of table 1). The rock of the western portion of the area strongly suggests Marcy anorthosite and grades into it. It is light gray and non- foliated with 10 to 20 per cent dark minerals and garnets and many blue labradorites. The Severance-Smith hill area, the pen shown on the map, comprises mostly rather uniform, very typical, Whiteface anortho- site (nos. 17 and 19 of table 1). At the extreme southern end it contains an admixture of Grenville. In the large area southwest of Bailey hill the Whiteface anor- thosite is mostly very typical. By the old road on the west side there are some rather gabbroid, garnetiferous, foliated zones, and in the eastern portion there are locally developed masses with many garnets and some scattering blue labradorites. A large ledge of Whiteface anorthosite at Loch Muller is exceed- ingly variable as regards both content of femic minerals and folia- tion. It contains some bluish labradorites and scattering garnets (no. 15, table 1). One-third of a mile farther west in the same area the rock is distinctly gabbroid and foliated and. carries 8 or IO per cent of quartz (no. 16, table 1). In the western part of the area the rock is very typical Whiteface anorthosite. The long, narrow area south of Hewitt road shows Whiteface anorthosite varying from light-colored, moderately gneissoid to dark-colored, gabbroid, very gneissoid facies. The rocks of the area west of Bigsby hill exhibit many local ‘variations from typical anorthosite to very gabbroid, gneissoid anorthosite. In some ledges quartz is visible to the naked eye. Nos. 13 and 14 of table 1 are from this area. A big ledge of gabbroid, very gneissoid Whiteface anorthosite (no. 11 of table 1) in the small area 114 miles a little west of north of Irishtown is intimately associated with Grenville horn- blende-garnet gneiss, the latter commonly occurring as distinct strips or lenslike inclusions in the anorthosite. The remaining small areas of Whiteface anorthosite require no special description here. Variable composition and structure of the anorthosite and its - significance. General statements. Contrary to Bowen’s statement that “anorthosites are made up almost exclusively of the single mineral plagioclase,” the writer’s experience in the field has made ‘toddn oy} Ul JOU yng Jared TOMO] DY) Ul JoUTSIp AIDA st ‘o}IJOpvaAqe] Jo syeysAID oSae] JO wistjoayjvsed epnsd 0} anp ‘uoreT[Osy ‘puod jeq JO JsoMYJIOU [TU B JO SYjIMOF-d914} Play ev UL o}ISOyJIOUR ADIeIY JO Japynog e JO aed FO MoIA APIN AI6T “OJOYM “IOITYIN “Lf “AY 4 Z 9 238Id GEOLOGY OF THE SCHROON LAKE QUADRANGLE Zu it clear that the Adirondack anorthosite is by no means an almost perfectly homogeneous mass of plagioclase. The main bulk of the Marcy anorthosite contains at least 5 to 10 per cent of minerals- other than plagioclase. Portions with about 10 per cent are com- mon, and in many places there are 10 to 20 per cent, or even more, of dark minerals. It is also true that some portions of the great mass contain less than 5 per cent of femic constituents. _Con- servatively estimated, the average Marcy anorthosite carries fully IO per cent of minerals other than plagioclase. In the writer’s work in both the Lake Placid and Schroon Lake quadrangles, many observations have been made of anorthosite- gabbro and more typical anorthosite exhibiting perfect gradations from one into the other. Such gabbroid facies exist locally through- out the body of Marcy anorthosite, in many places as rather dis- tinct zones or belts a few feet or rods wide, and in other places on much larger scales. Many other gabbroid portions are much more irregular in shape, and not so distinctly separated from the purer Marcy anorthosite. The anorthosite-gabbro very commonly, and the typical Marcy anorthosite less commonly, locally exhibit more or less well-devel- oped foliation with exceedingly variable strikes. Marked varia- tions in degree of foliation often occur in single ledges. It is also important to note that granulation, so prevalent throughout the anorthosite body, shows many extreme variations, often in single outcrops. Another variation of the anorthosite from a pure plagioclase rock consists in the dustlike (schillerization) inclusions of a dark mineral, probably ilmenite, in the labradorite. These are so numer- ous as to cause most of the labradorites to have a dark bluish gray color. Thus even the plagioclase crystals are not pure lime-soda feldspar. A Finally in this connection, attention should be called to the pres- ence of a very appreciable amount of potash in the typical Marcy anorthosite, as shown in an analysis made for Professor Kemp. Whether this potash exists in regular potash-feldspar form, or is part of the labradorite proper, it is additional proof that the anor- thosite is not a practically pure mass of lime-soda feldspar. Some examples of variations of Marcy anorthosite. Near the top of the hill 1 mile a little to the west of north of Blue Ridge village, the following variations across the strike from south are finely exhibited: first, there is typical Marcy anorthosite; then, a band 2 feet wide of gneissoid, moderately coarse-grained, gabbroid is) ie) NEW YORK STATE MUSEUM anorthosite with a few labradorite phenocrysts; then, a belt 40 feet wide of less coarse-grained anorthosite with a few labradorite phenocrysts and scarcely any femic minerals; next, a belt 35 feet wide of very coarse-grained, gabbroid anorthosite with pyroxene and labradorite crystals from 6 inches to 1 foot each in length. None of these belts or zones is very sharply separated, though in some cases the change from one into the other takes place within a few inches. At the rapids of Boreas river, just before the stream enters the Brace dam reservoir, a big ledge of typical Marcy anorthosite with very few femic minerals contains a very irregular shaped mass of highly femic and garnetiferous anorthosite some 30 feet long with a maximum width of 10 feet. Except for the 20 to 30 per cent of dark minerals, this femic anorthosite is much like the inclosing anorthosite. Boundaries against the typical anorthosite are not sharp, but the complete transition takes place within 5 or 6 inches. The femic rock is nonfoliated, but the typical Marcy anorthosite on one side of it has most of its labradorites (1 to 2 inches long) arranged parallel to the contact with the femic rock. This par- allelism is most evident close to the contact and not at all notice- able 6 or 8 feet out. By the road three-fourths of a mile east of where it crosses Boreas river, a 50-foot exposure of typical Marcy anorthosite, with less than 5 per cent femic constituents and with many labradorites an inch long, exhibits very distinct foliation due to parallelism of the labradorites. This rock grades into typical nonfoliated anor- thosite of the adjacent exposure. By the same road above mentioned, but one-third of a mile far- ther east, a 50-foot ledge of anorthosite with 10 or I5 per cent femic minerals contains several distinctly foliated zones not see SEOMICASG! TisOMN WS THESE OI mS inoyele, In a ledge of typical Marcy anorthosite on the middle-southern slope of Saywood hill, a distinctly foliated zone occurs in contact with nonfoliated anorthosite on either side. From Saywood hill to Clear Pond mountain there are large scale variations represented chiefly by typical, nongabbroid, mostly non- foliated, Marcy anorthosite with some labradorites up to 3 inches long on Saywood hill; very coarse, rather gabbroid, nonfoliated anorthosite containing labradorites up to 6 or 7 inches long and 10 to 20 per cent femic minerals on Clear Pond mountain; and many fine exposures of more typical Marcy anorthosite with usually 10 to 15 per cent femic minerals and little foliation. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 23 In the whole area from Blue Ridge mountain eastward to the map limit, there are many excellent exposures of remarkably uni- form, very typical Marcy anorthosite, there being few gabbroid or foliated variations in this large area. Where the road crosses the Branch brook a ledge of typical Marcy anorthosite contains an irregular gabbroid mass about 2 | feet wide without sharp boundaries against the inclosing rock. Variations similar to those just described were observed in many other places, but enough have been described to illustrate the nature of the variability of the anorthosite. Significance of the composition and variations of the Marcy anor- thosite. According to Bowen, “ anorthosites are made up almost exclusively of the single mineral plagioclase” and therefore “the conception of the mutual solution on minerals in the magma and the lowering of temperatures consequent thereon is no longer applicable.” But, in view of the facts above presented which show that the anorthosite averages fully 10 per cent femic minerals visible to the naked eye; that the labradorites carry myriads of tiny inclusions of a dark mineral; and that the anorthosite contains a notable percentage of potash, is the mutual solution theory neces- sarily precluded? Have we any proof that a rock with such a quantity and variety of constituents other than plagioclase could not have been, largely at least, molten as such? Is it safe to argue from experiments on small amounts of rather pure melts under ordinary laboratory conditions that a rock like the Adirondack anorthosite could not have existed as a true magma? Bowen says that “a rock containing 10 per cent diopside (and 90 per cent plagio- clase) could have had a maximum of 35 per cent liquid” in an arti- ficial melt, and that in a natural melt “the probability is that the amount of liquid would be relatively somewhat larger on account of the presence of orthoclase in the liquid.” But the Adirondack anorthosite would have formed a melt of notably more compli- cated composition than an artificial melt with 10 per cent diopside, and this under deep-seated geologic conditions. Is it safe to say, therefore, that such a melt may not have been a true magma with a*high percentage of liquid? Furthermore, allowance should be made for various agencies well within the earth, particularly dis- solved vapors the escape of which pressure tends to prevent, and which tend to increase fluidity. Since the foliation of the anorthosite is essentially a magmatic flow-structure, it shows that, at the very least, large portions of the 24 NEW YORK STATE MUSEUM body of anorthosite once possessed fluidity enough to permit dis- tinct magmatic currents or movements. The significance of the foliation is thus an important consideration. Even the typical Marcy anorthosite, almost entirely free from femic minerals, not rarely exhibits a magmatic flow-structure foliation (plate 6), the labradorite crystals having been strung out into crude parallelism in a yet molten portion of the rock. Not only was this interstitial liquid in sufficient quantity to permit the development of distinct magmatic flowage, but it was essentially molten plagioclase. It could have been nothing else. Hence we here have evidence directly opposed to Bowen’s statement that the anorthosite was never at a temperature sufficiently high to melt plagioclase. It is not argued, however, that the anorthosite as such necessarily was intruded in the form of a true magma to its present position, having been differentiated at a much lower level. Rather, it is probable that a gabbroid magma was the original intrusive which, either during the process of intrusion or after the magma came nearly to rest, or both, differentiated to give rise to the anorthosite which was then, in considerable part at least, really molten. This matter is more fully discussed below. Though the writer believes the anorthosite as such to have been molten to a very considerable degree at least, it is by no means necessary to assume that it was ever completely molten with a high degree of fluidity, or even only a moderate degree of viscosity. None of the field facts, however, necessarily preclude the hypothesis that the whole mass of the anorthosite may once have been com- pletely molten, but without a high degree of fluidity. Before leaving this consideration of the significance of the varia- bility of the anorthosite, emphasis should be placed upon the fact that, in many places, its mass shows unmistakable evidence of having differentiation phases of anorthosite-gabbro or even gabbro, while there is no positive evidence for its differentiation into sye- nite or granite as should be the case according to Bowen’s hypothesis. Relation of Whiteface and Marcy types of anorthosite. In the Schroon Lake quadrangle as elsewhere, it is clear that the White- face anorthosite is a gabbroid border facies of the Marcy anor- thosite with perfect gradations from one into the other, and with no evidence that syenite or granite was ever developed as a rock intermediate between the border phase and the true anorthosite as required by Bowen’s hypothesis. Though it has been notably cut into, and partly assimilated by the syenite-granite body, a glance at GEOLOGY OF THE SCHROON LAKE QUADRANGLE 25 the geologic map shows beyond question that this Whiteface anor- thosite was formerly a continuous border phase of the Marcy anor- thosite which latter occupies the whole northeastern one-third of the quadrangle. Three large bodies of the Whiteface anorthosite still lie against the Marcy anorthosite in their original positions. There is strong evidence that this border phase was formerly at least 7 or 8 miles wide because, within that distance out from the Marcy anorthosite, many smaller widely scattered masses of the Whiteface rock occur as inclusions in the syenite-granite series all the way across the quadrangle. In other words, only remnants of the original border rock now occur. Further, since this border rock is notably finer grained than the Marcy anorthosite, it is very reasonable to interpret it as a chilled gabbroid border phase com- parable in position and origin to Cushing’s Long Lake border phase of the anorthosite, though of lighter color and usually not so gabbroid. The Schroon Lake quadrangle Whiteface anorthosite ’ commonly carries 10 to 20 per cent dark minerals, but it is very variable, some phases containing only 5 per cent or even less, and some more than 20 per cent. There is strong evidence that the chilled gabbroid border phase developed not only as an outer limit but. also as an upper limit which formerly existed as a cover resting directly upon the whole great mass of anorthosite. Thus, as already pointed out in the writer’s Lake Placid report, the Whiteface anorthosite of that area does not exist merely as a definite fringe around the outer margin of the Marcy anorthosite. Whiteface anorthosite there occurs fully 14 or 15 miles within the present border of the anorthosite area, and inclusions in the syenite-granite series outside the gen- eral anorthosite area show that the Whiteface anorthosite formerly extended at least a few miles farther out than the present bound- ary. One area of Marcy anorthosite, 12 miles long within the Lake Placid quadrangle and extending an unknown distance into the Ausable quadrangle, is flanked on either side by Whiteface anor- thosite. It is hard to resist the suggestion that the Whiteface rock formerly covered this whole mass of Marcy anorthosite. There is thus a distinct difficulty in the way of considering this White- face anorthosite as merely an outer border facies. If we do regard it as merely an outer facies, we are forced to conclude that it is exceedingly thick, that is to say fully 10 or 15 miles, the width of the area containing Whiteface anorthosite representing practically the thickness of the border facies. This is scarcely conceivable. The Schroon Lake quadrangle yields similar evidence since, as 26 NEW YORK STATE MUSEUM above pointed out, the border facies (Whiteface type) there formerly extended fully 7 or 8 miles out beyond the present margin of the Marcy anorthosite as indicated by numerous inclusions in the syenite-granite series. In this connection, a very interesting inclusion of fragments of very typical Marcy anorthosite in the granite of Wilson mountain, over 6 miles out from the present border of that type of anorthosite, may be reasonably interpreted as Marcy anorthosite caught up in the granite magma at a lower level (below the Whiteface anorthosite cover) and carried upward to the present position (see figure 1). In any case it is certain that Marcy anorthosite existed that far out. Within the Schroon Lake quadrangle no Whiteface anorthosite was found within the large area of Marcy anorthosite, it apparently all having been removed by erosion. Unless definite areas of the basic chilled border facies are found far within the great anortho- site area, positive proof that such a border once existed as a cover over the whole will be wanting. But such a cover, if once unt- versally present, would show few, if any, remains far within the anorthosite area because of the widespread and deep erosion to which the region has been subjected. In short, the evidence from the outer portions of the great Adirondack anorthosite body strongly supports the view that a chilled gabbroid border facies should be regarded as having formerly existed as a cover resting upon the whole mass of Marcy anorthosite. The evidence from the interior is negative, but nothing in the field is opposed to the conception of a former universal cover. But this does not preclude Cushing’s conception of an outer chilled border of the anorthosite, provided we regard the anorthosite as a great laccolithic intrusive body (see figure 2) over all of which a border facies developed as an upper limit, and at the margins of which a border facies developed at the same time as an outer limit. The writer therefore agrees with Cushing that the area of anorthosite shown on the state geologic map shows practically ‘‘ the original size of the mass at the depth represented by the present erosion surface,’ and that the anorthosite can not extend out to, or even close to, the margins of the whole Adirondack region. According to Bowen, the femic constituents of a great gabbroid magma, as wide as the Adirondack region, first separated (or sank) by gravity, while the plagioclase crystals (then in the form of basic bytownite) remained practically suspended. At a later stage, when the liquid became light enough, plagioclase crystals (then in GEOLOGY OF THE SCHROON LAKE QUADRANGLE 27 the form of labradorite) accumulated by sinking, thus giving rise to the mass of the anorthosite, leaving the overlying liquid of such composition as to yield syenite or granite. In his first paper, Bowen does not consider the development of a chilled border of the Adi- rondack anorthosite. In his second paper, by way of reply to Cushing, he modifies his idea of the stratiform arrangement of the igneous complex by considering the development of a “ gab- broid chilled upper portion of a laccolithic mass extending far beyond the limits of the present exposure.’ Directly under the chilled border, according to Bowen, the great body of syenite- granite developed; still lower down the typical anorthosite formed; and at the bottom, pyroxenite and gabbro. Since the evidence above presented shows that the great body of Adirondack anorthosite has a chilled gabbroid border which can not possibly extend far out beyond the present exposure of the anorthosite, and evidence below presented is distinctly against existence of syenite or granite formed as a differentiate between the border facies and the typical anorthosite, it is clear that Bowen’s hypothesis of the origin of the anorthosite by the settling of plagioclase crystals is untenable. There simply is nothing from which they could have settled. The writer believes, therefore, that it is out of the question to interpret the Adirondack igneous com- plex as even in a general way a “ sheetlike mass with syenite above and anorthosite below” as required by Bowen’s hypothesis. Relation of the syenite-granite to the Whiteface anorthosite. According to Bowen, the syenite-granite and anorthosite are not distinctly separate intrusives, but both formed as differentiates from a single great body of intruded gabbroid magma. ‘Cushing and the writer both believe the syenite-granite series to be dis- ‘tinctly later, and the writer has found abundant evidence in sup- port of this view in both the Lake Placid and Schroon Lake quad- rangles. For the Long Lake quadrangle Cushing says*: “ The field evi- dence seems clear that the anorthosite had solidified, with a chilled border, and had then been attacked from the side by a mass of molten syenite, which in places cut deeply into it.” With this statement the writer agrees, but he would further say that both granite and syenite of the syenite-granite series have, in certain other districts like the Lake Placid and Schroon Lake quadrangles, not only cut deeply into, but also they have either largely cut out lotm Geol 25507... Tan: 28 NEW YORK STATE MUSEUM or more or less assimilated, the border facies of the anorthosite. Detailed field evidence in support of this view is presented below. Cushing maintains that the chilled border is fatal to Bowen’s conception that molten overlying syenite may have been faulted down against solid anorthosite so that it could have laterally attacked the anorthosite, thus accounting for the intrusive features including the syenite dikes. Much detailed field work by the writer shows that the chilled border (Whiteface anorthosite) grades directly into the typical anorthosite, and that there is no reason to think that the syenite-granite series developed between the chilled border and the typical Marcy anorthosite. Even if we assume, what has not been found in the field, that some such syenite or granite exists as a rock intermediate between the chilled border and the typical anorthosite, it is most unreasonable to suppose that the chilled border would, in some places, grade first into the syenite or granite and then into the Marcy anorthosite. Either one of these might be the case, but not both. Bowen suggests that the syenite-granite may have developed between the chilled border and the Marcy anorthosite, and then have been reintruded through the chilled border. But how can we possibly imagine such a vast bulk of syenite-granite to have been so largely reintruded that not any of it has been discovered in its supposedly original position? Also how can we imagine the rein- trusion of such a tremendous volume of syenite-granite through the chilled border facies, leaving this latter as a definite fringe about, and grading into, the Marcy anorthosite for so many miles? Dikes of syenite and granite.in anorthosite. Some years ago, in his report on the Geology of the Long Lake Quadrangle,’ Cush- ing showed that several narrow well-defined dikes of syenite there cut the typical Marcy anorthosite, one of these dikes being several miles within the border of the great anorthosite body. He also states that one of the small outlying masses of anorthosite is “definitely cut by syenite which sends dikes into it.” As a result of the surveys of both the Lake Placid and Schroon Lake quadrangles by the writer, various excellent examples of dikes and broad tongues of syenite and granite cutting anorthosite have come to light. A number of fine examples of such dikes are described in the report on the Geology of the Lake Placid Quad- rangle. *N. Y. State Mus, Bul. 115, p. 480-84. 1907. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 29 In the Schroon Lake quadrangle a number of clearly defined dikes of granitic syenite and granite were observed in the anortho- site. One of these is well shown by the road 1% miles west of Boreas river where a dike of granite 5 feet wide cuts rather femic Whiteface anorthosite without very sharp contacts. Another is a dike of typical pinkish gray granite 25 feet wide 1 mile west of the western summit of Sand Pond mountain. It sharply cuts Whiteface anorthosite which lies near, and closely resembles Marcy anorthosite. Both dikes just mentioned are quite certainly off-shoots from large bodies of typical granite which, in a general way, cut into the marginal portion of the great body of anortho- site. A wide dike of gray granite cuts Marcy anorthosite just north of the summit of Texas ridge (see map). The granite is very gneissoid with highly flattened quartz and feldspar crystals. The small mass of Whiteface anorthosite on the side of Beech hill (see map) is cut by a number of narrow dikes of granitic syenite and granite which are doubtless off-shoots from the large sur- rounding body of syenite-granite. Contacts between these dikes and the anorthosite are usually not very sharp. Also in the Schroon Lake quadrangle many dikes or narrow intrusive bodies of syenite and granite were observed in the areas of anorthosite and syenite-granite mixed rocks, and to some extent in the areas of Keene gneiss. Some of these are referred to below. The evidence, therefore, from the dikes, that the syenite- granite series is distinctly younger than the anorthosite series, is very strong. . Broad intrusive tongues of syenite and granite in anorthosite. Broad tongues of syenite and granite extending, in a number of places for miles, into the great body of anorthosite furnish per- haps even more impressive evidence than the dikes that the syenite- granite series is really younger than the anorthosite. Cushing’s Long Lake geologic map shows an intrusive tongue of syenite from 1 to 3 miles wide cutting into the anorthosite for a distance of 2 miles. The writer's Lake Placid geologic map shows a fine example of a tongue of syenite-granite with a maximum width of 1% miles cutting Whiteface anorthosite across a portion of Wilmington mountain. A great body of syenite-granite from 1 to 6 miles wide extends into the anorthosite for 13 miles across the Lake Placid quadrangle, and thence for an unknown distance into the Mount Marcy quadrangle on the south. 30 NEW YORK STATE MUSEUM In the Schroon Lake quadrangle, a tongue of granite from 2 to 4 miles wide in the vicinity of Cheney pond extends into the anortho- site for fully 4 miles, reaching all the way through the border facies and into the Marcy anorthosite (see map). The large intru- sive mass of later gabbro lies within this. salient and cuts out much of the originally present granite. Tiwo of the small dikes of granite above mentioned are off-shoots of this salient of granite in the anorthosite. : Inclusions of anorthosite in the syenite-granite. Inclusions of anorthosite in the syenite-granite series furnish very strong evi- dence that the syenite-granite body is an intrusive distinctly sepa- rate from, and later than, the anorthosite. Such evidence is scarcely, if at all, mentioned by Bowen, probably because few examples of such inclusions were known to him. Many excellent examples have come under the writer’s observation. It seems evident from a glance at the accompanying Schroon Lake geologic map that the anorthosite once extended out as a continuous broad belt at least 7 or 8 miles beyond the present margin of the Marcy anorthosite because, within that distance from the Marcy anorthosite, there are many inclusions of anortho- site (mostly of sufficient size to be mapped) in the syenite-granite series all the way across the quadrangle. In other words, only mere remnants of the former anorthosite are now visible. With the exception of one locality, these are all inclusions of Whiteface anorthosite. The exceptional locality is of particular interest. It is on top of Wilson mountain, and represented on the geologic map as a small area of mixed rocks. One patch of the granite 12 feet across contains large dark bluish gray labradorites an inch or more across and several small pieces of typical Marcy anorthosite as distinct inclusions, mostly arranged roughly parallel to the folia- tion of the granite (see figure 1). Immediately around the larger fragments the granite exhibits fine magmatic flow-structure. A similar exposure occurs close by. A reasonable interpretation is that the granite magma moving upward enveloped two small masses of Marcy anorthosite and tore them into small fragments which became somewhat scattered and arranged parallel to distinct mag- matic currents which moved up nearly vertically as shown by the high angle of dip of the magmatic flow-structure foliation. A fine example is in the bed of the brook 1 mile southeast of the summit of Oliver hill where a mass of Whiteface anorthosite 20 feet across is inclosed in the granite (see map). This outcrop con- GEOLOGY OF THE SCHROON LAKE QUADRANGLE 31 sists of alternating bands of partly white and partly rather gab- broid Whiteface anorthosite. An interesting ledge outcrops in the small mapped area 1%4 miles a little west of north of Irishtown. The rock is extremely gneis- soid, moderately gabbroid, Whiteface anorthosite containing many lens-shaped labradorities or “augen” up to 1% inches long, and in some portions red garnets. This anorthosite also has in it many SNe SRERETE TERRA TRY yee UN ASUS SS “ER a ic eae SP; % , SN Fig. 1. Sketch of part of an exposure on top of Wilson mountain showing small inclusions of [Marcy anorthosite in gneissoid granite. Note the magmatic flow-structure foliation about the larger fragments. inclusions of Grenville hornblende-garnet gneiss in the form of lenses, strips and layers from less than 1 foot long to I or 2 rods long, these being arranged parallel to the foliation of the ledge. It is thus certain that this anorthosite must have been in a truly magmatic state when it caught up the fragments of Grenville. The immediate relation of this ledge to the nearby syenite is obscured by drift, but no doubt it is an inclusion. Along the western side of the Beech hill anorthosite, which is an inclusion in the syenite-granite, there are, in the granite, some small, irregular inclusions of Whiteface anorthosite with indefinite boundaries, and with distinctly curving flow-structure in the granite around them. In the narrow belt one-fourth of a mile long, already described as extending across the southern brow of Cobble hill, many small inclusions of the Whiteface rock occur in the granite. A number of inclusions of the Whiteface rock, each from 1 to 20 feet across, are finely shown in the granitic syenite on top of the hill 1 mile east-southeast of Cobble hill. 32 NEW YORK STATE MUSEUM All the inclusions of anorthosite above mentioned bear exactly the same relations to the inclosing syenite-granite as do the inclu- sions of Grenville, and it seems clear that the upward moving syenite-granite magma enveloped masses of both these rock series in exactly the same manner. Thus we have just as strong evidence that the syenite-granite is distinctly younger than the anorthosite as that it is distinctly younger than the Grenville. Absence of Grenville and syenite-granite from the anorthosite area. It is a striking fact that both Grenville and syenite-granite are almost, if not quite, absent from a large part of the anorthosite area of the Adirondacks. In the northeastern half of the anortho- site area there are considerable developments of both Grenville and syenite-granite. In the southwestern half of the Adirondack anorthosite area, including the Schroon Lake quadrangle, the absence of Grenville and syenite or granite is, however, an impres- sive fact, though it must be remembered that many square miles of this have not been carefully studied. The detailed Long Lake, Schroon Lake and Paradox Lake maps, and the southern half of the Elizabethtown map, show no Grenville or syenite-granite well within the anorthosite there mapped. So far as known to the writer this is also true of the southern half of the Mount Marcy quadrangle. Bowen, in his paper on “The Problem of the Anorthosites,” dwells upon this absence of Grenville and syenite-granite from so much of the anorthosite, ‘and he offers an explanation briefly stated as follows:! “If one pictures the syenite and the anorthosite as conventional batholiths, some difficulty is experienced in accounting for the foregoing facts [see above paragraph]. It is necessary to imagine an early intrusion of a huge plug of anorthosite followed by an intrustion of syenite which took the form of a hollow cylinder circumscribing it and invading it only peripherally. . . . On the other hand, if one pictures the Adirondack complex as essentially a sheetlike mass with syenite overlying anorthosite . . . one would expect to find areas of Grenville roof covering the syenite in places and to find it relatively little disturbed. In the interior and eastern region of maximum uplift one would expect to find the deep- seated anorthosite laid bare and to find it free from areas of the roof.” Also, he says, because of the deep erosion in the region of maximum uplift one would expect to find the layer of syenite removed. 1 Jour. Geol., 25 :223-24. 1017. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 33 Some of the more important objections to the view just expressed are: (1) the anorthosite represents a separate and distinctly older intrusion than the syenite-granite, and so the sheetlike arrange- ment advocated by Biowen is out of the question; (2) the Adi- rondack anorthosite area is by no means practically free from masses of syenite-granite, this being particularly true of the whole northeastern half of the area where there are many large and small bodies of syenite and granite in the form of real intrusives in the anorthosite; and (3) it is not at all necessary to assume that both syenite-granite and anorthosite were batholithic intrusions. An explanation offered by the writer to account for the absence of Grenville and syenite-granite from so much of the anorthosite area may be briefly stated as follows. The anorthosite is con- sidered to be a laccolith not much greater across than the present area of outcrop. Its intrusion was soon followed by a very irregu- lar intrusion of the great body of generally rather highly fluid syenite-granite magma. That the syenite-granite magma was mostly rather highly fluid is proved by its great power to cross- cut, intimately penetrate, break up and tilt the Grenville strata. Only exceptionally did local portions of this magma invade the Grenville strata in true laccolithic fashion. Both the anorthosite and the syenite-granite are believed to have intruded a very thick mass of essentially undisturbed Grenville strata, largely or alto- gether free from orthogneiss. The southwestern half of the anorthosite body, which is so free from masses of Grenville and syenite-granite, is believed to represent the greatest bulk of the anorthosite where the laccolithic magma was thickest and reached its highest level. The northeastern half of the anorthosite as now exposed is regarded as the portion where the anorthosite magma spread out as a relatively much thinner layer whose surface was at a notably lower level than that of the thicker portion to the southwest (see figure 2).- Because of the greater uplift of the southwestern portion, the Grenville cover has there been almost, if not completely, removed by erosion. But many areas of the Gren- ville roof remain over the thinner northeastern part of the anortho- site where the uplift was much less. Thus we have a simple explanation of the absence of the Grenville from so much of the anorthosite area. After the solidification of the great body of anorthosite, the syenite-granite magma was batholithically intruded in a rather highly fluid state, and it tended to avoid penetration of the anorthosite which was much more massive, homogeneous and 34 NEW YORK STATE MUSEUM resistant than the great mass of surrounding practically undis- turbed Grenville strata. This satisfactorily explains not only why ‘syenite-granite masses are scarcer within the anorthosite area than in the Adirondack region in general, but also why syenite-granite is almost, or entirely, absent from the southwestern half of the anorthosite area. May not there have been a wide magmatic feed- ing channel extending northwest by southeast under the main body of the southwestern half of the anorthosite? On this view, the thickest portion of the laccolith developed directly over the wide feeding channel which extended far down, with the result that this portion of the anorthosite intrusive body was very resistant to intrusion’ by the syenite-granite magma. The northeastern por- tion of the anorthosite, because notably thinner, was penetrated by considerable masses of the syenite-granite magma, as, for example, in the Lake Placid and Ausable quadrangles. Here again we have a simple explanation of the field facts. Strongly supporting the above conception is the evidence from the distribution of the stocks of later gabbro. All the recent workers in Adirondack geology recognize this gabbro as distinctly younger than the syenite-granite series. It usually occurs in the form of stocks or pipelike bodies rarely more than a few miles across. Such stocks are common and widespread throughout the. Adirondack region, except the anorthosite area. Like the syenite- granite, this gabbro is singularly absent from the southwestern half of the anorthosite area. In the Schroon Lake and Elizabethtown quadrangles a number of such gabbro stocks each from 2 to 4 miles long lie right along the border of the anorthosite but none well within it. In the northeastern half of the anorthosite area gabbro stocks occur in moderate size and number. It is, then, very clear that this later gabbro shows the same sort of distribution with reference to the anorthosite as does the syenite-granite, and it is believed that the same explanation (see above) applies to both. Evidently the gabbro intrusions, too, were unable to penetrate the thick, very resistant southwestern half of the anorthosite laccolith. Origin of the anorthosite by differentiation in a laccolith of gabbroid magma. Laccolithic structure of the anorthosite. After considering a number of the better known anorthosite bodies of the world, Daly* concludes that all of them, including the Adirondack mass, are to be regarded as laccoliths. 2Teneous Rocks and Their Origin, p. 328-35. 10914. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 35 The writer believes the Adirondack anorthosite (not necessarily the anorthosite as such) was intruded essentially laccolithically, and the syenite-granite was intruded essentially batholithically. But it is not at all necessary to assume, as does Bowen, that both great bodies are batholithic if they are regarded as distinctly sepa- rate intrusions. As ca een " ‘ ie x 8 rece: Fee ey fe) 3) 3) S| 3 [SEIS e Ss) 8 [elsiele| Ele] & | 3 {sl} & | 2) 8 Is a) & les Ololalaiolm jalanaiolzial & | & lol « | S 1a fo g 5] 415]45| 8]1o 22 5 Allin 3 lhe 2livetane Ieioreecc line 4 B liweceustene a-2 2 6| 412/66] 4} 7]. I 2 3] 2 aerate at Dates Secale little} little]....|.. 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QOo bb olle Alera tc 14 little} little]....].. 5 25| 9d 3/35]15| 1 IONS ecole I repeats Vesa cee Al 0 Blecoolse 31] 10 g 2/57]. 35 Se ea Altec toni eat liseissses [eeeronee el) AME) 5 Booallaodolloc 32] 9 b1/33]..| 6|..] 4/35] 42] al..|..]..]..|ra] little 2/33 2! little|....| 4 BABI LOVOBlesligollacl SAA Sal awe Bil IAA Shen Aslan aaalloe IRAE oe coed locals o 35/8 f 25b]54]..] 2]..]../35 2 TAN alle all ae NNS is eaten oy eM ah 5 Eittle| peace. —=—— No. 5, by road one-third of a mile east of South Schroon; no. 6, quarry one-half of a mile east-northeast of South Schroon; no. 7, cross-roads one-half of a mile northeast of Muller pond; no. 26, one-half of a mile north-northwest of Bailey pond; no. 28, from granitic syenite area 134 miles northeast of Bailey pond; no. 49, southeastern base of Severance hill; no. 1, top of hill 1% miles southwest iof Taylors on Schroon; no. 2, quarry one-half of a mile a little west of north of Moxham pond; no. 3, lake shore one-third of a mile northwest of Adirondack village; no. 4, I mile east-northeast of Pat pond; no. 8, one-half of a mile northeast of summit of Cobble hill; no. 9, from tongue of granite cutting anorthosite t mile south of Sand pond; no. 25, old road crossing Minerva stream 1 mile north of mouth of Hewitt pond brook; no. 31, east of brook at north end of granite area 2 miles northeast of Bailey pond; no. 32, little hill just west of Hewitt pond; nos. 34 and 35, southern brow of Cobble hill. From table 2 it is seen that microperthite always occurs as the most prominent constituent of the syenite, while oligoclase and quartz are always present in smaller amounts. Orthoclase is more variable and sometimes absent. No. 7 is a fine example of a dis- tinctly basic or dioritic facies of the syenite. Nos. 26 and 49 show reaction rims of garnet around magnetite. No. 31 is highly granu- lated along some zones parallel to the foliation in the thin section. Description of granite and granite porphyry. The granite and granite porphyry are regarded as differentiation facies of the great Adirondack syenite-granite series. There are many places where 42 NEW YORK STATE MUSEUM the syenite grades through gramitic syenite into granite, but not a single locality was observed where syenite definitely cuts granite or vice versa. The writer has been unable to demonstrate the existence of any considerable mass of granite either distinctly older or younger than the normal syenite, though small pegmatite and aplite dikes are not uncommon. reat As regards granularity, granulation and foliation the statements above made with reference to the syenite apply almost equally well here. Excessively gneissoid granite with highly flattened quartz and feldspar were observed, among other places, one-fourth of a mile northeast of the summit of ‘Cobble hill, on the southern brow of Bigsby hill, at the summit of Oliver hill, and in the small area of granite just east of the brook near the trail 2 miles northeast of Bailey pond. Most of the granite is pinkish gray, to pink, or even reddish where fresh, but locally it is greenish gray or gray. It usually weathers to pinkish gray or hght brown. Like the syenite, the granite exhibits many local variations. A hand specimen from a ledge by the lake shore one-fifth of a mile north of the Adirondack village steamer landing is distinctly folli- ated and granulated, with one pink band especially rich in feldspar adjacent to a band very rich in quartz plus some garnets, these two bands having on either side granite consisting of quartz, feldspar, and hornblende with some biotite. These bands are not sharply separated. In the quarry one-half of a mile north of Moxham pond, the granite shows notable variations in coarseness of grain often within a foot or two. Table 2 shows the minerals contained in some thin sections of the granite. From this table it is seen that the two most conspicu- ous never failing constituents are microperthite and quartz. In a few slides microcline occurs, and in only two does it equal or exceed the microperthite. Orthoclase usually fails and it is never prominent. Granite with scattering garnets was observed in several places as, for example, the whole mass of Pine hill, three-fourths of a mile west-southwest of Taylors on Schroon, on top of Ledge hill, and by the road three-fourths of a mile north-northeast of Pat pond. In a number of localities numerous lenslike inclusions of horn- blende gneiss (metagabbro or Grenville), too small to be mapped, occur in the granite as, for example, one-half of a mile west of Oliver pond, at the swmmit of Cobble hill, and on Ledge hill just GEOLOGY OF THE SCHROON LAKE QUADRANGLE 43 north of the small gabbro stock. An inclusion of particular interest is shown in figure 8. The granite porphyry is quite certainly a differentiation phase of the granite, and it is only moderately developed within the quad- rangle. One small area is represented on the map in the very southeastern corner, and another on the southern brow of Ledge hill, while the largest area (about 1 square mile) takes in the vicinity of Pat pond. The granite porphyry differs from the granite only in being coarser grained and usually more or less porphyritic. Grenville or Hornblende Gneiss (Metagabbro?) and Syenite- granite Mixed Rocks A number of small areas of mixed rocks of this sort are repre- sented on the geologic map. The Grenville or hornblende gneiss (metagabbro?) and granite are so intimately associated that any attempt to separate them on the map would be unsatisfactory. The old rocks are usually cut to pieces by, or form inclusions in, the syenite-granite. In the small area just south of Calahan pond, typical granite contains small to large well-defined inclusions of Grenville. In the two garnet mines, the larger of which is located near the edge of the map and the other just to the west, the rocks are highly granu- lar red garnet in considerable masses closely associated with coarse _ pyroxenic crystalline limestone. Contacts are sharp against the granite in the smaller mime, but not in the larger one. A few rods to the north and by the old road, there is a small, sharply defined inclusion of limestone in the granite parallel to the foliation of the latter. In the area covering about one-half of a square mile southwest of Minerva there are many outcrops of both granite and Grenville, the two often being closely associated in single outcrops. Evi- dently the Grenville has here been badly cut to pieces by the granite. The mixed rocks of the small area 2 miles north of Minerva are described along with the associated iron ores in the last chapter of this bulletin. At and near Lester dam there are extensive outcrops of pinkish, very gneissoid granite containing much hornblende gneiss in the form of flattened or Ienslike inclusions more or less fused into the mass. 44 NEW YORK STATE MUSEUM The small area three-fourths of a mile north of Loch Muller shows good exposures of hornblende and hornblende-garnet gneisses shot through by some dikes of granite. Some of the garnets up to I or 2 inches in diameter have distinct rims of hornblende. In the small area three-fourths of a mile northwest of Loch Muller, hornblende gneiss (metagabbro?) is shot through by granite and considerable magnetite is associated with the rocks. Of the small areas west and southwest of Charley hill, the two farthest out are chiefly granite with considerable intermixed older dark gneisses, while the one nearer Charley hill is chiefly well-bedded hornblende gneiss shot through by irregular dikes of granitic syenite. The small area 1 mile south-southwest of South Schroon is mostly hornblende gneiss intricately cut into, and apparently more or less assimilated by, granite. The area of about one-fourth of a square mile 1 mile west of Schroon Lake village shows many good exposures of hornblende and hornblende-garnet gneisses, some very intimately associated with granite in the form of small streaks and bands, and some less inti- mately associated in bodies of considerable size. An exposure by the road 1% miles a little north of west of Schroon Lake village consists of very gneissoid to almost banded intimately mixed dark gneiss and granite. The small area 1 mile northeast of South Schroon contains very gneissoid syenite or granitic syenite more or less intimately asso- ciated with Grenville hornblende and pyroxene gneisses. Hornblende gneiss and syenite are associated in the area on the west side of Thurman pond. Keene Gneiss General statements. One of the most interesting rock types of the region is locally developed as belts or irregular bodies along or near portions of the borders between the anorthosite and the syenite-granite series. Both the Marcy and Whiteface types of anorthosite show such border rocks. There is very strong evi- dence, based upon field work and a study of thin sections, that this is really a transition rock between anorthosite and syenite or granite formed by actual digestion or assimilation of anorthosite by the invading syenite-granite magma along portions of its borders. The writer has proposed that this rock be called “ Keene gneiss,” because a fine exposure of the typical fresh rock occurs by the GEOLOGY OF THE SCHROON LAKE QUADRANGLE nO TAS road just north of the village of Keene in the Lake Placid quad- rangle. Fifteen areas of mostly Keene gneiss are represented on the writer's Lake Placid geologic map and the rocks are described in the accompanying report. Cushing has described rocks which probably belong in the same category, from two localities on the western side of the great anorthosite area. Cushing suggests that these rocks, particularly in the Long Lake quadrangle, are mag- matic assimilation products. Kemp has described certain peculiar types of gabbro, called the Woolen Mill and Split Rock Falls types, aS occurring in the Elizabethtown quadrangle. Kemp says nothing regarding the origin of these types, but, in the writer’s judgment, they are to be classed as Keene gneiss. These seem to be the only rocks of the sort in the Adirondack region regarding which even brief published statements by other workers have been made. The whole problem of the Keene gneiss is rather fully dis- cussed in the writer’s recent paper + on “Adirondack Anorthosite.” ~ Megascopic characters. The typical Keene gneiss presents a different appearance from any other Adirondack rock. In the Lake Placid and Schroon Lake quadrangles, the typical rock is medium grained, gneissoid, notably granulated, and looks much like some facies of the syenite-granite series except for scattering phenocrysts of bluish gray labradorites up to an inch long. These phenocrysts, which are rounded and usually elongated parallel to the foliation of the rock, doubtless represent cores of crystals which survived the process of granulation. Locally the pheno- crysts are absent or only sparingly present, and such facies of the Keene gneiss are often difficult to distinguish in the field from certain phases of the syenite-granite series. Under the micro- scope, however, the distinction may generally be made. A gneissoid structure is nearly always present but it varies notably, in some cases being practically absent. The fresh rock is usually greenish gray, and it weathers brown. Microscopic characters. The mineral contents of thin sections of selected samples of various phases of the rock from the Schroon Lake quadrangle are shown in table 3. It is quite clear from this table that the Keene gneiss is’ mostly distinctly intermediate in composition between the syenite-granite and the anorthosite. 1 Geol. Soc. Amer. Bul. v. 29, no. 4. 10918. A007 NEW YORK STATE MUSEUM Table 3 Thin sections of Keene gneiss Cant fo) ¢ abl a |e : a sl er = S 2 SU he SMe eile fey (UE. ox AS 2 ie iii e| a (£lelapemslelet 2 tet 3) = see SECT ceailivcen icra weal ie iidet || Os oy) St. eigenen a fea Selo} e ee) ate ho! @ a) < N |S! & {a 27 Of 2) ar 66 ae 7 2). pa | es 1) emer tee ees beaten pepe te ce caen di I| little SAN Nye ool e cll Oe: Wiesel Tas ate Aleta Bel sa chieusi litthhell-4 i ceal(aealfeereere So) NO) Ge Sy isl BSlossalh aus 5 4}. Pia dee Err Bilt 5|/o oc ccc ts o. 5 Beier ae Allee celle wal | Ofe 7\| 2 2 a bs | ited eae eed little}... 2. . P| eee 30 |Sfimgal “goll:s.| 56) To loc frétle|| 219 Teele Eee eee eee Zhe Si IZ%a F5|....|/. 36) tall ge ree 3| 4] little Bl... scan torpepeeiemetere Shey tee ae yp | MOM SG G8 T5 4 Bier 7) nineteol lc oodalaote allem ollb Goons 46 C5 OND ABs ase [te seed [tinsel [US| tone menel [tev eae eves 6 a Ze, Util ace 6 heehee eee 4 48 S.GiG| > Gelle geal ss El) 25 Zor. little] 6 4 Bo Trt ese eareee eters No. 27, one-half of a mile north-northwest of Bailey pond; no. 20, just north of the granite by the trail 2 miles northeast of Bailey pond; no. 30, 1 mile northeast of Bailey pond: no. 33, eastern slope of Bailey hill; nos. 36, 36a and 38, southern brow of Cobble hill; no. 46, just south of the brook 1 mile east of Hewitt pond; no, 48, one-fourth of a mile south of the mouth of Hewitt pond brook. Descriptions of occurrences in the Schroon Lake quadrangle. Most of the Keene gneiss of the quadrangle occurs in the two largest areas separately mapped as such, but in the areas mapped as anorthosite and syenite-granite mixed rocks, there are many excellent local developments, and certain of these will be con- sidered first. . An outcrop on the southern brow of Cobble hill, 1 mile due south of Bailey pond, is very significant because of the light it throws upon the local origin of the Keene gneiss. The accompanying sketch (figure 3) shows the relationships. This Keene gneiss is distinctly granitic or syenitic in appearance except for the many labradorite crystals, mostly an inch long, which stand out as phenocrysts more or less parallel to the crude foliation of the otherwise medium grained rock. Nos. 36, 36a and 38 represent thin sections of this Keene gneiss which, though variable, is dis- tinctly intermediate between the granite and the anorthosite in the same ledge. Within this Keene .gneiss there are inclusions of Whiteface anorthosite (no. 37 of table 1) which contain some large labradorites and also scattering femic minerals up to 2 inches long, more or less lenslike and parallel to a distinct foliation. Con- tacts between the inclusions and the Keene gneiss are not very GEOLOGY OF THE SCHROON LAKE QUADRANGLE 47 sharp. Immediately above this Keene gneiss, but not in very sharp contact with it, is a very gneissoid granite (nos. 34 and 35 of table 2) which contains many garnets. This gneissoid granite grades upward into typical, medium grained, only moderately foliated granite without garnets. A similar typical granite lies against the Keene gneiss at the bottom, but the contact there is quite sharp. The writer’s interpretation is that the upward moving granite magma more or less assimilated some Marcy or Whiteface elcied inaceueean enaeceet ERR as BREBBS0S0P5 fa YAAK KK RRS XK CODA ABEEE ER EEE EE EEE CEE EEEEEELE EEE UMN ed eit Yes Sos eeavneuueeeunenuees scaagaagandaaaaa A /\/\\ RP ea eo RAK RSet pooggo Mace ORK ba Wiens q ad acon aM, SEs @ YX KAVAAAY YW WN ‘A : YN \ nea sal me VAVAVAVANANANE? LX I KKK KIX Né. KK YX) VA VAVANANANA INA ANSTO KAM! (KAA Y LAZY) ERin— Fig. 3 Sketch of part of the great ledge at the southern brow of Cobble hill showing Keene gneiss in its relation to both granite and Whiteface anorthosite. Contacts between the Keene gneiss and both Whiteface anorthosite and garnetiferous granite are not sharp, but the contact between the Keene gneiss and the lower granite is rather sharp. anorthosite at a considerable depth, and that this molten mass (Keene gneiss magma) rose still higher and caught up and only partly fused the borders of fragments of Whiteface anorthosite. The origin of the garnetiferous granite is not so certain, though it may represent a mass of granite with a small quantity of anortho- site very thoroughly digested. 48 NEW YORK STATE MUSEUM An interesting assemblage of rocks is well exposed on the steep hillside one-half of a mile north-northwest of Bailey pond. Com- monest of all is good Whiteface anorthosite, but some tongues or dikes of granite cut through it, and still other rock is quite cer- tainly an assimilation product of the two, that is to say, Keene gneiss. Most of the rock taken to be Keene gneiss is of syenitic aspect both with and without quartz, but some contains pheno- crysts of labradorite. No. 27 of table 3 represents a thin section of this Keene gneiss, but the labradorite does not show in the thin section. Still other local developments in the large area of “ anorthosite and syenite-granite mixed rocks” are described below. A number of small (not mappable) inclusions of Whiteface anorthosite occur in the granite along the western side of the Beech hill Whiteface anorthosite area. The borders of these inclusions have been fused and assimilated by the granite which shows curved flow-structures around the inclusions. Interesting exposures occur in the small area of Whiteface anorthosite and syenite mixed rocks near the southeastern base of Severance hill. The rock is mostly quartz syenite (no. 49 of table 2) which contains numerous inclusions of Whiteface anortho- site. These inclusions are very irregular and usually only a few feet long without sharp boundaries against the syenite. Evidently syenite magma rising through Whiteface anorthosite caught up numerous small fragments of it, the borders having been assimilated to form Keene gneiss on small scales. On large scales the geologic map shows two areas of Keene gneiss, one occupying about 6 square miles, and the other nearly 3 square miles, in the central portion of the quadrangle. Before the intrusion of the large gabbro stock, the two areas were prob- ably connected with a total length of 7 miles, extending from Rogers pond to and beyond Bailey hill. These bodies of Keene gneiss lie mostly against typical Marcy anorthosite, but also, to some extent, against Whiteface anorthosite, the border facies of the anorthosite here having been very largely assimilated by the syenite-granite magma. Throughout the larger area especially, there are a good many small masses of Whiteface anorthosite, a few of sufficient size to be mapped. There are also some outcrops of fairly good granite and granitic syenite, thus showing that all the original Whiteface anorthosite was not assimilated. The main body of the rock is, however, quite typical Keene gneiss, there being GEOLOGY OF THE SCHROON LAKE QUADRANGLE 49 particularly fine exposures on the eastern slope of Bailey hill, and along the middle of the crest of Washburn ridge. Certain localities of special interest in the larger area will now be described. One of these is along the brook 2 miles northeast of Bailey pond. By the trail there is a large outcrop of peculiar, variable rock. There are some small patches of Whiteface anor- thosite embedded, but most of the rock has a granitoid texture and contains scattering bluish gray labradorites up to an inch long (see no. 29 of table 3). This latter rock looks much like the Cobble hill rock above described except for fewer labradorites, and it is considered to be Keene gneiss with a history similar to that on Cobble hill. Just across the brook to the east there is a big ledge of very highly foliated medium-grained granite gneiss with both the quartz and feldspar highly flattened out parallel to the foliation. An interesting lot of rocks occur on Washburn ridge 1 mile north-northeast of Bailey pond. A little to the north of this local- ity (see map) a considerable body of typical Whiteface anorthosite is exposed. A few rods to the south of the anorthosite there are exposures of mostly distinctly gneissoid rocks, syenitic in appear- ance but containing tiny garnets and some large bluish labradorites, these latter not always being arranged parallel to the foliation. No. 30 of table 3 represents a thin section of this rock, but none of the labradorite happened to appear in the section. This rock is quite certainly Keene gneiss. Some portions of these same ledges strongly suggest rather gabbroid garnetiferous facies of Whiteface anorthosite. A few rods still farther south, typical granitic syenite is exposed as shown on the geologic map. A careful study of these ledges on Washburn ridge strongly supports the view that White- face anorthosite has there been acted upon by granitic or syenitic magma, some of the anorthosite having remained unaffected, some having been partially assimilated, and still others completely assimi- lated, while unaffected granitic syenite outcrops at the south. The actual extent of the granitic syenite here is unknown because no exposures of any kind occur for fully a mile to the south. On the crest of the southern portion of Washburn ridge, and continuing for one-half of a mile north from the area of Whiteface anorthosite (see map), a somewhat variable, medium to fine-grained, basic, syenitic-looking rock full of tiny garnets shows in good exposures. Though large labradorites are absent, this rock is thought to have 50 NEW YORK STATE MUSEUM resulted from pretty thorough assimilation of Whiteface anorthosite by syenite or granite magma. Still farther north on Washburn ridge very typical Keene gneiss is well exposed. Many fine ledges of very typical Keene gneiss occur on the eastern face of Bailey hill, no. 33 of table 3 representing a thin section of this rock. In the smaller of the two largest areas of Keene gneiss, exposures are generally rather scarce except on the ridge north of Rogers pond where the rock toward the south contains relatively few large labradorites and suggests a gradation into granite, while toward the north the large labradorites are common and the rock appears to grade into the Marcy anorthosite. An area about 114 miles long of mostly Keene gneiss occupies approximately one-half of a square mile west, south and south- east of the mouth of Hewitt pond brook (see map). A number of good exposures show the rock to be somewhat variable, but it is unusually rich in hornblende and never contains phenocrysts of labradorite. In the. field the rock looks much like a gabbroid facies of Whiteface anorthosite, but thin sections (nos. 46 and 48 of table 3) and the field relations cause it to be rather confidently classed as Keene gneiss. Conclusion as to the origin of the Keene gneiss. Enough examples have been described to prove that the Keene gneiss of the Schroon Lake quadrangle has developed on small and large scales by assimilation of anorthosite by granite and syenite magmas. If we adopt Bowen’s hypothesis, this Keene gneiss must be regarded as having developed by differentiation 2m situ between an overlying sheet of syenite-granite and underlying anorthosite. If one admits, as the writer does not, that syenite usually may have developed by differentiation in situ close upon the Marcy anortho- site, how can one imagine, in places like in the Schroon Lake quadrangle, a similar development of granite close upon the anor- thosite? It might be argued that the granite magma formed at a higher level and was then forced downward. But, if so, it must have been forced downward through still lower syenitic material. Not only is the field evidence against this view, as already pointed out, but even if we grant it, we are still forced to conclude, by the obvious field facts,.that the granite magma produced the transi- tion rock (Keene gneiss) by assimilation of more or less anortho- GEOLOGY OF THE SCHROON LAKE QUADRANGLE 51 site, and that the Keene gneiss was not formed as a differentiate im situ between an overlying sheet of syenite-granite magma and underlying anorthosite. Significance of distribution of Keene gneiss. The Keene gneiss can not be a direct differentiate of either the syenite-granite series or the anorthosite because it never occurs except on the border, or close to the contact, between the syenite or granite and the anorthosite. If we make the very simple and plausible assumption that the anorthosite was still very hot when the syenite-granite magma was intruded, or, in other words, if this latter magma was forced up comparatively soon after the development of the anor- thosite, the usual strong objection to magmatic assimilation, namely, that a magma does not possess a sufficiently high temperature to raise relatively cold country rock to the point of fusion, is distinctly obviated. But the Keene gneiss is not universally present. In many cases where no Keene gneiss occurs along the borders between anorthosite and syenite or granite, it may be reasonably assumed that either the anorthosite or the syenite-granite, or both, in those places may not have been hot enough to permit assimilation. The presence of Keene gneiss in.one place and its absence from the same border nearby, may, in some cases, have been the result of unequal upward intrusion of Keene gneiss magma which orig- inated at lower levels. The small isolated masses of Keene gneiss some distance out from the main body of the anorthosite doubtless represent inclusions of anorthosite which were partly or completely assimilated by the enveloping syenite or granite magma. The failure to find any considerable assimilation of Grenville either along its borders with, or where involved with, the syenite- granite series may be explained on the basis of a temperature of the Grenville too low to have permitted any more than compara- tively slight assimilation by the invading syenite-granite magma. It should be borne in mind, however, as pointed out in a recent paper’ by the writer, that local assimilation of the Grenville is known to have taken place in certain parts of the Adirondack region. Anorthosite and Syenite-granite Mixed Rocks A very irregular-shaped area of about 514 square miles, includ- ing Hayes mountain, is represented on the map as anorthosite and 1Geol. Soc. Amer. Bul., 25:254-60. 10914. 52 NEW YORK STATE MUSEUM syenite-granite mixed rocks. Enough outcrops were observed to render it certain that practically all this area was originally White- face anorthosite which was intruded, and more or less cut to pieces, by the syenite-granite magma. Many individual outcrops are either anorthosite or syenite or granite clearly recognizable as such, but here and there local assimilation has taken place resulting in the development of some Keene gneiss. In a few cases the rocks are admittedly of doubtful origin. Some portions of the area show few if any exposures as, for example, north and northeast of Bailey pond, and in the valley between Hayes mountain and Cobble hill. In view of the facts just stated, it has seemed impossible to represent satisfactorily the various rock types on the geologic map. A few occurrences of particular interest will be described. Perhaps the most interesting occurrence in the area just men- tioned is at the summit of Cobble hill and in the belt containing Keene gneiss which extends east-west for fully one-fourth of a mile across the southern brow of the hill (see page 46). Sur- rounded by typical granite, there are inclusions of Whiteface anor- thosite, most of them not more than a few feet long, arranged roughly parallel to the foliation of the granite. Some of the inclu- sions are rather sharply separated from the granite, many of them had their borders assimilated, while still other anorthosite caught up in the granite magma was completely assimilated to form Keene gneiss. The interesting lot of rocks on the steep hillside one-half of a mile north-northwest of. Bailey pond has been described above under the caption “ Keene gneiss.” A big ledge in the brook at the old road crossing 1 mile west- northwest of the summit of Hayes mountain shows typical White- tace anorthosite closely involved with granite with apparently slight development of Keene gneiss. The margins of the small body of Whiteface anorthosite sep- arately mapped on top of Hayes mountain appear to have been assimilated and close to its borders the anorthosite carries quartz . (no. 18 of table 1). The small area of anorthosite and granite mixed rocks on top of Wilson mountain shows numerous little inclusions of Marcy anor- thosite in the granite, these having been described in the above dis- cussion of the anorthosite. The relations are shown in figure 1. GEOLOGY OF THE SCHROON LAKE QUADRANGLE ce In the small area near the southeastern base of Severance hill, syenite contains numerous inclusions of Whiteface anorthosite. These inclusions are usually only a few feet long and very irregular with their borders more or less assimilated by the syenite. Gabbro and Metagabbro(‘?) Distribution. These gabbro and metagabbro (?) bodies are, in most respects, very similar to those of the North Creek quadrangle next to the south which have been rather fully described by the ‘writer in his report on the Geology of the North Creek Quadrangle* and also in the Journal of Geology, volume 21, pages 160-80. On the accompanying Schroon Lake geologic map, twenty-five gabbro masses are represented, all but four of these lying wholly within the quadrangle. They are well scattered over the southeastern two-thirds of the quadrangle, but not one has been found within the area of Marcy anorthosite. A possible explanation of their absence from the anorthosite area is given above in the discussion of the anorthosite. As usual in the writer's experience in the Adirondacks, these gabbro masses appear to have rounded to elliptical ground plans and very steep walls. The variation in length of the areas of outcrop is from one-fifth of a mile or less to 3 miles. In a few of the areas but one or two outcrops could be located. A striking feature of the distribution is the fact that the three largest bodies of the quadrangle lie along the border of the Marcy anorthosite. Kemp’s Elizabethtown map shows a similar distribu- tion of the largest gabbro masses there. Also on Ogilvie's Paradox Lake map the largest mass of gabbro occurs along the anorthosite border. This remarkable distribution of the gabbro bodies with reference to the anorthosite may be merely a coincidence, or it may have a real significance. If the latter, the writer can think of no very plausible explanation. Age. Most or all of the gabbro is younger than the Grenville, anorthosite and syenite-granite series (1) because of the intrusive contacts against rocks of those series, (2) because dikes of gabbro extend into rocks of those series, and (3) because inclusions rep- 2N. Y. State Mus. Bul. 170. 54 NEW YORK STATE MUSEUM resenting fragments of all three series occur in the gabbro. Some of the metagabbro(?) is quite certainly older than the syenite- granite.? Pegmatite dikes and certain small aplite dikes have been observed as sharply defined intrusions in the gabbro. The diabase dikes are later intrusions than the gabbro as proved by their distinctly finer grain, and the fact that one actually cuts the gabbro in the northern part of the North Creek quadrangle. It is therefore evident that at least three very distinct minor intrusions succeeded the gabbro intrusions of the auadrangle. Megascopic features. The typical nonfoliated gabbro is readily distinguished from all the other rocks of the quadrangle. Such rock makes up the main or interior masses of nearly all the stocks, especially the larger ones. It is medium to moderately coarse grained, dark gray to almost black where fresh, and it weathers to a deep brown. The plagioclase feldspar varies in color from a light gray to a dark bluish gray. A diabasic texture is usually more or less well developed, this being particularly striking in the coarser grained facies. Minerals recognizable with the naked eye or hand lens include plagioclase, pyroxene, hornblende, ilmenite (or magnetite) and nearly always biotite and red garnet. Variations from the typical nonfoliated gabbro just described are common, one of the most abundant being highly foliated border facies (usually amphibolite) which do not show a diabasic texture. Taken by themselves, some of the amphibolitic border facies are very difficult to distinguish from certain Grenville hornblende gneisses, or even from certain very gneissoid gabbroid facies of the Whiteface anorthosite. Nearly always, however, the mode of’ occurrence or the gradation into more typical gabbro renders cer- tain the recognition of the gneissoid border facies of the gabbro (figure 4). Even the more typical inner portions of the gabbro stocks show many notable variations in structure, texture and mineralogical composition as pointed out below in the special descriptions. Microscopic features. In the following table the mineral con- tents of the gabbro is represented by thin sections of samples from several of the areas. 1 Recent work by the writer in the Lyon Mountain quadrangle has shown that most of the gabbro and metagabbro are there older than the syenite- granite series which leads to the suspicion that some of the Schroon Lake quadrangle gabbro may also be older but definite evidence is lacking. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 55 Table 4 Thin sections of gabbro and diabase om a> o = ¢ o oO . |e elale E 2 = ° Z 4s S Onalbena a |) 4S S © a S 3 2) | = i ati] <2 & a q ® ee iS 2 | oe o ro a] a * rot q rt Deel 5p =) ~ ° oO i= Z| 8 alsa ee eet cen eum || oe SAMOS Wess Ah = a ca SP Se aS ae er: tsp i yeaa stone ty) ysl, < N @ hc ° : = Z0l8 2e.2 8 47) 20 15 3 1} little} little} little I 5 a} 40] oht I5 45 8 5 Maas Pi Ree a) elititle |. 5 A 5 AI] 9h4 AGW 5 Sil YA 5 5 8 il Leen letters sl (een oe aes mas) a5 42| T2c4 AS 2G eyecare ce 6 4 Bes Litsble || eee es [esses 18 2 | 43) 159.3 48 30 GiRee eae GP Cc ieee aca Se ote see ro rQ = AAW GTO GMO) N)ssi-alloues. - Ao |Nees |i) wall alee ene Alb ee Antél el eee 8 No. 39, I mile southeast of Minerva; no. 40, 134 miles east of Bailey _ pond and near the mapped inclusion of granite; no. 41, middle of Texas ridge gabbro area; no. 42, 1%4 miles northeast of Lester dam; no. 43, top of Saywood hill; no. 44, one-third of a mile north of summit of Say- -wood hill. In the above table, nos. 41 and 42 are more typical of the gabbro . of the quadrangle, while nos. 39 and 4o are rather more special or acidic facies. The more normal rock is therefore an olivine- bearing hypersthene gabbro or norite. The garnet, which is no doubt of secondary origin, mostly forms granulated borders about granulated hypersthene. In slide no. 41 the biotite mostly forms reaction rims about magnetite, and granulated garnet forms rims around granulated hypersthene in nos. 41 and 42. Nearly colorless diallage in no. 41 exhibits wonderful parting and schillerization inclusions. The labradorite of nos. 41 and 42 are filled with tiny dustlike dark inclusions. Special descriptions. The Texas ridge mass is the finest large scale example of a gabbro stock in the quadrangle. It covers an area of approximately 314 square miles. An almost continuous outcrop occurs along the whole-crest of the ridge. Near the south- ern end of the ridge a considerable mass of well-foliated pinkish gray granite forms an inclusion in the gabbro (see map). Imme- diately south of this inclusion the gabbro is notably variable, being mostly moderately foliated, but some big ledges are medium grained and very massive. None of this rock exhibits a diabasic texture. No. 42 of the table shows the mineral contents of a thin section of the more common rock, and this is seen to be a distinctly acidic or dioritic facies even carrying considerable orthoclase. The near- 56 NEW YORK STATE MUSEUM ness of this facies to the inclusion of granite from which it is not very sharply separated, taken in the light of various observations made by the writer on the North Creek quadrangle gabbro, strongly supports the view that this acidic facies of the gabbro was pro- duced by assimilation of some granite during the intrusion of the gabbro magma. In this same vicinity some outcrops of rather coarse-grained, nonfoliated gabbro show 5 to Io per cent red garnets ranging in diameter from a millimeter or two to one-third of an inch. These variations all occur within a stone’s throw. Just north of the granite inclusion, the gabbro is medium to fine grained, very gneissoid, and relatively richer in feldspar. Gabbro similar to this latter also appears on the ridge crest about three-fourths of a mile northeast of the granite inclusion; otherwise the many exposures along the whole ridge crest are very typical, medium grained, nonfoliated gabbro with diabasic texture. No. 41 of table 4 shows the mineral content of a thin section of this typical gabbro. Similar gabbro outcrops in considerable force near the extreme southwestern end of the area, and also on the ridge along the eastern side of the area. ' The Cheney pond stock is the second largest. It covers nearly 3 square miles. There are many good exposures. Most of this gabbro is very typical in every way, being medium to moderately coarse grained, nonfoliated, and possesses a diabasic texture. No. 42 of table 4 shows the minerals contained in a thin section. Good exposures of the amphibolitic border facies occur along the south- ern border between the pond and the old road, on the little island in the pond, and where the river enters the pond. In a field a few rods south of where the river enters the pond, a sharply defined 8-inch inclusion of typical Whiteface anorthosite occurs in the gneissoid gabbro. A body of granite large enough to be mapped occurs as an inclusion in the gabbro 114 miles northeast of the Lester dam. Whether or not the gabbro near this inclusion is more acidic than usual was not determined. The large stock partly shown within the map limits northwest of Cheney pond is mostly very typical gabbro with considerable amphibolite developed as a border facies. In a field a few rods north of the house (where the trail leads off) there are some very interesting ledges showing amphibolitic gabbro and Whiteface ° anorthosite rather intimately assoctated. A number of good exposures show the gabbro of the stock about a mile southeast of Minerva to be mostly medium grained and massive with only poor development of diabasic texture. Locnlly GEOLOGY OF THE SCHROON LAKE QUADRANGLE Sih a gneissoid structure is clearly evident. Much of this rock well exhibits the peculiar mottled appearance so often seen in those Adirondack gabbros which are relatively free from diabasic texture and foliation, this mottling being due to the irregular distribution of black minerals through the more or less granulated mass of feldspar. No. 39 of table 4 gives the mineral content of a thin section. This is a distinctly acidic facies and, like the local acidic facies of the Texas ridge gabbro above described, may have resulted from assimilation of granitic material by the gabbro. The small gabbro stock on the hill one-half of a mile west of Irishtown contains a 10-foot inclusion of thin-bedded Grenville quartzite. ' Fig. 4 A small exposure showing three facies of gabbro at the eastern margin of the Oliver hill stock. The gabbro is cut by aplite and pegmatite dikes. Some interesting features were observed in connection with the Oliver hill gabbro stock. Just south of the summit of the hill the gabbro sends three dikes into the granite. None of these dikes is more than a few rods wide, and one is amphibolitic. At the extreme eastern end of the stock a small outcrop shows three facies of gabbro— one nonfoliated, another highly foliated, and a third 58 NEW YORK STATE MUSEUM amphibolitic — cut by several white, fine-grained, aplite dikes and a pegmatite dike. The relations are brought out in figure 4. The stock southeast of North pond shows large developments of very gneissoid to amphibolitic facies of gabbro, especially in its eastern portion. Ajledge of rather typical, medium-grained gabbro just east of the brook one-fourth of a mile north of its junction with Rogers brook, contains many lenses and strips of nearly white Whiteface anorthosite as inclusions with parallel arrange- ment. A number of small faults intersect the ledge. The rela- tions are brought out in figure 5. On the small hill in the west- ern part of the area, typical nonfoliated gabbro is involved with ZaSGkY (EERGEAY éARDBRRERSRRSSL IL : HE) ARR REE? AZO oe HAN ieee * ASREERS AOE CCCCCACLC Saaey Nae ooo «am 4. oe P| ap | | | a geese BH AL Fig. 5 A sketch of part of an outcrop near the brook at the southern margin of the gabbro stock southeast of North pond. The normal gabbro (cross-lines) contains manv narallel strips of Whiteface anorthosite (black), and the whole is intersected by several minor faults. well-foliated gabbro, these two facies forming zones or belts not very sharply separated from each other. This foliation is very clearly a flow-structure due to magmatic currents, with the wavy GEOLOGY OF THE SCHROON LAKE QUADRANGLE 59 flow-lines clearly preserved. Further, these well-foliated zones bear a distinct resemblance to the gneissoid or amphibolitic border facies of the gabbro already described, and thus we have here evidence strongly supporting the view that the foliation of the amphibolitic border facies of the gabbro is really essentially the result of mag- matic flowage. The northern part of the small stock near the southern end of Ledge hill is typical gabbro cut by one small pegmatite dike and several small aplite dikes. Two small masses, one on Cobble hill and the other three-fourths of a mile northwest of Loch Muller are hornblende gneiss (meta- gabbro?) quite certainly older than the granite. Aplite and Pegmatite Dikes Aplite. Aplite dikes were observed in only a few localities but probably others occur within the quadrangle. These are repre- sented only in a general way on the geologic map. They probably do not all belong to the same period of intrusion. The best display of aplite dikes is on Wilson mountain. These are all medium to fine grained and none are foliated, neither do they show any notable difference in coarseness of grain between center and sides. On the western summit of the mountain a num- ber of small aplite dikes, none over a foot wide, cut clearly gneissoid, coarse-grained, pinkish granite. These do not have very sharp boundaries against the granite. This fact, together with their uniform medium-grained texture, suggests that these aplite dikes were intruded under fairly deep-seated conditions not long after the intrusion of the granite, or at least before the granite cooled very much, so that the aplite magma was able to blend with the walls of the granite country rock. On the eastern summit of Wilson mountain, numerous aplite dikes very similar to those just described, and with a maximum width of 4 feet, cut gneissoid medium-grained granite also without very sharp contacts. The small mass of anorthosite and granite mixed rocks on Wilson mountain (see map) is cut by a number of medium-grained aplite dikes, the widest being 5 inches, and all showing rather sharp contacts against the granite. Another locality is near the southern end of Ledge hill where several aplite dikes very sharply cut the small gabbro stock. The 60 NEW YORK STATE MUSEUM largest is 5 inches wide, visible for 10 or 12 feet, and has a branch bearing off abruptly at right angles. Another is 2 inches wide and traceable for 20 feet in the gabbro. None of these dikes could be traced into the surrounding granite. In certain respects these aplite dikes are quite different from those on Wilson mountain. Most of the dike material is fine grained, particularly so at the mar- gins, but this grades into a medium-grained, narrow, middle por- tion which is very persistent. The dike rock is somewhat weathered and of light-brown color, this latter probably due to stains from iron-bearing minerals in the gabbro. Because these dikes sharply cut the gabbro, which is distinctly later than the granite, and because of their chilled margins, it is believed that they were intruded considerably later than the aplite dikes on Wilson mountain above described. A thin section shows the following mineral percentages: microperthite, 65; oligoclase, 1; quartz, 20; diallage, 12; mag- netite, 2; and very little zircon. The thin section shows a granitoid texture and no granulation. At the eastern end of the Oliver hill gabbro stock a few branch- ing, fine-grained, white, aplite dikes a few inches wide cut the gabbro, the relations being shown in figure 4. Although these dikes are white and do not have distinctly coarse portions, it is probable that they were intruded at about the same time as those on Ledge hill. Pegmatite. A number of pegmatite dikes were observed in the granite on top of Ledge hill for one-half of a mile northward from the gabbro stock. None of these is more than 2 feet wide, and they all cut sharply across the foliation of the granite very irregularly. Near the eastern margin of the gabbro stock a very small pegmatite dike cuts across the foliation of the granite, and nearby another cuts the gabbro. On the western summit of Wilson mountain near the aplite dikes, a number of very small pegmatite dikes sharply cut the granite. Near the eastern margin of the Grenville area on the western face of Wilson mountain, several small pegmatite dikes cut a mixture of Grenville and granite. At the eastern end of the Oliver hill gabbro stock the same ledge which contains the aplite dikes (see figure 4) is also cut by a small pegmatite dike which is without very sharp contacts against the gabbro. Whether this is older or younger than the aplite was not determined. Pegmatite dikes are scarcer in the Schroon Lake quadrangle than is usual in the Adirondack region. Not one was observed in GEOLOGY OF THE SCHROON LAKE QUADRANGLE 61 the large body of anorthosite. In certain other quadrangles, like the Blue Mountain, the writer has found at least two sets of pegmatite dikes notably different in age, one occurring in the form of narrow masses essentially parallel to the foliation of, and not very sharply separated from, the inclosing syenite or granite, and the other, generally coarser grained, cutting across the foliation of, and in sharp contact with, syenite or granite. The second set is quite certainly the younger, and probably all the observed peg- matites in the granites of the Schroon Lake quadrangle belong with the younger set.! Diabase Dikes- Diabase dikes were observed in nine localities within the quad- rangle, but doubtless others exist. They are represented on the geologic map. Most of these are like the usual diabase dikes of the Adirondacks, more particularly like those of the North Creek quadrangle described by the writer. Unlike the gabbro, aplite, and pegmatite, several of the diabase dikes cut the anorthosite. The diabase probably represents the latest Precambrian intrusion in the Adirondack region as shown by the fine-grained texture and usually very distinct chilled borders, and also by the fact that a diabase dike actually cuts one of the late pegmatite dikes in the adjoining North Creek quadrangle. A diabasic texture is not always evident to the naked eye, but in thin section it is generally recognizable. None are porphyritic, but several show very distinct magmatic flow-structure foliation. All have sharp contacts against the coun- try rocks. About one-fifth of a mile north of the old graphite mine at the - western base of Catamount hill, a small typical diabase dike with strike N 40° E cuts Grenville gneisses. . A diabase dike 2 feet wide with strike S 20° W is well exposed in the syenite of the quarry one-half of a mile east-northeast of South Schroon. In a ledge of gneissoid granite by the road 1 mile west of Schroon Lake village, there are several small dikes varying in width from 2 to 8 inches. One is faulted 6 or 8 inches at two places. A very typical diabase dike with a maximum width of 4o feet and strike N 20° E is clearly traceable for fully one-half of a mile in the Whiteface anorthosite about 11% miles north-northwest of * Certain Adirondack pegmatites are discussed by the writer in a recent paper (Jour. Geol., vol. 27, no, 1, 1919) where it is shown that some pegma- tites developed as satellites of the cooling magmas of the late gabbros. 62 NEW YORK STATE MUSEUM Schroon Lake village. At one place many small off-shoots from the dike were observed to cut sharply the Whiteface anorthosite. A dike 6 inches wide with strike N 20° E cuts Whiteface anor- thosite at the summit of Severance hill. A dike of very typical diabase with maximum width of 40 feet cuts pinkish granite for one-quarter of a mile across the top of the little hill 134 miles due west of Grove Point. Three dikes of particular mterest cut typical Marcy anorthosite at the summit of Saywood hill. They vary in width from 6 inches to 1% feet and strike N 20° W. ‘These dikes all show rather dis- tinct magmatic flow-structure foliation. Diabasic texture is absent, and the fresh rock is dark gray with numerous black ferro-mag- nesian minerals each from I to 3 millimeters long. A close inspec- tion reveals many tiny red garnets. In thin section (no. 43 of table 4) this rock is seen to be a hypersthene diabase. Near the top of the hill one-third of a mile due north of the summit of Saywood hill there are two diabase dikes, one 15 feet wide and the other 2 feet wide, traceable for a number of yards in sharp contact with the Marcy anorthosite. The narrower dike is probably a branch of the wider one. These dikes have a good diabasic texture, and they are finer grained toward their margins. Myriads of tiny red garnets are visible under the hand lens. They show no foliation. A thin section (no. 44 of table 4) shows these dikes to differ from those on Saywood hill by carrying to per cent diallage, and oligoclase to labradorite instead of labradorite alone. On the ridge one-half of a mile north-northwest of Blue Ridge village a dike 2 feet wide sharply cuts the Marcy anorthosite with strike N 40° W. This dike looks almost exactly like those on Saywood hill above described. PALBOZOIG ROC OUTER Two outliers of early Paleozoic strata occur within the Schroon Lake quadrangle. One of these, in and near the village of Schroon Lake, has long been known, but the other, 11% miles southwest of the village, was located by the writer in 1916. During 1917 the writer discovered another outlier in the valley of Schroon river 7 miles north of Schroon Lake village. The outliers at and near the village are of particular geological significance, having been formerly connected with the main body of early Paleozoic strata of both the Champlain and Mohawk valleys, but now being isolated masses from 13 to 16 miles from the Champlain valley strata. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 63 Potsdam Sandstone Southwest of Schroon Lake Village This area of Potsdam sandstone lies 1% to 2 miles southwest of Schroon Lake village, or about 1 mile west to southwest of Grove Point. It was discovered by the writer in 1916. Just south- west of the forks of the road three-fourths of a mile west of Grove Point, there are four exposures, three of them in the road and the other just across the fence to the south of the road. The largest outcrop is several rods long. Paced at right angles across the strike of these exposures the distance is 45 yards. Since the dip is west 5°, a thickness of about 12 feet of the sandstone occurs here with neither top nor bottom visible. The strata strike N 30° E. In the brook just north of these exposures there are many angular fragments of the sandstone, but still farther north neither fragments nor outcrops occur, so that the northern limit of the area must be about as indicated on the accompanying geologic map. For fully one-half of a mile to the south-southwest, within the area mapped, a number of small exposures of the sandstone were observed, and also hundreds of angular fragments up to sev- eral feet across. Hundreds of angular fragments of the sand- stone also occur on both the north and south sides of Thurman pond, but a careful search failed to reveal an outcrop. Probably these are simply fragments in the glacial drift. In all the outcrops the rock is in every way typical Potsdam sandstone, being gray, well stratified, often cross-bedded, and not very coarse grained. The layers are generally from a few inches to a foot thick. No fossils were found. That these beds are very close to the bottom of the Potsdam formation is evident from the fact that granitic syenite, the immediately underlying rock, out- crops close by on the east (see map). A fault passes along the foot of the hills just west and this probably marks the western boundary of the sandstone, though no exposures of any kind occur close to the fault on its east side. Little Falls (?) Dolomite in and near Schroon Lake Village Description of occurrences. In a paper dealing with the iron ores,of northern New York published by C. E. Hall* in 1879, men- tion is made of this outlier. In his Preliminary Report on the Geology of Essex County,? _ Professor Kemp briefly describes the outlier and discusses its significance. | *N. Y. State Mus. Rep’t 32, p. 130-40. 1870. *N. Y. State Geol., 15th Annual Rep’t, 1805, p. 596-08. 64 NEW YORK STATE MUSEUM Since no detailed study of this outlier has yet been published, ~ the observations made by the writer during the summers of 1916 © and 1917 are here somewhat fully recorded. The dolomitic limestone is well exposed for a distance of fully 100 feet along the shore of the lake just north of the steamer | landing in the village. Plate 7 shows the general appearance of — the outcrop. The strike of the beds is N 50° E and the dip N 23°. — A detailed measured section follows: Sreits ; Feet IJnchesmy 6) Dolomitichliniestone without@ehenien sete er 2 ) 5 Dolomitic limestone with much dark chert in the form of irregular bunches up to 6 inches or even a MEOOb LOme a wi (ae snr aie vias, ee ea aie eee sae 8a 4 Dolomitic limestone without chert or calcite...... 2 one 3 Dolomitic limestone much like 2 below, except that chert is less conspicuous and not in layers. 3 8 2 Dolomitic limestone with much chert mostly in thin layers, but some in irregular bunches. Also numerous veinlets and bunches of calcite, some of which is dark to black with bituminous mat- ter. On the weathered surface there are signs of stratification surfaces separating the rock into thin layers’). viiee ome bed oko) oine eae nceee nae 5 ae 6 I Dolomitic limestone with considerable chert (below the -water')’ ore 2a: Gee a lal ila ele ratcinln Gen oes ane ane 2 Totals. 5,28. Baten se Ree ans Ee ec Seen 19 10 The dolomitic limestone of this section is dark gray weathering to light gray, crystalline, fine grained and compact in texture. It © contains numerous rounded quartz-sand grains not visible to the naked eye, but bits of the rock treated with hot hydrochloric acid — leave considerable residues of the fine quartz-sand grains. Weath- — ered surfaces of the rock are generally rough and deeply pitted due to more rapid removal of the irregular calcite bunches. The greatest thickness of limestone exposed in any one section is in the bed of Rogers brook between its mouth and the main — road. These beds strike N xo° E and dip.N 23°, and the stream — descends about 25 feet as a cascade over the ledge. The approxi- mate thickness of this section, based upon careful pacing (160 — feet) across the strike, is 85 feet. There are several intervals in the section, a thickness of 5 or 6 feet being concealed in one place. — ISE[[IA Wye] UOOIYIS Ul SUIPUR] JoWIed}s oY} JO YOU SpOI Mog B BIOYS OAL] IY} Aq ayiwoyop (2) S][®y eV] FO espe] oy Ly 9161 ‘OJOYd “I9TTIIN “fF “AN ~— ie. L aid aes Maen OU eaev ar GEOLOGY OF THE SCHROON LAKE QUADRANGLE 65 Most of the beds are from 6 inches to 2 feet thick with stratification surfaces between them very evident. Such beds are in nearly every way like those above described as occurring just north of the steamer landing. Chert is often present. Kemp, in the paper above referred to, states that “thin sections of the chert merely exhibit a brown, nearly isotropic base with numerous rhombohedra of calcite or dolomite scattered through it.” Some relatively thin layers are, however, very sandy. Considering the strike, dip and location of this section and the one just north of the steamer landing, it is quite clear that the latter underlies the former with an intervening thickness not definitely known, but probably about Io feet. Adding this 10 feet to the combined thickness of the two known sections, the thickness of the dolomitic limestone underlying this part of the village is at least 115 feet, with neither top nor bottom visible. Another excellent outcrop occurs in the quarry in the north- eastern portion of the village. This exposure is about 150 feet long (1917) parallel to the strike which is N 50° E. At the north end the dip is W 34°, and at the south end W 30°. A thickness of 28 feet was measured across the southern end of the quarry, and 30 feet across the northern end. ‘The rocks are very distinctly bedded in layers a few inches to 2 feet thick, usually 1 to 2 feet. Plate 8 gives a good idea of the appearance of the rock in the quarry. Except for a few thin, black shale and sandy shale partings, the rock is all dark gray, fine grained, crystalline, dolomitic limestone very similar to that of the other localities above described. Scat- tering veinlets and bunches of calcite, often dark with organic mat- ter, are common, but no chert was observed. The rock weathers to a light gray. Judging by the strike, dip and location, this quarry section probably lies in part at the horizon of the upper beds of the Rogers brook section, but mostly above it. On this basis, and barring the possibility of an intervening fault, a thickness of some- thing like 20 feet should be added to the thickness above deter- mined for the southern part of the village. This would make the total thickness of dolomitic limestone under the village approxi- mately 135 feet, with neither top nor bottom exposed. On the lake shore one-third of a mile southwest of the mouth of Rogers brook, there are two small exposures of dolomitic lime- stone in beds from 6 inches to 1 foot thick, with a total thickness of 10 feet. These beds, with strike N 60° E and dip W 7°, are about on a line with, and look much like, the beds at the steamer 66 NEW YORK STATE MUSEUM landing. On the weathered surfaces the rock is very rough and deeply pitted due to dissolving out of calcite bunches. A very careful search ‘southwest, west and north of the village failed to bring to light any other exposure of either dolomitic limestone or Potsdam sandstone than those above described, the glacial drift masking the underlying rocks to the foot of the hills (see map). Neither does the drift in this area anywhere carry angular fragments of either sandstone or dolomite which would strongly suggest the existence of concealed ledges. In fact, even rounded fragments are very rare. An angular fragment of typical Trenton limestone with fossils just west of the southern end of Thurman pond suggests such limestone in place, either now or just before the Ice age, not farther south than the vicinity of Schroon Lake village. Age of the dolomite. A diligent search through the dolomitic limestone of all the exposures failed to reveal any remains of organisms. Kemp, in his report of 1895, likewise states that he was unable to find fossils. This absence of fossils, combined with the isolation of the limestone at Schroon Lake, renders it prac- tically impossible to correlate very definitely or determine the age of this limestone. C. E. Hall, in the paper above mentioned, makes the following very brief statement: “At Schroon Lake village the Chazy limestone occurs with fossils. The outcrops are not exten- sive, being covered by a sand clay deposit.”’ With Hall, however, consideration of the Schroon Lake outlier was an incidental matter and more than likely, on the basis of general resemblance, the Schroon Lake limestone was classed with the fossiliferous Chazy limestone of the Champlain valley, the fossils having been assumed to be present. Kemp! notes the close resemblance of the Schroon Lake lime- stone “to the cherty magnesian limestones that are undoubtedly Calciferous (in age) and nonfossiliferous on Lake Champlain,” and with some hesitation he correlates them. The writer believes Kemp essentially correct in this view. But the old Calciferous formation, many hundreds of feet thick in the Champlain valley, was then considered to be wholly Ordovician in age, with cherty beds in the lower portion. As a result of more recent work, important changes of view regarding the old Calciferous formation have taken place, these changes being concisely stated by Cushing? as follows: “ The name *r5th Annual Rep’t N. Y. State Geol., 1895, p. 507. 2IN= Ya" Staten Vins biul16Os ps 42eurOns Plate 8 n or oe Lda ov Puy Onn ey Lo} — Gaia =155) = = 8 5 5 E ep x oe =| | S CB) iy A near view of Little Falls (?) dolomite in the quarry in the northern part of Schroon Lal upon the rock. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 67 “Calciferous’ was originally applied to the considerable thickness of dolomitic rocks which overlies the Potsdam sandstone in the Champlain and Mohawk valleys. Later on Clarke and Schuchert replaced this by the name Beekmantown, and to the rather unfossili- ferous phase of the formation in the Mohawk valley gave the local name of Little Falls dolomite. . . . Recent work of Ulrich, Rue- demann and Cushing showed that the Little Falls dolomite of the Mohawk valley was the equivalent” of the lower portion of the Champlain Beekmantown, and that it was really separated from the overlying Beekmantown by unconformity and graded through transition beds (Theresa) into the underlying Potsdam sandstone. The Schroon Lake and Little Falls dolomitic limestones are almost exactly alike in nearly every way, both being very largely dark-gray, fine-grained, crystalline, usually rather thick bedded, dolomitic, sandy limestones with considerable chert as irregular masses and irregular bunches of crystalline calcite at certain hori- zons, and almost, or entirely, devoid of fossils. Cavities containing very clear quartz crystals, so characteristic of certain horizons of the Little Falls dolomite of the Mohawk valley, were not observed at Schroon Lake, but it is quite possible either that the proper horizons are not there exposed or that such cavities may never have formed there. It is also of interest to note that Potsdam sandstone, the rock with which the Little Falls dolomite is almost invariably affiliated, outcrops to the southwest of the Schroon Lake dolomite. All points considered, then, it is very probable that the Schroon Lake dolomitic limestone should be regarded as Little Falls (Upper Cambrian) dolomite. Newly Found Outlier in the Paradox Lake Quadrangle During the summer of 1917 the writer discovered an outlier of Paleozoic rock in the Schroon river valley of the Paradox Lake quadrangle 214 miles due north of Schroon Falls, or 7 miles north of Schroon Lake village. It lies west of the river and only one- fourth of a mile east of the boundary of the Schroon Lake quad- rangle. In an area of about 2 acres there are exposures of dolo- mite in fairly thick beds resting upon sandstone, a total thickness of not over 25 feet being visible. These strata lie in practically horizontal position. Whether this is true Little Falls dolomite resting upon Potsdam sandstone, or the rocks represent transition $i 68 NEW YORK STATE MUSEUM (Theresa) beds between the two, the writer does not know. In any case, it is quite certain that the rocks of this outlier are to be classed with the Potsdam-Little Falls series in general. Significance of the Outliers The significance of the outliers of Paleozoic rocks at and near Schroon Lake should be considered in the light of all the outliers of Paleozoic strata in the southeastern portion of the Adirondack region. Altogether they afford positive evidence that early Pale- ozoic sea waters spread over all or nearly all of that region. All the definitely known outliers which occur well within the area of Precambrian rocks of the southeastern Adirondacks are as follows: 1 A small exposure of Potsdam sandstone near the southwestern corner of the Elizabethtown quadrangle. 2, 3, 4 Three small areas of Potsdam sandstone along the. eastern side of the Paradox Lake quadrangle. 5 Little Falls (?) dolomite at Schroon Lake village. 6 Potsdam sandstone 11% miles southwest of Schroon Lake | village. 7 A small area of sandstone and dolomite belonging to the Pots- dam-Little Falls series 2% miles due north of Schroon Falls in the Paradox Lake quadrangle. 8 A small mass of Potsdam sandstone 11% miles west of North River village in the Thirteenth Lake quadrangle. g A small body of sandstone and dolomite belonging to the Pots- dam-Little Falls series 1 mile west of High Street village in the . northern part of the Luzerne quadrangle. 10 A large outlier, several miles long, in the Sacandaga river valley at Wells in the Lake Pleasant quadrangle where are well- exposed Potsdam sandstone, Theresa transition beds, Little Falls dolomite, Black River (Lowville) limestone, Glens Fal's l'mesto-e and Canajoharie (Trenton) shale. 11 A considerable outlier showing Theresa beds, Little Falls dolomite, and Black River limestone between 1 and 3 miles north of Hope in the Sacandaga valley of the Lake Pleasant quadrangle. Of these, nos. 6, 7, 9 and 11 have been discovered by the writer during the last 6 or 7 years. Besides the above, a number of out- liers occur close to the main body of Paleozoic strata. Wherever detailed geologic maps have been made in the south- eastern Adirondacks, the region is shown to be literally cut to GEOLOGY OF THE SCHROON LAKE QUADRANGLE 69 pieces by numerous normal faults, the most prominent of which usually strike from north-south to northeast-southwest, with known displacements ranging from a few hundred to 2000 feet or more. It is important to note that the outliers above listed, except pos- sibly nos. 2, 3 and 4, lie on the downthrow sides of such faults. Thus a prominent fault bounds the Schroon Lake valley on the west. It appears, therefore, that the valleys containing these out- liers have been largely produced by faulting, and that the Paleozoic strata formerly lay at much higher levels, that is, the general level of the surface of Precambrian rocks of the region. Were the early Paleozoic sediments deposited in embayments or estuaries of the sea extending well into the area of Precambrian rocks, or were they deposited as a general mantle over the Pre- cambrian rocks of the whole southeastern Adirondack region? As a result of detailed studies it has been established that the southern half or two-thirds of the Adirondack area was, by the beginning of Potsdam time of the late Cambrian period, worn down to the condition of a peneplain upon whose surface only a few minor knobs or prominences existed. This being the case, notable embay- ments or estuaries could scarcely have existed. Still further evi- dence against the embayment idea comes out of the character of the sediments. Thus the rocks of the outliers, including those of Schroon Lake and Wells, are distinctly marine formations of exactly the same character as those of the same age in the general Pale- ozoic rock area of the Champlain and Mohawk valleys. Estuarine deposits would show certain distinct local variations and hence the very uniformity of the marine sediments in the outliers precludes the possibility of their deposition in estuaries. Thus we conclude that when the early Paleozoic, or more precisely late Cambrian, sea encroached upon the southeastern Adirondack area a general mantle of sediments was deposited over the whole region includ- ing much at least of the area of the Schroon Lake quadrangle, and that, subsequent to the emergence of the region, normal faulting took place whereby portions of the Paleozoic strata were, in many places, carried so far down that remnants have to this day been protected against complete removal by erosion. Thus we explain the existence of the outliers of early Paleozoic marine strata in the Schroon valley. Early and Middle Cambrian strata are unknown in northern New York, and there is no evidence that early and middle Cambrian seas ever spread over any portion of that area. But with the late 7O NEW YORK STATE MUSEUM Cambrian the case is different. The first deposit to form in the late Cambrian sea was the Potsdam sandstone which is well repre- sented in the St Lawrence, Champlain and Mohawk valleys, these regions all having been submerged under the Potsdam sea. In the southeastern Adirondacks the Potsdam sea certainly extended in as far as Wells (southern Hamilton county), North River (norti- western Warren county), and Schroon Lake (southern Essex county), because small outlying masses of Potsdam sandstone occur in those localities, having been formerly connected with the larger areas around the Adirondacks as above explained. The Potsdam sea surrounded and more or less lapped over on the borders of the Adirondack region, particularly the southeastern portion. There is no evidence that the interior of the Adirondack region was sub- merged, but rather it almost certainly formed a large island in the Potsdam sea. Marine conditions continued with the deposition of alternating layers of sandstone and dolomite upon the Potsdam. This is called the Theresa formation. After still greater submergence, the impor- tant formation known as the Little Falls dolomite was deposited layer upon layer to a thickness of usually several hundred feet in the comparatively clear waters of the latest Cambrian sea. The Little Falls sea swept all around the Adirondacks. Occurrences of the formation in the outliers at Wells (Hamilton county) and at Schroon Lake prove that the Little Falls sea extended well over the eastern Adirondack area, including much at least of the Schroon Lake quadrangle. Map figure 6 graphically shows the approximate relations of land and water during late Cambrian time. The Cambrian period closed with all of northern New York above sea level, but early in the Ordovician period a submergence set in, reaching a maximum about the middle of the period. Even at the time of maximum submergence in the Middle Ordovician, the best evidence points to the existence of a considerable island comprising the interior of the Adirondack region (see map figure 6).4. Mid-Ordovician strata at Wells indicates the presence of the sea of that age over southern Hamilton county. Though mid- Ordovician strata are not exposed at or near Schroon Lake, such rocks may be there concealed, or they may formerly have been present. In any case, their strong development in the Champlain valley only 15 or 20 miles to the east renders it highly probable *The early Paleozoic physiography of the southern Adirondacks is dis- cussed by the writer in a paper in N. Y. State Mus. Bul. 164, p. 80-04. 1913. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 71 that the mid-Ordovician sea spread far enough westward to cover at least the eastern part of the Schroon Lake quadrangle. We have no positive evidence that any part of the Schroon Lake quadrangle has ever been submerged under sea water since mid- Ordovician time. rc FRANKLIN ST LAWRENCE Fig. 6 Map of northern New York showing the general relations of land and water during parts of the Cambrian and Ordovician periods. The whole shaded portion represents land during the late Cambrian time, and the cross-lined portion represents land during the middle of the Ordovician. STRUCTURAL GEOLOGY Structure of the Grenville Series Tilting and folding. [:vidence has recently been presented by the writer! to show that the Grenville strata of the Adirondacks * Jour. Geol., 24:588-96. 1916 7/2 NEW YORK STATE MUSEUM have never been highly folded or severely compressed. Many broad belts of the strata are known to be practically horizontal or only very moderately folded, while many masses are merely tilted or domed at various angles. Very locally the strata exhibit con- tortions. The many scattering bodies of Grenville strata through- out the Adirondacks do not show any very persistent strike as would be the case had they been subjected to notable orogenic pressure. The structural relations of the Adirondack Grenville strata are reasonably explained as having been the result of the slow, irregular upwelling of the great bodies of more or less plastic magmas, probably under very moderate compression, whereby the strata, previously deformed little or none at all, were either broken up, tilted, lifted or domed, or engulfed in the magmas. According to this view, many large blocks or belts of Grenville strata, or several such rather locally separated by intrusive masses, with strike of intrusive masses parallel to the strike of the Grenville, show mono- clinical dips; many masses of Grenville were shifted around in the irregularly rising magmas to show various strikes and dips accord- ing to the direction of magmatic currents; some bodies of Grenville were merely domed over bodies of laccolithically rising magma and hence exhibit more or less quaquaversal strikes and dips; some masses of strata were considerably bent or even folded into syn- clines by being caught between bodies of magma upwelling at about the same rate; some masses, especially the more plastic limestones, were locally contorted near the igneous contacts; and many masses of strata were caught up or enveloped by the rising magmas. The Grenville series within the Schroon Lake quadrangle is not extensively developed, and the exposures are mostly too scattering to throw much light upon its structure, but most of the types of occurrence above mentioned seem to be present, except probably the laccolithic. Strikes and dips are platted on the accompanying geologic map, though where several similar observations were made within one-fourth of a mile of each other but one is usually recorded. In the Minerva area the Grenville strata seem to show a synclinal structure with a west-northwest strike of the axis through the vil- lage, but the outcrops are too scant to make this certain. If syn- clinal, it 1s not a very sharp fold because the dips generally vary from 30 to 50 degrees. A structure of this sort may be readily explained as due to greater upwelling of the granite magma on both the north and south sides of the mass of Grenville causing GEOLOGY OF THE SCHROON LAKE QUADRANGLE 73 the strata to be notably bent upward along those sides. It should be noted, in accordance with this view, that the strikes of the Gren- ville strata and the adjacent igneous rocks are essentially parallel. In the northern portion of the Olmstedville area five good obser- vations show the Grenville to have persistent dips of from 20 to 70 degrees northward, which is precisely the opposite of the Gren- ville of the northern portion of the nearby Minerva area, this latter being on the same strike. Such a sharp change would scarcely be expected as a result of ordinary orogenic folding, and it is more likely the result of the magmatic intrusion. The granite magma north of Olmstedville apparently broke through and flowed Ol!Imstedvil/le Snyder Hill => 8 ACS / / Hill ode x — ~ ~ hay, Sea jeve) Fig. 7 An early ncrth-south section through Olmstedville illustrating the geologic structure and the probable mode of origin of the valley in the vicinity of the village and the escarpment on the north. Several stages of erosion are shown from the late Mesozoic or early Cenozoic penepla n level (dotted upper line) to the present surface (heavy lower line). Length of section, 4 miles. Vertical scale, 214 times the horizontal. intrusively upon the Grenville strata, thus accounting for the north- ward dip of both granite and Grenville with the latter dipping under the former. Because of the much greater resistance of the granite to weathering and erosion, it stands out as a local scarp (see map), while the much weaker Grenville has been notably worn down to form the valley around Olmstedville. Figure 7 illustrates the principles here involved. The very irregular dips and strikes in the small area of Gren- ville just east of North pond are no doubt due to deformation of this block of strata by one or more of the various intrusive masses which rose adjacent to, or possibly engulfed it. A similar con- dition is true of the Grenville south of Adirondack village. The other mapped areas of Grenville are relatively small, and they are merely inclusions in the syenite-granite series. They 74 ‘NEW YORK STATE MUSEUM are usually lenslike or elliptical in ground plan and essentially parallel to the foliation of the inclosing rocks. Figure 8 shows an interesting case of a sharply bent small mass of Grenville gneiss in granite on Ledge hill. Foliation of the Intrusive Rocks The anorthosite and syenite-granite series. The great instru- sives of the quadrangle, including both the anorthosite and the syenite-granite series, exhibit more or less foliation, though large Fig. 8 Sketch showing ground plan of part of an exposure near the east- ern border of the gabbro stock on Ledge hill. The gneissoid granite, with its sharply curving foliation, wraps about a portion of a sharply bent small inclusion of hornblende gneiss. portions of the Marcy anorthosite commonly show practically none. In the syenite-granite series at least a faint foliation seldom fails to appear, and it varies from this to very highly foliated. The degree of foliation often varies notably within very short dis- tances. Both strike and dip of the foliation also often vary notably, though the general trend or strike is from east-west to northwest- southeast. Regarding the foliation in the adjoining Paradox Lake quadrangle, Doctor Ogilvie says: “ The general direction of strike is similar. A direction of N 40° E is the prevailing one, with low southeast dips.” According to this, the general strike of foliation of the Schroon Lake quadrangle is almost at right angles to that of the Paradox Lake quadrangle. In many ledges the general strike GEOLOGY OF THE SCHROON LAKE QUADRANGLE 75 can be made out but not the dip, this being particularly true of the locally gneissoid portions of the Marcy anorthosite. The gneissoid structure is usually accentuated by the roughly parallel arrangement of dark minerals, though locally the granite, compara- tively free from dark minerals, is strikingly gneissoid due to excessive flattening of feldspar and quartz. Granulation of minerals, especially feldspar, is common in many localities and often highly developed, the more highly foliated rocks generally being most granulated. On the accompanying geologic map there are recorded represen- tative strikes and dips of foliation selected from many field observations. The writer considers the foliated igneous rocks to be so-called “primary gneisses’ whose gneissoid structure was developed as a sort of magmatic flow-structure under moderate compression rather than by severe lateral (orogenic) pressure brought to bear upon the region after the cooling of the magmas. Briefly stated, the writer’s explanation follows. | During the processes of intru- sion, which were long continued, the great magmatic masses were under only enough lateral pressure to control the general strike of the uprising magmas with consequent tendency toward parallel arrangement of instrusives and invaded Grenville strata; the folia- tion is essentially a flow-structure produced by magmatic currents under moderate pressure during the intrusions; the sharp variaticns of strike on large and small scales, and rapid variations in degree of foliation, are essentially the result of varying magmatic currents under differential pressure, principally during a late stage of magma consolidation; the almost universal but varied granulation of these rocks was produced mostly by movements in the partially solidified magma, and possibly to some extent by moderate pressure after complete solidification; and the mineral flattening or elongation was caused by crystallization under differential pressure in the cooling magma. It would seem, therefore, that the general absence of foliation from so much of the Marcy anorthosite is best explained as the result of the much more uniform (laccolithic) intrusion of this single great body which is much less involved with Grenville masses, or, in other words, to much less forced differential flowage. Figure 8 shows a case of sharp variations in strike within a few feet in the granite of Ledge hill. *The writer has presented a rather full discussion of this subject in Jour. Geol., 24:600-16. 1916. 76 NEW YORK STATE MUSEUM It is quite possible that much or all of the pressure within the intruding magmas was simply “ shouldering pressure exerted (by the magmas) on the adjacent rocks under bathylithic, or deep- seated, conditions” as suggested by Cushing. The gabbro and diabase. As already stated, the interior por- tions of most of the gabbro stocks are nonfoliated and they pos- sess a diabasic texture, while the outer portions are usually highly foliated rocks, often true amphibolites. More or less granulation is common as seen in the thin sections. In many places the degree of foliation varies considerably within single stocks, a very fine example already having been described as occurring on the little hill just south of North pond (see page 58). The foliation shows a strong tendency to box the compass around the borders of the stocks, and, therefore, often strikes across the structures of the older adjacent rocks. If due essentially to regional compression after the solidification of the gabbro, should not the foliation every- where strike at least approximately at right angles to the direction of application of the pressure? Also, how are the notable varia- tions in foliation and granulation to be explained on the basis of regional pressure? It is believed that the foliation and granulation of the gabbro stocks are largely, if not wholly, primary features due to move- ments in the magma before final consolidation. Considerable pres- sures must have obtained within the stock chambers while the magmas were being intruded under deep-seated conditions. Such pressure against the country rock, combined with the development of differential flowage particularly in the magmatic borders, would readily account for the peripheral foliated zones which were, no doubt, produced during a late stage of magma consolidation. But the conditions of magmatic pressure and flowage must have varied considerably, and thus the local variations in degree of foliation and granulation are accounted for. , Certain of the diabase dikes which cut the Marcy anorthosite in the vicinity of Blue Ridge village are also more or less foliated, their borders particularly so. As in the gabbro stocks, so here, the foliation is considered to have been due to differential magmatic flowage under moderate pressure during a late stage of magma consolidation. In these dikes, however, the foliation was developed parallel to the strike of the dikes because cross-sections of these magma chambers were long and narrow rather than rounded or elliptical as in the gabbro stocks. GEOLOGY OF THE SCHROON LAKE QUADRANGLE Vi Faults and Zones of Excessive Jointing General features. The Schroon Lake quadrangle lies in the midst of the faulted eastern Adirondack region. Fifteen earth fractures are represented on the accompanying geologic map. More than likely there are others, but only those which show at least fairly satisfactory evidence for their existence are mapped. In most cases these earth fractures are rather well-defined faults, while in others they appear to be zones or belts of excessive joint- ing in which more or less crushing and minor faulting have taken place. These faults or broken-rock zones are relatively straight for considerable distances, ranging from a mile or two to 10 or 12 miles within the quadrangle. Where observations were made, the fault crush-zones are commonly from 25 to roo feet wide. In accordance with most of the more conspicuous faults of the eastern Adirondacks, those of the Schroon Lake quadrangle mostly strike north-northeast. The topographic influence of the fault zones is usually very striking as a glance at the geologic map will reveal. It is very important to note that the fault zones of weakness, mostly clearly marked by long, narrow valleys, nearly all trend almost or quite at right angles to the strike of the foliation of all the rocks and to the general trend of the belts of relatively weak Grenville which are essentially parallel to the foliation (see map). The faults are all of the normal type with fault surfaces vertical or very steep. Within the area of Precambrian rocks of the eastern Adirondacks. it is often difficult to demonstrate the existence of faults and, when a given fault has been proved to exist, it is usually difficult or impossible to trace it across country with any great degree of accuracy because of scarcity of exposures due to accu- mulation of glacial and postglacial deposits in the fault valleys. Because of the character and structure of the rock masses (mostly igneous) and the lack of any very clearly defined stratigraphic relations, it is practically impossible to determine the actual amounts of displacements, though in some instances minimum figures can be given. Within the quadrangle such minimum figures are not definitely known to be more than some hundreds of feet, but actual displacements may have been many times as great. Among the more positive criteria for the recognition of the faults and zones of excessive jointing in the quadrangle are the following: (1) long, narrow, almost straight valleys which trend at high angles across the strike of the older rock structures such as the foliation and the belts of Grenyille strata; (2) steep to vertical 78 NEW YORK STATE MUSEUM scarps, often miles long, in hard, homogeneous rock; (3) actual presence of crushed, sheared, slickensided or brecciated rock zones ; and (4) Paleozoic strata lying at the base of steep hills of Pre- cambrian rocks. Age of the faulting. That some Adirondack faulting took place in Precambrian time has been pretty well established, but, so far as definitely known, such fractures are of minor importance. There is no positive evidence for such faulting in the Schroon Lake quadrangle. It seems quite likely as Cushing has suggested, that considerable faulting took place during, or toward the close of, the Paleozoic era. Any fault scarps, ridges or valleys which may have been pro- duced by the close of the Paleozoic must have been nearly or quite obliterated by the long subsequent time of erosion. If so, how do we account for the present Adirondack ridges and valleys which follow the fault lines or zones? Accompanying the uplift of the late Mesozoic or early Cenozoic peneplain of the Atlantic coast region, or following it, there was either new faulting, or renewed movement along old faults, or old fault zones, including zones of excessive jointing with little displacement, were not affected by new movements. How much is new faulting, and how much renewed faulting along old lines or zones of fracture is not known, but it is quite certain that considerable faulting in the eastern Adirondacks must date from the uplift of the peneplain just mentioned as shown by fault scarps in homogeneous rocks and by the existence of tilted fault blocks which have been little modi- fied by erosion. Some relatively long, deep, narrow, valleys of the Schroon Lake quadrangle, like that which follows the Minerva stream fault or the Hoffman notch fault (see below), are due essentially to erosion along the fault or broken-rock zones of weak- ness irrespective of when they originated, while others which are broader, like the Schroon Lake valley and the lowland between Green hill and Oliver hill, are due either to comparatively recent sinking of fault blocks, or removal of weaker rocks by erosion whereby old fault scarps are renewed, or both. Distinctly tilted fault blocks, like some in the North Creek quadrangle just to the south, are not certainly present in the Schroon Lake quadrangle. Schroon valley fault. As represented on the geologic map, this is one of the two longest and most conspicuous faults of the © quadrangle. Its scarp marks the western boundary of the Schroon *N. Y. State Mus. Bul. 095, p. 405. ‘ W. J. Miller, photo, 1917 The zone of excessive jointing accompanied by some faulting in the road metal quarry by the main road one-half mile east-northeast of South Schroon GEOLOGY OF THE SCHROON LAKE QUADRANGLE 79 valley for 12 miles across the quadrangle and beyond (northward) for fully 8 miles more. As regards both length and topographic influence, this fracture takes rank as one of the most prominent faults in the eastern Adirondacks. It probably does not extend south of the quadrangle limit. The topographic evidence for the fault is very strong (plate 3). The Potsdam sandstone east of Grove Point and the sandstone and dolomite in the valley 7 miles north of Schroon Lake village also both lie against the base of the scarp and hence furnish strong evidence for faulting with down- throw side on the east. Several ledges in the bed of Horseshoe pond brook are badly broken parallel to the course of the stream and these furnish still more positive evidence for the existence of the fault. Nowhere else along the immediate base of the scarp were outcrops of any kind observed, so that further evidence such as slickensides and crushed or brecciated zones, is lacking. From Thurman pond southward the trace of this fault 1s much less cer- tain. Some idea of the minimum displacement along this fault may be gained not only from the height of the scarp but also from the positions of the outliers of Paleozoic strata. Thus the sand- stone and dolomite 7 miles north of Schroon Lake village lie at an altitude of 900 feet, while the summit of the mountain just west is nearly 2300 feet, thus indicating a minimum downthrow of about 1300 feet on the east side of the fault. The position of the Pots- dam sandstone west of Grove Point indicates a minimum displace- ment of at least 400 feet, and probably 600 feet. Schroon lake faults. The topographic evidence for a fault, or at least a zone of excessive jointing, along the western side of Schroon lake is strong, as shown on the map. A very conspicuous zone of excessive jointing accompanied by moderate faulting (see plate 9) occurs in the road metal quarry one-half of a mile east- northeast of South Schroon. The strike of this jointed zone is parallel to the strike of the fracture as mapped but at a high angle to the strike of the foliation of the rocks. Probably the jointing exhibited in the quarry lies a little to the west of a real fault, because the topography strongly points to a downthrow of fully 200 feet on the east side. From Adirondack village southward close to the lake shore there is a fault which is but the northern extension of a rather prominent fault several miles long which has been mapped and described in the writer’s report on the North Creek quadrangle. Along the eastern lake shore at the base of Quackenbush hill, and extending several miles into the Paradox Lake quadrangle, a 8o NEW YORK STATE MUSEUM long, nearly straight line, with hills rising steeply hundreds of feet above it and at right angles to the old rock structures, makes the existence of a line or zone of fracturing there almost certain. This being the case, the outliers of Paleozoic strata in and near Schroon Lake village really le in a “ graben” or fault trough. Fuller brook fault. This zone of fracture separates Pine hill and Ledge hill rather sharply and continues northward at least to Horseshoe pond. The topographic evidence is quite clear and, in the bed of the little brook about a mile south of Marsh pond, the rock is considerably broken as a result of earth movements. The topography suggests a moderate downthrow on the east, but instead of being a true fault this may be simply a zone of excessive joint- ing with little displacement. Alder brook and Trout brook faults. That Alder brook and Trout brook follow fault zones for several miles as shown on the map is quite certain. Not only are these valleys narrow and remarkably straight, but they have been cut into granite at right angles to its structure. Such could scarcely be the case unless the positions of the valleys were determined by zones of weakness due to faulting. Further, the earth block between these two streams is very distinctly depressed below the country immediately on either side. The evidence, then, renders quite certain the existence of a fault block from 1% to nearly 3 miles wide and several miles long which has sunk between two faults, one along Alder brook and the other along Trout brook. The topographic influence of this sunken fault block is particularly striking in its southern half where the Pine-Green hill mass on the east and the Oliver-Snyder hill mass on the west each rise hundreds of feet very abruptly. Direct evi- dence for the faulting from ledges along the fracture lines or zones is wholly wanting, not a single outcrop occurring on either of the brooks. The Alder brook fault continues for several miles south into the North Creek quadrangle (see North Creek geologic map). Minerva stream fault. As regards both length and topographic influence, this fault takes rank as one of the most prominent known lines of fracture in the eastern Adirondacks. On the accompany- ing map it shows a length of 12% miles. It continues southward for 614 miles across the northwestern part of the North Creek quadrangle and thence for at least 3 miles into the Thirteenth Lake quadrangle. Its total length is, therefore, at least 22 miles. Its topographic influence is very striking since a deep, usually narrow, nearly straight valley has been cut out along this zone of weakness along its whole course of over 12 miles in the Schroon be) ‘oinjeseduia} JO sasuvyo 0} anp Yo payeac SUIARY oy1uaAs DIPURIS IY} JO sqeys years Auris ‘oWOp UOl}eI]O}xXe Ue fo osjdwexs oUy & SI SINT, ‘9Sseq Ss} suoye sossed YIM INeZ Weoij]s PAIOUIPY OY} FO sprs MorYyydn 9Y} UO Sat] WT pue YSty JoofF OOQ ST UIe}JUNOU 9Y} FO IdvF oy, “9seq oY} JO jsvo ofl jJyey-au0 yurod e WoO} Us0S se puod weyxoy{ JO JSAMYNOS oIW I Ule}UNOW doaqs oy, LIGE ‘OJOYd ‘TOTTI “£ “AV OL 93eIg GEOLOGY OF THE SCHROON LAKE QUADRANGLE SI Lake quadrangle (plate 10). Southward, also, the topographic influence is pronounced. It seems quite clear that the downthrow side is on the east, this being most evident in the North Creek quadrangle where, just east of the Gore mountain mass, the dis- placement is at least 1500 feet. Within the Schroon Lake quad- rangle the topography does not indicate so much displacement, though it is mostly at least some hundreds of feet except at the north where it is much less. In the Minerva stream valley no out- crops occur along the fault, but in the bed of the brook just west of Washburn ridge there are several exposures of rock badly broken by the faulting in zones parallel to the course of the stream. It is very important to note that the strike of this fault is almost exactly at right angles to the strike of the foliation of all the rocks, and also at right angles to the strike of the prominent belt of Grenville strata around Minerva and Olmstedville. It is difficult to con- ceive how such a long, narrow valley could have developed for 12 miles across these structures except along.a fault zone of weakness in the rocks. The lowlands in the vicinity of Minerva and Olmsted- ville, and also in the vicinity of North Creek, are due to more rapid erosion of the comparatively weak Grenville strata in those localities. Hoffman notch fault. Evidence for either a fault or zone of crushed or excessively jointed rock in the Hoffman notch valley is twofold. In the first place, the long, straight, deep, narrow valley, with north-northeast strike parallel to most of the prominent faults of the eastern Adirondacks and at right angles to the rock struc- tures of the immediate region, almost certainly must have been carved out along a fault zone of weakness. This valley is 5% miles long with a maximum depth of 1200 to 1500 feet. In the ‘second place, actual crushed to even brecciated rock zones in the bottom of the valley and parallel to it were observed at a number of places, the principal ones being as follows: several ledges in the brook between one-half and 114 miles north of the pond in Hoff- man notch and several ledges in the brook between 1% and 2 miles south of the same pond. The brook northeast of Hoffman notch pond follows a short branch fault for about one-half of a mile with much evidence of crushed rock. That the Hoffman notch fault continues northward across the east-west Blue Ridge- Boreas river road is proved by the existence of a ledge in the Branch brook just north of the road where closely spaced jointing with strike N 20° E is well shown. 82 NEW YORK STATE MUSEUM Faults between Hayes mountain and Hewitt pond. West of Hayes mountain, Minerva stream flows through a narrow north- south valley which for 2%4 miles has been carved out along a dis- tinct fault zone of weakness. In the bed of the stream three-fourths of a mile north of the place marked “Camp” on the map, the granite is considerably broken due to the faulting. Along the stream one-third and three-fourths of a mile, respectively, south of “Camp,” there are ledges distinctly broken or excessively jointed parallel to the stream channel. In one case a crushed-rock zone 10 to 15 feet wide is finely exhibited. The topography suggests moderate downthrow on the west. A ledge in the bed of the stream one-half of a mile southeast of the mouth of Hewitt pond shows a distinct crush-zone with almost north-south’ strike, but with little or no topographic influence. Hewitt pond brook also follows a fault zone of weakness with nearly east-west strike, this being the only definite fault in the quadrangle with such a strike. A few rods above the mouth of the brook in a small gorge the rock is considerably broken parallel to the channel. Wolf pond brook fault. A narrow nearly straight valley 5% miles long extends from Lester dam to north of Wolf pond. It has probably been developed along a zone of excessive jointing rather than along a distinct fault. In the bed of Wolf pond brook, one-third of a mile from its mouth, a big ledge is considerably broken by closely spaced joints parallel to the channel. Boreas river fault. Boreas river, for 1% miles after it enters the map area, quite certainly follows a channel which has been cut out along a fault zone or a zone of excessive jointing. One ledge along the stream shows the broken rock. This fault zone is really only the southern end of what is evidently a very prominent earth fracture extending far into the Mount Marcy quadrangle. The Ausable lakes are there located in this fault zone. The topographic influence in the Mount Marcy quadrangle is very striking. Niagara brook fault. The long, deep, straight, narrow valley occupied in part by Niagara brook has quite certainly been deter- mined by a fault or joint-zone of weakness. Counting its northern extension beyond the map area where its topographic influence is even more pronounced, this fault or joint-zone is 6 miles long. No broken-rock zone was observed within the Schroon Lake quad- rangle, the bed of the brook there all being in glacial drift. Other faults. A big ledge at the road corners southeast of Oliver pond is all cracked into small blocks. Also, ledges by the GEOLOGY OF THE SCHROON LAKE QUADRANGLE 83 road one-third of a mile west of Oliver pond show many closely spaced joints with nearly north-south strike. These zones of broken rock are apparently minor, and since they have no topo- graphic influence they are not mapped. The steep southern face of Moxham mountain strongly sug- gests a fault scarp, but it might have resulted by removal of Gren- ville strata, such rock now forming a considerable belt not far to the south. In the bed of Boreas river 1 mile below Lester dam, the granite is much broken and badly weathered in a fault zone of weakness with nearly north-south strike, but there appears to be no topo- graphic influence. In still other places the topography suggests the presence of fault zones, but in no case has the evidence seemed strong enough to warrant mapping. PEBISHOCENE GEOLOGY General Statements It is well known that, during the great Ice Age of the Quaternary period, all of New York State except portions of the extreme ‘southern side was buried under a sheet of ice. That this great sheet of ice was thick enough to bury even the highest mountains of northern New York is proved by the presence of glacial pebbles and boulders at or close to many of their summits. This is true in the Schroon Lake quadrangle. In some cases striae and glaciated ledges have been observed several thousand feet above sea level, the highest which happened to be noted in the Schroon Lake quad- rangle being at 2200 feet. Adirondack glacial lakes at altitudes of several thousand feet above sea level also bear strong testimony to great depth of ice. The general direction of movement of the ice across the Adirondacks was toward the south and southwest, with comparatively few local exceptions. Such a persistent direction of movement also strongly argues for complete burial of the region under ice. The ice spread southward as a part of the great Labra- dorean ice sheet of eastern Canada. When the ice, early in its southward movement, struck the Adirondack highland district, one portion flowed southward through the Champlain valley and sent a branch lobe westward into the Mohawk valley. At the same time another portion flowed around the western side of the moun- tains and sent a lobe eastward into the Mohawk valley. The two lobes, one from the east and the other from the west, met in the 84 NEW YORK STATE MUSEUM Mohawk valley leaving the main portion of the Adirondacks free from ice. But, as the ice increased in volume, more and more of the Adirondack region was covered till finally even the highest points were buried. In a paper published by the writer some years ago, the movement of the great ice sheet across northern New York is discussed.1. During the ice retreat the higher east-central Adirondack region was the first to be freed from the ice, and the ice-freed portion gradually increased in size. Direction of Ice Movement The direction of ice movement across the Schroon Lake quad- rangle is clearly recorded by both glacial scratches (striae) and the distribution of glacial boulders. Distinct glacial striae were observed in twenty localities, their bearings and locations being plotted on the accompanying geologic map. They are as follows: 1 S 10° W. On Grenville gneiss 114 miles west-southwest of Schroon Lake village. 2 5 10° E. On granite by the road 114 miles west-northwest of Schroon Lake village. 3 S 10° E. Ondiabase 1% Ae due west of Grove Point. 4 N-S. On granite three-fourths of a mile northeast of Charley hill. 5 N-S. On granitic syenite near the summit of Beech hill. 6 S 10° E. On granite by the road 1 mile west of Charley hill. 7 N-S. On granitic syenite by the road,1 mile northwest of Taylors on Schroon. 8,9 S 10° E. Two records one-fifth of a mile apart on granite by the road three-fourths of a mile north-northeast of Pat pond. 10 S 10° E. On Grenville gneiss three-fourths of a mile due west of Minerva. ; 11 S 10° E. On granite by the road just south of Oliver pond. 12 N-S. On granite by the road one-third of a mile west-south- west of Oliver pond. 13 S 30° W. On granite by the road one-half of a mile west- southwest of Oliver pond. 14 S 10° EF. On syenite by the road one-half of a mile north- east of Muller pond. 15 5 10° E. On Whiteface anorthosite by the road 134 miles west-northwest of Boreas river. 1Amer, Jour. Sci., 27:289-98. 1900. GEOLOGY OF THE SCHROON LAKE QUADRANGLE 85 16 S 15° E. On Marcy anorthosite near the creek three-fourths of a mile northeast of Boreas river. 17, 18, 19, 20 S 10° E. Four records on Marcy anorthosite by _ the road between 1 and 134 miles east-northeast of Boreas river. It will be seen from this list that the extreme range in direction of the glacial striae is from S 15° E to S 30° W. Further, all but two sets of the striae run from N-S to S 15° E. It is evident, therefore, that the general direction of movement of the ice over the quadrangle, except possibly its northeastern one-fourth where no striae were observed, was a little to the east of south. This harmonizes closely with the sixty sets of glacial striae observed by the writer’ in the North Creek quadrangle next to the south, the average direction of which is almost exactly N-S. Regarding the Paradox Lake quadrangle which lies just east, Doctor Ogilvie says:* “ The more southerly and easterly parts of the quadrangle were in the region of the southwesterly moving ice current.’ Professor Kemp* has reached a similar conclusion regarding the southeastern portion of the Elizabethtown quad- rangle, and further observations there by the writer reinforce this view. In the Blue Mountain quadrangle, the second to the west of the Schroon Lake quadrangle, the writer* has recently shown that the general direction of ice movement was southwestward. Pro- fessor Cushing® reached the same conclusion regarding the Long Lake quadrangle. A's shown by the writer,® the general ice cur- rent was southwestward across the Lake Pleasant quadrangle in the south-central Adirondacks. From the above facts it is evident that the southward to even slightly southeastward movement of the ice across the Schroon Lake and North Creek quadrangles was rather strikingly excep- tional, having been surrounded by the great sheet of generally southwestward moving ice. The writer has no explanation for this puzzling fact. Local topographic control of the ice current in the Schroon Lake area can not have been the cause of the deflection because most of the prominent ridges and valleys have a north- northeasterly strike and the others vary from east-west to north- west, so that the ice moved across these sets of valleys at angles of from 20 to 90 degrees. The location and strike of striae in valleys, Y. State Mus. Bul. 170, p. 66. ro14. Y. State Mus. Bul. 96, p. 470. 1905. . Y. State Mus. Bul. 138, p. 95. ro910. Y. State Mus. Bul. 192, p. 48. 1076. Y. State Mus. Bul. 115, p. 495. 1907. Y. State Mus. Bul. 182, p. 63-64. 10916. 1 2 3 4 5 6 Zee ae 8&6 NEW YORK STATE MUSEUM like those north of Pat pond and east of Boreas river or at the summit of Beech hill, clearly prove the failure of the topography to determine the direction of the ice movement. Ice Erosion There is no evidence that the ice was a vigorous agent of erosion within the quadrangle. It may possibly have scoured out and somewhat deepened the basin of Schroon lake, but definite proof is lacking. Certainly none of the more prominent valleys were produced by ice erosion, for, as above shown, the main body oi the ice flowed across the trend of the valleys rather than parallel to them as would have been necessary for ice erosion to have been very effective for their development or even notable modification. It is quite certain, however, that the ice did remove from its original position practically all the preglacial soils and most of the rotten rock. Further, the vast number of glacial pebbles and boulders of comparatively fresh rocks clearly show that much relatively fresh rock must have been removed probably by the process of plucking or pushing off joint blocks which during trans- portation became more or less rounded. Altogether, however, the total amount of material eroded by the ice made no marked dif- ference in the preglacial topography. The dumping of glacial material in the valleys during and after the ice retreat has probably altered the topography more than erosion by the ice. Glacial Deposits Morainic deposits. Typical morainic deposits, mostly glacial till or ground morainic material, are common throughout the quad- rangle though usually they are more or less associated with strati- fied or fluvio-glacial materials. Boulder clay is seldom seen. Morainic deposits are particularly well developed over the lower lands or valleys, while well up on the hills and mountains they are usually absent or thin. It is evident that, during the retreat of the great ice sheet, the burden of morainic material was largely dumped in the valleys either by direct deposition from the ice or by water in connection with the ice, or both. The most extensive development of morainic and fluvio-glacial deposits is in the area of over 6 square miles mapped as Pleisto- cene in the central portion of the quadrangle. Within this area the hard rocks are everywhere concealed under glacial deposits ‘O91 OY} Aq jJo] SEM jt dDUIS Uddo yds Udaq Sey Jopynoq dy} ‘yors19 yuLOf v Suoje 19}eM JO SUIZII1F PUB SULIOYJBIM 0} ONC “aSVW so] oY} SuLmMp oot oy} Aq oSpoy Juosred sqrt wiosy sop Moy ve JSBo] 32 pelizeo sem I] “YSsty joog Se pue ‘oprm jyooy Zz ‘suoy joay CF ATayeumxoidde st j{ ‘JaJOFT S,uerIeA\ JO jsoMy nos sur e FO SYANOF-o91y} [IY Vqqoy Jo oseq Usojseayjnos 9y} JedU ayIsOYJIoUe ADIVP JO Japynog [emr[s jeais Vy 916 ‘O}0Ud “JOTITIN “Lf. “AN 7, Ot URES hea’ ee LS eeaby FIR | ak z TT MONEE - GEOLOGY OF THE SCHROON LAKE QUADRANGLE 87 except at the four places indicated on the map. A little west cf the middle of this area, there is an area of nearly a square mile, mostly an old clearing, where a boulder moraine is conspicuously shown. In the area of Pleistocene east and southeast of Olmstedville morainic and fluvio-glacial deposits are also well exhibited, with boulders especially prominent in the northern half. In and near Olmstedville, in the area of Grenville, there are also fine develop- ments of morainic and fluvio-glacial materials with boulders common. Very conspicuous boulder morainic deposits occur for a mile on either side of the Trout Brook valley from 1 to 1% miles south- east of Muller pond. The Pleistocene of the area between South Schroon and Grove Point is largely morainic material. Among many smaller scale morainic deposits are those in the valley east of Catamount hill, and three-fourths of a mile south- west of Irishtown. Glacial boulders (erratics). Glacial boulders or erratics are very abundant and widespread over the quadrangle, though they are much less common on the tops of mountains and hills than over the lowlands. Some of the more prominent groupings of boulders in so-called “boulder moraines” are mentioned above. In addi- tion to those there should be noted the accumulation of hundreds of large and small angular masses of Potsdam sandstone just south- west of Thurman pond and all over the area of ‘Potsdam sand- stone north of the pond. An 8-inch angular fragment of typical Trenton limestone was noted a few rods west of the south end of Thurman pond. This suggests either a hidden ledge of such rock in this portion of the Schroon valley, or a mass scraped off and broken up by the ice, though the fragment might possibly have been carried by the ice for many miles. While numerous boulders represent various types of the region, most of the largest ones are of Marcy anorthosite. The writer was particularly impressed by many boulders, usually only moder- ately rounded, ranging from 10 to 20 feet in diameter in the woods on the southern portion of Texas ridge. A very large and interesting glacial boulder of Marcy anorthosite lies in an old field near the southeastern base of Cobble hill three- fourths of a mile southwest of Warren’s hotel. Roughly meas- 88 NEW YORK STATE MUSEUM ured, it is 33 feet long, 27 feet wide and 25 feet high. Since its deposition by the ice it has been split open along a joint surface. Plate 11 shows the appearance of this boulder. It was transported at least several miles, since the nearest outcrops of Marcy anor- thosite are that far to the north. Two remarkable boulders of Marcy anorthosite are shown in plate 12. They are close to the road two-thirds of a mile south of Wolf pond. Both are notably rounded, suggesting transportation for a number of miles at least. One of them, at least 14 feet in diameter, rests in a remarkably balanced position upon the other large one which is partially buried in the glacial drift. It scarcely seems possible that the upper boulder can retain such a position, and yet it remains there in spite of an attempt some years ago to pry it off. Kames and eskers. Kames and eskers definitely recognizable as such are not common in the quadrangle. In the areas of heavy glacial and fluvio-glacial deposits, some of the little hills strongly suggest their origin as kames, but, since their structure is rarely ever revealed, this is not certain. But one clearly defined esker was observed, and this is a oe fine one. It lies just northwest of Schroon Lake village with a sinuous course and a general north-south strike for more than two- thirds of a mile. Its northern end comes against the base of the steep hill. The contour map only roughly suggests its position. It consists of sand and well-rounded small to large pebbles. In height it varies from 20 to 75 feet. Toward the north where it is highest and covered with trees, it is a very steep-sided narrow ridge. Plate 13 shows part of it toward the south in an open field where it is neither so high nor so sharply defined. This esker was probably formed by a debris-laden stream from the hillside upon or under the ice of the great waning ice sheet which still lay in the valley. Lakes and Their Deposits Extinct lakes. Glacial Lake Pottersville. This former large lake was first recognized by the writer and described in his report on the North Creek quadrangle.t. It is named from the village of Pottersville which lies on the old lake bottom. Its waters spread through the Schroon valley from near Chestertown, over the site of Schroon lake, and to north of North Hudson. Branches of the IN. Y. State Mus. Bul. 170, p. 70-72. 1014. , photo, 1917 Miller. W. J. ue fe) n ~ a5 Go ie fe) S ea ~ ise) (o) u u v He m4 n o i) Ww {fe} jaa) 1 oO op BS 4 vo = (aa) vo a f=) a) ao as iS) ie} u 4 fe} ue} & “4 E 39) 7p) o) Be) a a4 ° Ww v = 3 >) ia) = (D) ite Toy i) iS a gS ) a 3 Ss Ss om wy mz) fo) a ue) oO i=) 5 rae: 2V6 Se Ye) GE Giaic eos 3 & Ou OHO + aos 3 fe42 ©) re 2 oD © om lat & o Hn ww oOo 8 oO & 8 Mo} i= ie (cD) oO uy i Lol = 3 GH (cD) a n (eo) oo Q ee H (o) (= ro) (9°) aa) a a © 5 S Se [o) wu (cD) AS 5} ° DQ ‘3 oO & on io} (cD) 9) S 5} (eo) H geology.....-....-. Evidence bearing on postglacial Description and interpretation of history of Hudson-Champlain PHC CMEMOSIESS: v.00 sees ss Se valley.. _ The Lake Albany deposits Recent deena rene of the upper terrace Review and summary. pe cop tent of the lower terrace ‘ ALBANY ‘THE UNIVERSITY OF THE STATE OF NEW YORK aa 1920 ; THE UNIVERSITY OF THE STATE OF NEW YORK Regents of the University With years when terms expire (Revised to January 1, 1920) 1926 Puiny T. Sexton LL.B. LL.D. Chancellor - - Palmyra 1927 ALBERT VANDER VEER M.D: M.A. Ph.D. LL.D. — Vice Chancellor Albany President of the University and Commissioner of Education Joun H. Fintey M.A. LL.D. L.H.D. Deputy Commissioner and Counsel FRANK B. GILBERT B.A. Assistant Commissioner and Director of Professional Education Avucustus S. Downine M.A. L.H.D. LL.D. Pd.D. Assistant Commissioner for Secondaty Education CHARLES F. WHEELOCK B.S. LL.D. Acting Assistant Commissioner for Elementary Education GeorceE M. WILry M.A. Director of State Library James I. Wyer, Jr, M.L.S. Pd.D. Director of Science and State Museum Joun M. Crarke D.Sc. LL.D. Chiefs and Directors of Divisions 1922 CHESTER S. Lorp M.A.LL.D. - - - - - Brooklyn 1930 WiLttiAM NottincHaM M.A. Ph.D, LL.D. - - Syracuse | 1924 ADELBERT Moot LL.D. - - - - - - - = Buffalo 1925 CHARLES B. ALEXANDER M.A. LL.B. LL.D. | Litt.D. - - - - - - - - -+ = Tuxedo: 1928 WALTER GUEST KELLOGG 8. A LL. D. - - - Ogdensburg | 1920 JAMES ByrngE B.A. LL.B. LL.D. - - - - - New York 1929 HERBERT L. BRipGMAN M.A. - - - - - = Brooklyn 1931 THomas J. Mancan M.A. - - - - - - - Binghamton : Administration, Hiram C. Case Agricultural and Industrial Education, Lewis A. WILSON Archives and History, James SuLLivan M.A. Ph.D. Attendance, JAMES D. SULLIVAN Educational Extension, WILLIAM R. Watson B.S. Examinations and Inspections, GEorcE M. Witey M.A. Law, FRANK B. Giupert B.A., Counsel Library School, James I. Wyver, Jr, M.L.S. Pd.D. School Buildings and Grounds, Frank H..Woop M.A School Libraries, SHERMAN: WILLIAMS Pd.D. Visual Instruction, ALFRED W. ABRAMS Ph.B. The University of the State of New York & Science Department, November o, 1918 Dr John H. Finley President of the University SIR : Bl beg to communicate herewith and to recommend for publica- ion, as a Bulletin of the State Museum, a manuscript entitled cial Geology of the Cohoes Quadrangle, which has been pre- | red, at my request, by Prof. J. H. Stoller. Sincerely yours 1a Joun M. CLARKE Director _ Approved for publication, November 14, 1916 ae President of the University New York State Museum Bulletin Entered as second-class matter November 27, 1915, at the Post Office at Albany, New York’ Published monthly by The University of the State of New York Nos. 215, 216 AMLAIBVAIND I IN|, YW November-December 1918 The University of the State of New York New York State Museum Joun M. Crarke, Director GLACIAL GEOLOGY OF THE COHOES QUADRANGLE BYGSVMES ie Sit © MEER INTRODUCTION The period of geological history known as the Glacial or Pleistocene Period and characterized by the extension of a great ice sheet from the region of Labrador southwestward beyond the boundary of the State of New York has its record in the materials left by the ice and by the flooded waters following the melting of the ice. This bulletin deals with the Pleistocene geology of the area of the Cohoes quadrangle. The materials for study consist in general of the mantle of clay, sand, gravel and boulders that overlies bed- rock. The distribution and mode of arrangement of these materials and the surface forms which they exhibit — whether hills of definite topographic features, terraces along the courses of stredms, or slopes bordering ravines and valleys — reveal the agencies which brought these materials to their present locations and gave them their present forms. To the extent that the several kinds of earthy materials occur in separate areas of distribution, the mapping of the glacial deposits becomes, in a general way, a survey of soils. In the region here reported upon the dependence of soil composition upon geological origin is, over considerable portions of the area, somewhat close and the accompanying map is therefore of interest not only from the standpoint of geologic science but also that of agriculture. Thus the soils that originated as sediments, consisting of finely divided particles of clay and sand deposited in bodies of 6 NEW YORK STATE MUSEUM water forming temporary lakes, at the close of the ice age, are of quite different character from the unassorted materials left from the melting ice. Some of the glacial deposits are also of economic importance in other ways, especially the clays extensively used for making bricks and the sands for building and molding purposes. It may be noted that in other ways the industrial life of the people is dependent upon factors. and conditions resulting from the changes wrought upon the country during the Ice Age. The largest city, Cohoes, owes its growth as a manufacturing center to the source of power afforded by the falls in the postglacial gorge of the Mohawk near its mouth. The villages of Schaghticoke and Valley Falls are similarly related in location and industry to the rapids of the Hoosic river where in its lower course it has carved a channel in rock, since the close of the glacial period. A’ further instance of the relation of human interests to conditions deter- mined by glacial agencies is that of the restoration of an extinct glacial lake — Lake Tomhannock, on the Cohoes quadrangle — in order to form a storage reservoir for the water supply of the city of Troy. The history of the drainage of the area, especially of the streams tributary to the Hudson, as deduced from the facts gathered in the present work, is of exceptional interest and throws light on some of the larger problems of the postglacial history of the Hudson- Champlain valley. The data bearing on these questions and a dis- cussion of them are given in the body of this report. PHYSICAL GEOGRAPHY “AND GENERAL GEhOl@Gis The Cohoes quadrangle is intersected by the Hudson river, which enters the area at about the middle of the northern border (latitude 43°) and flows southwestward and southward crossing the southern border (latitude 42° 45’) about 1 mile above the head of navigation of the river at Troy. The elevation of the river at the northern margin of the sheet falls between the 80 and 100 foot contour lines and at the southern border is less than 20 feet above sea level. The segment of the Hudson river here included belongs, therefore, to the upper or what may be termed the river portion proper, in dis- tinction to the lower, or estuarine portion, which is within the influence of the ocean tidal movements. In considering the geology of this portion of the Hudson valley it is helpful to distinguish at the outset between the preglacial valley which is now largely filled with sand and clay deposits of Pleistocene age and the present valley which belongs to the recent GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 7 period, that is, has been formed since the time of the subsidence of the body of glacial waters in which the sands and clays were deposited. The preglacial valley is cut in rock and is somewhat complex in form, consisting of a broad and open outer portion and an inner portion with steeper slopes. The whole, as a physiographic Al Fig. 1 Diagram showing preglacial topography of the Hudson valley ay Ze feature, may be described as a gorge within a valley. This ancient rock valley represents the erosive work of the Hudson river in the Cenozoic (Post-Cretacic) era of geologic time and its double form is considered to be the result of an uplift of the general region fol- lowing an earlier period of valley erosion. Its form and dimen- sions are now evidenced by outcrops of rock that occur near the lateral border of the clay and sand area and by the depths of the ravines which have been cut into the filling of the ancient rock valley and in places into the underlying bedrock. From these data it is shown that the ancient valley has an average breadth of between 4 and 5 miles and a depth in its middle portion of 200 feet or more. The width of the imner valley or gorge is on the average about 2 miles: its depth, of course, is the same as that of the broader valley. The present valley of the Hudson, as here considered, is the broad depression on the bottom of which the river flows in a more or less winding course and the sides of which are the steep clay banks which rise 100 feet or more above the valley bottom. The present valley lies within the old rock gorge, its bottom being coin- cident with the middle portion of the floor of the latter. The present channel of the river, however, in the greater part of its extent, is cut into the floor of the old gorge, forming a shallow rock gorge representing the erosive work of the river in the recent period. The present valley bottom, threaded by the channel, has a width varying from three-fourths of a mile to one and one-half miles. Where the river enters the quadrangle and for several miles southward this bottom is an alluvial plain, but from Stillwater to 8 NEW YORK STATE MUSEUM the southern edge of the sheet the valley bottom stands generally above the level of overflow of the present river and its materials are chiefly of glacial origin or, in large areas, of bared rock or residual soils derived from the rock in the recent period. Legend o © a S ~ g oO 6 u a, S oO te > » <6 be Nes _ S = o fe e (3) 0 C 3 oie me - x = ‘J ley i L = 5 cs) o o © o o > = me} rd foe, rai vate aS 6 re 3 fe} a. iS 5 5 4 ae wl = = - Sands or | | | | Clayey sands 300 ft a ood oh Pa ea arn eS — oy 0.09 ong SS a a ‘oo ft. —_ Se Sn ee \ Ror Oo \\\y Rock Fig. 2 Section across the Hudson valley showing present surface features and relations of Pleistocene deposits to the underlying rock surface. The surface line is drawn to scale along an approximately east-west line taken about 3 miles south of Mechanicville. Rising from the flat valley bottom on either side are steep slopes or bluffs, the materials of which are the stratified Pleistocene clays. From the summit of these bluffs, extending outward from the valley, are expanses of clay or sandy clay lands forming terraces. These terraces occur on both sides of the river at approximately cor- responding levels, showing that they are remnants of a continuous plain that has been divided by the erosive work of the Hudson waters. At the outward margin of these terraces the surface again rises, in some places rather abruptly and in other places gradually, form- ing a slope the rise of which is, as a general average, about 60 feet. Outward from the summit of this slope the surface again becomes flat or moderately sloping toward the valley and extends north and south somewhat as a bench or terrace normal to the river valley. This area, which will be referred to in this report as the upper terrace, consists of soils in which there is a larger proportion of sand than in the clay soils of the lower terrace. Beyond the out- ward limit of the upper terrace rise the uplands areas, the surface materials of which consist chiefly of till or materials derived from or left by the melting of the ice sheet. . Within the limits of the quadrangle the Hudson receives its largest tributary, the Mohawk river, from the west; and one of its largest tributaries from the east, the Hoosic river. ‘uOISO19 afoyjod Aq apew jatueyd MOIIeU © SuTAdNIDO IayeM MOT je UeII]S SUIMOYS yueq yyNos Wolz MIA ‘sT[ey Sa0yod I 93®[d GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 9 The segment of the Mohawk valley included in the southwestern part of the sheet belongs to the portion of the river (from Aqueduct near Schenectady, to its confluence with the Hudson) which occu- pies a postglacial valley.t. The evidence of this is that the valley of the river, for a distance of 5 miles east of Aqueduct, is a gorge cut into the rocks and extending like a trench across the face of the country. There is no buried old valley, as in the case of the Hudson, lying outside the present valley. These features, which ~ are. well marked in the upper portion of the preglacial valley, are considerably modified in the lower portion. The course of the stream becomes irregular, the valley broadens and its slopes are less steep. These differences are due in part, especially in the segment of the valley falling within the Cohoes sheet, to structural features of the underlying rocks which here have their strata steeply inclined, dipping to the east, and in part to the fact that the Mohawk here enters the region of the old eroded rock valley of the Hudson. The river has, however, lowered its bed into the floor of the rock valley and in the last 3 miles of its course occupies a -rock gorge. This portion of the river is marked by the well-known falls at Cohoes. On the north (northeast) side of the river, stretching back from the summit of the gorge, there is an area, several square miles in extent, consisting of rock with a thin covering of clayey soil. This area has evidently been swept by the currents of the Mohawk when _ the river flowed at a level about 80 feet higher than its present bed, above the falls. The Pleistocene clays were removed and sub- sequently the existing clays were formed as a residuum from the weathering of the exposed rock surface. On the south side of the gorge only a narrow strip of the Pleistocene clays was removed by river erosion and the surface topography of the clay formation exhibits terraced forms, normal to the Hudson valley, as above described. See figure 7, page 36. About three-fourths of a mile below the falls at Cohoes the Mohawk waters divide into several divergent streams which enter the Hudson by as many channels, thus forming a group of rock islands. These multiple mouths of the Mohawk are interpreted as originally delta distributaries which became intrenched in the under- lying weak rocks after the removal of the delta deposits from their beds by erosion. *Stoller. Glacial Geology of the Schenectady Quadrangle. N, Y, State Mus, Bul. 154, p. U1, 1@) NEW YORK STATE MUSEUM The Hoosic river, which has its sources on the western slopes of the mountainous region of the New York-New England border, enters the quadrangle in the northeastern quarter of the sheet and flows in a meandering course westward and northward, discharging into the Hudson at the head of the rock channel at Stillwater. The river valley except for a short length west of Johnsonville, is every- where bordered by deposits of sands and gravel. Westward from Schaghticoke the river penetrates an immense mass of fine gravels and coarse sands which clearly originated as a delta built by the river into the body of waters that occupied the Hudson valley in late glacial times. The delta formation is of the characteristic triangular shape and at its base, fronting the Hudson valley, has a breadth of about 7 miles. Its areal extent may be estimated at 20 square miles. In its course through the delta the present river is flanked by a series of terraces which rise at successively higher levels to the general summit level of the Pleistocene clays of the Hudson valley. A fuller description of the Hoosic delta, together with a discussion of its development and that of the system of terraces, will be given further on in this report. A valley of exceptional interest from the standpoint of Pleisto- cene history is that which enters the Hudson valley from the west at Mechanicville. It is occupied by a small stream, Anthony kill, which in its present size is quite out of proportion to the breadth and depth of the valley. Anthony kill is the outlet of Round lake (see map, p 46) which in turn receives the outlet stream of Balls- ton lake, the latter lying at the bottom of a preglacial channel that communicates with the valley of the Mohawk east of Schenectady. There is quite conclusive evidence! that in late glacial times waters from the flooded Mohawk river coursed through this system of channels, discharging into the waters of the Hudson valley at Mechanicville. At a later time the Mohawk became established in its present course, and Anthony kill, draining the old channel as far back as the divide at the head of Ballston lake, is the shrunken remnant of the much larger stream through whose erosive work the present relatively large valley was formed. As in the case of the Mohawk river, Anthony kill, entering the Hudson from the west, runs athwart the ancient rock valley of the Hudson. From Willow Glen eastward the floor of the valley is * Stoller. Op. cit. p. 29-31; Fairchild. Pleistocene Uplift of New York and Adjacent Territory. Bul. Geol. Soc. of Amer., 27:251. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 1 rock with a slope to the east of 80 feet in a distance of 2 miles. This is a part of the old valley floor, though now reduced by erosion. In somewhat sharp contrast to the system of valley depressions thus far described are the uplands portions of the quadrangle. The uplands, as here referred to, stood above the level of inundation by the glacial waters and are clearly marked off from the area covered by waters both in respect to topographic features and the materials of which the soils are composed. The Pleistocene deposits filling the valley depressions, although now trenched by the great river courses and ravined by the minor streams, still represent, especially where deltas have been developed, the general level of the body of waters in which they were laid down. The uplands stand out in marked relief above this level. This contrast is very striking in the field when one stands at a point commanding a view of the two topographic regions. The surface of the uplands is in general highly irregular. This is due primarily to the structure of the underlying rocks and to the effects of differential erosion upon the rock surfaces in pre- glacial times. The rocks are shales and sandstones of the Cambric and Ordovicic series and possess the folded structure and altera- tions due to metamorphism common to these rocks as they occur in the Hudson valley region. The strike of the folds is in a general north-south direction and this gives to many of the hills an elon- gated form, with long axes trending north and south. Two of the highest elevations, Rice mountain and Mount Rafinesque, in the middle portion of the southern third of the quadrangle, are, how- ever of irregular, massive form. The highest elevation of surface is near the southeastern corner of the sheet where a ridge of steeply inclined strata attains the height of 1265 feet. The surface of the uplands bears evidence of considerable modifi- cation by ice agencies. Many of the hills which show exposures of rock have somewhat even and smoothed outlines indicating the effects of abrasion by moving ice. In many cases the more smoothed surfaces face north, indicating the wear of the rock on the side from which the ice approached. In some instances low hills of topographic form approaching that of drumlins are found to be reduced rock hills, partly covered by glacial till. The group of hills west of the Saratoga battlefield near the northern edge of the sheet is of this character. In general, the minor topographical aspects of the surface ot the uplands are due to deposits of glacial origin, a description of I2 NEW YORK STATE MUSEUM which is given below. These deposits form a mantle everywhere overlying bedrock, except where ridges and masses of rock pro- trude through the covering. The relief is that of a region in the mature stage of erosion but with irregularities of surface some- what reduced by ice abrasion and by deposits of Pleistocene and Recent Age. The drainage of the uplands region is mainly through small . streams that flow directly to the Hudson or to the tributary rivers, named above. The streams that discharge into the Hudson show interesting changes in the character of their valleys as they pass from the uplands areas and cross the clay and sand formation. In their upper courses the streams are adjusted to the slopes of the surface and to underlying rock structure and they wind between the hills in open valleys, but as they debouch upon the plain of the clay and sand deposits their courses become more direct and their val- leys narrower and deeper, forming ravines. It is probable that in their upper courses the streams occupy mainly preglacial valleys while obviously the ravines have been formed in postglacial times, that is, since the withdrawal of the waters in which the clays and sands were deposited. The largest stream of the uplands region is Tomhannock creek, which has its rise near the southeastern corner of the quadrangle and flows northerly, emptying into the Hoosic river about 3 miles from its mouth. In the upper and again in the middle part of its course this stream follows broad depressions of surface which are the beds of extinct lakes. In its lower course it penetrates the Hoosic delta. A fuller statement of the steps of glacial history recorded in these physiographic features is given later. DESCRIPTION AND INTERPRETATION OF sii: DEROSMS Till or ground moraine. Till or rock debris derived from the ice sheet, whether left from the bottom or deposited from the ice at the time of melting, forms the mantle of materials overlying the bedrock generally. In the uplands it constitutes the greater part of the body of soils and subsoils but in the great valley depressions it is covered by the lacustrine clays and sands, except where the latter have been swept away by stream erosion. It includes all rock frag- ments derived from the ice of whatever size, from boulders to grains of sand and particles of clay. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE © 13 The boulders are nearly all of rock different from the underlying country rock, showing that they were brought by the ice from regions lying to the north. But the finer parts of the till include many bits of the local rock and there is everywhere a noticeable correspondence between the predominant mineral elements of the till and those of the nearby exposures of the underlying rocks. As the country rocks of the region are largely shales (slates), they give to the soil a predominantly clayey character. It is in general -well adapted to agricultural purposes. The thickness of the till varies greatly in different parts of the area. Near the summit of the main rock ridges and masses the till sheet is generally thin and, as noted above, there are frequent exposures of bare rock. In places these exposed rocks have under- gone decomposition to a considerable extent, and the residual prod- ucts, having fallen or having been washed from the slopes of the rock surfaces, are added to the materials of the till. In the valleys and depressions between the rock hills the till is in general thicker than on the tops and sides of the hills. This may be due in part to the valleys having been occupied by the ice for a longer time than the hilltops or to a relatively greater amount of till having been originally lodged in the valleys, but it is probably also due to removal of till from the hills by washing. The occur- rence of boulders resting on the exposed rock of the hills is evidence of this, the finer materials of the till having been washed away. In contrast with rock hills veneered by till are those hills which are apparently made up wholly of till. Many of the low hills, and some of larger proportions, are of this character. The most noticeable one is that southeast of South Easton, marked by a depression contour on its western slope. As far as could be deter- mined by inspection, the materials of this hill are till and the depres- sion is due to irregularity of heaping of the debris derived from the ice. Another hill apparently composed wholly of till is that north of Crandall Corners and crossed by the road. This is of the type of a drumlin. An interesting drumlin is that which occurs on the floor of the Hudson valley, east of the river and directly opposite Bemis Heights. It stands as a conspicuous oval hill, stréwn with cobbles and boulders, rising above the level of the alluvial plain. It is evident that this hill was once covered with lacustrine clays and that when the latter were swept away by flooded stream erosion, the more resistant materials of the hill remained, 14 NEW YORK STATE MUSEUM Hills of Sand and Gravel. Kames. In the uplands region there are a number of isolated groups of hills, composed mainly of sands and gravel and presenting the characteristic features of kame topo- graphy. Their locations are shown on the accompanying map. The largest of these kame areas lies northward from the valley of the eastern branch of Tomhannock creek and near the village of that name. The surface of this area, made up of hills and hollows of irregular shapes and without order of arrangement, is conspicuously different from that of the surrounding country, the features of which are largely controlled by the underlying rock surfaces. Many of the hills have steep slopes and a degree of evenness of front that indicates deposition of the sand and gravel materials against a stationary mass of ice. These groups of hills are interpreted as recessional moraines, marking a temporary cessation of retreat of the general ice sheet at the time of melting in the localities where the heaps of debris occur. In the case of the moraine just described it seems probable that its development was incident to the slower melting of the thick ice that filled the preglacial valley now followed by the creek. There is evidence that the moraine originally extended farther south across the valley and that it has been reduced at its southern edge by stream erosion, the finer materials having been carried by the stream to glacial Lake Tomhannock, there building a delta, as described below. Ridges. Ina number of localities there were observed accumu- lations of sand and gravel with admixture of clay and fragments of slate rock having the general topographic form of ridges. In some of them, as the one near Melrose and that north of Speigle- town, the materials, as exposed in gravel pits, show a stratified arrangement. The location of these ridges (see map) presents a certain uniformity; that is, they are all located on the uplands but within a short distance from the clay and sand deposits of the Hudson valley. Their elevation above the latter varies from 20 to 60 feet. The direction of the ridges is in general parallel with that of the edge of the valley deposits. The inference drawn from these data is that these ridges repre- sent deposits made marginal to the lobe of ice that occupied the Hudson valley after the disappearance of the general ice sheet from the uplands. A fuller statement of the evidence of the persistence of an ice lobe in the Hudson valley long after the melting of the icé from the uplands will be given later in this report. It is believed GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 15 that in places accumulations of materials from the melting of the ice lobe at its margins gave rise to lateral morainic deposits, thus forming these ridges. Glacial lakes. In the middle eastern and southeastern rec- tangular divisions of the Cohoes sheet there are two elongated tracts conspicuous by their flatness as contrasted with the highly irregular surface of the uplands country surrounding them. The more northerly of these tracts, or intervales, extending from near Raymertown northwesterly and having a length of about 5 miles and an average breadth of about one-half of a mile, has ‘recently been converted into a reservoir for the public water supply of the city of Troy. This was accomplished by constructing a dam across Tomhannock creek at the place where this stream, after following in meandering course the length of the flattened area, entered a gorge about I mile south of East Schaghticoke. Lake Tomhannock. ‘There is quite conclusive evidence that this area, now an artificial lake, was in early postglacial times a natural lake. The stream that flows past the village of Tomhannock built a delta in this postglacial lake which now shows quite perfectly as a sand and gravel bench or terrace at the 400-foot level and border- ing that arm of the artificial lake which extends northeasterly toward Tomhannock. The materials of the terrace are well exposed in road gradings and show horizontal stratification. It is believed that this glacial lake (which may be named Lake Tomhannock) originated through the gathering of waters in an old stream valley across the course of which a dam was formed by deposits from the ice sheet. This preglacial stream flowed north- westerly from near Raymertown and then southwesterly toward Melrose and the glacial dam was formed in the latter portion of the stream course and near where at present the divide at the 400- foot level occurs. For a time the waters of the glacial lake, held back by the ice front, overflowed the dam and the lake had its out- let in the stream that flows southwesterly past Melrose to the Hudson river. When the ice front had retreated as far north as the plain south of East Schaghticoke, a lower outlet for Lake Tomhannock was afforded in the line of its present course. The outflow stream thus established degraded its bed and eventually the waters of the lake - were drained off. The other intervale, farther to the south, also marks an extinct glacial lake. This tract continues southward on the Troy sheet and 16 NEW YORK STATE MUSEUM this southern extension is drained by Quacken kill which joins Poesten kill, the latter stream discharging into the Hudson river at Troy. It is inferred that in preglacial times a stream heading near Raymertown flowed southward, developing the valley which now forms the intervale area and that at the close of the Ice Age a barrier of glacial deposits was left across this valley at the place where the divide now occurs, about 114 miles from the edge of the sheet. Waters were ponded north of this barrier and this glacial lake had its outlet in a stream that flowed past Raymertown and emptied ‘into Lake Tomhannock. This outlet stream had a fall of 100 feet and, through downcutting, the lake was finally drained off. The axis of drainage of the two glacial jakes thus led to the exten- sion of Tomhannock creek southward to its present source. A chain of small glacial lakes occupying depressions in the gen- eral surface of the country developed in the region southwest of Rice mountain beginning south of Haynersville. These were eventually drained away by Deep kill, which has cut a deep gorge on the eastern flank of the mountain. On the map two of these areas have been designated as extinct lakes and the others as swamps, the latter being partially covered with standing water. Lake Hoosic. ‘There is quite good evidence that a temporary glacial lake existed in that portion of the Hoosic valley crossed by the eastern margin of the sheet. North of the river theresised plain, traversed by Whiteside brook, the materials of which are sand and fine gravel. They are distinctly stratified in arrange- ment as shown in cuts along the Greenwich and Johnsonville Rail- road. The general elevation of this plain is 420 feet. South of the river in the neighborhood of Johnsonville the surface materials are of sand and gravel character and in places rise to about the same level as the plain opposite. It is believed that these deposits represent a glacial lake, the waters of which gathered behind a dam across the preglacial Hoosic valley made by drift, or deposits from the ice sheet. About a mile below Johnsonville till rises from the left bank of the river to the 440-foot level and on the opposite side there is a hill of till 420 feet in elevation. The latter hill slopes toward the river, the stream _ curving at its base. It is inferred that a mass of till of which these hills are remnants originally extended across the valley forming a dam behind which the waters were held in check, converting this portion of the valley into a temporary lake. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 17 aD eA MEDAN DE POSMS The body of glacial waters in which the stratified clays of the upper Hudson valley were deposited was named by Woodworth Lake Albany. He limited the extent of Lake Albany to the waters represented by the deposits extending from near Rhinebeck on the south to the Fort Edward district on the north* (north of the Cohoes quadrangle). In his view, the gathering of the waters of Lake Albany was pari passu with the melting of the ice sheet in its retreat northward in the middle Hudson valley. Another view is that the deposits are estuarine, having been laid down in the sea-level waters which extended as an inlet up the Hudson valley from the ocean at New York.? Fairchild has stated the conclusion that the body of waters in which the Hudson valley clays and sands were deposited was at sea level and at its highest development formed a strait connecting the oceanic waters which then occupied the St Lawrence valley with the ocean at New York. “As the ice front melted back the ocean followed it and flooded the valley. The waters were at first the Hudson inlet; later, the Hudson-Champlain inlet; and finally, the Hudson-Champlain strait.’* In this report we shall refer to the waters as Lake Albany, though without implication as to the correctness of the first men- tioned of the above interpretations. We shall, however, below call attention to certain facts of topography which seem to afford clear proof that the body of waters in question subsided (that is, dwindled to a river) while drainage from the great interior lakes (Algonquin-Iroquois stage) was still through the Mohawk valley. The inference is that Lake Albany disappeared prior to the opening of the St Lawrence channel (as due to ice melting) ; that is to say, prior to the invasion of marine waters in the St Lawrence basin. The writer would also state that in this report the term “ sub- sidence ” is used as pertaining to the fact of the withdrawal of the Lake Albany waters but without implication as to whether the *Ancient Water Levels. N. Y. State Mus. Bul. 84, p. 177 and 242, 1905. ?Merrill, Quaternary ‘Geology of the MHudson River Valley. oth Annual Rep’t of the State Geol, 1890. Peet, Glacial and Postglacial History of the Hudson and Champlain Valleys. Journal of Geol., 12:640. 1904. This author considers two alternation hypotheses: (1) the water body was a lake made by.a barrier at the south, (2) the water body was an arm of the sea. * Fairchild. Ann. Rep’t of N. Y. State Geol. 1912, p. 24. 18 NEW YORK STATE MUSEUM cause of the subsidence was the removal of a barrier at the south which held in the waters or to regional uplift. The Lake Albany deposits comprise (1) the mass of stratified clays and sands whose surface forms the terraced slopes of the Hudson valley and (2) the sands and gravels of the Hoosic delta. The clay and sand formation, as already stated, forms the filling of the ancient rock valley of the Hudson. The lower beds of the formation consist predominantly of clay and are the source of the well-known brick clays of the upper Hudson region. As seen in the pits at the brick-making plants, the clays are fine grained, evenly laminated and of a bluish color below passing to yellowish above. As exposed in mass at the slopes fronting the river valley or along the ravines, the weathered surfaces are of a buff or yellowish color. The compact clays make up perhaps the lower 100 feet of the formation, above which they grade into sand, clays or clayey sands. The latter, in certain localities (as 1 mile south- west of Mechanicville) have the composition requisite for mold- ing sands. Farther back from the river the materials of the Lake Albany- deposits are coarser and consist more largely of sands. In places, however, the clay constituent still predominates and there are tracts of considerable extent at or near the 300-foot level, as west of Melrose, where the lands are of clayey character. The surface of the clay and sand formations is marked by strik- ing topographic features. These are (1) the terraces of which an upper and a lower are distinguished and (2) the ravines which cross the terraces, dividing them, especially the lower one, into segments. The upper terrace is less well defined than the lower. In places (as west of Cohoes and southwest of Mechanicville) it appears as a nearly level expanse, one-half of a mile or more in breadth, bordered at its outward side by a slope toward the uplands and at its side toward the river by a more gradual slope to the level of the lower terrace. This description applies generally also to the upper terrace on the east side of the valley as it appears north of Crandall Corners and northwest of Melrose. In other places (as west of Stillwater) the upper terrace is less perfectly expressed, being narrower and with surface falling toward the river. In places, also, as at the Saratoga battlefield, the level of the terrace is broken by hills of till (or till-covered rock hills) which rise above the lacustrine deposits. East of Lansingburg the upper terrace (as also the lower) disappears as a distinct form feature, the steep rock GLACIAL GEOLOGY OF THE COHOES QUADRANGLE £9 wall of the valley here controlling the topography. These modifi- cations of the terrace form (apart from the effects of underlying rock features) are clearly due in part to postglacial erosion but probably in larger part to the conditions under which the materials were laid down. EVO FOR vii Ot Sih UPPER) TERRACE It 1s believed that the sands and clays of the upper terrace were in large part laid down at that stage of the melting of the ice when the uplands had been bared, while a broad lobe of ice still lingered in the Hudson valley. In the lateral depressions, between the central mass of ice and the bared slopes of the valley, waters gathered and flowed southward discharging into the open lake waters along the dwindling southern limit of the ice lobe. These currents bore sediments partly derived from the debris of the melting ice and partly received from the tributary streams draining » the bordering uplands. The finer parts of these sediments were deposited mainly where the currents were checked by the quiet waters of the lower end of the marginal channel, or embayment between the ice lobe and the shore of the lake. The coarser materials were deposited in the bed of the channels. Also as the latter shifted in position, due to the shrinking of the lobe of ice, the deposits were made progressively farther inward from shore. In this way the accumulations acquired the form of a shoal plat- form with face sloping toward the middle of the lake. With the subsidence of the lake waters, at a later time, the shoal became a terrace of similar slope. (See fig. 3, page 22.) At times bodies of comparatively static waters were held in portions of the lateral depressions conforming to topographic features of the adjoining slopes and to irregularities of the ice border. When tributary streams from the uplands discharged into’ these quiet waters . deposition took place, forming deltas. With the subsidence of the waters, at a later time, these deltas emerged as terraces of more even and level surfaces than those described in the preceding paragraph. It is believed that an example of a terrace form developed in this way is the flat area northwest of Melrose at the 300-foot level at its outer border. On the north side of the Mohawk river and both north and south of Anthony kill the plain of the upper terrace becomes continuous with that of Lake Albany deposits bordering these streams and extending westward to the general sand plain region of the Schenec- 20 NEW YORK STATE MUSEUM tady quadrangle. The terrace surface, in these westward exten- sions, Shows a gradual increase in elevation. The general or average elevation of the upper terrace may be stated as 300 feet. For the most part the 300-foot contour line of the sheet marks the outer border of the terrace plain, although, in places, the lacustrine deposits rise to a higher level. As a rule no definite line of contact of the clays and sands with the till of the uplands can be observed in the field, and in mapping this boundary has been drawn somewhat arbitrarily. As pointed out by Fair- child, the summit level of the body of glacial waters was often higher than the plain of the deposits built into it. In the Lake Albany waters the deltas formed at the mouths of the larger streams, now represented by extensive sand plains, as that south of Schenectady (Mohawk delta), north of Ballston (Hudson delta) and that of the Hoosic delta, described below, probably indicate closely the height of the lake waters. (Present differences in ele- vation are to be accounted for by postglacial deformation.)? But the deposits made in Lake Albany, other than the great deltas, were not usually built up to water level. Thus the plain of the Hoosic delta near its head, as in the broad expanse northwest of Schaghticoke, stands 340 to 360 feet elevation, while the upper terrace which extends northward from the delta has an elevation of 320 feet. This difference is interpreted as due to a less amount of deposition taking place in the marginal channels, in the early stages of the development of the lake, as above described, than at the mouth of the large rivers, at the later stage when the deltas were built. Also differences in elevation of the upper terrace in different localities are understood as due primarily to differences in amount of sedimentation. . The lower terrace is a quite definite topographic feature. On the west side of the river it is continuous from the northern to the southern margin of the sheet, except as broken by the numerous ravines that cross it and where, in the localities of Mechanicville and Waterford, broad stretches of the terrace were swept away by the flooded Mohawk waters of late glacial times. On the east side of the river the terrace shows as a distinct form feature except where interrupted by the Hoosic delta and by the steep rock wall of the valley at Lansingburgh. The terrace is best developed in the middle part of the sheet where it attains a breadth on each * Bul. Geol. Soc. of Amer., 27 :230. *Stoller. Glacial Geology of the Saratoga Quadrangle. N. Y. State Mus. Bul. 183. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 21 side of the valley,of a mile or more. These terrace plains form evident and striking features of the landscape. In the field, to the observer looking north and south and ignoring the depressions of the gullies, the terrace surface appears as one level expanse; or, looking across the valley, as a bench broken by the ravines and with the upper terrace slope and plain and the rising hills of the uplands in the background. DEVELOPMENT Ob THE LOWER TERRACE _ The conditions under which the lower terrace was developed are believed to be as follows: With the disappearance, through melt- ing, of the ice lobe from the Hudson valley, the middle portion of the valley became the seat of sedimentation. It had already received debris derived from the melting of the ice lobe, together with some accessions of finer sediments borne by the currents flow- ing in the marginal channels and checked by the quiet waters of the embayments lateral to the terminal portion of the ice lobe. The conditions of an established body of lake waters now permitted deposition from the currents normal to the lake. As the outlet of the lake was at its southern end, we may assume constant south- ward flowing midlake currents. These currents, moving in a body of water of considerable magnitude, were of low velocity and car- ried only fine sediments. Under the fluctuations incident to varying seasonal, climatic and other physical factors, deposition of these sediments took place and thus layers of silts and fine sands were laid down on the floor of the middle portion of the lake. At length came the time of the subsidence of the Lake Albany waters. At the first stage of subsidence the lateral portions of the lake bottom had emerged as land surface, forming the upper ter- races, above described. The erosion of the surfaces of these ter- races immediately began and many small streams, heading in the uplands, extended their courses across the terraces and discharged into the shrunken lake. The sediments brought by these streams to the lake were distributed over the same area of the lake floor that had received deposits from the midlake currents. From these two sources were derived the silts now forming the clays of the lower terrace. The emergence of these deposits, thus giving rise to the present terrace, was due to a further subsidence of the Lake Albany waters. The accompanying diagrams are believed to represent the suc- cessive steps in the development of the upper and lower terraces. ending with the production of the present features of the valley. 22 NEW YORK STATE MUSEUM REDROCK SAND WITH aay CLAY LYING TIL Fig. 3 Diagrams showing the conditions of deposition of the sands and clays of the Hudson valley ‘and the development of the terraces No. 1 shows the ice lobe occupying the inner preglacial valley of the Hudson and the waters (embayments of Lake Albany) filling the depressions hetween the lateral margins of the ice lobe and the rim of “the outer valley. Deposits made in these waters were largely of sands. No. 2 shows the shrunken ice lobe and the consequent broader embayments. Depositions of finer sediments, mainly clays, were made in the deeper and more quiet waters. No. 3 shows the conditions when Lake Albany was at the height of its development. In the quiet mid-waters of the lake abundant clay sediments were deposited. No. 4 shows conditions at the end of the first stage of marked subsidence of the lake waters. The outer portions of the lake bottom have emerged forming the present upper terrace. No. 5 shows the conditions after the second stage of marked subsidence. The lower terrace has emerged. No. 6 shows the deposits in their present relations and the present topographical features of the valley. GLACIAL GEOLOGX OF THE COHOES QUADRANGLE 23 The Hoosic delta. The Hoosic delta, like the other deltas built by large streams which discharged their sediments into Lake Albany, in its present surface features bears the character of a sand plain. The continuity of the plain is broken, however, by the valley of the present river which has sunk its bed deeply into the sands and, through meandering, swept away a broad path through the delta. The marginal limits of the delta plain are indicated partly by differences in the topographic features of the delta, as contrasted with the terraced deposits above described, and partly by differences in the character of the materials of the two forma- tions. ‘In general, the delta materials as seen at the surface are coarser and less coherent than those of the terraced areas, the proportion of sands and fine gravels being much larger. The shape of the delta is that characteristic of this type of con- structional formation. The materials are spread out fanlike from the original head of the delta or place where the river debouched into the lake. This may be taken as at Schaghticoke. The outward margin of the delta mass, fronting the Hudson valley, is somewhat of the form of an arc but this has been considerably modified by river erosion. The Hudson currents, deflected eastward from Bemis Heights, have cut deeply into the northward extension of the delta border. Also, at an earlier time, the Iroquois-Mohawk currents which followed the present course of Anthony kill, sweep- ing across the subsiding waters of Lake Albany, cut deeply into the marginal lobe of the delta at Reynolds forming the upper and lower erosion terraces to be described below. (Further reference to this stage of Pleistocene history will be given below.) The surface of the delta plain varies much as to composition of materials and minor topographic features. The soils are for the most part too deficient in clay constituents to be valuable for agri- culture. Considerable areas are left uncultivated and there are tracts of coarse sands where wild vegetation is scanty. The lack of coherence of the soil particles has resulted in extensive gullying of the surface over considerable areas. In the region east of Reynolds the plain is deeply dissected by many ravines producing the irregularities of surface indicated by the contour lines of the sheet. The above description applies to the surface materials and features of the delta where the plain has not been reduced by river 24 NEW YORK STATE MUSEUM erosion. Where the Hoosic river has cut deep into the delta, form- ing a succession of terraces on either side of the valley, thus expos- ing the materials of the delta at different levels and at varying dis- tances from the head of the delta at Schaghticoke, they differ con- siderably from the materials of the surface of the plain. In gen- eral, the terraces of the lower levels are of mixed clay and sand composition, forming soils which are well adapted for farming and gardening. For instance, the extensive flat at the 100-foot level crossed by the road running northeasterly from Reynolds is com- posed of fine-grained soils of high fertility. The materials of the terrace plain on the opposite side of the river, beyond the alluvial flat and rising to the 140-foot level, are also finely divided and include a considerable proportion of clay in their composition. The fine sands and clays, lying at the base of the delta deposits and far out from the head of the delta, are interpreted as the bottom-set beds of the formation. They were laid down at an early stage in the building up of the delta, representing the finer sediments borne by the Hoosic river and dropped where the cur- rents were checked by the quiet waters of the body of the lake. The materials of the higher terraces become progressively coarser in order of elevation and of nearness to the head cf the delta. This is well shown to the observer who follows the road south of the river, beginning where the road crosses Tomhannock creek and continuing eastward and southward to the 360-foot level of the delta plain beyond where the highway crosses the railroad. 360 ft == 310.0 tia = 200 “ ——— O10 Fig. 4 Profile of terraces in delta of Hoosic river. The terraces south of the river are shown on a line extending from the delta plain west of East Schaghticoke to the Hocsic river at the mouth of the Tomhannock creek; the terraces north of the river on a line extending from the latter point northeasterly to the delta plain northwest of Schaghticoke. See lines on map. Thus the materials of the successive terrace plains were noted as follows: 140-foot terrace, sandy loam; 180-foot terrace, coarse sandy or loamy soil; 220-foot terrace, fine to coarse gravel; 320- foot terrace, gravel, largely uncultivated; 360-foot level (south of railroad), sand and fine gravel. The materials of the terrace plains on the opposite side of the river are predominantly sand and gravel, although the extensive plain at the 340-foot level has a considerable admixture of clay. To the east of the ravine, however, this plain gradually merges into an area of blown sands, GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 25 The coarse sands and gravels making up the middle layers of the delta formation and rising well toward its stirface are inter- preted as the fore-set beds. They are the coarser sediments which were deposited at first at the head of the delta and then successively added to, thus building up the delta progressively toward the body of the lake. A section of the lower and middle beds of the delta, together with the underlying till, is shown on the right bank of the river about 1 mile below the gorge west of Schaghticoke. At the base there is a thickness of about 40 feet of materials of bluish color, mixed composition, including boulders, and without evident strati- fication. Above this and somewhat sharply defined from it, though without evident unconformity, are beds of yellow sands with approximately horizontal stratification, as seen in this section. There is an exposure of perhaps 30 feet of these sands as seen in nearly vertical section, and at a higher level the sands are con- tinued on a sloping surface. The elevation of the highest terrace plain of the delta is about 360 feet. The extensive plain northwest of Schaghticoke, bisected by the ravine, is 340 feet at its inner margin and rises to 360 feet at its outer margin. Southwest of Schaghticoke there is a narrow but distinct plain (crossed by the road to Schaghticoke hill) which is at 360 feet elevation. It is believed that these plains represent the level of the waters of Lake Albany. The former has an areal extent of several square miles and it is scarcely open to question that its materials were laid down below or at the level of the lake waters. It evidently consists of the top-set beds of the delta which were spread out horizontally over the fore-set beds. It will be noted that this elevation is considerably above that of the general or average elevation of the upper terrace of the body of deposits in the lake north and south of the area of the delta. We have now to consider the sand and gravel deposits which border the Hoosic valley for several miles eastward from Schaghti- coke. At East Schaghticoke these deposits are 380 feet in eleva- tion and the village of Valley Falls, one and one-half miles to the east, is built on a river terrace of the same elevation. Also on the north side of the river and farther to the east there is a distinct terrace of sand and fine gravel. This terrace is sharply distinguish- able, both in regard to materials of composition and topographic form from the hill of till adjoining it to the east and which formed a part of the dam of glacial debris behind which were ponded the waters which formed the glacial lake north of Johnsonville. 26 NEW YORK STATE MUSEUM These deposits are interpreted as a valleyward extension of the delta and as representing that portion of the delta which was built up above the level of the general delta platform of the lake. This principle of delta growth has been stated as follows: “At the same time the channel of the stream above the original head of the delta is aggraded, for the current there is checked by the aggrada- tion of the delta. Thus alluvial deposits continuous with the delta are extended landward.”? IDS VIDIO WOSING (Oe Wists. IslOOSWIC Wi SIKUAVCIE S The river had built into Lake Albany a great delta, the plain of which had been raised above the level of the water at the head of the delta, near Schaghticoke, and stood very slightly below the water level for a considerable distance outward from the head. When at length Lake Albany began to subside this portion of the delta plain, covered by shallow water, emerged as land surface. During the emergence the river maintained its channel across the added area but as the extent of the level or slightly sloping surface increased, the stream was gradually thrown into a winding course and eventually broad meanders were developed. The continued degradation of the bed of the river resulted in lowering the level of the plain within the belt of meandering. In the shifting of the channel of the stream from side to side terraces were left at the outer limit of each meander. These terraces were formed at suc- cessively lower levels according to the level of the lowering plain at each successive swing of the river. The subsidence of Lake Albany by stages, bringing to the sur- face at different times added areas of the delta surface, was undoubtedly an important factor in the development of the terraces. It is possible that the slopes bounding some of the terraces repre- sent in fact abandoned shore lines of the lake. The terrace on the north side of the river at the 280-foot level at its inner margin and bounded at its outer margin by the slope that separates it from the 340-foot level of the delta plain lends itself to this explanation. The contour lines that mark the 20 feet of slope trend abruptly to the northeast and can scarcely be interpreted as indicating the limit of a meander. The writer has not found it possible, however, on the basis of topographic evidence, to differentiate between the effects to be immediately connected with subsidence and those due to erosion and meandering as described above. _*Chamberlin and Salisbury. Geology, 1:189. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 27 Fig. 5 Diagram showing terraces in delta of Hcosic river EROSION TERRACES Near Mechanicville on either side of the Hudson valley there is a well-defined terrace at the 200-foot level. These terraces are quite certainly of different origin from the other terraces bordering the valley and described above as the upper and lower terraces of the Lake Albany deposits. The terrace west of the river (south- west of Mechanicville) stands 40 feet below the lower lake terrace and is separated from the latter by a steep slope. It was evidently formed by the cutting down of the inner portion of the area of the lake terrace. The terrace on the east side of the river is likewise evidently a terrace of erosion having been carved out of the Hoosic delta deposits. It is evident that the currents which formed these symmetrical erosion terraces issued from the valley now followed by Anthony kill. The west terrace has the location and trend of outlines which would result from erosion by a western tributary river occupying 28 NEW YORK STATE MUSEUM this valley and discharging into waters flowing southward in the udson valley. The east terrace likewise has the location and form relations which would result from currents from the same tributary river sweeping across the Hudson valley waters and impinging against a frontal lobe of the delta mass. o oO © ge ae . : S ees es - = a om) + (Be » a a= Arenson S = uo \ ome oO oe) ne) a, O CG o a mn Qu s fe) O oO ie) 5 rs) am fe) S S i SY teh ae J | 300ft— | | 200 i5—= 100 a Fig. 6 Surface profile across the Hudson valley at Mechanicville showing the symmetrical erosion’ terraces. Horizontal scale and relief scale cor- respond to those of topographic sheet. The line on which the profile is drawn is shown on the map. These terraces are therefore interpreted as follows: When the waters of Lake Albany had so far subsided as to bring to the surface the deposits which now form the lower, or brick-clay, ter- . race of the Hudson valley, the Iroquois-Mohawk ‘waters still dis- charged into the lake through the northern (Anthony kill) channel. In the progress of the subsidence the river currents, shifting east- ward, cut down the inner portion of the clay terrace at Mechanic- ville and, due to the deflection of the Iroquois-Mohawk currents, southward through confluence with the southward-flowing lake currents, the area of reduced clay surface developed southeasterly. This process of erosion was brought to an end by a renewed and more rapid subsidence of the lake waters, thus causing the eroded area to emerge as land surface and forming the present terrace. This terrace and the corresponding one on the opposite side of the valley are therefore features due to the destructive (degrad- ing) work of river currents in contrast with the clay terraces which were built up through the deposition of sediments in Lake Albany. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 29 In both cases, however, the marginal slope, de‘ermining the front of the terrace, is due to downcutting by currents shifted from a broader to a narrower range of erosion consequent upon the sub- sidence of the Lake Albany waters. The downcutting which attended the renewed subsidence of the lake waters is definitely recorded in the steep slopes which bound the erosion terraces at their inner margins. As shown by the contour lines of the sheet the slope, or bluff, of the west terrace (facing the flattened area on which Mechanicville is built) is 60 feet in height and the bluff of the east terrace (extending northwest- erly from Reynolds) is 80 feet. The trend of the lines of these bluffs is quite evidently such as would be caused by currents issuing from the Anthony kill channel. And these currents must have been of considerable power, seeing that their force was not spent in their diagonal course across the lake waters. It is therefore inferred that the Iroquois-Mohawk was still discharging into Lake Albany at Mechanicville when the waters of the lake had subsided to the level of the eroded area at the foot of the bluff west of Mechanicville. The eroded area just referred to has the physio- graphic form of a terrace normal to the river at the present level © of its channel. The corresponding terrace on the east side of the river is the level tract extending toward the river from the foot of the bluff running northwesterly from Reynolds. These symmetrical terraces may be designated the lower erosion terraces in contra- distinction to the upper erosion terraces described above. EVIDENCE (BEARING ON POSTGLACIAL HISTORY OF EDSON CEAVIPO AN VALE These topographic features, due to erosion by the Iroquois- Mohawk currents, afford a datum for determining the time ot subsidence of Lake Albany with reference to the location of the front of the ice sheet in its retreat from the Hudson and Cham- plain valleys. The outlet of the interior glacial lakes (Algonquin- Iroquois stage) continued through the Mohawk valley until such time as the receding ice front opened an outlet along the northward slope of the Adirondacks. It follows that the subsidence of Lake Albany had proceeded to the extent that its waters had lowered from the 360-foot level (that of the Hoosic delta) to the 100-foot level (that of the lower erosion terraces at Mechanicville) within the period of time the ice front was in process of retreat to the northern end of the Champlain region. For during the continuance 30 NEW YORK STATE MUSEUM of the Iroquois-Mohawk outlet its currents lowered their bed in the Lake Albany deposits pari passu with the subsidence of the lake waters from the surface of the deposits to the level of 100 feet. There is no evidence that the waters of the Hudson valley, after their subsidence to the level indicated by the eroded area at Mechan- icville, rose again to a higher level. The present major topographic features of the valley (the terraces and their slopes) have certainly not been modified by overflowing waters since their origin. If therefore a water connection existed between the Champlain arm of the sea and the ocean at New York, this strait had a breadth at Mechanicville not greater than approximately the space between the 100-foot contour lines on the opposite sides of the valley; that is a breadth not greater than that of the present valley bottom. These deductions, drawn from the facts of topography, are opposed to the conception of a body of marine waters filling the Hudson valley to a height indicated by the river deltas and con- tinuous with marine waters in the Champlain depression. If we suppose that the Hudson valley waters in which the sands and clays were deposited were estuarine, opening into the sea at New York, then that portion of the estuary included in the area of the Cohoes quadrangle had become changed to a fresh-water river while yet the St Lawrence basin was filled with ice. We are thus led to conclude that at no time was there a continuous body of marine waters connecting the St Lawrence arm of the sea with the ocean at New York. Clays, sands and gravels on the floor of the Hudson valley. The materials of the floor of the Hudson valley are varied in char- acter and over considerable extents of the surface are not readily resolvable into areas of distribution according to their composition and origin. This complexity is due to the varied factors that have determined deposition of materials and their subsequent degrada- tion during the successive stages of Pleistocene history. The strong currents which through downcutting brought into relief the clay bluffs bordering the valley floor did not sweep away all the deposits laid down on the middle portion of the basin of Lake Albany. In places, therefore, the soil is made up largely ot clays representing original lacustrine deposits. Where these clays thin out or where they have been largely removed by erosion, glacial till appears, often with boulders at the surface. Where the erosion has gone on to the extent that the till has been removed, areas of bare rocks, or rocks covered with postglacial residual soils, occur. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 31 At the base of the clay bluffs and in places extending well out toward the middle line of the valley there are low heaps or sloping banks of mixed clays and sands that have been washed down or have slidden in loosened masses from the slope. At a number of places there are evidences that landslides of considerable propor- tions have occurred. Thus on the left bank of the river above Stillwater, near the Washington-Rensselaer county boundary lines, the broken slope and partially detached masses of the clayey materials are quite evidently the result of landslides. Also 2 miles north of Waterford there is a conspicuous sloping bank, marked by the curve of the Champlain canal, which is believed to represent a landslide. The conditions and factors determining the occurrence of landslides of the Hudson valley clays have been carefully studied by Newland.* It is quite probable that a considerable proportion of the fine- grained materials of the soils of the valley floor have been derived as silts washed from the numerous ravines that open into the val- ley. There are, however, no well-formed alluvial fans fron’ing _ the mouths of the ravines. In explanation of this it is to be remem- bered that the development of the ravines began as soon as the terraces emerged from the Lake Albany waters and that the sedi- ments washed from the ravines were for a long time spread out on the bed of the lake when its shore line corresponded with the present bluffs of the lower terrace. There occur here and there on the valley floor deposits of gravels ; that is, rounded pebbles and cobbles, usually mingled with coarse- grained sands. Some of these occurrences admit of ready explana- tion. For instance, on the eroded tract crossed by the road that runs southwesterly from Reynolds the gravels, forming much ot the soil of the fields, have evidently been derived from the materials of the Hoosic delta. The currents which reduced this portion of the front of the delta mass left behind the coarser parts which were too heavy to be transported. There are frequent occurrences of masses of gravel in which there is a stratified arrangement of the materials. Immediately north of Waterford, in the angle between the canal and the highway, there is a conspicuous gravel bank in which the following features of composition and structure were noted: (1) Layers of coarse gravel mixed with dark sand 3 to 15 feet thick and Io to 15 feet Newland. Landslides in Unconsolidated Sediments. 12th Rep’t of the Director of the State Mus., p. 79. 1916. Re NEW YORK STATE MUSEUM in length; these layers mostly dipping to south. (2) Layers of dark sand mixed with pebbles and worn fragments of shale rock 3 to 10 feet thick. (3) Thinner layers of stratified yellow sands a few inches to 3 or 4 feet thick. A gravel pit and slope showing a thickness of about 40 feet occurs along the road that crosses the eroded area northwest of Waterford near where the small stream crosses the road. This is apparently an exposure of the same gravel mass described in the preceding paragraph. Also on the northern part of Peobles island, south of Waterford, sand and gravel are obtained from deposits which apparently fill depressions of the rock surface. The materials show a stratified arrangement and consist of water-worn fragments of rock, ranging from the size of pebbles to cobbles, with irregularly _ -interstratified layers and lenses of coarse sand, mingled with worn fragments of local rock. These bodies of gravel are interpreted as representing kames, or morainic accumulations formed at the ice front in the retreat of the ice lobe which occupied the general valley of the Hudson after the melting of the ice from the uplands. As lacustrine condi- | tions supervened these ice deposits were covered over with the clay sediments but in the localities mentioned, as elsewhere on the floor of the Hudson, they have been stripped of the clays and more or less reduced by stream erosion. An interesting occurrence of gravels is that found on Green island and on the east side of the river, south of Lansingburg. Here the surface materials are limited to a thin layer of coarse sand and fine gravel immediately overlying bedrock. The thick- ness of this deposit, as observed, is nowhere in excess of 3 or 4 feet and in places it thins out to a few inches: The deposit lies unconformably on the rock surface, filling and smoothing over depressions in the rock. These sands and fine gravels are inter- preted as outwash deposits from the morainic accumulations to the north and referred to in the preceding paragraphs. The Willow Glen gravel bank. At Willow Glen the north slope of the valley now followed by Anthony kill presents an exposure of a thick mass of sand and gravel. The materials are utilized for building purposes and a spur of the railroad extends to the bank. The general composition and structural features are similar to those of the sand and gravel bank at North Albany. In general, the entire mass shows irregular stratification: layers of coarse gravels intermixed with coarse sands are clearly marked off GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 33 from layers of less coarse compesition. Some of the layers are of dark color, due mainly to water-worn fragments of the local rock. At the base of the bed there are cobbles and boulders that have been separated from the sands in the work of excavation. It is believed that these deposits are morainic in character and were laid down under conditions of standing water. They evidently occupy a preglacial depression and the retreating ice front may have halted or entered upon a phase of slow recession at this place. At the same time waters gathered in the depression and the materials derived from the melting ice were partially sorted as they were laid down. This formation of sands and gravels, and others of similar com- position and structure as they occur in the Hudson valley where lacustrine conditions immediately supervened upon the withdrawal of the ice sheet, may be designated as subaqueous recessional moraines. Residual clays of postglacial age. The Mohawk waters which coursed through the Anthony kill channel swept from their path the Lake Albany deposits and laid bare the underlying rock. Much of this rock surface thus exposed to weathering is now covered with residual clay soils. In general, the floor of the valley from Willow Glen eastward to the river (except where bare rock is now exposed) is mantled with a thin layer of rock detritus soils of post- glacial age. They are well shown in cuttings made in grading the macadamized road, and the transition from the fine-grained surface soil to the slightly altered rock below is readily noticeable. The depth of the soil, as observed, varies from a few inches to several feet. The park area of the city of Mechanicville is composed of this residual clay soil with some additions of materials from the lacustrine clays and sands that have been washed down from the slope bounding the erosion terrace. When the Mohawk river became established in its present course (the Aqueduct-Cohoes channel) its flooded waters likewise swept away a broad path through the Lake Albany deposits. In this way was formed the broad depression extending southeastward from Crescent to the islands at the mouth of the Mohawk. The greater portion of the floor of this depression lies east of the present course of the river and is marked by striking irregularities of surface. The larger features are clearly due to the effects of weathering and stream erosion, mainly in preglacial times, of steeply tilted rocks composed of unequally resistant strata. The topography of this 34 NEW YORK STATE MUSEUM area is therefore essentially preglacial and represents, in fact, a portion of the ancient rock valley of the Hudson stripped of its Pleistocene covering and somewhat modified by postglacial erosion and weathering. The same area shows in its minor surface features the action of strong currents laden with fragments of hard rock as cutting tools. There are numerous depressions marking ancient potholes, now partially or wholly filled with the residual clays. Some of these are exposed where the clay is thin or has been removed; for example, on the left bank of the river near the falls.* The surface materials of this area consist mainly of residual clays derived from the underlying shale (or slate) rocks. The section of the state barge canal which extends from Waterford to the Mohawk, at a point about 1 mile above Cohoes falls, crosses this area and is everywhere cut in bedrock. The layer of residual soil overlying rock is thus clearly exposed. Along the gorge of the Mohawk the weathered rock surface, forming a dark-colored clay soil, is also well shown. ‘The thickness of the clay mantle is nowhere great, varying from a few inches to perhaps 5 or 6 feet. These clays have certainly originated as the products of rock- weathering since the end of the epoch of flooded Mohawk waters. While the covering of this area consists predominantly of residual clays, there occur in places materials of the glacial till which escaped removal by flood erosion. These are scattered boulders and cob- bles; also, in places, especially in the eastern portion of the area, some of the less coarse materials of the till still persist in the covy- ering of the bedrock. Areas of residual clays also occur on the floor of the Hudson valley.. The largest of these forms a broad tract lying west of the curve of the river between Bemis Heights and Stillwater and extending in narrower development southward to near Mechanic- ville. This area includes many patches of outcropping or thinly ~ covered rock, the distribution of which corresponds in general with the highest parts of the surface. In that portion of the area which lies east of the abandoned canal (which follows a line of drainage depression) the parts of highest elevation are shown by the looped contours marking the 1oo-fcct level. But west of the road that runs northerly from Stillwater there is an elongated hill of rock with thin covering of detritus which is 160 feet in elevation. There *For a full description of these potholes with measurements, see paper by G. K. Gilbert (Deposition of the Mastodon at Cohoes), N. Y. State Cabinet Nat. Hist., 21st Annual Report, 1871. p. 129-48. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 35 is a depression of surface between this hill and the clay bluff which bounds the lower lacustrine terrace. The interpretation placed upon these features is as follows: In the course of the lowering of the Lake Albany waters to the level marked by the base of the bluff fronting the lower terrace, the character of this body of waters had gradually become changed from lacustrine to fluviatile. Strong currents from the north flowed in the channel formed by the shrunken bed of the lake. At Bemis Heights these currents sweep southwestward along the clay bluff; subsequently the line of strongest currents shifted easterly, denuding the broad tract now covered with residual soils, and finally occupy- ing the present channel of the Hudson. In a number of places farther to the south there is like evidence of the erosive work of strong currents which flowed over the floor of the Hudson valley. The rock surfaces thus laid bare. are now covered mainly by residual clays. The attempt has been made to map these areas, but in some places there are no clear delimitations and the boundaries as shown on the map are to be taken as approximate. Areas of bared rocks. The areas of exposed rock surface on the floor of the Hudson valley and the two tributary valleys from the west are not sharply separable from the areas of residual clays described above. Both were originally swept bare by the same flood currents and it is probable that, excepting the rock islands of the Hudson river and other small exposures adjacent to the present streams, much of the area now bare was formerly cov- ered with residual clays. The larger towns of the valley, Cohoes, -Lansingburg, Waterford and Mechanicville, are built wholly or in part on rock and it is evident that human agencies have played a part in denuding these areas. Postglacial gorges. The Mohawk river from near Crescent to its mouth has its bed on rock and in the last 3 miles of its course occupies a rock gorge marked by the well-known falls at Cohoes. A dam has been built across the upper portion of the gorge, in order to supply power for the industries of Cohoes. The level of the water in the dam is 156 feet. From the dam to the falls the river has the character of a rapids descending 20 feet in the dis- tance of three-fourths of a mile. It then falls 70 feet over a preci- pice of rock. The water does not descend abruptly as a vertical sheet but flows over the steeply inclined rock declivity. The slope of this declivity corresponds in general to the dip of the rocks but 36 NEW YORK STATE MUSEUM in the middle portion of the falls the rocks have been worn and broken so that the angle of fall is less than that of the dip and in places the falling water has the character of a cascade. At about one-third of the width of the river from the left bank there is a projecting mass of smoothed rock over which little water passes. At the inner side of this mass the volume of falling water is greater than elsewhere and at the base there is a deep pool of water occupying a depression worn into the rocks. | — if 1 | CAS < Z Residual é cya WS Mi On 6 “TT “| of Yaa, «0° diy, < TL) |(\\S COONS [7 = Mii p ian \ | A\\\\ \\, # MAS : 1 > = Se 7 ° Fig. 7 Block diagram of the Cohoes region of the lower Mohawk. The development of the topographic features here shown is explained in the Lex Below the falls the river flows on a bed of jagged rock but with slower currents, descending in the course of a mile from the level of 60 feet at the foot of the falls to 51 feet at the head of the lower rapids where the river divides into three streams forming the islands on the floor of the Hudson valley. In the summer when the river is low most of the water below the falls is confined to a deep-water channel which extends from the deep-water pool at the falls. In interpreting these features it is to be remembered that in this portion of its course the Mohawk flows across the ancient rock valley of the Hudson. The outer boundary of this rock valley is clearly indicated by the ridge (although now mostly covered) extending north and south from Crescent station. The postglacial Mohawk river broke through this boundary at Crescent. Then bending southward, its course partly determined by the strike of GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 37 the rock beds and partly by the slope of the old valley floor, the river eroded its present channel. Where it passed over the rim of the narrower inner portion, or gorge (see page 7), of the ancient rock valley, rapids were formed and, owing to the steep dip of the rocks, the rapids developed into a waterfall. This was the origin of the Cohoes falls. The height of the rock wall of the gorge below the falls as seen on the east side is 120 feet. About three-eighths of a mile below the falls this wall falls away to a height of 40 feet. The contours of the upper portion of the wall, representing 80 feet, here become continuous with the slope extending northeasterly and bounding the present valley floor of the Hudson. This slope (crossed by the road a short distance back from the summit of the gorge) is composed of rock covered with residual clays. The continuation of this escarpment is seen on the opposite side of the gorge though much reduced in height and angle of slope for some distance back from the river. This is due to the flooded Mohawk waters of late glacial times, which laid bare the rocks on which the lower (northern) portion of the city of Cohoes is built. The trend of the currents southward due to their confluence with the Hudson waters, caused a greater reduction of the scarp immediately south of the gorge. But farther to the south, west of the railway tracks, where the surface of the rock is exposed in a ravine, the scarp shows at its full height. It is quite evident that this slope of rock is the rim of the inner portion of the ancient rock valley and that the place where the height of the wall of the gorge below the falls abruptly lessens marks the original location of the falls of the river. The present Cohoes falls is located approximately 2000 feet back from this landmark, showing that a recession of the falls has taken place to that extent in postglacial times and subsequent to the with- drawal of the Lake Albany waters. This small amount of recession compared with other postglacial falls (Niagara Falls has receded 7 miles in postglacial times) is - explained, at least as to the main factors concerned, by the materials and structure of the rocks through which the gorge has. been cut. The rock consists of indurated shales (slates) and sand- stones, dipping steeply in a general direction to the east. The amount and direction of dip varies locally, due to contortions of the strata resulting from compression. In general, the sandstone layers predominate in the rock and layers of a thickness of from 38 NEW YORK STATE MUSEUM several inches to a foot or more occur interbedded with the thinner layers. The direction of flow is with the dip so that in general the wear of the rocks at the front of the precipice is on the faces of their bedding planes. Because of this the process of wear goes on slowly. But at the summit of the falls the water flows over the edges of the rocks and the destructive process is more rapid. The erosive agents lodge in the depressions resulting from unequal wear of alternating soft and hard strata and deepen them into pot- holes. There are very many of these in the bed of the river imme- diately above the falls. Due to the more rapid wear of the strata on their upper ends than on their faces, the angle of slope of the falls is greater than that of the dip of the strata. At the base of the falls where the impetus of the falling water is greatest somewhat rapid wear takes place, forming pools, and the eddies in these pools, through undermining, may contribute somewhat to the recession of the falls. The Hoosic gorge. A postglacial gorge of interesting physi- ographic and scenic features is that of the Hoosic river west of Schaghticoke. The river has here sunk its bed through the mass of delta deposits and into the underlying bedrock. Where the stream enters the gorge at Schaghticoke its course turns abruptly northward, evidently in conformity to the strike of the rocks. After emerging from the first gorge the river turns westward and its slopes consist of the delta materials. It then enters the second rock gorge and its further course describes the shape of the letter U, the direction of the arms of the U corresponding to the dip of the strata. There is a fall of 120 feet from the head of the upper gorge to the foot of the lower rock gorge, furnishing abundant power. This has long been utilized for manufacturing industries and, in recent years, for the generating of electric energy. East of Schaghticoke the general valley of the Hoosic has the appearance of a preglacial valley although the shallow rock gorge at Valley Falls may mark a diversion of the river from its old bed. The course of the preglacial Hoosic from near Schaghticoke to the Hudson is unknown. In that portion of the course of Tomhannock creek which crosses the delta formation, the stream has in places sunk its bed into the underlying rock forming gorges and cascades. One of these occurs a short distance northwest of Schaghticoke hill and another of pic- turesque scenic features about one and one-half miles farther on. Plate 2 Falls of the Mohawk at Cohoes. The amount of rock erosion both above and below the falls on the left bank of the river is shown in the picture. The gorge of the Hoosic river below Schaghticoke. The building in the middle background is the power house. GLACIAL GEOLOGY O& THE COHOES QUADRANGLE 39 RECENT DEPOSITS The deposits representing the recent period of geological history, or epoch that has elapsed since the final subsidence and disappear- ance of glacial waters, are (1) wind-blown sands, (2) stream allu- vium and (3) vegetable debris or peaty accumulations in swamps. Wind-blown sands. In the western and northwestern parts of the quadrangle there are extensive areas of country thickly mantled with loose sands. These sand fields are the eastern por- tions of a broad belt of sands that extends southwest from the region of Saratoga lake to the Mohawk river. To a large extent the sand is heaped in dunes, although, along the eastern margins of the tracts, there are stretches of nearly level country where the sand has been distributed somewhat evenly over the underlying till or lacustrine deposits. Many of the dunes are of live sand and show evidence of constantly changing size and position. They exhibit no general uniformity of shape but in individual cases it may be observed that their present growth is toward the form of a ridge with axis corresponding to the direction of the prevailing strong winds. For the most part these sand tracts, especially the one extending southward from Saratoga lake, are uncultivated. Only the marginal portions of the areas where the depth of sand is not great are of any important agricultural value. The native vegetation consists of coarse grasses and of trees — pines, white birches and occasional oaks and maples. These trees are of second growth and are mostly undersized and often of stunted character. The source of these blown sands is undoubtedly from deposits originally made in Lake Albany. To the westward from the sand fields south of Saratoga lake there is a nearly ‘level plain (the Malta plain, Schenectady sheet) which bears evidence of having undergone denudation. The inference seems warranted that much of the sand of this field has been transported by the winds from the area of this plain to its present location. There is a similar relation between the sand region north of Crescent and a leveled tract to the west on the area of the Schenectady quadrangle. It is, of course, also to be considered that the prevailing strong winds of this general region are west or northwest. There are two areas of wind-blown sands with well-developed dunes on the surface of the Hoosic delta deposits. Both of them lie near the eastern border of the delta region and are evidently composed of fine sands that have been sorted from the delta 40 NEW YORK STATR MUSEUM materials by winds blowing from the west. Their locations are shown on the map. In other portions of the surface of the delta there are occasional dunes, but in general the materials of the delta are too coarse to be lifted by the winds. Alluvium. The Hudson river is bordered by broad valley flats in its course from the northern edge of the sheet as far as Still- water. The surface materials of these flats are the fine sediments . or silts that have been deposited at times of high water when the river overflowed its banks. From Stillwater south to the head of tide water at Troy the work of the river in the recent epoch has been rather to lower its bed by erosion than to build up a flood plain. Some narrow areas of alluvial lands occur along the banks and in the curve of the river north of Lansingburg there are two islands of alluvial origin. Along the Hoosic river the flats east and south of Schaghticoke constitute an interesting physiographical feature. It is evident that at a former time the river described a meander both on its right and its left bank. A factor in this shifting of its course was the rock barrier west of Schaghticoke which in times of flood held back the waters, causing the river to overflow its banks and divert- ing its currents against the valley slope. As this barrier was gradually reduced through erosion, forming the present gorge, the river straightened its course. The meanders were cut off from the main channel leaving, however, as a remnant, the present linked channels on the north flat. An extensive alluvial flat, representing a recent meander of the river, occurs along the Hoosic in its lower course. As observed on the left bank of the river, the soil of this area is an alluvium with admixture of mold; it is of a high degree of fertility and is cultivated for market gardening products. Swamps. Areas of swampy or partially drained lands, repre- senting glacial lakes or ponds which have been filled in by sedi- ments and overrun by vegetation, have been indicated on the map as far as observed. GLACIAL GEOLOGY OF THE COHOES QUADRANGLE Al REVIEW AND SUMMARY The following is a classification of stages of the pleistocene period and present period as recorded on the area of the Cohoes quadrangle: NAME OF STAGE PROCESS RECORD PPR CCeNL eyes ha ee og es Stream and wind Alluvium, wind- = erosion and depo- blown sands, swamp ag sition muck S Glacio-lacustrine 2 Substage e.... Erosion by fluviatile waters. Erosion terraces and eroded AY bottom of present Hudson : valley ~~ Substage d.... Later subsidence of Lake ‘$ ANDEAN 5h ay 5 Gan nee Lower terrace S Substage c.... Earlier subsidence of Lake S PAINTING ele oy oes Sere ce tocar Upper terrace S Substage b.... Lacustrine waters occupy 8 iEtudsonivalley. = oe... 4.0) Lake Albany deposits = Substage a.... Ice lobe occupies Hudson 8 SINS oes canoer eee Marginal moraines R&R, Wisconsin...... Last general glaciation..... Till Pre-Wisconsin... (Interglacial interval)...... noe Gm of Saratoga lake (: In a previous report? the writer has presented what seems con- clusive evidence that the Hudson river in its course across the southeastern spur of the Adirondack mountains, from Corinth to west of Glens Falls, occupies a valley cut during an interglacial epoch, immediately preceding the last or Wisconsin period of glacia- tion. On the area of the Cohoes quadrangle, however, no certain evidence of an earlier period of glaciation has been found. But mention may be made of the possibility that the rock depression occupied by Saratoga lake is a part of the valley eroded by the interglacial Hudson in its course southward from the place of emergence from the Adirondack region onto the Hudson plain west of Glens Falls. It has been thought permissible, in the classi- fication above given, to recognize, in a tentative way, this inter- pretation of the rock basin of Saratoga lake with which may be connected that of Round lake, 4 miles farther to the south. Wood- worth has suggested as follows: “It seems probable that Round and Saratoga lakes are unfilled depressions marking the site of an old’ valley west of the present Hudson gorge.’” * Glacial Geology of the Saratoga Quadrangle. N. Y. State Mus. Bul. 183, p. 30-35. * Woodworth. Op. cit. p. 76. 42 NEW YORK STATE MUSEUM The effects of a general ice sheet moving in a north-south direc- tion, whether representing only the last invasion of the ice or the last, together with previous invasions, are recorded on the area of the Cohoes quadrangle in the smoothed surfaces of rock hills and in glacial scratches. The drumlinized forms of many of the rock hills are conspicuous to the eye in the field and are also clearly indicated by the contour lines of the topographic sheet. The char- acter of the rocks (indurated shales and sandstones) and their steeply inclined planes of stratification are unfavorable for register- ing the ice movements by glacial scratches and they were observed only in two localities, as follows: about 124 miles northwest of Stillwater, on the surface of a projecting mass of rock in a field south of the highway (see map), 10° west of south; about 1% miles south of Valley Falls on rock at roadside, 5° east of south. The close of the latest period of general prevalence of ice, marked by the retreat of the ice sheet to the north) 1s 1econdedsammnie materials left from the melting ice and forming the till sheet, or ground moraine of the uplands portions of the quadrangle. The recession of the ice front appears to have been relatively steady and uninterrupted. This is inferred from the fact that there is no recessional moraine of any considerable continuity. In a few local- ities on the eastern uplands areas, groups of hills of definite mor- ainic character occur, evidently marking temporary and local stand- ings of the ice front. In the gradual process of the melting of the ice sheet the uplands were bared before the thicker ice filling the broad valley of the Hudson had wasted. A broad and deep lobe of ice thus lingered in the valley, probably for a long time after the upland areas were ice-free. South of the southern limit of the valley ice, and con- stantly extending northward with the retreat of the ice lobe, as well as spreading laterally over depressed areas adjacent to the Hudson valley, gathered and for a long time stood at a permanent level the body of waters which formed Lake Albany. Due to the more rapid melting of the ice in its lateral portions than in the thicker middle portion, the ice lobe narrowed gradually toward its southern end and thus were formed two embayments of the lake waters, lying on either side of the elongated wedge of ice. These embayments received sediments derived from the melt- ing ice and especially from streams from the north which developed in the depressions between the lateral margins of the lobe of ice and the bared land slopes. The coarser sediments were deposited in the upper and narrower parts of the embayments while the finer GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 43 materials were carried farther and laid down in the quiet waters lateral to the dwindling end of the ice lobe. As a general result of this sorting of the sediments, the materials deposited on the floor of the upper and outer portion of the preglacial valley of the Hudson are coarser (sands and clays of the upper terrace) than those which form the filling of the inner portion of the valley (brick clays of the lower terrace). The latter were added to, how- ever, at a later time, by depositions of fine sediments from the midcurrents of Lake Albany. Fig. 8 Sketch map showing the distribution of land and water on the areas of the Schenectady and \Cohoes quadrangles when Lake Albany was at the height of its development, its level corresponding to the present 360- foot contour When the ice lobe had melted back beyond the northern limit of the quadrangle, all parts of the area the elevation of which is below approximately 360 feet on the northern portion of the present map and 320 feet in the southern were covered by the waters of Lake Albany. The lake waters rose beyond the height of the western marginal boundary of the preglacial rock valley of the Hudson and extended in two broad sheets westerly, communicating with the expanse of Lake Albany that overspread the eastern and southern portion of the area of the Schenectady quadrangle. The body of waters thus developed received the Hoosic river at its eastern border and the flooded Iroquois-Mohawk (then the outlet 44 NEW YORK STATE MUSEUM of the great interior glacial lakes) at its western border. Each of these streams built extensive deltas into the lake. The magnitude of these deltas affords evidence of a prolonged period of stable con- ditions of the Lake Albany waters. When at length the waters of Lake Albany began to subside the great deltas emerged as land surfaces. The emergence of the delta of the Mohawk influenced greatly the subsequent drainage history of the Mohawk-Hudson region. As the waters shallowed at the head of the delta near Schenectady, the checked Iroquois-Mohawk | (Viecher a om: Pe Fig. 9 Sketch map showing areal extent of Lake Albany and drainage courses on the areas of the Schenectady and Cohoes quadrangles at the time when the Lake Albany waters had subsided to the level represented by the present 320-foot contour currents, impeded by their own deposits, were diverted northeast- ward through the Ballston channel, the latter opening into Lake Albany in the Saratoga-Round Lake region. At the same time, due to partial obstruction of the Ballston channel by sediments, a spillway across the barrier of rocks at Aqueduct was formed and a portion of the Mohawk waters discharged into Lake Albany at Vischer Ferry. The northward course of the Mohawk waters continued for a long time. As the subsidence of Lake Albany progressed, bringing to the surface the lake bottom in the region of East Line, the cur- rents eroded channels in the lacustrine deposits and eventually GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 45 the main course became established in the channel extending south- easterly to the Round Lake inlet of Lake Albany. At a later time, with a further subsidence of the lake waters, the Iroquois-Mohawk eroded out the broad and deep valley now followed by Anthony kill. The Hoosic river, unlike the Mohawk, maintained its course across the emerged area of the delta, repeatedly shifting its channel from side to side and thus building a series of terraces. The subsidence of the Lake Albany waters took place inter- mittently, as is shown by the distinctly terraced forms of the Fig. 10 Sketch map showing Lake Albany and drainage courses on the areas of the Schenectady and Cohoes quadrangles when the lake waters had subsided to the level represented by the present 240-foot contour deposits. With the withdrawal of the waters to the level now represented by the 300-foot contour, or somewhat lower, the outer portions of the lake bottom in which the coarser sediments had been deposited emerged as land surface. Thus originated the present upper terrace of the Hudson valley. At the next stage of marked subsidence, when the water had receded to the level represented by the 240-foot contour, or some- what lower, the more even portion of the lake bottom which had been built up by deposition of the finer sediments, emerged as land surface, forming the plain of the lower or brick clay terrace. 46 NEW YORK STATE MUSEUM The lake, then greatly narrowed, began to take on the char- acter of a broad river and strong currents, coming both from the north and from the Iroquois-Mohawk which still discharged into the Hudson waters at Mechanicville, cut deeply into the sediments still filling the midportion of the general Hudson valley. As a result of downcutting, symmetrical erosion terraces were developed at two levels on opposite sides of the valley at Mechanic- ville. The locations and configurations of these terraces show (S) tound Lake Anth 7? on, Liz, (Mechanicville SS) (Aqueduct ) Schenectady Basin \e ° a Se rong Fig. 11 Sketch map showing drainage of the areas of the Schenectady and Cohoes quadrangles and breadth of waters occupying valleys when Lake Albany had receded to the level represented by the present 100-foot contour line and had taken on the character of a broad river. The Mohawk river had lowered its gorge at Aqueduct to the 300-foot level. conclusively that they were the work of the Iroquois-Mohawk currents and establish the fact that the postglacial body of waters of the Hudson valley became greatly diminished prior to the time of the opening of the channel northward to the Adirondack region as the outlet of the waters of the great interior lakes. The spillway across the rock barrier at Aqueduct gradually deep- ened, through erosion, into a gorge of capacity sufficient to contain the volume of the Mohawk waters. The flooded currents cut a broad path through the lacustrine deposits southeast of Crescent, laying bare the rock floor of the preglacial Hudson valley. Where the river flowed over the rocky slope which marked the rim of the GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 47 ancient valley a falls developed which, through recession, formed the present falls and gorge of the Mohawk at Cohoes. The stage of flooded waters in the Mohawk valley lasted until the general ice sheet had retreated to the north so far as to open a passage for the overflow waters of the great interior lakes north of the Adirondack region, thus diverting the outlet to the sea from _ the Mohawk valley. Whether flooded waters continued for a still longer time in the Hudson valley depends upon whether the northern outlet of the great lakes, when first opened, connected with the sea through the St Lawrence basin as now or, for a time, found a course to the sea through the Champlain-Hudson valley. Assuming the latter case, there is no evidence that the flooded waters ever rose to a level higher than the foot of the clay bluffs bordering the present valley floor of the Hudson. IN De xX Albany Lake, 42; deposits, 17-19; sketch map, 43, 44, 45 Alluvium, 40 Anthony kill, 10, 23 Aqueduct, 46 Ballston lake, Io Chamberlin, cited, 26 Clays, Lake Albany deposits, 18; on floor of Hudson valley, 30-32; residual, of postglacial age, 33-35 Cohoes quadrangle, sketch map showing drainage, 46 Crescent, 35, 46 Drumlins, 13 East Schaghticoke, 15 Erosion terraces, 27-29 Fairchild, cited, 10, 17, 20 Gilbert, G. K., cited, 34 Glacial lakes, 15 Gorges, postglacial, 35-38 Gravel, hills of, 14; Willow Glen gravel bank, 32 - Gravels, of Hoosic delta, 18; on floor of Hudson valley, 30-32 Ground moraine, I2 Haynersville, 16 Hoosic delta, 23-26 Hoosic gorge, 38 Hoosic Lake, 16 Hoosic river, 10 Hoosic terraces, development of, 26 Hudson river, 6, 41 Kames, 14 Lake Albany, 42; deposits, 17-19; sketch map, 43, 44, 45 Lake Hoosic, 16 Lake Tomhannock, 6, 15 Lakes, glacial, 15 Lower terrace, development of, 21-26 Mechanicville, 27 Melrose, 15 Merrill, cited, 17 Mohawk valley, 9 Moraine, ground, 12 Mount Rafinesque, II Newland, cited, 31 Physical geography, 6-12 Poesten kill, 16 Postglacial history of Champlain valley, 29-40 Hudson- Quacken kill, 16 Raymertown, 15 Rice mountain, II Ridges, 14 Rocks, areas of bared rocks, 35 Round lake, 10, 41 Salisbury, cited, 26 Sand, hills of, 14 Sands, Lake Albany deposits, 18; of Hoosic delta, 18; on floor of Hud- son valley, 30-32; wind-blown sands, 39 Saratoga lake, 41 Schaghticoke, 23, 25, 38 Schenectady quadrangle, sketch map showing drainage, 46 Speigletown, 14 Stoller, cited, 9, 10, 20 Swamps, 40 Dili x12 Tomhannock creek, 12, 14, 38 Tomhannock, Lake, 6, 15 Upper terrace, development of, 19-21 Valley Falls, 25 Waterford, 31 Willow Glen gravel bank, 32 Woodworth, cited, 41 JOHN M, CLARKE UNIVERSITY OF THE STATE OF NEW YORK STATE GEOLOGIST STATE MUSEUM BULLETIN 215-16 COHSES QUADRANGLE LEGEND Swamps or artially drained areas; mainly vegetable debris. Areas of wind blown sands with well defined dunes; overlying till or Lake Albany deposits: Rooks Jald bare by late glactal or post glacial Streim erosion; gorges are indicated by Mnes at right angles tostream COUrSeS: Residual olays; derived from rocks laid bare by powerful currents of Water (Mohawk and Hudson rivers) of Inte glacial times. Olays, sands and gravels; in part original deposits made in Lake Alban and) tn part materials washed from gullies or moved by landslides and deposited on the floor of the Hudson channel. In places till (boulders) occurs. and’ slopes of the emerged basin of Lake bany. Olays ays); de- posits made Lake Albany and emerged (Schenectady) (Hoosick) dnoring the later stages of subsidence. of the lake waters thelr sur- face forming a lower terrace. Fine gravels, sands and clayey sands; delta de- posits in Lake Albany made by Hoosie river. Sunds or clayey sands; deposits made in Lake Albany and emerged during the carly stages of the subsidence of the lake waters, thelr sur- face forming an upper terrace and slope. Deposits mai of glacial lak: uplands tne silts thinly ov ing glactal rill; Hoosle Valley, sands aud fine gravels. Hills of sand and gravel; @) Kames, marking, re- Gesstonal moraines, (2) Ridges, marking moraines as lateral to the Hudson Valley ice lobe. 11) or ground moraine; (lacking or scanty where rocks or rock detritus solls form the surface materials). Glacial soratohes Mi Rafines Geology by James H. Stoller. Scale #3600 1916-1917 ~ 3 o a a A. » Milew " “ 3 o 2 = 2 re |, Hilometers Contour interval 20 feet Darurn in mean sex levet oh cwnsce ies aR aS \ ‘ Re: | { ‘ew York State Museum Bulletin it Entered as second-class matter November 27, 191s, at the) Post Office at Albany, N Y, “under the act of August 24, T912 i Published monthly By The University of the > State of New York © Nos. 217, 218 o AEP ANG) ee 1919 The University of the State of New York New York State Museum Joun M. Crarke, Director Si) a _ THE PALEOZOIC ROCKS OF THE CANTON | QUADRANGLE BY 4 yg . ‘ -G, H. CHADWICK fs | wh : PAGE PAGE, ‘ Patrotuction : I ok EER Re a =5 | The geological history. . . aan ot 42 _ The geological formations ....... 8 Interpretation of the Paleozoic - General statements...........- 8 TECorG. ht. itiue athe Om a 42 _ Potsdam sandstones ........-.-. 11'| Subsequent geclogic history .... 47 fhe basal contact. .:... ... 3... 07 | Surface geology . 2). yc ase ae 48 The concealed zone........-.-- 20 Preglacial and glacial.......... 49 "Theresa mixed: beds...........- 24 Postglacial shorelines.......... 50 ' Heuvelton white sandstone..,.. 26 | Later features ..............-. 51 _ Bucks Bridge mixed beds....... *28) |’ Economic resources... 5 oie 52 Beekmantown (Ogdensburg) Sandstones and limestones ..... 52 ; BNCHIthe hs ania Waele oe oe eS 36 | ‘Iromvore....)......6.0 20 tae Pe NE _. PossibleTrentonlimestoneoutlier 39 Literature and maps............ 53 Resumé of stratigraphy ........ Vis Gy pects a>. a immane my MTA Na 4 5 | 59. ALBANY THE UNIVERSITY OF THE STATE OF NEW YORK * , oat ‘Warrér,Gurst Kettoce B.A. LL. DB. — Col alan cg Director of State Library CE he 3 _ JAMEs I. Wyer, Jr, M.S. PAD. ey : f Pals PLiny TE EXTON L! [ “19 30 Cee N. OTTINGHAM M. yt Ph. ce iy | ge 5 ‘Cuartes B. ALEXANDER M. A. ies, iD 1929 Hersert L. BRIDGMAN Tee bag es 1931 Tuomas J. Manean M.A. = ae ape Juan H. Fintey M.A. LL.D. LHD. eo eee ALBERT VANDER VEER I ie De He ; 1923 Asram I. Evxus LEB LL. D. D.C.L. =" - ey -N © —1924 “ADELBERT Moor MEAD. Liner) oe 2 Lit. D. - - ---- - ie 1920 James Byrne B.A. LL.B. LL.D. Se arch ( President of the University and Commissioner of Education ; Deputy Commissioner and Counsel — ed eS ie = 4PRaNK Bs GILBERT BoA. 0 7) Gee ; Assistant Commissioner and Director of Professional Education! a ; _ Aucustus S. DowNINnG M.A. L.H.D. LL: D. Pd. ee _ Assistant Commissioner for Secondary Education - Cartes F. WHEELOCK B.S. LL.D. ‘radars Assistant Commissioner for Elementary dueation a Grorce M. Winey M.A. Z. om 4 Director of Science and State Museum Joun M. CuarkE D.Sc. LL.D. : i Chiefs and Directors of Divisions Administration, Hiram C. CasE . Agricultural and Industrial Education, Lewis A. Witson” “es Archives and History, James Suttivan M.A. Ph.D. 4 ; 5, Attendance, James D. SULLIVAN | ee - Educational Extension, Witttam R. Watson B.S.” Pa Ey Examinations and Inspections, Gzorcz M. WILEY M. A, Staten Law, Frank B. GILBERT B.A., Counsel BEY Library Sehool.iites 1. Wika Jean LG Pe meee School Buildings and Grounds, Frank H. ‘Woop M. JAS, School Libraries, SHERMAN WitiaMs Pd. D. Visual Instruction, ALFRED Ww. ens. Ph Pe lags 4, int 5. ps The University of the State of New York Science Department, November 9, 1918 Dr John H. Finley President of the University SIR: I beg to communicate herewith and to recommend for publica- tion, as a bulletin of the State Museum, a manuscript entitled The Paleozoic Rocks of the Canton Quadrangle, which has been pre- pared, at my request, by Prof. George H. Chadwick. Respectfully yours Joun M. CLARKE Director THE UNIVERSITY OF THE STATE OF NEW YORK THE STATE DEPARTMENT OF EDUCATION Approved for publication this 12th day of November 1918 [Raia President of the Umversity beeen ar.) — 3 New York State Museum Bulletin Entered as second-class matter November 27, 1915, at the Post Office at Albany, N. Y., under the act of August 24, I912 Published monthly by The University of th: State of New York Nos. 217, 218 ALBANY, N. Y. JANUARY—FEBRUARY. 1919 The University of the State of New York New York State Museum Joun M. CLARKE, Director THE PALEOZOIC ROCKS OF THE CANTON QUADRANGLE BY G. H. CHADWICK INTRODUCTION? The Canton quadrangle lies in the St Lawrence valley,? between the parallels of 44° 30’ and 44° 45’ north and the meridians of 75° and 75° 15’ west. In its southeast corner begin to rise the hills that mark the declining north edge of the Adirondack upland.’ Of the two physiographic areas mentioned, the valley is a drift- mantled peneplain cut in the softer, Paleozoic sedimentary rocks; the upland is a dissected Cretaceous peneplain of the hard, Pre- cambrian gneisses. A third, vastly older (pre-Potsdam) and sub- sequently deformed, peneplain is represented here at the contact of the Paleozoic rocks with the underlying crystalline Precambrians, and is now reexposed over a part of the quadrangle by removal of the Paleozoic cover. The village of Canton is situated at the approximate merging point of all three of these plains, the signifi- cance and history of which are discussed on a later page. (See figure 2.) *To Doctor Martin, interpreter of the crystalline rocks of the same area, to Doctor Ruedemann and Doctor Ulrich, paleontologists respec- tively of the state and national surveys, to Professor Cushing, his prede- cessor, and to Doctor Clarke, his chief, the writer gladly acknowledges his indebtedness. Valuable aid has been received also from the residents of the territory studied, particularly the following: Prof. and Mrs C. S. Phelps, Rev. C. H. Fenton, G. A. Manley and Alexander Veitch of Can- ton, O. A. Babcock of Madrid, and two of my students who served with- out pay in the field, Erle M. Billings and John A. Shea. To these and all others who assisted I would record my gratitude. Ge EL Gs 7N. Y. State Mus. Bul. 168, p. 22, fig. 2, opp. p. 15. 6 NEW YORK STATE MUSEUM The present relief of the surface is moderate. In the northern portion of the map the irregularities are seldom due to rock but represent almost entirely a drumlinized morainal blanket, the work of the latest ice sheet. In the southern part they are rock hills, with a few conspicuous exceptions like the Waterman Hill drum- lin. Benway hill, the highest point, in the extreme southeast corner, constitutes a ““monadnock” or erosional remnant rising above the Cretaceous peneplain and giving a minimum measure for the earlier pre-Potsdam peneplain in that direction. Fig. t Key map of northern New York showing location of the Canton quadrangle and the belts of Paleozoic HOES adjacent thereto (Geology after Logan and Merrill) While there are many eccentricities in the water courses, in gen- eral the drainage lines are controlled at the south by the rock topography, which is in turn largely influenced by rock structure and hardness; whereas at the north even the larger streams wander in fortuitous pathways among the drumlins and are let down upon bedrock at irregular intervals, thus giving rise to waterpowers determining the location of the early settlements.1 The gradually ‘The broader story of the geography and settlement of the county has been set forth by Edgar G. Blankman in his ‘‘ Geography of St Lawrence County.” PALEOZOIC ROCKS OF THE CANTON QUADRANGLE Zi curving courses of the Grass and Raquette rivers to their mouths, after leaving the crystalline rocks, agree so nearly with the curving orientation of the drumlins as to need no better explanation, though within the map limits the Raquette is for a space bandied back and forth among the drumlins. The lowest point on the map is not on either of these principal rivers but at the exit of Trout brook, intermediate between them. Even in the southern part the drain- age is not wholly adjusted to the rock belts, for its devious chan- nels there are determined in part by glacial and postglacial deposits, including the delta sand plains built by the streams themselves awhile ago into the lowering series of glacial lake and marine water levels whose history is summarized beyond. In the nature of its Paleozoic rock geology the Canton district is intermediate or transitional in type from an extensive belt on the east where the Paleozoics are said* to abut continuously against a rather abrupt Precambrian front from which they decline quite steadily northward presenting linear zones of outcrop, to a mark- edly different area at the southwest where* the Paleozoic rocks, at least the so-called Potsdam, are somewhat folded and now largely cut up by erosion into scattered outliers among the crystallines.* yt ADIRONDACK : UPLAND REY SDM FRE Qu ST LAWRENCE § VALLEY i) 4 "TERTIARY" PENEPLA/NY __-—--- ee Fig. 2 Diagrammatic north-south profile showing the relations of the three peneplains in the vicinity of Canton; drift omitted. The peneplains are numbered in order of age. (Vertical scale greatly exaggerated) The transition is accompanied by a sharp offset in the formation boundaries as they enter our quadrangle from the east (see the key map, figure 1), signifying the emergence at this point of a rugged sub-Potsdam surface that seems to be deeply buried in *16th Rep’t N. Y. State Geologist, p. 5~6, 15, and the map. Also N. Y. State Mus. Bul. 95, p. 433—34. “19th Rep’t N. Y. State Geologist, map opp. p. r85. Also 13th Rep’t ibid., p. 496 and map opp. p. 492. 316th Rep’t cit, p. 6. Also s5oth Rep’'t N. Y. State Mus., p. 10, and N. Y. State Mus. Bul. 145, p. 112-15; maps. Compare also the paper by Brooks in Amer. Jour. of Sci., 4:24 (1872). 8 NEW YORK STATE MUSEUM that direction. In short, whereas the Paleozoic frontier corresponds with the margin of the St Lawrence valley as far west as the Raquette river, there these two suddenly part company, the Pre- cambrian exposures extending down into and becoming a part of the valley floor but preserving many Paleozoic remnants in their hollows. At the same time, as noted by Cushing,* a folded group of weaker Grenville metasediments appears intercalated in the massive Saranac gneisses that have alone formed the Precambrian on the east; and it is probably these weaker crystalline zones yield- ing more readily to compression that have occasioned the undula- tions in the overlying strata.” Smooth zones of outcrop with incon- spicuous dips therefore give way to vigorous zigzags and visible tiltings while both outliers and inliers become frequent. With the more nearly complete substitution of Grenville rocks for gneiss as we pass southwestward into the town of Gouverneur the Paleozoic embed is again offset toward the St Lawrence and the archipelago of outliers reaches its fullest development. It will be seen that the transition span accordingly includes also the Ogdensburg quad- rangle next west, recently mapped by Professor Cushing.* THE GEOLOGICAL FORMATIONS General Statements Five divisions are recognized in the Paleozoic rocks of the Can- ton quadrangle as colored on the map.* These are, in ascending order:> the Potsdam sandstones, the Theresa mixed beds, the Heuvelton white sandstone, the Bucks Bridge mixed beds, the Ogdensburg dolomite. In age, these rocks range from Cambrian (Ozarkian of Doctor *On p. 6 of the 16th report, before cited. * Geol. Soc. of Amer. Bul. 26, p. 290-94. *N. Y. State Mus. Bul. 191. “Two other possible formations are suggested in the text, one the upper or white Potsdam, which may require separate recognition, the other the mass of Trenton shaly limestone at locality 4, recorded on page 39. °Geol. Soc. of Amer. Bul. 26, p. 289. For convenience of the reader the position of these divisions in the standard time-scale is indicated by the italics below: Precambrian time (Rocks described in Bulletin 185) Paleozoic time Cambrian period: Georgian epoch Acadian epoch PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 9 Ulrich*) to early Ordovician (Canadian?). The Potsdam and Theresa formations are currently referred to the former and the Ogdensburg or upper Beekmantown limestone is a typical repre- sentative of the latter, but there is still some doubt as to the exact position of the intervening two, as explained beyond. Briefly it may be said that the Heuvelton seems linked stratigraphically with the Theresa below, though its few fossils suggest a later age; while the Bucks Bridge beds are approximately what has been called “Tribes Hill” in Jefferson county and are therefore probably Canadian, though they may prove not to be a unit. These Paleozoic formations occupy in general the northern two- fifths of the Canton quadrangle (localities 1 to 68 of our map) but under a nearly unbroken drift cover so that exposures there are very few. In the southern half of the quadrangle where outcrops are more frequent are also several outliers of the Potsdam sand- stones (localities 69 to 89) resting upon the crystallines, but these sandstones are either absent or thoroughly concealed in the northern belt, so that the sequence between them and the Theresa beds is here interrupted and must be inferred from neighboring areas, where they are found to pass gradually up into the latter without break or unconformity.’ Over the northern area the general attitude of the beds is nearly horizontal, with dips averaging I or 2 degrees and seldom exceed- ing 4 or 5, though a dip of 12 degrees has been measured; but these -dips are in all directions and continually changing. They thus indicate a series of gentle undulations of irregular character, low, pitching folds and domes, which it becomes practically impossible - Saratogan epoch (Potsdam, Theresa and Little Falls) Ordovician period: Canadian epoch (Tribes Hill, Beekman- town and Chazy) Mohawkian epoch (Black River and Trenton) Cincinnatian epoch Silurian period Devonian period Carboniferous period Mesozoic time (Triassic, Jurassic and Cretaceous). Cenozoic time (Tertiary, Glacial, Postglacial and Recent). But Doctor Ulrich proposes to insert an Ozarkian period between the Cambrian and Ordovician, and to refer to it our Saratogan rocks. He also considers the Canadian, exclusive of the Chazy, as a distinct period. See next footnote. *Geol. Soc. of Amer. Bul. 22, p. 627, 647. 7,N. Y. State Mus. Bul. 145, p. 66. IO NEW YORK STATE MUSEUM to trace in detail across the concealed spaces. Away from the actual outcrops the map boundaries have to be generalized, with a result far from satisfactory. But the dominant strike is every- where northeast and southwest, showing that the axes of the stronger system of folds correspond roughly with the belts of the underlying crystalline rocks and are approximately parallel to the general direction of the St Lawrence valley. It is these stronger folds that are apparent in the zigzags of the geologic map and in the colored cross section diagrams, in which is also evident the gradual decline of the whole series to the northward, where although the land is lower the higher beds appear. But another set of weaker waves is gridironed across these, shown by the fact that at several points (for example, localities 52 and 59) upward domings of the strata (particularly where unroofed by stream trenching) reveal inliers* of the layers or formations below, while at others (as localities 30 and 23) occur erosional remnants or outliers of the higher formations filling sags in those beneath. Could the obscuring drift mantle be lifted the number of such isolated patches, inliers or outliers, would undoubtedly be found much greater than now known, and the actual boundaries of the forma- tions far more complex than portrayed on the basis of the visible evidence. This is likely the real reason why in the map the strata appear so much more involved along the eastern margin of the sheet where the Raquette river unmantles them than along the riverless western border. It is to be noted in passing that these rocks represent but the basal portion, spared by erosion, of a great series of sedimentary strata perhaps thousands of feet thick that have been eroded away from over this region. Only beneath such a superincumbent “load” could the layers have been so folded or the lower sand- stones so thoroughly consolidated. These beds rested upon the more ancient Precambrian crystallines, as they do today over the areas from which they have not since been stripped by erosion. The smaller residual patches (70 to 89) in the southern half of the quadrangle, beyond the edge of the main mass, prove the former extension of the Paleozoic cover in this direction. These consist entirely of the Potsdam sandstones, now to be described, and they are considerably more disturbed than the strata to the north, dips of 30 degrees being not uncommon. ‘A suggestive paper on inliers, by Doctor Ruedemann, is contained in N. Yo State Muss Bulsng3) ps 104: PALEOZOIC ROCKS OF THE CANTON QUADRANGLE II Potsdam Sandstones This name is here used in the plural because of the growing probability that the formation as at present understood is not a unit, and also because of its varied lithologic expression. The exposures of these rocks within the quadrangle are limited entirely to outliers, unless those in the Grass river near the county house (locality 69) are connected with the main mass of Paleozoic rocks on the north. The remaining outcrops are isolated from the general embed, forming scattered patches whose relations and character are of peculiar interest. One of the most extensive of these Potsdam outliers lies about two miles south-southeast from Canton village (localities 76 to 80) but is badly drift covered, with the outcrops in five or six separated groups that bear little resemblance to one another. At locality 77 all the exposures show the white saccharoidal sand- stone of the upper ‘“ Potsdam” dipping uniformly southward about 5 degrees, without any sign of faulting. The actual contact with the vertical reddish quartzose Grenville rocks beneath is seen at the north end. One-half of a mile south, at locality 76, are glaciated ledges of a much more indurated red quartz sandstone full of micro- faulting, forming an “autoclastic”’ rock. The lowest ledge is very red typical Potsdam; higher up are hematitic iron spherules in a whitish layer; banding is common and some of the most brecciated portions are gray rather than red. In the field to the east a small surface just above the soil is flesh pink, its glacial polish like glass indicating intense induration. In attitude, these beds of locality 76 appear to surmount the white layers of the previous locality, but in every other way they look to be much older and it seems safe to assume that the dip changes in the interval, if indeed the two formations are not totally unconformable. One and one-fourth miles due east, at locality 80, it is possible to work out a fairly strong anticline and syncline in rather similar indurated and microfaulted beds of various red, buff and leaden colors, as is shown in the cross-section diagram of this locality in pocket. This diagram, drawn to scale without exaggeration, shows the true dips, at some points exceeding 30 degrees. A core of red jaspery quartzite protrudes through layer C at the east end north of the line of section. Not far southwest of the west end, across the brooklet, is a small exposure of white to pnk sandstone more 12 NEW YORK STATE MUSEUM nearly horizontal and perhaps belonging to the upper series. The total section here was measured as follows: M 1 foot Light red sandstone L 2 feet White or gray sandstone K Concealed (unknown amount) J 10 feet Conglomerate, red-brown matrix, with pebbles of white quartz and red sandstone I 5 “. Brownish orange sandstone with black and white specks Lot shown in diagram ce ly 3 Uniformly dark leaden purple sandstone Goo .. f Brilliant orange-red sandstone 1d] Concealed, combined with preceding in total estimate E 5 “ Reddish, buff etc., rather banded sandstone, containing ID LO ©? occasional white quartz pebbles Ci@ ~ “Sioa B 15 Concealed, estimated A 10 “ Similar to C, rather light colored. Base concealed Total 78 feet, not including K, L and M Special attention should be called to the conglomerate J, which although represented as conformable in the diagram, has not been proved to be so, and by carrying some pebbles of red sandstone similar to the undoubted Potsdam beneath adds one more point to the accumulating evidence that there is a break between this and the widely distributed upper so-called “ white Potsdam ” beds. A sandstone closely resembling G of the above section has been quarried at the most northerly of the group of outcrops included in locality 79, north of the preceding. The other outcrops of this group on the south side of the road do not in fact show any sand- stone at all, in place, though fragments abound in the plowed fields, but we have here the remains of some of the ferruginous basal contact masses that are presently to be described, half veiling an islandlike knoll of Grenville marble and quartzite and carrying a workable body of red iron ore, by the roadside. Northwest of this group is an old quarry in red or purplish- banded sandstone of ordinary Potsdam type on Judge Hale’s farm, locality 78. This rock also is faulted, and the color bands show a secondary intersecting set running steeply across the bedding ones, as in the Unkpapa sandstone of the Black hills. Some at least of the multitudinous little faultslips at this quarry appear to have PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 1035 ‘occurred while the sand was as yet unconsolidated, so that all the layers have been stretched or dragged, along a zone of appreciable width. In the glacial kame sands of Cobb’s hill, Rochester, similar faulting is demonstrably due to ice thrust; but it does not follow that the same agency operated in these Paleozoic sands. A mile south, at Mr Martin’s place, locality 81, there crops up a vitreous exceedingly tough cream-white sandstone or quartzite, without visible bedding. Its relations to all other exposures are unknown, but it is not to be confused with the more mctamorplosed Grenville quartzites. The above outcrops have been eccrine in detail because they afford many of the chief types of rocks included under the name “Potsdam sandstones” and illustrate the rapidity of variation in ° short distances or in successive layers. Together they constitute an instructive and easily accessible group, presumably a single out- lier, closely surrounded on all sides by the outcrops of the crystal- lines and underlaid mostly by the weaker Grenville limestones. Beginning with the area just described and extending thence southwestward in a direct line up the strike valley of the Grass river and Harrison creek, following the marble belt, is a chain of at least five other Potsdam remnants, four of them (72-75) within the limits of the quadrangle and the fifth (71) just outside. Doctor Martin reports another a mile farther up the valley. The suggestion that these remnants sketch the course of a pre-Potsdam valley is strengthened as one sees the old gneissic rocks rising, sometimes a hundred feet higher, on either hand and the sand- stone abutting against their slopes with interesting contact phenomena. Each member of this chain is individual. At the nearest (locality 75), on the south bank of the Grass river a mile southwest of the large area already described, there is a heavy ledge of white Pots- dam with small dip to south running almost “end on” into a steeply dipping mass of deep red basal Potsdam striking approximately at right angles to the white, with merely a shallow gully intervening. There are suggestions of a coarse conglomerate (see plate 3) at the base of the white beds, quite different from the talus breccia (plates 5 and 6) at the bottom of the red immediately adjoining. But the question of an unconformity here between white and red is still debatable. Just south of the white ledge lies a large rec- tangular block that shows a few sinuous worm trails, the only fossil seen in the “ Potsdam” rocks of our area. 14 NEW YORK STATE MUSEUM A mile and one-half above on the same side of the river, due: north of Pyrites, is a varied display of the basal contact stuff shading off into red sandstone (locality 74). Some of the rock is deep blood red with large pebbles of pure white quartzite. A mile farther, at the road corners on the north side of Harrison creek (locality 73) a small bit of the same contact material is reported by Doctor Martin. Another mile above, on the south bank and protruding barrierlike across the valley (locality 72), is a plicated mass of considerable thickness, chiefly of very light or red sandstone somewhat microfaulted, without conglomerates, but in part weak and thin-bedded. Although this area is isolated from the surrounding crystallines by a valley on all sides (contouring erroneous), a quartzite core appears in it as usual, consisting as so frequently of the red jaspery variety, though ordinary white vitreous quartzite is also present. Presumably these quartzite cores have retarded glacial removal of the Potsdam patches. In the western outcrops of this area the beds are pink or cream color like those of the upper division. The highest dips measured, some as high as 30 degrees, were in the redder layers and toward the southeast, alternating repeatedly with lesser dips in the opposite direction which indicate a succession of anticlines and synclines. This plication seems to have resulted from compression of the underlying marble belt.1 The two remaining areas (71 and one not shown) outcrop off the map, as learned from Doctor Martin. The prolongation of this chain northeastward is covered by drift, except the tiny occurrence of iron-charged contact stuff in the state road gutter at the cemetery crossing east of Canton (locality 70). The remaining exposures lie well to the east and southeast, that near the county house excepted. Old quarries in red to whitish layers are located on the Bullis farm at the foot of Waterman hill (83) and on the Spaulding farm (82) a mile and one-third north. A mile northeast of the latter the bed of Grannis brook is on Pots- dam above the mouth of Boyden brook as far as the road to Crary Mills? (locality 89). The strata are much disturbed, with dips in various directions, making discontinuous exposures in the bed of the brook visible at low water. The chief interest in the locality * Geol. Soc. of Amer. Bul. 26, p. 292-93. *I am indebted to Mrs C. S. Phelps for the notes on this locaJity, which had been overlooked. A. Basal Potsdam conglomerate resembling a tillyte, at Mr Dillabaugh’s (locality 85), south of Pierrepont The main ledge lies just behind, in the trees. (Looking north by east) See pages 15 and 43. B. Potsdam boulder in rear of Mr Dillabaugh’s One of a large cluster derived from the ledge of the preceding view, which lies to the left (across the road) in the trees, at the foot of the Precambrian cliff. The knoll on which the house stands is Grenville limestone. (Looking south- east ) ' See pages I5 and 50. "GI a8ed 99S : yosnyod sure[q yoeag fo jsvayjnos osprliq ot} adoge ‘(9g Ayr[ed0]) Yaet0 Javjessuey ueA Fo Yuq yyNos uo d}eIBWO[SUOD Weps}od [eseq Jo Japjnog ut “Of Aq ojceud $ ; Z 31d PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 15 lies in the occurrence here of the “tree trunk” concretions described by Hough,’ Ells,” Cushing? and others from other regions. A mile east of the last, well drillers on the Henry Douglas farm just northeast of Crary’s Mills (88) struck sandstone of rather light color about 45 feet below the surface, and penetrated it for some distance. Though the extent of this area is unknown, the find emphasizes the fact that Potsdam strata are likely to be encountered anywhere in the drift-mantied places and that their actual distribution may be much more general than has been sup- posed. More surprising proof of this was afforded by the well at Frank J. Crary’s (locality 84’) one and one-half miles west of Pierrepont, where the drill passing through 28 feet of till found about 150 feet of typical red Potsdam sandstone, at the bottom of which it dropped into a water pocket believed to mark the basal contact. In the brook channel three-fourths of a mile west, below the falls (600 foot contour), there are hematite-charged schists indicating that the Potsdam has been but recently removed, while one and one-fourth miles northward (84) in the brook bed north of the brick schoolhouse is a close pavement of red, purple and saffron sandstone blocks that have been quarried for foundation stones. All these circumstances point to a large area of sandstone underlying this big morainal hill. The most interesting Potsdam locality of all is the out-of-the- way one at Mr Dillabaugh’s (85) in the southeast corner of the quadrangle (plate 1). Here stowed away under Benway hill at an elevation of over 800 feet is a little ledge and glaciated knoll (figure A) on the east side of the road and a quantity of loose masses (figure B) on the other side, of the ferruginous basal Pots- dam breccia, whose cavities contain elegant crystallizations of hematite and quartz. The rock is highly indurated, hardly clastic in appearance, and but little of the ordinary sandstone is seen. Beneath are Grenville limestones, while behind are nearly vertical ‘cliffs of gneiss embracing and sheltering the ledge within the sig- moidal curve described by Doctor Martin.* Two miles southwest (86) in the same valley of Van Rensselaer creek large loose blocks of somewhat similar stuff (plate 2) are piled thickly for many 13d Ann. Rep’t, N. Y. State Mus. (1850), p. 32-33, figure; and Proc. Am. Assn. for Adv. of Sci. 4 (1851), p. 352-54. airove soc. ot Can. Irans., Ser. 2), 9 (no. 4),ep. 103: (Geol. Sur. of Can. Ann. Rep’t for 1901, 14:176A (1905). *N. Y. State Mus. Bul. 145, p. 61, pl. 13. 4N. Y. State Mus. Bul. 185, p. 96. 16 NEW YORK STATE MUSEUM rods along the stream with a wall of quartzose Grenville rising behind; but actual outcrops are lacking. There remains the area (locality 69) exposed only at low water in the bed of the Grass river north of Canton, as diametrically opposite to that at Mr Dillabaugh’s (85) in lithologic character as in location, altitude and stratigraphic position. As those beds are the highest in present altitude but probably the lowest strati- graphically, these are the lowest in altitude but probably the highest beds of the series. They are white saccharoidal sandstone, contain- ing a few white quartz pebbles up to 5 inches diameter, like the first described outcrops of locality 77. The area is cut off down stream by a heavy mass of red granite-gneiss and it is hard to believe that the sandstone can extend itself over this beneath the drift to connect with the main belt of sandstone on the north, though this may happen. The surprising thing about these outliers is the variability of color, structure and texture in passing from one to another. It is almost incredible that they can all represent a single formation. The range of colors includes pure white, ashen, creamy, buff mot- tled, faint pink striped, light to dark garnet red and deep wine color either uniform or variously striped, bright orange-brown, dark grizzled purple, light tan with violet stripes, rosy gray, hematite red, and many intervening shades and combinations. The textures range all the way from fine, uniform arenytes through pebble con- glomerates to reconsolidated talus breccias, the medium to coarse sandstone types (arenytes) being the most common. In degree of induration the beds vary from rather crumbling saccharoidal rocks, usually light colored or white, through excellent building stones of clean fracture and great durability, usually bright colored and chiefly red, to light flesh-colored white or creamy quartzites of exceeding toughness and vitreous surface, and to a calico con- glomerate with red jasperized matrix very difficult to distinguish from the Grenville jasperite though the amorphous jasper can apparently be traced directly into the ordinary red, sandy matrix by perfect gradations. The conglomerates, as might be expected, seldom show much stratification and the quartzitelike portions appear almost wholly structureless, but the commoner sandstones vary from coarsely to closely stratified or even thin-laminated and generally display more or less cross-bedding or flow-and-plunge structure (see figure A of plate 4). a Boulder of “middle Potsdam” conglomerate in field south of “The Bunch” cottage (locality 75) on the east bank of the Grass river south of Canton (Looking northeast) The pebbles consist chiefly of red jasper which has been bleached to milk white by pre-‘‘ Potsdam” weathering, except at the hearts of the larger pieces. The sand-matrix also is decolorized. Contrast the basal beds. See pages 13 and 44. A. Cross-bedding and a pebble band in upper (white) “ Potsdam” sandstones south of “The Bunch” cottage (locality 75), on east bank of Grass river south of Canton. (Piece tipped out of the ledge for photographing) (Looking southeast) See pages 16 and 44. B. General view of exposures at “The Bunch” shown in detail in the two following plates. Professor Fairchild sits on the ledge of plate 5. The ledge of plate 6 is behind Mrs Phelps’s camera. Deep-red Potsdam sand- stone caps the knoll to left; main ledge of white sandstone is in trees behind. (Looking east-northeast ) See pages 13 and 18. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 77, The Basal Contact The interesting nature of the Potsdam-Precambrian contact has already been suggested. Marking as it does the greatest hiatus and unconformity in the entire known geological record, it would in any case attract attention but the variety of forms which it assumes in the outliers south of Canton is remarkable. Following the post- Laurentian uplift, which completed the metamorphism of at least such. parts as now remain of the Grenville and associated rocks, our region was approximately base-leveled. But either the process of peneplaination lacked completion or was followed by some reju- venation, for the irregularity of the sub-Potsdam surface, already described by Professor Cushing for the Theresa region’ and else where in northern New York, is equally well shown hereabouts. As today, so then, the Precambrian crystallines standing at high angles outcropped in long belts or strike ridges, the stronger gneisses and quartzite upstanding, the softer marbles and schists mostly excavated by shallow stream-valleys or wind-erosion hollows. The suggestion is strong that at least the closing phases of this land cycle were arid, and probably cold. Rock destruction by atmospheric and solar agencies probably went on unhindered, the resulting residual soil becoming charged with the insoluble red oxide of iron derived from the various iron-bearing minerals of these older rocks, whose other stable products were chiefly quartz sand and clay. The removal of the latter product was quite likely effected by wind work comparable to that now going on over the Great Plains, and its final resting place may be in part the Georgian (Lower Cambrian) red shales in Vermont. The sand remained, in part at least, and furnished material for the overlying forma- tions. There are points (as at locality 75; summit of the quartzite knoll southeast of the main mass) where the sandstone may be found fitting into undercut spaces beneath the old crystalline ledges, hinting at wind erosion of the desert type. Similar cases are described by Cushing. There are other places (as at locality 74) where the basal Cambrian is a reconsolidated talus breccia banked against the foot of a steep quartzite ledge and showing a com- pletely residual, nonassorted character. There are even places (localities 74, 75, 70, 79) where through some 10 to 20 feet of beds a complete gradation exists between ordinary fresh Grenville rocks 1N. Y. State Mus. Bul. 145, p. 54. See also footnote 3, page 20. 18 NEW YORK STATE MUSEUM beneath and the normal stratified red Potsdam sandstone above through a Grenville regolith constituting a basal Potsdam breccia. This is comparable to the gradations existing today in our southern states from live rock below through various intensities of rock disintegration into residual soils and finally to reworked surface materials above. In the process of Potsdam consolidation these disintegration products were reconverted into solid rock, furnish- ing many puzzling phenomena. At many points merely a faint veneer of this material remains coating the Precambrian surfaces, or in glaciated ledges of the quartzite it is sometimes removed from all but the tiny corrosion hollows and pittings of the ancient surface, or is found filling ancient joint cracks so as to simulate a vein. These phenomena are displayed in wonderful variety at the two outliers along the Grass river north of Pyrites (localities 74 and 75). In particular at the more northerly of these, in the knoll behind ‘The Bunch” cottage, a peculiar thin-laminated silicious Grenville rock, weathering with strong reddish color banding, has been uncovered by late erosion (chiefly glacial?) in such a way as to show its face in part plastered over with a mosaic of its own small fragments, which fill also its former joint fissures, and pass upward into a sand-matrix breccia and finally into ordinary red Potsdam. The illustrations (plates 5 and 6) give but an inade- quate idea of this occurrence. Twenty rods west of this, and again on the summit of the (second) knoll 80 rods south, are fine examples of basal breccias filling weather-widened joints in the crystallines. Apart from the revelations of the past afforded by these contact deposits, they have a more general interest from the red iron ores they contain.2 These usually occupy slight pre-Potsdam hollows *To this sort of deceptive gradation undoubtedly we may ascribe Brooks’s belief that the Grenville and Potsdam were conformable mem- bers of one continuous Cambrian (Taconic) series; Amer. Jour. of Sci., 4 (1872) : 22-26. ? The divergent views of various writers as to the origin of these ores may be gleaned from Emmons 1842 (Second District, p. 97), Vanuxem 1842 (Third District, p. 267), T. S. Hunt 1871 (N. Y. State Mus. Rep’t 21, p. 88-89), Brooks 1872 (just cited), Smock 1889 (Bulletin 7, p. 10, 43-48), the note by Dr U. S. Grant in Winchell 1893 (21st Minnesota, p. 106-8), Smyth 1894 (13th Rep’t N. Y. State Geologist, p. 495-09) and D. H. New- land 1907 (N. Y. State Mus. Bul. 112, p. 38-39). While these writings pertain to the Antwerp-Rossie district, which the writer has not visited, the observations given here, as they were written before any of this litera- ture had been examined, serve as independent corroboration of Smyth’s ‘@ ‘b ojeyd pur gt a8ed aac (sea Aq }seayjiou Suryoo7) *(unasnyy 2181S ‘SouUO]Spues Weps}Og pai IMO ST JO JI9UGA B SUIAIIVS JSTYS I]][IAUDIF) YSIppo1 papueg ATOKR MON PY} Ul Mou aderd) J9MIMIeY Joddn oy} 1apun peArtesaid jsaq a1e asoyy, 94} FO JIVJUOD [seq 9Y} SuTjUssoIde1 SyuaUIseIy oO ~ * Tein ‘q ‘Vv ajejd pue ‘gr osed 99¢ (Qsvoyjiou surjooy) ‘pat ysryurd surroyyeom ‘QIIO[YD si }SIyOS oy], “Jowwey oy} MOjoq [JOM JfNIs Tos1eOD dy} OS]Te 9]ON “oUO}spues Weps}og poi oy} JO uonsod Teseq oy} OUT ssed ‘Vyfoy IY} UO “YOTYA FO S}USUSeIY IY} “ISTYDS I[[IAUdIN) FO SulioyeoM weps}Og-I1q 9 23P8Id PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 19 at the meeting of Grenville quartzite and marble, and consist mostly of a reconsolidated ferruginous earth, with some silicious frag- ments, or else of a silicious regolithic breccia whose cracks and interstices often gleam with “combs” of crystalline quartz and hematite. Some of the most beautiful of these mineralizations come from the tiny outlier at Mr Dillabaugh’s (locality 85) in the southeast corner of the quadrangle. Where there has been some reworking of the talus adjacent to a cliff, we have brilliant ‘“ calico conglomerates,’ with a deep-red or blood-red sand-matrix inclosing all-sized rounded to angular fragments of white, yellowish and reddish quartzite, or dull-red jasper. In some cases the sand-matrix becomes jasperized and the rock closely approaches certain portions of the Grenville in appearance, possibly because the jasperization of both rocks was accomplished simultaneously. This may have been by hot alkaline waters working up from beneath through the limestone, but whether these were the same mineralizing solutions that put the zinc in the latter at Edwards and converted its tremolite into talc, or whether they were of later date, can not now be said. In any case they have not lightened the task of mapping the frayed and tattered contact line in which no real division plane exists. A visit to localities 74 and 75 will show how hopeless is the attempt to por- tray the facts on a map, even where the rocks are completely bare. But there are other localities, for example 77, where the contact of the two rocks is abrupt, suggesting an ancient sea-cliff slowly drowned and silted over by advancing waves. It is noteworthy that such occurrences are chiefly in the upper white beds of the Potsdam series, a division that bears more evidence of construc- tion in and under water than do the lower, possibly anemoclastic and continental, red beds. Yet even here the Potsdam is always so thoroughly bonded to the rock beneath that only closest scrutiny reveals the division line; and nowhere has the writer seen the two rocks tending to separate smoothly from each other on weather- ing, as do all the higher formations. The one has arisen largely from the dissolution of the other in situ. interpretations so far as they are applicable to our deposits. It may be safely asserted (a) that the ore was residual from the crystallines, likely including the oxidation of pyrite as Smyth surmised, (b) that it was washed down into the marble valleys and there precipitated, probably by reaction with the limestone, and (c) that to the associated quartzite bands we owe in our region the preservation of the existing patches from erosion long subsequent. 20 NEW YORK STATE MUSEUM Over the entire area explored, no contacts approaching the hori- zontal have actually been seen between the Potsdam and the Pre- cambrian. Everywhere the former is found resting upon steeply sloping hillsides of the latter and thus is rapidly cut out, often along the strike. Such relations, if the contact were not visible, would readily suggest a faulted condition, but no actual faults, other than the microfaulting, have been seen anywhere in the quadrangle.1 The Potsdam outlier at locality 83 dips inward under the north face of Waterman Hill, whereas Mr Bullis’s well on the top of the hill (locality 87) entered gneiss (overlaid by till) at 96 feet depth, which is over 140 feet higher, while gneiss also outcrops in the summit due south of the outlier, 250 feet above it. A fault was suspected here, and again in the exposures northwest of West Potsdam (localities 44 to 50) there are some puzzles possibly due to a minor slip; but in view of all the other evidence, especially Doctor Martin’s Precambrian investigations, any consid- erable faulting in our region appears to be out of the question.’ We may safely look upon Waterman hill, then, as indicating a pre- Potsdam or sub-Potsdam relief of at least 250 feet magnitude. The presence of a deep pre-Potsdam valley to the north of this hill, thus denoted, ties in with other facts to be presented. The Concealed Zone In contrast with the outliers, when we turn to the northern embed for the main mass of the Potsdam strata we find, clear across the quadrangle, a mile and one-half wide zone without outcrops between the outposts of the Precambrian rocks and the nearest Paleozoic ledges. The first outcrops are invariably well up in the Theresa formation or higher. It is within this concealed zone that the main belt of Potsdam must lie, if it exists across our map area. Eastward from the Oswe- gatchie Professor Cushing maps a narrowing wedge of Potsdam *Cushing’s belief in major faulting at Hannawa, just east of our map, (16th Rep’t N. Y. State Geol. (1808), p. 14, 24), seems to be purely infer- ential, with another explanation equally plausible. 7Dr R. W. Ells, who studied and mapped the faults in the Paleozoics about Ottawa, specifically remarks their absence in these same rocks along the Canadian side of the St Lawrence, a district also mapped by him. Trans. Roy. Soc. Can., 6, (no. 4), p. 118, (1900). *Since the above was written a masterly treatment of the whole prob- lem of pre-Potsdam topography has appeared in Mus. Bul. 18, Canada Dep’t of Mines, by Kindle and Burling (1915). PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 21 (the upper white portion alone present), with its last exposure ‘at ““ The Ledges” in the Indian Creek swamp, about a mile west of our borders. Here these sandstones vanish under glacial drift together with a large part of the thickness of the Theresa, of which, with one possible exception, not more than the top 20 feet have been positively seen on the quadrangle. At locality 42, southwest of West Potsdam, in the bottom of a small brook valley, among a great mass of stream-washed boulders, is a disrupted ledge about a rod long of white sandstone, varied buffy and reddish, that is | quite massive and with brilliantly glittering surfaces due to recrystallization of quartz, like the higher Potsdam; but its south- erly dip and proximity to extensive Heuvelton and even Bucks Bridge outcrops favor a reference to one of the lower hard sand- stones in the Theresa west of our district. It would seem that if present, so resistant a formation as the Potsdam ought to outcrop, as it does both east and west. At Rensselaer Falls it is extensively displayed in the bed of the Oswe- gatchie, making rapids, whereas both the Grass and the Raquette cross from the Precambrian to the Theresa without a ripple. On the Raquette moreover there is scant room for any Potsdam between the gneiss at Potsdam village and the topmost Theresa beds above Sissonville (locality 33). Cushing? noted this fact but invoked faulting and considered the gneiss at Potsdam an isolated _ knob or “inlier ” with the main belt of Potsdam sandstone passing behind (south of) it. This is conjectural, for the nearest outcrops to the southwest, though remote, are of Grenville tied up with numerous Precambrian masses beyond, while the accumulating © evidence is contrary fo major faulting in our area. Just at the point where the Potsdam belt enters the east edge of the Canton sheet, the Precambrian outcrops begin to protrude far -to the north (see the key map, figure 1), narrowing the space between them and the Beekmantown across the Canton quadrangle, while the space between the Heuvelton and the Beekmantown is not similarly compressed. That this great Precambrian promon- tory cuts out the Potsdam for a few miles is therefore not incred- ible. There is no question that the lower part of the sandstone series, including at least the entire thickness of the typical red beds, is thus interrupted, since the white layers of the upper division ‘ *16th Rep’t N. Y. State Geol., p. 24. Cushing’s observations along the Raquette were of the pioneer type, just at the close of the field season. See page 55. 22 NEW YORK STATE MUSEUM --T- —_—<——-— 4 PlrerrepoA¢ aa Pont we Fig. 3 Outline map of the Canton quadrangle to illustrate possible distribu- tion of the Potsdam sandstones = Ogdensburg Heuvelton [ee3ese.] “ White Potsdam ” aolomite; sandstone; Ltege’e® sandstone; geeeae] Red Potsdam ene Possible limit Limit of known 29 0G sandstone; of Theresa; Precambrian outcrops; _— Limit of abundant Precambrian exposures Between these two limits there may be extensive concealed areas of the Potsdam sandstones PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 23 rest directly upon the crystallines in the more northerly outliers, whereas southward the outliers become mostly red beds, at feast 75 feet in thickness at locality 80 and 150 feet at Frank Crary’s a Potsdam Bie 4 TES It Precambrian No JZ Fig. 4 Cross sections showing variant possibilities as to the presence or absence of the Potsdam beds within the concealed zone south of Morley. No. I is a portion of figure B—B of the colored sections, with the Pots- dam “lapped out” by the Theresa beds. No. 2 shows the alternative mapped in figure 3. No. 3 represents an intermediate interpretation. (Scale is one and one-fourth times that of the colored map.) (locality 84’), with the summit and white beds removed by erosion. Evidently the sub-Potsdam floor was higher:at the north than at the south when they were laid down, and it is believable that its summits were not wholly buried under the accumulating sediments before Theresa time; in which case the presence or absence today 24 NEW YORK STATE MUSEUM of a mappable belt of Potsdam on the north side of this crystalline ridge depends on whether the overlapping Theresa has been suf- ficiently stripped away to reexpose it. It must be observed that the concealing drift is not in the nature of a morainal ridge, but that the outcropless zone is mostly low and extensively swampy, giving the impression of a refilled valley. That a belt of Potsdam of considerable thickness and of resistant character might lie buried in such a valley is shown by its occur- rence along the shores of Black lake on the Brier Hill quadrangle, with the Precambrian and Theresa rising above on either side. (Compare the alternative cross sections in figure 4.) There is even a possibility that the Potsdam underlies the drift throughout nearly all the area mapped as undifferentiated Precambrian, with the crystalline outcrops merely fenestrated through it. (Com- pare figure 3.) The deep wells at Mr Cranys and) MasSsizers (localities 84’ and 88) both found sandstone, and there are abund- ant drift blocks of it all over the district. New outcrops may reward further search both here and in the blank zone, and well records will be of incalculable aid. Theresa Mixed Beds The series of alternating beds of blue dolomitic limestones and rather weak grayish white or creamy sandstones that succeed the Potsdam is the Theresa formation of Professor Cushing.t On the Canton quadrangle these beds are seldom well exposed, and are nowhere seen in contact with the Potsdam sandstone. Their thickness here is therefore unknown though probably somewhere between 50 and 100 feet. The well at Mr Cunningham’s on the Ogdensburg state road one mile west of our limits (Woodbridge’s Corners) starting below the summit of. the Theresa, which crops out in the adjacent road-gutter, was still in these mixed beds at 50 feet depth. About 20 feet of the top beds, in contact with the overlying Heu- velton sandstone, show on the west bank of the Raquette above the Sissonville dam (localities 31 to 33). This is a short distance below Potsdam village, with no exposure of Potsdam sandstone known between these Theresa outcrops and those of the Pre- cambrian gneisses in the falls at that village (see figure 3). It is then 3 miles farther up the Raquette, without intervening out- 1 Geol. Soc. of Amer. Bul. 10, p. 160. N. Y. State Mus. Bul. 121, p. 12. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 25 crops, to the quarries of the type red Potsdam sandstone below Hannawa Falls (on the Potsdam quadrangle). Between the Raquette and the Grass are found only occasional small sometimes doubtful exposures of the Theresa beds, usually immediately beneath the Heuvelton ledges (localities 45, 48, 49, 42°). Of these, the most interesting is that at locality 42, West Potsdam, already described. On the Grass river just above Morley a rather strong anticline brings up these beds, chiefly in the river itself and on the west bank above the cemetery (locality 61; com- pare figure A of plate 7). Immediately below the Morley bridge (locality 59) they are again unroofed for a few rods on the west side of the stream. Finally the latter phenomenon is repeated one-fourth of a mile below the ruined dam at Bucks Bridge, where typical Theresa strata are seen on the east bank in a little slough (locality 52). Much better exposures occur on the Oswegatchie river above Heuvelton, several miles west of our map. The rocks of the Theresa formation are generally blue-gray when fresh. This color is usually retained, on weathering, by the strictly calcareous layers, while the sandy portions turn either ashen or more commonly brownish. On long rotting, the color deepens to a chocolate and the beds become very weak; but the calcareous layers may slowly dissolve away without rotting. Calcite is the cementing material throughout, so that fresh specimens foam freely in dilute acid. The gleaming surfaces described by Cushing, due to cleavage of this crystalline calcite cement, are frequently seen on fresh fracture, and are usually slightly warped or curving; but these occur also in higher strata. The stratification in the Theresa is crude and irregular; usually not in very heavy beds. Small lentils or pockets of the soluble blue limestone show at intervals throughout the sandy layers, which are inclined to be crudely cross-bedded, while stringers and knots of sand break the calcareous portions. ‘Pittings of the size of a finger tip frequently develop on the weathered surfaces of the coarsely sandy streaks. In general these rocks tend to become very craggy on exposure, furnishing an admirable foothold for mosses and small herbs. No organic remains have been found. The pittings above men- tioned are the surface expression of tubular chocolate-colored stains extending irregularly through the rock in fucoidal fashion; but whether these are really of organic origin (burrows or alga stems) remains to be determined. In Jefferson county a brachiopod *N. Y. State Mus. Bul. 145, p. 65. 26 NEW YORK STATE MUSEUM shell, Lingulepis acuminata,’ is said to be common in this formation. This fixes the age of the beds as Upper Cambrian (Saratogan, Ozarkian of Ulrich). While actual outcrops of the Theresa are few across this quad- rangle, boulders from the formation are abundant along the same belt and to the southward. Sometimes, as at Slab City (locality 41, old dam site below the bridge), and in the brook bed three- fourths of a mile northeast (locality 40), these boulders from the blue calcareous layers are so massed that an outcrop closely adjoin- ing seems inevitable, whereas none is found. The boulders clearly recognized as Theresa are usually chunky, while those from the rather similar Bucks Bridge formation are frequently slabby and sometimes of large area. Heuvelton White Sandstone Without any marked stratigraphic break, the lower Theresa beds give place above to the “twenty-foot sandstone” of Professor Cushing which according to him? is shown by its relations farther west to be merely a lentil in the Theresa, though on our meridian it constitutes the apparent summit of that formation. From the resistant character of this rock, and of the beds just overlying, it has furnished the most important index to the rock structures in the northern area. It forms extensive ledges in the Grass river at Morley (locality 59) as shown in plate 7, and again on the west bank below Bucks Bridge (locality 53), being responsible for the water power at both places. It is conspicuous at several points north of Casey Corners (localities 51, 50, 48), and three times comes to the surface on Trout and Stony brooks (localities 46, 38, 35), besides affording the water power on the Raquette at Sisson- ville (locality 31). And it is this same rock that, rising again in a low anticline at Norwood (localities 19, 20), once more barricades the Raquette. Westward of this quadrangle the same strong sand- stone ledges appear to furnish the only conspicuous outcrops as far as the Oswegatchie river, on the south bank of which they are strikingly developed at Heuvelton, the type locality.® *Lingula antiqua Hall, Paleontology of N. Y. 1:3-4; pl. 1, fis. 3a-e. ?'N. Y. State Mus. Bul. 173, p. 61. * Geol. Soc. of Amer. Bul. 26, p. 280. A. Heuvelton sandstone ledge above Morley on the east bank of the Grass river (locality 61). Block undermined by solution of the Theresa beds. (Actual dip of the strata here is to the right.) (Looking east of north) See pages 25 and 206. B. Summit of the Heuvelton at Pollock’s ledge, east bank of Grass river below Morley (locality 57’), showing laminated structure and marked contrast with overlying basal Bucks Bridge, above Mr Billings’s hand. (Looking northerly) See page 26, and compare plate 8. 4 PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 27 The Heuvelton formation consists of white, vitreous sandstone often with a decided platy structure and much ripple-marking and minor cross-bedding. In stream beds the surface of the rock is usually strongly stained with reddish brown iron rust or is even nearly black, and the lamination is clearly brought out; but the glaciated ledges commonly show the rock in about three heavy benches of glistening whiteness. The cement is clearly silicious, with the original sand grains fine and uniform, so that these polished surfaces are nearly indestructible and essentially a quartzite. Very rarely there is a small lentil or even a thin stratum of slightly cal- careous material. At Sissonville especially (locality 31) the number and liminess of such lentils is more marked than to the westward. This sandstone may, therefore, become less pronounced eastward of our area. Yet at Norwood the masses thrown out in construct- ing the concrete dam (locality 19)* indicate no loss of strength at this point, and the full thickness of 20 feet is said to have been encountered; also that it was an exceedingly difficult rock to drill on account of its flintiness. Unlike the formations below, the Heuvelton is fossiliferous, though its fossils are poorly preserved as in general with our for- mations.. A large, flatly coiled shell not unlike the Eccyliopterus types of the Beekmantown (Ogdensburg) and sometimes reaching a diameter of three and one-half inches, occurs sparingly, especially near the summit. Doctor Ulrich suggests that this species may pos- sibly be Helicotoma uniangulata,? “which is char- acteristic of the Chepultepec (upper) series of the Ozarkian.” It is possible, however, that more than one form is represented by the crude molds that have been seen. Besides the shells, a characteristic burrowlike or fucoidal struc- ture is oftentimes pronounced. This consists of tubular windings, about the size of a slate pencil, and filled with either the same white or a bluish sand, or rarely weathering more rusty. They penetrate the strata at all angles, and by a tendency to radiate in twos or threes from a center frequently give to the weathered surfaces the appearance of being covered with turkey tracks. This *The new dam is situated about 25 rods farther up the stream than the dam shown on the map, in line with the end of the street on the east side of the river. *Euomphalus uniangulatus Hall, Paleontology of N. Y. 1:9; pl. 13, fig. 1, 1a. There is a very fine specimen of this species in the col- lection of St Lawrence University, besides some poorer ones, all in loose rotten rock of the glacial drift; but these are evidently out of the succeed- ing Bucks Bridge formation. 28 NEW YORK STATE MUSEUM fossil has been described and figured in the “ Geology of Canada,” page 101, as Scolithus canadensis. A vety similangon identical form occurs in the Upper Cambrian (St Croixan) Eau Claire sandstone of Minnesota. That the Heuvelton sandstone may furnish a valuable building stone is shown in the school building and the Episcopal chapel at Morley. The rock used is ashen gray with a tendency to a rusty buff stain, and was quarried on the river bank just behind the chapel, the trimmings being from the Hannawa Potsdam quarries. Quarries have also been opened in this rock elsewhere, as at Heu- velton and near Sissonville (locality 32), the latter for road metal and extending downward into the Theresa beds. The Heuvelton sandstone varies somewhat in thickness, appar- ently through irregularity of its summit plane, certain upper layers being sometimes present and sometimes absent. It is thinnest at the old mill site below Bucks Bridge (locality 54) where the over- lying beds are thickest, and has its full thickness at the Stony Brook falls (localities 35, 36) where the overlying ledge is thin. (See figure A, plate 9.) At the latter locality there is even some appearance of calcareous (rotten) upper Theresa sediments above the Heuvelton, exposed on the north-south roadway, but too thin for mapping. If correctly so interpreted, this is the only locality vet known on our quadrangle where there remains any trace of the upper Theresa beds that lie above the Heuvelton lentil on the Brier Hill and Ogdensburg quadrangles. They seem otherwise to have been removed by erosion, together often with some portions of the top of the Heuvelton, before the succeeding Bucks Bridge beds were deposited. Bucks Bridge Mixed Beds The Heuvelton sandstone is succeeded by another white, sandy mass of different aspect, considerably more calcareous, passing gradually upward into heavy, dark, silicious dolomites with only rare sandstone layers, and these in turn becoming more quartzose again as the summit of the group is approached. No complete section is available for measurement, but the total thickness may be safely put at over 50 feet and perhaps nearer 70, though a cursory view of the occasional thin exposures would not at once suggest so great a bulk. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 29 Basal division. The lowest beds of this series have a tendency to form a solid ledge, 5 or 6 feet high, rising abruptly from the broad surfaces of the Heuvelton with a rounded and glittering white forehead, followed sometimes by one or two other tiers of similar aspect. There may be in all 15 or 20 feet of such beds. They consist of frequent alternations of somewhat calcareous (or dolomitic) sandstones with purer sandstones, and are mostly of fine texture, usually rather weak and granular within but vitrifying and bleaching on the surface into a nearly pure white resistant crust about 3 millimeters thick, just beneath which the oxides of iron form dark stains. Like the Theresa, the limiest bands sometimes 6 show the characteristic “sand crystal” cleavages of the calcare- ous cement noted by Cushing’ as common in these mixed or transi- tion beds between the Potsdam and the Beekmantown; and nodules of crystalline calcite are not lacking. The color of the fresh rock is a mouse-gray or drab-gray, stained as it leaches with various rusty colors (especially wood-browns) arranged in striking patterns, marbled or clouded. Weathering develops more buffy tones in cracks and seams, but often bleaches the exposed faces as above stated to an ashy white, frequently overgrown with dark Protococcids. | _ As compared w:.th the Heuvelton, these layers are darker within and whiten on exposure, while the former is whiter within and gener- ally develops a dark crust on the surface. Moreover that rock tends to maintain angular edges because of its silicious character, whereas these beds become more rounded, with solution along joint planes, and otherwise give testimony of their more calcareous nature.” The cross-bedding too, while still abundant, is smaller and even more irregular, while the rock when thoroughly weathered is a rottenstone full of closely interwoven, branching, fucoidal struc- tures, the Palaeophycus beverleyense of Billings.° The contact of these basal beds with the underlying Heuvelton shows many signs of disconformity, indicating a break in the IN. Y. State Mus. Bul. 145, p. 64. ? They furnish a foothold for such rare lime-loving plants as the slender cliff-brake (at locality 57’), the bulblet bladder-fern, and the walking-leaf (locality 35), besides many commoner forms. Canadian Paleozoic Fossils, 1:97, fig. 86. 30 NEW YORK STATE MUSEUM process of deposition. Its irregular character is seen in the ledge on the Grass river at Pollock’s woods below Morley (local.ty 57’), illustrated in plates 7 and 8. At the old mill site below Bucks Bridge (locality 54) several inches of soft, deeply undercut shaly layers are present at the contact, immediately followed by the rotten fucoidal stuff. There seems reason to think, also, that the layers making the base of the formation at some localities are not identical with those at other localities, several feet of the lowest beds being present or absent as the case may be. A similar difference in the top of the Heuvelton below this contact has already been mentioned. Besides the localities marked on the map along the Heuvelton contact (namely, 57’, 55, 54, 38, 35,28), these white basal layers are exposed also in broad surfaces, the summit of a low, domed uplift, east of Madrid depot (locality 7) near the north edge of our quadrangle; and again similarly on the west bank of the Raquette between Hewittville and Norwood (locality 22) mostly just east of our limits. They appear also at and above the Hewitt- ville upper dam (localities 26 and 27), and a mass of boulders of ‘this horizon occurs just south of Madrid (locality 9). The maximum thickness of these basal layers appears to be repre- sented at Bucks Bridge in the beds of Nettle creek and the Grass river (locality 55), where a hurried estimate indicated from 20 to 25 feet of crass-bedded, ripple-marked and sun-cracked, fucoidal, partly calcareous sandy strata. Where these ledges cross the river, making a considerable rapid (locality 54), gastropod shells of the Ophileta type occur in them, especially at the old millrace on the west bank (See figure B, plate 9). A good specimen from here bears, according to Doctor Ruedemann, a considerable resemblance to Cle- land’s Pleurotomaria hunterensis? of the Mohawk valley Tribes Hill beds. Similar gastropods, though usually poorly preserved and infrequent, characterize all levels of the Bucks Bridge formation at practically all localities visited, and thus often furnish a means of distinguishing isolated outcrops from those of the Theresa. They appear to represent Vanuxem’s Ophileta complanata,! to which Cleland’s species is probably equivalent. Bul. of Amer. Paleontology, 33252; pl: 17, fis: 1) 2) 7, 8; ibider4 16; pl. 4, fig. 1-2. According to U. S. Nat. Mus. Bul. 92, p. 1020, the present name is Polygyrata hunterensis. But see the next footnote. A. Basal contact of the Bucks Bridge beds disconformably on the Heuvelton at Pollock’s ledge, east bank of Grass river below Morley (locality 57’). Irregular, wavy contact at Mr Billings’s hand. (Looking east) See page 30, and compare plate 7. B. Detail of the preceding, retouched to emphasize the wavy nature of the contact Plate 9 ee) Bot by Mrs C. S. Phelps A. Ledge of basal Bucks Bridge calcareous sandstone with Heuvelton sand- stone surface in foreground, at Stony Brook falls east of West Potsdam (locality 35). (Looking east) See pages 26 and 28. © "Photo by Mrs C. S. Phelps B. Higher layers of the lower Bucks Bridge beds in the old mill race on west bank of the Grass river at Bucks Bridge (locality 54) where gastropods were secured. (Looking southeast) See page 30. a * < Los) atin) PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 31 Middle division. The transition to the more calcareous or, rather, dolomitic beds of the middle Bucks Bridge is not abrupt though fairly rapid, and some heavy uniform bluish dolomites not unlike the Beekmantown make their appearance. But they are harder, darker and more sandy, with the “ sand-crystal” cleavages . of the passage beds and without the soft, velvety surface of the true Ogdensburg dolomite. They are exposed at but few localities and their relations to the lower beds are poorly shown at most of these, while their exact relation to the upper beds is still unsatis- factorily determined. The best development of these layers is seen (at low water) in the bed of the Raquette river just above the Hewittville bridge (locality 24), where the exposures are nearly continuous with those of the lower beds just upstream from them, adjoining the dam (locality 26). Gastropod shells are abundant in the upper surface of the bottom layer and continue frequent through the 10 feet or so of beds here shown. Some of them are of large size and suggest Eccyliopterus. A vitreous, white, cross-bedded sandstone layer (about 2 feet thick) caps the series at the east end of the bridge, and fucoidal rottenstones follow not far below the bridge; the latter being thought to correlate with the beds else- where referred to the upper division. To this middle division belong apparently the beds formerly quar- ried south of Madrid bridge (locality 8), of which the bridge itself and the “twin mills’? beside it were built. They reappear at Nor- wood both above the railway bridge (locality 17) and in the brook bed back of the Episcopal church (locality 18), 120 rods over on the Potsdam quadrangle. On Stony brook they make picturesque ledges northeast of West Potsdam (locality 37), while the layers at their base cause a small fall in Trout brook at locality 44. Above Geolmortnersc) Dist.) p..360, fey 2) (Hall, Pal: of N. Yours. plas: fig. 6). Doctor Ulrich assures me that Cleland’s shell is the same as the O. complanata of Vanuxem, but the “O. complanata and O. compacta (both younger fossils) of Salter, Billings and Whitfield and all subsequent authors” are not the same species but are even of different genera. In this case our shell would appear to stand correctly i Polyeyrata complanata (Vanuxem), since the type of Ophileta is clearly O. levata (loc. cit., fig. 1) and not this species as sometimes asserted. *It is to be regretted that the reconstruction of the west m'‘ll after a recent fire was not carried out on the original lines, hence they are no longer twin. 32 NEW YORK STATE MUSEUM Bucks Bridge they are best seen at very low water in the Grass river (at locality 57). Again on the Raquette below Sissonville they have a small exposure 10 feet above the basal beds at locality 29. West of our limits about one-half of a mile (locality 68) similar beds occur on the James Dandy farm and in the adjacent road gutters; while north of the quadrangle some 60 rods (locality 15; Waddington sheet) layers resembling those at Madrid appear in the brook that runs near Dailey Ridge church, but this last iden- tification 1s not wholly certain. Upper division. What are believed to be the highest beds of the Bucks Bridge formation are splendidly shown in the bare ledges on Trout brook at the Rutland Railway (locality 12), where approximately 25 feet of these strata are present below the Ogdens- burg dolomite with a disconformable contact. These beds are sandy and silicious dolomites, rather flaggy in structure and highly fucoi- dal as they weather, but still distinguishable from the basal division. They seem much like the beds that immediately succeed the middle division below Hewittville bridge, and it is likely that the base of this Trout brook section actually ties to the top of that one, though of course still other unknown beds may intervene. Inasmuch as there are, below the Ogdensburg at the Hewittville lower mills, some quite different calcilutites next to be described, it would seem that these ought to be present somewhere at this locality. A very small development of similar calcilutites does appear on the east bank just north of the preceding (locality 13) about 50 rods below the railway bridge, dipping under the basal Ogdensburg on the opposite side of the brook. Again in the railway cutting next west (locality 11) are sandy layers and calcilutites forming a low anti- cline, which may be in part of the Hewittville horizon, but the examination of these was hurried and they may really be Ogdens- burg. These beds are surely absent from the exposure by the rail- way bridge, thus indicating an unconformity by pre-Ogdensburg erosion. ‘The fucoidal beds reappear in several exposures farther down Trout brook (localities 13 and 14), with a short, concealed interval between them and the Ogdensburg rocks at the road bridge (13). No “ Hewittville° layers are seen here, though they may possibly occupy the covered space. Fossiliferous and fucoidal beds like the above form the hill slope east of Brandy brook not far below the Andrew Walker bridge (locality 5), just over on the Waddington quadrangle. These beds dip strongly west by north, indicating one limb of a fold that in PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 33 conjunction with the valley of the brook produces a deep reentrant in the Ogdensburg front. A second similar reentrant is formed by the coincidence of the Grass River valley with a second similar low anticline that brings up the basal Bucks Bridge at Madrid depot (locality 7; see previous, page 30). A third reentrant is developed along the Trout brook depression, with its Dailey Ridge tributary ; while the Raquette valley is the occasion for a fourth. It will be seen by the map that these sinuosities aline well with the ins and outs manifested by the outcrops of the lower formations, and that finally they all bear some relation to the belts of Precambrian rocks that pass under them.* See map in Museum bulletin 185. In the exposure at the Hewittville lower mills (locality 23) described on page 34, the lowest four and one-half feet are consid- ered to belong to the division just defined. To the already mentioned gastropods and fucoids (Palaeophy- cus) of the Bucks Bridge fauna, which are even better displayed in the upper division than below, these upper beds contribute a more significant element in a little graptolite from the highest layers of the formation at locality 12 on Trout brook just north of the Rutland bridge. Concerning our provisional reference of the speci- mens to his Deep Kill species Dictyonema rectilinea- tum,? Doctor Ruedemann writes: ‘“ The Dictyonema is, in the best preserved specimen, finer than the typical D. rectilineatum, though having all the characters of it. It has 18 branches in 10 mm against 12 to 14 of that species. Another fragment has 14 to 16. Also the branches themselves are finer; otherwise, however, they are alike in form. Probably these differences are due to the preservation in different matrices.” But the species may also be compared with D. sociale of Salter, generally made a synonym of D. flabelliforme, a widespread horizon-marker that Doc- tor Ruedemann has recognized’ in the Schaghticoke shale of the Hudson valley, below the Deep Kill. Hewittville beds.* Capping the Bucks Bridge formation on the west bank of the Raquette river just below the concrete dam of the lower mills at Hewittville (locality 23) and so just east of this *Geol. Soc. of Amer. Bul. 26, p. 287-94, “ Post-Ordovician Deformation in the Saint Lawrence Valley.” 7N. Y. State Mus. Memoir 7, p. 607, fig. 29; pl. 3: fig. 9, 10. °N. Y. State Mus. Bul. 60, p. 934-58. *This name is not intended in a formational sense, but is used kere for convenience only. 34 NEW YORK STATE MUSEUM quadrangle, are a few feet of beds lithologically more peculiar than any others above the red Potsdam in our Paleozoic section. These are rather argillaceous, lightish (smoky) gray, firm and compact dull limy mudstones (calcilutites or exceedingly fine calcarenites). They weather to vivid tones, light clay-buffs and mud colors, some- times gaily banded or streaked with brown, indicating zones full of rounded quartz grains. The distribution of these sand grains in streaks or winnowings, the curdled (pebbly) or breccialike appearance of certain of the beds, and the irregular bedding dis- continuous horizontally, with the absence of fossils,’ are all remin- iscent of shoal water conditions within a lagoon (barachois) at tide level. The variable nature of the deposits is expressed in the following section: Section on west bank of Raquette river at Hewittville lower mills Ogdensburg formation Ft. In. T Coarsely ribboned geodiferous dolomite............... Bo iit S Deeply weathered contact; contains fragments of R, Cie eer ee Ae aes SMT ye eos Moana Gg oO Ob ETD 2 SOON Ft. In. 4 5 Bucks Bridge formation (Hewittville beds) R Exceedingly fine, flaggy, light gray colomarenite; Weathenrssto (Ciminamon.. cease errata te aero Oc arr Q Massy, argillaceous dolomilutite, with small scattered Pebbles omlichter colons ee ose ee cee eee o 7% P Exceedingly fine, ribboned, calcarenite, with some Sand esramspandwarshalemscaniemee ieee oO 10 O Exceedingly fine, platy, calcilutite, with scattered sand grains; weathers banded............ PE Metta On PAs N Similar to M but with closer irregular alternations Of Satrdy:sursacey . Slashedmcn sa eee eeemnne eee 0) 50 M Heavy stratum; more or less breccialike and rib- boned, fine calcarenite and dolomilutite, with many nodules of pinkish calcite; base banded........... 2s EP Avidagk shalyjseamn simitlatyeto mailers tae One K Lutite alternating with very fine dolomarenite con- taining coarser grains; weathers ribboned......... Onn J Weak, thin-shaly, exceedingly fine dolomarenite..... Onna I Thin-layered coarse calcilutite, ribboned.............. Ome H Like J but more variegated; weathers dark......... Om Id *A single, small, poorly preserved and dubious gastropod, perhaps a Maclurites, was seen in bed N. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 35 G Solid layer of calcilutite with conchoidal tough frac- Ft. In. ture; white ‘chert: ticar baSess.ceccse. csc er ue seus oO II (Greenish shale film) F Compact lutite; weathers gaily ribboned................. Qo ul (Greenish shale film) E Banded lutite and fine calcarenite; weathers strongly banded) bister and clove DrOwilscccess seceoone oes o 6 (Greenish shale film) D Banded as above, with much medium to coarse quartz sand grains in both parts, the grains sparkling on WISAPMERECUSibACE) cc iarctelatietthc sien aie bioreien era rea o 6 (Greenish shale film) Motalelvewittville! yc Reet cn cee eee 8 8% C Very fine tough calcarenite with 30 to 50 per cent of medium quartz sand; wpper surface with flat Pennles or very, fine buffy calcarenites...¢ meen if 2 B Similar but not so tough; weathers “pocked”’...... Tas A Like last; base of Clift. “ine Waters cas vacmocee eee o «68 X In midstream; medium grained, calcareous sandstone; WUC A LITEGS RD ILLOON ws, fae Fide 4.5: seis iene a e'vad alu e & atecore meee 1) aco) 4 6 MO TalmSeChiOniMEx POSE: £1,504 ss earache ta ee Le Beds C and below are referred to the summit of the normal Bucks Bridge terrane. They are light, neutral gray, rather lustrous calcarenites or calcareous sandstones, weathering brown. Elsewhere than at Hewittville these 8 or 9 feet of yellow-weather- ing waterlimes fail to appear, either because concealed beneath ledges of the Ogdensburg or because discontinuous through: erosion or through lateral change. Abundant fragments occur in the glacial drift at Bucks Bridge and some other points, but the sources of such strays are unknown. It is questionable whether these strata do or do not belong in the Bucks Bridge formation, but since no break is evident at the supposed contact it has not seemed wise to separate them until they can be traced farther east. Summary. Combining the measurements or estimates for the different divisions, we obtain the following sums: Minimum estimate Maximum estimate Calcilutites at Hewittville.... 8 feet g feet Upper fucoidal layers......... 25 feet or more 27 feet (perhaps more) Middle dolomites ............ TOL Me aeih ? AE nde Basal quartzose beds......... Shah: SO ab B25 sae 36 NEW YORK STATE MUSEUM Of these the maximum figures are the more probable. These strata thus constitute a formation of considerable thickness, with a fauna essentially the same throughout, and distinct both litholog- ically and faunally from the formations above and below, from each of which it appears to be set off by an erosional break (discon- formity). They appertain to the Theresa or “ passage” beds as originally defined by Professor ‘Cushing, and are the equivalents roughly of. the upper portion which on the Theresa and adjacent quadrangles he and Doctor Ulrich have more recently referred to the Tribes Hill.t Considering the absence here of the rich Tribes Hill fauna, the isolation of these northern New York strata from the typical beds of that horizon in the Mohawk valley, and their very different lithologic constitution and local subdivisions, a dis- tinctive local name is needed for them. No satisfactory type locality having as yet offered, the name here used owes its selection chiefly to the fact that it was not likely to be preoccupied, and it should be permitted to lapse as soon as a permanent one can replace it. Beekmantown (Ogdensburg) Dolomite The rocks occupying the area that was assigned to the “ Calci- ferous”’ (now called Beekmantown) on the state geologic map are, in our region, fine-grained, firm, fairly uniform, gray to drab dolomites and dolomarenites usually with a rather dull, velvety surface when fresh and often a coarsely ribboned or thin-lamellated appearance when weathered. Sand grains are absent except in restricted layers, and while the rock is sometimes slightly argillace- ous it is seldom silicious. The magnesian content varies; most lay- ers effervesce poorly, but some strongly and some not at all in dilute acid.2 The sand-crystal cleavages so frequent in beds below (Theresa and Bucks Bridge) are here wanting or at least very rare. Like the Lockport dolomite of western New York, this rock usually consists of tiny sandlike crystal grains of dolomite in a calcite or dolomite cement, and like that rock it furnishes an excellent build- ing stone. Masses and nodules of cleavable crystalline calcite occur more or less commonly, as also exactly similar ones of dolomite, dis- tinguishable only by failure to foam with dilute acid. These masses *N. Y. State Mus. Bul. 145, p. 64-66. *The larger the percentage of magnesia (dolomite instead of calcite) in a limestone, the less readily it will effervesce (foam) with weak acid. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 37 range from a few millimeters up to several inches in size, or some- times become veinlike and parallel to the bedding. They vary from white to salmon or flesh colors, buff, or even gray like the matrix. Less commonly, but specially near the base of the forma- tion, small geode cavities are found, lined with dogtooth calcite, dolomite rhombohedrons, or clear, sparkling quartz crystals. Although a firm rock when fresh, even running quite tough and hard to work, it usually weathers rather weak or even very soft, with rounded edges. In the typical sections near Ogdensburg occur two or three lentils of hard, creamy white sandstone abruptly inter- calated in the limestones, each in turn overlaid by a bed composed of the peculiar spongelike fossil, Cryptozoon. These may be mostly of higher horizons than the basal stuff that appears on our map area; but Cryptozoon masses are so abundant in the drift of the northwest corner (locality 3) as to suggest a local derivation, and a Cryptozoon stratum in place occurs in the Rutland Railway cut at the Madrid-Potsdam turnpike crossing (locality 10). The under- lying sandstone lentils have not, however, been observed here. “ Black” shaly partings in the lower beds, such as are shown well in the Cedar Croft quarry on the state road west of Ogdens- burg, have been noted in the old quarry north of the Rutland Rail- way a mile west of Norwood (locality 16) and also in the state road quarry on the east bank of the Raquette river 2 miles south of Norwood (on the Potsdam quadrangle) where one of the shale seams divides this formation from that next below (Hewittville beds). Dark (“black”) chert nodules have been found along the Raquette river in loose blocks apparently from these lower beds, associated with or replacing Cryptozoa and Orthocerata. The dolomitization of the rock, or perhaps rather its recrystalliza- tion during dolomitization, has fairly obliterated what must once have been an abundant fauna,’ judging from the faint traces of fossils common in many of the layers. Occasionally something of interest has withstood the process. A loose block in the river at *Doctor Ulrich comments (in litt.): “According to my observations there is no warrant for the common belief that dolomitization has oblit- erated any considerable part of the fossil contents of dolomitic forma- tions.” Blackwelder, however, in his study of the Bighorn dolomite (Geol. Soc. Amer. Bul. 24, p. 624 et ante) has reached a different con- clusion; and the writer knows of no other explanation for the facts seen repeatedly in dolomites, such, for example, as the Lockport of western New York. Compare also Van Tuyl in Science No. 1141, Nov. 10, 10916, especially p. 688. 38 NEW YORK STATE MUSEUM Yaleville (Waddington quadrangle), furnished a closely chambered cephalopod shell resembling Cameroceras tenuiseptum of the Chazy.* This may be merely a well-grown specimen of Proterocameroceras brainerdi, a Fort Cassin Beek- mantown fossil* with which silicified specimens in poor condition were provisionally identified from the basal beds below the Rutland Railway bridge over Trout brook (locality 12). Gastropods are more abundant; species of Eccyliopterus (?)* with solute body- whorl in the old quarry south of the Rutland tracks at locality 16 a mile west of Norwood, besides many loose specimens that Doctor Ruedemann calls ““Maclurea compare sordida and matu- tina’ the former of Fort Cassin and the latter of Tribes Hill age elsewhere; also an Ophileta like O. levata,® numerous in a loose slab below the Hewittville lower dam (locality 23) on the Potsdam sheet. In a gutter exposure along the Rutland tracks just beyond the old quarry above mentioned, a single layer contained a small, pointed ‘Linguloid, probably Linguwlepis = acunmmare sequens’ described from the Beekmantown of Ticonderoga, and two other poorly preserved species of brachiopods which Doctor Ruedemann assigned to Syntrophia lateralis® and Poly- *Orthoceras tenuiseptum Hall, Paleontology of N. Y. 1:35; pl. 7, fig. 6. See N. Y. State Mus. Bul. 90, p. 408; pl. 3-6. Doctor Ulrich suggests that this specimen may represent a species, “like Endoceras montrealense, that is common about this horizon and distinct from C. tenuiseptum.” (See Orthoceras montrealensis Bil- lings, Geol. of Can., p. 121, fig. 37 a-c. )N..Y: State Mus. Bulb compinos ?Orthoceras brainerdi Whitfield. See N. Y. State Mus. Bul. 90, p. 405; pl. 1-2. *Doctor Ulrich thinks this shell may be his E. planidorsalis (unpublished?), “‘a characteristic and very widely distributed species.” ‘Hall, Paleontology of N. Y. 1:10; pl. 3, figs. 2-2a and 3, respectively. Maclurites sordidus and matutinwus, in U. S. Nat. Mus. Bul. 92, p. 780. * Both, according to Ulrich, occurring in division D of the Beekman- town, however. " *Vanuxem,. 3d Dist., p. 36, fig. 1. See Pal) of N. Yo 1:11, fo. neplaes fig. 4-5. Given as from the Little Falls formation in U. S. Nat. Mus. Bul. 92, p. 879. This may be one of the various forms called O. com- planata or perhaps more likely the O. compacta of Salter (see Geol. of Can., p. 102, fig. 9a-b; and p. 115, fig. 23a-b). 7 Walcott, Smithsonian Misc. Coll. 53, p. 72, pl. 8, fig. 4. Lingula acuminata in Pal. of N. Y. 8, pt 1, pl. 1, fig. 1-2, not of Conrad. *Triplesia lateralis? Whitheldis | SeerRaly tom s\n emo Dee p. 216, pl. 62, fig. I-10. Plate Io A. Disconformity(?) in the Beekmantown beds in old quarry on Raquette river, west of Yaleville one mile north of Norwood (Waddington quad- rangle). The locality where Winchell and Schuchert collected. (Looking . northeasterly ) See page 38. B. Perspective view of same ledge. The beds above and below this break appear to be alike, supposedly Ogdensburg; but unless those below are actually Bucks Bridge, or some new member, this may be a “ pseudo- disconformity.” PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 39 toechia apicalis(?)* of the Fort Cassin fauna. Two or more species of Cryptozoon” from localities already specified, and a finely branching structure supposed to be a nullipore (calcareous seaweed) from the townline road bridge over Trout brook 2 miles east of Madrid (locality 13), complete the forms collected by the writer on the Canton quadrangle. The higher portions of the formation on the Ogdensburg and Waddington sheets contain a larger number of species and beiter preserved, yet the forms enu- merated here are sufficient to show in these lowest beds the pres- ence of the Ogdensburg fauna and its near relations to that of the “ division D” Beekmantown or Cassin formation of Cushing.° With the exception of the Cryptozoon layers previously men- tioned, it seems possible that all our exposures fall within the basal 10 or 15 feet of the formation, though this base may not be the same at all localities on account of unconformity with the subfloor. This unconformity may be seen on the west bank of Trout brook (locality 12) in the joint faces of the beds, and is emphasized by the discontinuous distribution of the Hewittville calcilutites, as well as by the abrupt lithologic change. At Hewittville the contact zone is rendered conspicuous by being a water-bearing plane with sec- ondary solution and recrystallization, while in the quarry farther downstream it consists of a strong shale parting as before noted. The hiatus corresponds to the absence of at least “ division C” of the Beekmantown. Possible Trenton Limestone Outlier On Thomas Veitch’s farm just southwest of the road bridge over Brandy brook (locality 4) may be seen by the roadside large slabs of undoubted Trenton shaly limestone full of finely preserved shells of the brachiopod Rhynchotrema increbescens,* and *Hemipronites apicalis Whitfield. See ibid. 8, pt 1, p. 230, pl. 7A, fig. 26-30. *The species .described from the Beekmantown formation are C. steeli, C. wingi, and C. saxiroseum of Seely from the Cham- plain valley (5th Vermont Rep’t), C. lachutense of Dawson from Quebec, C. giganteum of Chaney and C. minnesotense of Winchell (with var. libertatis) from Minnesota (Shakopee dolom- ite). The columnar form from locality 10 is a new species, Doctor Ulrich says. *N. Y. State Mus. Bul. 95, p. 363. eiialiveqas Atrypa), Pal. (of (NY. «12146; (280; pl. 33, “fig. orga: Rhynchotrema inaequivalve of Schuchert and others, but see U. S. Nat. Mus. Bul. 92, p. 1124-25. Identified by courtesy of Doctor Ruedemann. 40 NEW YORK STATE MUSEUM with other characteristic Trenton bryozoa and brachiopods such as stictopora elegantula’) and )Dianort hismepcenae nella.” Now Mr Veitch and his sons state that these fragments were removed as an originally single and continuous slab about Io by 15 feet but only 5 inches thick, from a ledge which lay so near the surface as to interfere with the plow. They say that this was lifted with crowbars and afterwards broken for removal, and that similar shaly and shelly rock formed a supposedly solid ledge under it. The spot is now recovered with earth, the location being marked only approximately by a swell of ground. | It is difficult to believe that this thin-bedded material could have been glacially transported in such broad slabs from the nearest known exposures in Canada without disruption, since these are fully 25 miles away (see the outline map on page 6). All the other Tren- ton drift fragments known to the writer in this region are small (not over 3 feet) and well rounded. To be sure, Bucks Bridge slabs up to 12 feet square are known, but these have not traveled far and are both thicker and tougher. On the other hand it is entirely contrary to expectation that there should be here any Trenton strata in place or other than erratic. The Trenton limestone belongs far above the Ogdensburg, with the Chazy and other formations intervening. But this mass lies in one of the anticlinal reentrants of the Beekmantown front and close down to lower Bucks Bridge rocks (perhaps not in place but nevertheless significant) in the bed of the brook hard by. If not a glacial erratic, then a great post-Beekmantown, pre-Trenton erosion is here indicated. The little knoll on which Mr Veitch’s house stands is a small drumloid, as shown by a well he was digging, but just possibly its core may be a tiny Trenton outlier resting down on Bucks Bridge with entire absence by erosion of the Ogdensburg beds (the Chazy and Black River may not have been deposited in this area). In that case it would be a most interesting link between the now sundered Trenton limestones of Jefferson county and Canada. The spot where it lies is well suited for preservation of such a remnant. It must be admitted, however, that the facts fail to prove this theory, though they justify directing the attention of others thus to the locality. * Hall, Pal. N. Y. 1:75, pl. 26, fig. ga-g. Identified by the writer. SOietiiis MPeECtimelila Idurmnems, Acl IDsisi,, D, dou, we 2 See lPzill. ING NG5, 1083, joll, Bar ies, ior PALEOZOIC ROCKS OF THE CANTON QUADRANGLE Al Resumé of Stratigraphy Inasmuch as the Heuvelton sandstone is the only one of the Paleozoic formations on the Canton quadrangle that can be seen in anything like continuous section from base to summit with both contacts exposed, our knowledge of the thickness of the others must finally depend on intelligent and accurately kept records of deep wells or borings. Such records will be of great public service if the drillers will cooperate with the State Geologist in making them available. The composite section obtained by the uncertain patching together of many scattered outcrops gives the following recognizable divisions, in ascending order, with these approximate thicknesses : Cambrian or Taconic Age uncertain, perhaps older than Saratogan Typical Potsdam (red) sandstones and conglom- SMCS eae Vil 5 lees lay sie es rap ahen ce pilioh e! Giss Re Fageeeneee o-150++ ft. (Possible unconformity ) Saratogan or Ozarkian “Potsdam” (Keeseville?) sandstone (mostly TRVIOUUES Pave ee sea Ree mete eM Pr o?-100? ft. (Sequence interrupted; conformable else- where) Theresa mixed beds, dolomites and _ sand- SHOE Ay Oe oc Gat De EMR RPC CRE CRORE at least 50 ft. Age uncertain, probably Ozarkian lcimeltom winter saimdStOne. wes -mmeiae ee acne 10-25? ft. (Disconformity ) Ordovician or Champlainic Canadian (Beekmantownian )* Bucks Bridge mixed beds, dolomite and sand- SOMME es ee a cacs Weise aia etovauer « Lodisicpity «iodo at a, ar aie ahaa 50-75 ft. (Unconformity ) Ogdensburg dolomite, basal part only...... perhaps 30 ft. (Section continued on the Waddington sheet) *Dr P. E. Raymond has advanced the suggestion that the Tribes Hill beds are Ozarkian rather tham Canadian, so that our Bucks Bridge, if equivalent, may need to be reclassified above. See Amer. Jour. of Sci., 30:344. 42 NEW YORK STATE MUSEUM A well drilled in the northwest corner of the quadrangle might therefore pass through 400 or 500 feet of Paleozoic strata before reaching the Precambrian crystallines. The supposed underground relations of these rocks are shown, with great exaggeration of thick- nesses and dips, in the diagrammatic colored cross-sections. Ogdensburg dolomite Hewittville calcilutites Trenton limestone? Bucks Bridge mixed beds Heuvelton sandstone Theresa mixed beds (Sequence concealed) “White Potsdam ’’ sandstone Precambrian rocks (gneiss, schist, marble, quartzite, gabbro etc.) Typical red Potsdam sandstone Precambrian Fig. 5 Columnar diagram of strata, showing the relations to one another, and to the Precambrian, of the Paleozoic formations described on the Canton quadrangle THE GEOLOGICAL HISTORY Interpretation of the Paleozoic Record To reclothe the bones of the dead past is the primary purpose of geology. So closely are fact and interpretation interwoven that the latter has inevitably obtruded here and there into the discussion of the rocks and their distribution. For an orderly presentation of the strangely varied past of our region yet other items must now be elicited, and the narrative must involve some repetition of what has already been said. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 43 The sandstones of the Potsdam represent the residuum of insolu- ble, perdurable quartz sand from prolonged deep and thorough weathering of the Precambrian gneisses and quartzites. Their red color marks the complete oxidation of the iron content of those rocks freed by the total destruction of the amphiboles (hornblende etc.), pyroxenes and dark micas of the gneisses. At favored points this iron was concentrated in the regolith of the rotting crystallines, and incorporated as ore deposits in the basement of the Potsdam sands accumulating above. The sands themselves bear evidence at many places of being wind-drifted, more particularly in their lower portions. The cross-beddings in the Hannawa quarries are quaquaversal, on a giant scale and at depositional angles too steep for water-saturated sands. Quite confidently these are petrified sand dunes. The total absence of fossils, the undercut erosion, so evidently of a sandblast character, in the Grenville quartzites at some of the contacts, and the fine, even nature of the sand itself right up to the contacts, all suggest eolation. In short, our early Potsdam land was a vast desert of wind-shifting sands when it sank slowly beneath the advancing Cambrian sea. Its surface was not flat, but rather it had the form of a corroded peneplain above which rose, often steeply, knobs and ridges of the more resistant quartzites and granite-gneiss, sometimes to heights of 200 or 300 feet. These summits were probably bare rock, rounded or etched by the wind and exfoliating under the glare of the sun. Quite possibly they had been not long since glaciated by the Cambrian glaciers. They bore little or no vegetation even of the low types such as mosses and lichens then in existence, and rainfall upon them would appear to have been scant and infrequent. The suggestion of glaciation, made less improbable by the dis- covery of unquestioned tillite (boulder-clay rock with striated peb- bles) in the Cambrian strata of Norway, Australia etc., is drawn partly from the frequent association of glacial conditions with red- rock accumulations, and partly from the tillitelike nature of the curious deposit at Mr Dillabaugh’s (locality 85). Here, in the pro- tection of an almost overhanging encircling ledge of the gneiss, is a mass that consists at base of a regolithic or talus-heap breccia with residual-earth matrix and secondary quartz and hematite crystallizations of great beauty; but above this lies an indurated quartzose conglomerate of very perplexing nature. In lack of Stratification, complete jumbling of material of all sizes, and com- pact character of the matrix this closely resembles a glacial ground- moraine, but the convincing witness of striated pebbles has not vet been secured. AA NEW YORK STATE MUSEUM The order of events now indicated is (a) peneplaination, then (b) slight uplift and further deep weathering or rotting under moist and warm climate, next possibly (c) glaciation, followed by (d) arid, cold, desert conditions with free sweep to the winds, finally (e) slow submergence under an encroaching sea. That this sea came in from the northeast is well known.’ It appears to have first invaded our quadrangle from the east as a bay making westward from Hannawa and finally penetrating nar- rowly through the Harrison Creek strait as far as Dekalb (Gou- verneur sheet). Whether it was simultaneously entering the north- ern border of the quadrangle as the edge of a large and deeper bay occupying the primitive St Lawrence valley can not be certainly told until well-drilling proves the existence of the red beds there, but such is the general assumption and our cross-sections are based upon it. The sea continued to advance and red sandstones to be deposited until probably the most of the southern third of the quadrangle was submerged and a hundred feet or more of strata had been laid down in the deeper hollows. At this juncture a slight uplift with some disturbance, crushing and faulting, of the unconsolidated sands seems to have taken place; and the time interval appears to have been sufficient for induration of the sands into firm sandstone. In places, heated waters seemingly percolated up through the beds, jasperizing the sand matrix of the basal breccias and possibly some of the adjacent Grenville quartzites at the same time. Mineraliza- tion of the residual iron ores at Dillabaugh’s and elsewhere may also be the work of this time. The extent of this disturbance and the length of time it consumed can not now be affirmed. There are some reasons for thinking it was a break of major importance, so that the true red Potsdam sandstones would be much older than the upper white division which carries the Saratogan fossils — possibly even Lower Cambrian (Georgian) or Keweenawan. But other facts seem to point to a lesser import. However great or however slight the interruption, the returning sea found a change in climate, with vegetation decolorizing the sands now supplied to it. Its waters reoccupied the Hannawa- Canton bay spreading a thin basement of pebbly sands, and crept upon us also from the north and west (Rensselaer Falls), gradually *TIt is highly desirable that the reader should become familiar with Professor Cushing’s conclusions in Bulletins 95 (pages 272 to 294) and 145 (pages 8 to 60) of the N. Y. State Museum, without which these pages would not likely have been written. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 45 burying the intervening irregular promontory of granite-gneiss that now became mostly a group of islands. Thus the upper “ white” Potsdam strata were deposited. At the close of this stage the quad- rangle had changed into a sandy tidal flat many miles across, inhabited by wormlike creatures of which our knowledge is limited, and the burrowing Lingulas. As the shore pushed farther south and west, giving more open, deeper waters hereabouts, various lime-secreting organisms of the ocean found living conditions on the clean, sandy bottom no longer churned by the waves. These may have been mostly calcareous algae, precipitating magnesium, as well as calcium, carbonates. Thus the white sands began to have thin interbedded layers of dolomitic muds washed inshore from the reefs. The amount of such calcareous inwash soon about equaled the landwash of sand, and fluctuating currents built up the alternating beds of the Theresa formation. Submergence, perhaps always intermittent and oscillating, event- ually gave place to renewed elevation, and once more a beach deposit of white, cross-bedded, ripple-marked sand was spread out across several quadrangles with a rather remarkably uniform thickness of about 20 feet, the Heuvelton sandstone. In these sands the waves sowed large sea-snails’ shells, drifted gas-buoyed from deeper haunts, and burrowing “ worms ” still found sustenance. The immediate sequel is not decipherable on our quadrangle, but before very long afterward the area again became land for a short time. Whatever deposits lay above the Heuvelton were swept off, and the summit of the latter more or less pared away in places. This paring may have been mostly the work of waves during the return of the sea in the next period. Submergence was resumed at no remote time, and somewhat the same succession of events was repeated; the advancing sea spread beach-sands, the basal Bucks Bridge, this time more calcareous from the presence of the Theresa dolomites in the area undergoing erosion and of gastropods along the strand, followed by fairly heavy sandy dolomites carrying plenty of molluscan shells, suc- ceeded in turn by the sandier sediments of the withdrawing waters as uplift again ensued. Finally we have barachois (“lagoon”) conditions and the precipitation of fine lime-muds streaked with storm sands — the Hewittville beds. The sequel again is not recognizable until areas to the east are better known. Land was finally established and a distinct erosion 46 NEW YORK STATE MUSEUM was effected before the ocean came back. But land detritus seems by this time to have been largely exhausted or the rivers turned elsewhere, for great beds of nearly pure magnesian limestone, the Ogdensburg, now accumulated, Cryptozoon reefs grew widely and a normal marine fauna of molluscs and brachiopods thrived. Yet in the very midst of these limestones an occasional thin bed of pure sandstone marks a sudden flood or sweep of current, and upon each such sand waste a new Cryptozoon colony sprang up. The continuation of the Paleozoic sedimentary record lies north- ward (see the key map, figure 1) across the St Lawrence. Here we find evidence of further oscillations,’ the Chazy limestones with a basal (Aylmer) sandstone resting upon eroded surfaces of the Beekmantown, while above these follow the Black River and Tren- ton series of limestones and calcareous shales. ‘Whether the Chazy beds ever reached into our quadrangle is unknown. If the Trenton mass at Mr Veitch’s (see page 39) 1s a true outlier, then deep erosion of the Beekmantown dolomites was proceeding in our area during Chazy and Black River time; and the Trenton sea transgressed over the beveled edges of the Chazy and Ogdensburg strata, already arched into the undulations of today, and laid its sediments down upon those of the Tribes Hill division and possibly on still lower beds. After the completion of sedimentation in our region, or perhaps (if the preceding is correct) immediately at the close of Beek- mantown time, the rocks laid down in originally horizontal strata were thrown into the gentle undulations they now exhibit. This movement may not have been single and simple. More likely it was renewed from time to time with each doming of the Adirondack massif, and perhaps in slightly different directions. The total result, conditioned in part by the belted and uneven Precambrian © floor, is complicated, and by the drift covering rendered most per- plexing. The colored cross sections show diagrammatically (with a vertical exaggeration of eleven times) the simplest possible inter- pretation of the observed data. Southward, in the Potsdam out- liers, the amount of compression becomes clearly greater, perhaps because in part referable to a disturbance older than the upper white sandstones (see page 44), but also in part involving these (as at locality 75). The colored cross section at locality 80 *Consult N. Y. State Mus. Bul. 145, p. 17-20; Geol. of Can., p. 123-97; G. S. of Can! Rep't, for 1890))voli 12, n: s.(10902)),) Reps Gijiee Ame oumson Sci. (1905) 20:353-66. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 47 shows the actual dips there observed, without the exaggeration of the other sections. Brecciation, or microfaulting, is among the other evidences of the crushing to which these brittle sandstones have been subjected, apparently through being squeezed between the jaws of a Precambrian vise that consisted of an older synclinal fold of gneiss with a marble core. Subsequent Geologic History The complete induration of the Potsdam sandstones seems to imply that they were for a long time under the “load” of many hundreds of feet of overlying strata. What these strata could have been is not so easy to answer. Discounting the conjectural Trenton outlier, they may have consisted in part of the Beekman- town, Chazy, and perhaps Black River, Trenton, Utica and less probably the Lorraine and Queenston formations. To these, or without them, it is even possible there were added now vanished Silurian and Devonian deposits. In fact we can not be sure that all marine deposition ceased in the upper St Lawrence valley until the end of Middle Devonian time, and unknown continental fillings may have continued to be heaped in from the wasting Adirondacks only to be carried on out again.” By general consent the area has come to be looked upon as one that has remained moderately near to sea level throughout the long post-Precambrian times, but this may be erroneous. It may have been much depressed, and also much elevated, though today (per- haps accidentally) back at about the same stand. But at the close of the Mesozoic? it, and the areas adjacent even far into the Adi- rondacks, had reached the flatness of surface that comes from long erosion at one level and which is called a peneplain. The surface of this peneplain (figure 2) is that of the present high land from Waterman hill southward, visible from Canton as a nearly smooth sky line but far more impressive when seen from the standpipe hill south of Gouverneur. Into this peneplain, after its elevation, the rivers of Tertiary time cut deep and often not very wide valleys. But at the same time they opened out a wide flat-bottomed valley (figure 2) along the belt of Paleozoic rocks for the St Lawrence *Geol. Soc. of Amer. Bul. 26, p. 292-04, figs. 7-0. "A summary of the evidence bearing on the former thickness and extent of the Paleozoic strata is contained in Museum Bulletin 18 of the Canada Department of Mines, pages 19 to 22 (1915), by % M. Kindle and L. D. Burling. 48 NEW YORK STATE MUSEUM of today, and the character of this flat bottom as a late Tertiary peneplain is also manifest when one views it from the summit of Waterman hill. It is interesting to note how closely this series of events parallels those that preceded the Potsdam deposition, when a mature Precambrian peneplain was gently elevated and corroded, just prior possibly to glaciation. Once again that sort of a mature peneplain, hewed mostly across the same crystalline rocks and at very nearly the same level in them, is gently uplifted and incised just before glaciation. In our immediate region the coincidence of the two planes is so intimate that one can not be sure it is not actually the reuncovered sub-Potsdam peneplain that we see from Gouverneur or Canton. The writer would be unwilling to assert too confidently that it is not just that, though theoretically the Mesozoic plain should control as one goes southward. On account of the warping and probable disfiguration of the older plain (figure 2) by the later movements already discussed, it seems more likely that this very conspicuous, smooth, upland surface is the product of the much later period of erosion which elsewhere has given us the well-known late Mesozoic (Cretaceous) peneplains.* Over this surface, then, probably wandered the huge dinosaurian reptiles of those days, and above them flew the dragonlike ptero- saurs. But the morasses and river silts into which their skeletons fell have long since disappeared from here by erosion, and nothing remains of their gruesome occupancy. After them came the great mammals of the Cenozoic (Tertiary); and they too have passed away, along with the land surface on which they trod. Yet the St Lawrence region as they saw it must have been in many ways a good deal like the present, with many of the same hills and valleys. The closing chapters are those of the ice invasions and their aftermath of glacial lakes and marine submergence, a brief account of which follows. SURE ACH GEOBO G4 The Pleistocene geology of the Canton quadrangle is fully as complex in its mappable elements as is that of the rocks, and since these can not therefore be shawn on the present map, they will be merely summarized here. *The currently assigned ages of these peneplains (preferably spelled “peneplanes”’) has been lately (1916) questioned by Eugene Wesley Shaw at the Albany meeting of The Geological Society of America. Mr Shaw believes them to be of much more recent date. G. S. A. Bul. 28:128. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 49 Preglacial and Glacial ; Preglacial erosion and drainage. Whatever form erosion took during the long stretches of later Paleozoic, Mesozoic and Tertiary time, whether canyon-cutting through rapidly uplifted strata with subsequent reduction of the divides, or slow, continuous, base- leveling of a slowly rising surface, its net preglacial product could not have differed much from that of today. Professor Fairchild believes that the stream adjustment on this northwestern side of the Adirondacks was similar to that now existing on their south- western flank, namely, that a major valley was developed in a tangential direction along the surface contact of the crystallines with the edge of the overlapping Paleozoics, and that this received the radial flow from the highland within.1 Our concealed zone with its absence of outcrops along the Paleozoic frontier may be a local remnant of the course of this ancient trunk valley through this heavily ice-scoured trough. More certain is it that the ancient rock-valley of the Raquette past South Colton continues northwest from Higley Falls into the southeast corner of our sheet, where it is now occupied by only tiny Conner (Leonard) brook. The present deflection of the Raquette toward Colton and Potsdam is maintained merely by a weak remnant of its gravelly delta built in Lake Iroquois (see beyond). Since the other known rock-valleys on the map, except that of the Grass at and above Pyrites, are in belts of weak rock accordant with the direction of glacial flow, it seems unsafe to assert for them any preglacial significance. Some are more truly resurrected pre-Potsdam. Over the Paleozoic area the rock surface appears to be almost featureless, the present relief being wholly that of the glacial drift. Glaciation. The Pleistocene glaciation of this district was from the northeast, and the heavier movement seems always to have been influenced, at least the basal currents, by the course of the St Lawrence trough and its included strike ridges. The thin edge of the waning ice appears, however, to have had a spreading flow, and as this gave the rocks their final polishing, the compass direc- tion of the striations is generally about south, frequently two or three degrees east of south. The drumlinized hills show a similar orientation, as they too were the product of this thin spreading ice margin. The drumlins in particular reveal a curving aline- ment, swinging slowly and regularly from southwest in the northern *N. Y. State Mus. Bul. 145, p. 141-45. 50 NEW YORK STATE MUSEUM part of the sheet (Morey Ridge for example) to a trifle east of south on the parallel of Canton. All this accords with theoretical expectation. Over most of the quadrangle the depth of moraine is great, and exposures are very few. On the entire Paleozoic area, all the hills are drumlins, or at least drift in some form. This drift is very stony, with crystalline boulders from Canada, and slabs of Pale- ozoic limestones and sandstones. It is also very sandy, lacking clayey stiffening because of absence of shales to contribute such. In the southern third of the sheet, the crystalline district, the rock surfaces are more extensively bared and scrubbed, but occasional drumlins and much ground moraine exist all through. Waterman hill is one of the largest of these drumlinized masses. Kame gravels are found chiefly in small patehes, but the Beach plains (see beyond) and its feeding esker represent constructional work by waters of glacial melting, such as exists more abundantly in the Colton region immediately east of our sheet. Erratic boulders reach huge proportions along the southern margin of the map, sometimes as large as haystacks. (Plate 11; also plate 2.) Nearly all the glacial constructional features have been subse- quently softened or modified by the action of static waters about to be mentioned. Postglacial Shorelines? The blockade of the lower St Lawrence valley by the waning ice sheet produced a lowering succession of glacial lakes, whose beaches encircle our steeper hill slopes and blend with delta plains at the crossings of the stream valleys. These beaches are those of ‘“ Lake Iroquois,’ at 860 to 890 feet present altitude, and lower, “Lake Emmons” at 690 feet, and ‘‘ Lake Vermont ” ranging down- ward from 600 to about 500 feet. At still lower levels, from about 460 feet downward, are the undoubtedly marine beaches of “ Gil- bert gulf” (Woodworth’s Hochelagan sea) representing a slow postglacial uplift of our region out of the ocean.? Professor Fair- *Attention should be called here to Cushing’s acute early observations on these phenomena (50th Rep’t N. Y. State Mus., 2:7) which consider- ably antedated those of Professor Fairchild and the writer but were not known to the latter when he entered the region ten years later. * These have furnished salt-water shells such.as Macoma, Saxicava etc., and even barnacles, at Massena, Norwood, Ogdensburg, and other points adjacent to our quadrangle. "oS ased 20S ‘SIOp[NOg BSOO] 1B MoTA 9} UL Sosseur aq} [[V ‘osuripenb uojzue) jo ulsivm yInos jo YNOs jsnf ‘JuodaIIoT| jsaA\ Je stop[nog [ewes IsnyT yooysuroyg “yf Aq oj0y4g II 331d PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 51 child has recently presented strong evidence that the “ Lake Ver- mont” shore (or Vermont-New York, as he calls it in our region) is really only a higher (earlier) stage of the marine levels, but with possibly still fresh or brackish waters because of the narrowness of its connection with open ocean and the large influx from the melting glacier. Such questions of interpretation do not, however, affect the fact that these ‘several beach lines are distinct features marking fairly prolonged stands of wide and deep bodies of water, with heavy wave action. The Beach Plains represent an esker-fan (proglacial delta) in — Lake Iroquois, whose feeding esker is seen along the road to Boyden’s Corners. Good beaches of Lake Emmons may be seen just on the south margin of the quadrangle above North Russell. The Vermont beach skirts Waterman hill, with deltas at Boyden’s Corners, the North Russell mill and Pyrites village, especially west of the last. Some of the best beaches on this shore line are a mile southeast of Langdon’s Corners, and again 2 miles south of west from Little River settlement. The Gilbert Gulf beaches are in general best displayed on the high drumlins in the northern third of the quadrangle. Splendid examples exist on the hills about Norwood (especially at the stand- pipe), north of West Potsdam, and east of Morley; also on Morey ridge. Characteristic diversions of the streams have been wrought by their own deltas at Pyrites, North Russell and elsewhere, thus making available water power at these places. Later Features Abandoned channels. Several rather interesting abandoned channels exist along the course of the Grass river, especially at Canton and Madrid. They range from occupancy at present by flood waters, up to 20 feet or more above present river level. The most remarkable one begins just northwest of the “345” road corners, opposite the sharp bend in the river below Canton; that is at the corners where the road to the county house turns off from Water street, 2 miles out from Canton. It continues (plate 12, figure A) for a mile along the northeast side of the Morley road, from which it may occasionally be seen, and loses itself finally in the broad marshes east of that road. A huge rib of the red granite-gneiss crosses it at the north end of the first hill that it skirts, forming a dry cataract. This channel agrees in level with the sand plain 52 IBA Z MEOMRORS SAAMI, MEIGS MAUI AL extending behind it south and east for a mile or more, for which it is probably responsible. Wind work. Sand dunes are common throughout much of the qttadrangle. Usually they are small, 3 to 10 feet high, and grassed over. Three miles east of Canton, north of the Crary Mills road, they constitute a drifting area. No such conspicuous dune areas as those on the Potsdam quadrangle to the east have been found on our sheet, the best bit seen being shown in plate 12, figure B. Recent ferruginous conglomerates. Along the right bank of the Grass river below Morley, the rock exposures in the river bed are coated with a firm conglomerate containing millions of old iron nails cemented by their own rust. Rev. C. H. Fenton states that an “ ashery ” was conducted at this point by his grand- father. The deposit extends for many yards, has a thickness of several inches, and successfully resists removal by the stream. A more extensive iron-conglomerate was found by Doctor Martin in the river bed above the mills at Pyrites. This is an indurated mass of talus or shingle, containing boulders up to half a ton in weight, with a limonitic matrix derived probably from the tailings of the old pyrite mine. It covers many square rods, often to a depth of 2 or 3 feet, thus mask.ng a part of the rock exposures. ECONOMIC RESOURCES Sandstones and Limestones Active quarrying on the Canton quadrangle, except for road metal is not going on today, though everywhere are the remains of past workings and many sightly structures have arisen from their output. The reason for this decadence is the expansion of the Potsdam sandstone quarries at Hannawa just over the one border, and of the marble at Gouverneur not far over the other. The red Potsdam is not likely to be again exploited on our- quadrangle, nor is the white (upper) sandstone favorable for building stone, but that at the old south quarry of locality 77, near Canton vil- lage, ought to be tested as an abrasive. The Theresa sandy dolomites are good road metal, fairly tough and inclined to “ bind,” but deteriorate on weathering. The Heu- velton, though too silicious and brittle for the roads, has been used as a building stone at Morley (page 28). The middle limestones in the Bucks Bridge, which have been quarried and used at Madrid (locality 8) in the stone bridge and mills, are the most satisfactory and enduring rock in the quadrangle. The Ogdensburg formation Plate 12 A. Abandoned channel of the Grass river two miles north-northwest of Canton (north of locality 69), east of the road to Morley. Looking south-south- west obliquely down upon the channel, which appears darker than the side slopes. See page 51. _ B. Wind-drifted sand burying a cedar grove south of the Rutland Railway three miles east of Madrid depot (north from Burnham Corners). (Look- ing easterly) See page 52. ‘ ve ; y i? i 4 ' A = Sate 5 1 * PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 5 io) also carries good stone for buildings and for lime, but the better localities are somewhat beyond our boundaries. This stone was burned on the “ Jake to farm (locality 6), 2 miles west of Madrid depot. Iron Ore The iron ore workings are also but vestiges. The deposits, how- ever interesting scientifically, proved altogether too limited and uncertain for extraction. ‘The principal prospect holes were at localities 74 and 79 with other occurrences of the ore at 70 and 85, the material in all cases being red, earthy hematite, accompanied by more or less of the shining black crystals in cracks and vugs. LITERATURE AND MAPS 1836. In the apportionment of the State among the geologists of the original survey, northern New York (the “ second district ’’) fell to Prof. Ebenezer Emmons of Williams College.t| In common with his colleagues, Emmons submitted annual reports of progress which were published as legislative matter, but their contents were assembled in the final reports. The pages special to our area are from the following Assembly documents: 1837, no. 161, p. 29-32 (Beck on iron ores) ; 1838, no. 200, p. 209, 214-19 (Emmons on iron ore and Potsdam sandstone) ; 1839, no. 275, p. 62-63 (Conrad’s classification of the “ New York System” of rocks) ; 1840, no. 50, Pp. 347-49 (Emmons on Potsdam sandstone). 1842. In 1842 appeared Emmons’s final “ Report on the Geology of the Second District” as volume 2 of part 4 Geology, of the “ Natural History of the State of New York.’ Our Paleozoic rocks were all included in the two divisions “‘ Potsdam Sandstone ” and “ Calciferous Sandrock”’ of the ‘Champlain group” and are described in detail on pages 99 to 106,? their distribution in St Lawrence county being given in pages 360 to 363 and in the sec- 1Consult State Museum Bulletin 56, page 8, etc. Interesting accounts, with portraits, of many of the men mentioned in this chapter will be found in the History of American Geology by Dr George P. Merrill in the 1904 report of the U. S. National Museum, pages 180-734. Two earlier papers are worth mention, namely John Finch’s “Essay on the Mineralogy and Geology of St Lawrence County,” Amer. Jour. Sci., 19:220-28 (1831), and the “ Sketch of the Mineralogy of a Portion of Jefferson and St Law- rence Counties” by Dr J. B. Crawe and Asa Gray, ibid. 25:346-50 (1834). ?Emmons made the curious mistake of locating Hannawa on the Grass river (page 360), a slip that has been followed by several subsequent writers on our building stones. 54 NEW YORK STATE MUSEUM tion diagrams on plates VII and IX, as well as depicted on the separately published 1842 “Geologic Map of the State of New York” by Emmons, Vanuxem, Mather and Hall. Emmons’s ideas on the origin of the red iron ore (pages 97-98) have already been mentioned. i 1863. Across the river lies Canada, and the dividing line although a river is not a geologic boundary, as the key map (figure 1) clearly shows. In 1863 appeared Sir William E. Logan’s “ Geol- ogy of Canada,’ using Emmons’s names for the formations and giving much detail of their distribution just over the line (pages 87, to 122). Tt is easy to! recognize, im the carefull scetioms arue various members to which we are now supplying names. The map in the atlas accompanying this book (not printed until 1865) covers New York State also, this portion contributed by our own State Geologist, Dr James Hall. But this map was only a reduced prelim- inary copy of the large “ Geological Map of Canada” issued the fol- lowing year, copies of which are very rare. A few years later T. B. Brooks examined the iron mines of Rossie, near Keene, and published his observations already commented on (American Journal of Science, July 1872, 4:22-26). 1875. Except for a map of the eastern United States by Hall in the 27th Museum Report (1875), and the notes in Macfarlane’s “ Geological Railway Guide” (1879), nothing further of conse- quence was printed concerning our area until 1888, when the New York State Museum bulletins began to appear. In bulletins 3, 7 and 10 (1888, 1889, 1890) Prof. J. C. Smock of Rutgers College reviewed the economic aspects of our building stones and iron ores, but without specific mention of any workings within our quad- rangle. Charles D. Walcott’s papers on the correlation of the Cambrian in bulletin 81 of the U. S. Geological Survey include several mentions of our rocks, especially pages 203-5, 244, 341-42, 363, 381, and the maps of plates I and II (1891). Incidental value attaches also to the papers by Prof. C. H. Smyth, jr, then of Ham- ilton College, ‘““A Geological Reconnoissance in the Vicinity of Gouverneur” in the Transactions of the New York Academy of Science, 12: 97-108 (1893), especially pages 102-4; and “ General and Economic Geology of Four Townships in St Lawrence and Jefferson Counties” in the 13th Report of the State Geologist (1894), pages 491 to 515, especially pages 500-11; and by Prof. N. H. Winchell, geologist of Minnesota, on “The Potsdam Sand- stone at Potsdam, N. Y.” in the 21st Minnesota report, pages 99 to 112 (1893), all of which have been cited in the preceding pages. PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 55 1894. Map work was resumed in 1894 with the appearance of Hall’s “ Preliminary Geologic Map of New York,” a large wall map compiled by W. J. McGee of the U. S. Geological Survey, followed by Dr F. J. H. Merrill’s “Economic and Geologic Map” of the State, which was reissued in Bulletins 15 (1895) and 85 (1905). The latter marks no advance in the knowledge of our area, while the former recognizes the inadequacy of previous work by leaving most of our region blank! Attention thus being directed to our needs, results soon followed. 1895. Mention may be made here of the fourth edition of Dana’s “Manual of Geology” for its improved classifications and its con- cise summary of previous knowledge, which render it a starting point for future work (1895), and of an important paper by Dr R. W. Ells on “ The Potsdam and Calciferous formations of Que- bec and Eastern Ontario” (Can. Roy. Soc. Proc. and Trans., 12, sect. 4, p. 21-30, 1895), in which he argues for the union and even (citing Emmons, p. 347) partial contemporaneity of these two groups (a view later urged by Grabaw), and assigns the Potsdam to the base of the Ordovician (“Cambro-Silurian”). Ells’s remarks apply, of course, to the fossiliferous “ white Potsdam.” In the same year, Winchell again declared his belief in the Keween- awan age of the true (red) Potsdam at Hannawa (American Geologist, 16: 205-13) and in 1897 Merrill discussed the road metals of the State (bulletin 17) with maps still based on the old surveys. More important was Merrill’s “ Guide to the Study of the Geological Collections of the New York State Museum” published in 1898 as Bulletin 19 of the museum; particularly pages 141-47, 187-88, 216 and 219. The handsome map in this bulletin adds little to the early work on our area. ; 1598. In 1898 appeared Mr Edgar G. Blankman’s ‘ Geography of St Lawrence County,’ with a section on its geology (pages 29 to 31) and a small colored map based on that of 1842. A new era began, however, with the advent of Prof. H. P. Cushing of Western Reserve University, whose “Report on the Boundary between the Potsdam and Precambrian Rocks North of the Adi- rondacks” constituting pages 5 to 27 of the 16th Report of the State Geologist (1898) recorded the first detailed formation trac- ing in this region since the days of Emmons. Professor Cushing worked into the Canton quadrangle from the east, but did not cross it, being interrupted by the close of his field season. He recog- nized, however, the great difficulties presented by the drift-laden 56 NEW YORK STATE MUSEUM area encountered here (page 26), together with the irregularity of the sub-Potsdam surface (pages 6 and 14); he also pointed out the distinction between the lower and upper portions of the “ Pots- dam” and the upward gradation of the latter into the “passage beds” to the “ Calciferous”” (page 13). While he noted some dis- turbance of the strata, he ascribed it to the faulting with which he had been familiar in the Champlain valley, applying this explana- tion to thé gneiss exposed at Potsdam village and the red sandstone area at Hannawa Falls (pages 13, 14, 24). Hus statement (page 24) that the rocks along the Raquette from Potsdam to Norwood “are all with the same dip [northwesterly], and manifestly in a continuous and undisturbed section” shows that time limitations prevented his seeing all the exposures, and must today be qualified. 1899. The epochal nature of the times was signalized in two other quarters. Through three different media Dr John M. Clarke and Prof. Charles Schuchert wrought a revolution in the classifi- cation and naming of the New York Paleozoic formations (Science 10:874-78, December 15, 1899; Amer. Geol., 25 :114-10, February 1900; Memoir 3 of the New York State Museum: pages 8 to 12,1900). For “Calciferous sandrock ” of Eaton and Emmons they propose the name Beekmantown limestone, and restore the early names Taconic and Champlainic in place of Cambrian and Ordovician. In the following year (1901) Director Merrill of the Museum put out the present standard “ Geologic Map of New York State” on the same scale as the McGee map of 1894, which it was intended to replace. For our area Cushing’s boundaries and unpublished work by Smyth were used. This represents the last mapping done on the Canton district until Doctor Martin and the writer entered the field. toor. In directions other than mapping much, however, has been accomplished in the past sixteen years. In the 19th Report of the Geologist, pages r9g8 to r103 (1901) Smyth described minutely the character of the Potsdam sandstones and of the surface on which they were laid down, in the Thousand Islands region; and in the 20th report page r37 (1902) the existence of the Adirondack pene- plain is suggested by Cushing for our county. The character of the Potsdam invasion is discussed by Dr E. O. Ulrich and Professor Schuchert in Museum Bulletin 52, pages 636-37 (1902). In. Bul- letin 56 of the same year, Merrill describes the new state map (of I9Q0I), reviewing in a table the classifications of our rocks from 1823 to date. Walcott in 1903 (Journal of Geology, 11:318) pro- posed Saratogan (“Saratogian’’) to replace Potsdamian for the PALEOZOIC ROCKS OF THE CANTON QUADRANGLE 5 NI Upper Cambrian, and in the same year the Museum issued a Hand- book (no. 19) on the Classification of the New York Series of Geologic Formations, followed in the next year by one (no. 17) on Economic Geology, and an important short paper on the “ Eco- nomic Products of St Lawrence County” in the 22d Report of the Geologist, pages r118 to r124, by Prof. W. N. Logan, then of St Lawrence University. The activity of this first five years of the new century culminated in the appearance of Cushing’s great bul- letin (95 of the State Museum) on the “ Geology of the Northern Adirondack Region,’ indispensable companion of all subsequent workers. The pages that bear particularly on the problems of our own quadrangle are 276-89, 354-64, 386-94, 403, 406 and 418. Since this is available at a nominal price to all, it is useless here to do more than acknowledge again our great indebtedness to it. 1906. Fire tests of the Potsdam sandstone were reported by W. E. McCourt in Museum Bulletin 100 (1906) and D. H. New- land summarized Smyth’s theory of the origin of the red iron ores in Bulletin 112, page 38 (1907). The name Theresa for the “passage beds ” was proposed by Cushing in the Geological Society of America Bulletin 19, page 160 (1908) and coincidently in the Director’s Report (Bulletin 121), page 12, together in the former journal with a resumé of the Paleozoic stratigraphy and geography of our region, a subject which was also assailed by Dr A. W. Grabau of Columbia University (Science, new series, 29: 351-56,- 358; Journal of Geology 17: 211-26; 1909) who readvanced the theory of Emmons and Ells. In 1909 also, H. Leighton published in the Director’s Report (Bulletin 133, p. 115-55) a list of geologic maps of the State and a color reproduction of Amos Eaton’s New York State map of 1830, the first geologic map of the State. This five-year period culminates with the reentry of Doctor Ulrich in the field of New York stratigraphy (Museum Bulletin 140, pages II, 127 to 140, in which the name Tribes Hill limestone is pro- posed).and the publication of the “ Geology of the Thousand Islands Region” (Bulletin 145; 1910) by Cushing and others (see pages 14-24, 53-68, 78 footnote 2, 92-97, 112-18, 120-26). A note by Dr P. E. Raymond in the American Journal of Science for the same year (30:344) suggests the Ozarkian rather than Canadian age of the Tribes Hill. ro1r. The last five-year period opens with Ulrich’s “ Revision of the Paleozoic Systems” (Geological Society of America Bul- letin 22: 281-680, 1911) and the geologic map of North America 58 NEW YORK STATE MUSEUM by Bailey Willis (Washington, 1911) followed in i912 by its description in professional paper 71 of the U. S. survey: “Index to the Stratigraphy of North America” which gives a summary of everything to date (consult pages 120-27, 183-86 for our area). The State Museum also put forth a revised edition of its Hand- book 19 on “ Classification of New York Series,’ which is the present standard. In 1914 came Prof. W. J. Miller’s “ Geological History of New York State” (Bulletin 168), in which special reference may be made to pages 41 to 51 and others; and Cushing, Martin and Chadwick reported progress on their respective fields in the Director's Report (Bulletin 173) pages 61-67. The last papers to mention are Chadwick's “ Post-Ordovician Deformation im the Saint Lawrence Valley” (Geological Society of Amer.ca Bulletin 26:287-94; 1915) in which the names Heuvelton and Bucks Bridge were first employed and a black and white map of the Canton quadrangle Paleozoics was given, and the stratigraphic tables in Bulletin 92 of the U. S. National Museum, by Bassler. In addition to these, Professor Cushing’s bulletin on the Ogdens- burg and Brier Hill quadrangles will probably be issued before this paper is printed. In the above catalog no account has been taken of publications on the surface geology, that being reserved for the time when the Pleistocene formations of our quadrangle shall receive the special description that they merit. Papers purely paleontologic have been omitted for citation in the text. Of the works named, the most indispensable to local student or amateurs are probably Bulletins 95, 145 and 168 of the State Museum, which may be secured at small cost from Albany, Logan’s economic report in the 22d of the State Geologist (56th of the Museum), the revised edition of Handbook 19 which is free on request, and the U. S. Geological Survey professional paper 71. Emmons’s 1842 Report on the Second District and the 1863 Geology of Canada are still useful and may be obtained at old book stores. The last state map (1901) is now sold in atlas form only. INDEX Abandoned channels, 51 Babcock, O. A., acknowledgments LOWS Basal contact, 17-20 Beekmantown (Ogdensburg) dolo- mite, 8, 30-30 Benway hill, 6 Billings, Erle M., acknowledgments to, 5 Black lake, 24 Blackwelder, cited, 37 Blankman, Edgar G., cited, 6 Boyden brook, 14 Brandy brook, 32 Brooks, cited, 18 Bucks Bridge, 26, 28, 30 Bucks Bridge mixed beds, 8, 28-36 Burling, L. D., cited, 20, 47 Cameroceras tenuiseptum, 38 Canton, 5, II, 16 Casey Corners, 26 Clarke, Dr John M., acknowledg- ments to, 5 Concealed zone, 20-24 Crary Mills, 14, 15 Cryptozoon, 39 giganteum, 39 lachutense, 30 minnesotense, 39 saxiroseum, 39 steeli, 39 wingi, 39 Cushing, Prof., acknowledgments to, Becited os, 15, 172 2024) AA Dictyonema flabelliforme, 33 rectilineatum, 33 sociale, 33 Dinorthis pectinella, 40 Eccyliopterus, 31 planidorsalis, 38 Economic resources, 52 Ells, Dr-R. W., cited, 15, 20 Emmons, cited, 18 Endoceras montrealense, 38 Euomphalus uniangulatus, 27 Fenton, Rev. C. Hk, ments to, 5 Ferruginous conglomerates, 52 acknowledg- Geological history, 42-48 Glaciation, 49 Grannis brook, 14 Grassy fiver, 7. 133) LO.255 2m Geese Grass River valley, 33 Hannawa Falls, 25 Harrison creek, 13, 14 Helicotoma uniangulata, 27 Hemipronites apicalis, 39 Heuvelton, 25, 20 Heuvelton ledges, 25 Heuvelton white sandstone, 8, Hewittville, 30, 33, 30 Hewittville beds, 33-36 Hough, cited, 15 Hunt, i. S5 ‘citeds 18 26-28 Indian Creek swamp, 21 Iron ore, 53 Kindle, E. M., cited, 20, 47 Limestones, 52 Lingula acuminata, 38 antiqua, 26 Lingulepis acuminata, 26 sequens, 38 Literature, 53-58 Maclurea compare sordida and matutina, 38 Maclurites sordidus and matutinus, 38 Madrid, 30, 39 Manley, G. A., acknowledgments to, 5 [59] 60 NEW YORK STATE MUSEUM Maps, 53-58 Martin, Dr, acknowledgments to, 5 Morley, 25, 26, 30 Nettle creek, 30 Newland, D. H., cited, 18 Norwood, 26, 27, 30, 31, 37 Ogdensburg dolomite, 8, 36-390 Ophileta compacta, 31 complanata, 30, 31 levata, 31, 38 Orthis pectinella, 40 Orthoceras brainerdi, 38 compacta, 38 complanata, 38 montrealensis, 38 tenuiseptum, 38 Oswegatchie river, 25, 20 Palaeophycus beverleyense, 29 Paleozoic record, 42-47 Phelps, Mrs C. S., acknowledgments to, 5, 14 Phelps, Prof. ments to, 5 Pierrepont, 15 Pleurotomaria hunterensis, 30 Polygyrata complanata, 31 hunterensis, 30 Polytoechia apicalis, 39 Postglacial shorelines, 50 Potsdam sandstones, 8, 11-16, 43 Potsdam village, 21 Preglacial erosion and drainage, 49 Proterocameroceras brainerdi, 38 Pyrites, 14 C. S., acknowledg- Raquette river, 7, 24, 26, 30, 31, 32 Raquette valley, 33 Raymond, Dr P. E., cited, 41 Rensselaer falls, 21 Rhynchotrema inaequivalve, 30 increbescens, 39 Ruedemann, Dr, to, 5; cited, 10 acknowledgments Sandstones, 52 Scolithus canadensis, 28 Shaw, Eugene Wesley, cited, 48 Shea, John A., acknowledgments to, 5 Sissonville, 21, 26, 27, 28, 32 Sissonville dam, 24 Slab City, 26 Smock, cited, 18 Smyth, cited, 18 Stictopora elegantula, 40 Stony brook, 26 Stony Brook falls, 28 Stratigraphy, resumé of, 41 Surface geology, 48-52 Syntrophia lateralis, 38 Theresa mixed beds, 8, 24-26, 36 Trenton limestone outlier, 8, 390 Tribes Hill beds, 9, 36, 41 Triplesia lateralis, 38 Trout brook, 7, 26, 31;)32) sauce Ulrich, Dr, acknowledgments to, 5; cited, 9, 27, 36, 37 Van Rensselaer creek, 15 Vanuxem, cite’, 18 Veitch, Alexander, acknowledgments to, 5 Waterman hill, 14, 20 Waterman Hill drumlin, 6 West Potsdam, 21, 25, 31 Winchell, cited, 18 Wind work, 52 ee a ee er < = ee : a EE ee Se eet eee - a -PALEOZOIC R it JOHN M, CLARKE STATE GEOLOGIST UNIVERSITY OF THE STATE OF NEW YORK STATE MUSEUM ~ 2978 Ting Coding . aXe im BULLETIN 217-18 PALEOZOIC ROCKS OF THE CANTON QUADRANGLE Scale axs60 St o a 2 3 : 3 o a 2 > “ Geology by George H. Chadwick. = Miles Kilometers 3 (er ee Contour interval 20 feet. Dane ix mean 20a level. CHAMPLAINIC CAMBRIC (OZARKIAN) SYMBOLS CONVENTIONAL i 1 ' 1 1 t { | 1 1 1 t Bucks Bri mixed re DISCONFORMITY pene Houvelton sandstone. Rio Chie Theresa mixed bods. (Probably Including some Potsdam in the concealed area.) Potsdam sandstones. UNCONFORMITY f =| [essa Less] Known contacts, feo [ers] Inferred contacts [ye] Dip and strike of neared oUtorop, 43 Numbors refer to descriptions tu the coxt. x Quarries. A A Lines of sections Wells. Actual exposures are shown by red spots: i a . | aa 4 4 a Hd NEW YORK STATE MUSEUM BULLETIN 217-18 CANTON QUADRANGLE GEOLOGIC CROSS SECTION DIAGRAMS (Slightly enlarged) ALONG LINES A-A TO E-B, SHOWN ON MAP WITH MUCH ENLARGED SECTION AT LOCALITY 80 , = MOREY RIDGE —, Ao ip LZ, Zy, v ARLE Wf eo ees) BUCK Ss BRIDGE Norwoop ue v eases Section at 80 (WEST) SCALE C= et — 100 FEET bain sas ere: a ; ee iy pais a4) rit rere ; TY arer Beeeetgpe aR hha d sAAR, pap sansa dar 48, a ae Qgeslanne*\., ‘aa ' a EeAa j an pann®s 3 iN Rat | aa, F en tel canbe nn hina. Wee Nala aaa) “ “4* Bray pat SO ge = = magn hAet: 5 werent me nen? af AR TT) | : seem a: ‘ aaaa. 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