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HITCHCOCK, NEW YORK: rur.i.isiiKi) v.\ iri.iL's iuf.n, is i'ark i'lack. i88:(. • • ••« •• •••* • •••«• •• •«* •• I k • t 1 I • , , at! I I • > . - - . *i» •••'till It I 111 S t 1 » 4 8 * > • A « • ft • • • • . ■' *• • • • ••■ • • • •• ••• •••• •••• • ••• "• •• •• •• • • » • GEOLOGICAL MAPOFTHE UNITED STATES, COMPILED HV C. H. HITCHCOCK. ■' Since printing the pamphlet, we have been enabled to color approximately the outlines of the Eocene and Mio- cene in Florida, as furnished by Prof. E. A. Smith, the details to be published in the American Journal of SciKXlE. « « <;. M. DAWSON, C. E. DUTTON, S. F. KMMON'S,' W. .M. FONTAINE, G. K. GILBERT, ARNOLD HAliUE, .1. r. LKS1.1^\, S. S. I. VON, w. J. .M((;kk, J. S. NEWBERRY RICHARD OWEN, J. W. POWELL. C. A. UHM JH;XS, \V. M. KONTAINE, G. K, GILBERT, ARNOLD I [AGUE, JAMES HALL, E. V. HAVDEN, E. W. inLi;ARD, E. S. HOLMES, E. E. HOWELL, T. STERR\' IH'NT, \y. C. KERR, CLARENCE KLNCi, H. C. LEWIS, j. W LESLEY, S. S. LVON, W. J. McGEE, J. S. NEWBERRY. RICHARD' OWEN, , J. w. 1'owi:ll. R. I'UMPELLV, W. B. ROGERS, J. .M. SAFEORD, A. R. C. SELWYN, N. S. SilALER, E. A. SMITH, J. J. STEVENSON, G. C. SWALLOW, W. Ll'IIAM, C. A. WHITE, R. 1'. WHITEEIELD, J. D. WHIINEY, A. WINCHELL, N. H. WINCHELL, A. IL WORTHEN. All the i)ublished reports by the United States and State Goverments, as well as the minor publications enu- merated in Frederick Prime, junior's catalogue, have been made use of as far as practicable. Tlie effort, to prepare this map took shape nearly fifteen years since. At first we proposed to issue separate niajjs of the different States and territories, using such scales of dimension as best suited the perfection of the facts and the size of the districts. These maps were to have been published in atlas form, accompanied by descriptive text, prepared, when possible, by the authors of the respective maps. In answer to our solicitations, many maps and manuscripts made their appearance, some of which have since been published ; but our desire for greater accuracy of information and its accpiisition by tedious held-work in New England prevented the execution of the original scheme. Meanwhile we have presented to the public an epitome of our materials: hrst, in connection with the report of the Superintendent of the Ninth Census ; second, in the report of the Commissioner of Mining Statistics ; thirdly, in Walker's Statistical \tlas, 1874; and founhly, upon a large scale for the exhibit of the Smithsonian Insti- tution at the International Exhibition at Philadelphia in 1876. Prof. W. P. Blake assisted us in the (^reparation of these f(jur editions. We have now to announce the completion of our labors in the publication of this geological map of the L^nited States, by Julius Bien, of New York. The base used is the Centennial map of the United States (edition of 1879). drawn upon the scale of twenty miles to the inch. This gives, when mounted, a sheet thirteen feet long and eight feet wide. It is made for a wall map, and hence cannot exhibit minute details of topography. The principal lakes, rivers, railroads, cities, towns, railroad stations, mountain ranges, and all the counties are represented. Prof. Blake has prepared for us the coloration of California and por- tions of Nevada and Arizona. We have not yet a universally acceptable scheme of ? ■' i\ nomenclature for the formations, nor have ^rcologists agreed as to the C(ilors which will most appropriately designate them. Our endeavor is to employ those names of groups which are in common use, with the frequent mention of synonyms. The minute suodivisions of the New York and other systems of classifications cannot be carried out all over the country, and therefore many dit>iculties ol termi- nology are avoided, since only the more general terms need to be stated. The following table expresses the classification adopted in the legend: Quaternary. Newer. Middle. Older. o o u •s Laramie or Lignitic ^n-oup. Cretaceous. Jurassic and Triassic. Permo-Carboniferous. Upper Coal Measures, usually above the Pitts- burg Coal. Lower Coal Measures, including the Millstone Grit. Lower or Sub-Carboniferous. Devonian |Catskill to Oriskany|, Upper Silurian [Lower Helderberg to Oneida]. Lower or Cambro-Silurian [Lorraine or Hudson River to Calciferous Sandrock]. Cambrian. Huronian. Gneiss of Atlantic slope, including Montalban, and metamorphic Paleozoic. Labrador or Norian. Lauren tian. m •^ I Granite. a' I Volcanic. ^ i. Southern margin of the Eastern American ice s'aeet : also, terminal moraines east and west of Ohio. The Quaternary includes recent rivei deposits, oceanic additions to the Tertiary continent, desert sands, and lacustrine deposits of the Far West. An attempt is also made to show the course of the supposed glacial terminal moraines, from Cape Cod to the Saskatchewan region. The terms Pliocene, Miocene, and Eocene are essentially synonymous with our designations of Upper, Middle, and Lower Tertiary — the latter allowing more latitude of refer- ence than the former. The Laramie group is represented by itself, partly because of its importance, ana partly be- cause of some disagreement as to its exact place in the sei.es. Perhaps a twofold subdivision of the rest of the Cretaceous might have been practicable. I^rominence is given to the scverc'l members of the Carboniferous, because of the economic importance of the Coal Measures. Recent observations suggest the presence of several areas of the Permo-Carbouiferous, both in the east and the west. The evidence for it in Pennsylvania and West Virginia is less satisfactory than in Texas, Indian Territory, Kansas, and Colorado. The lower division of the Coal Measures ex- tends to include the conglomerate at their base, and hence to include a larger area than is actually underlaid by workable coal. The Catskill group is taken for the upper and the Orishany for the lower limit of the Devonian, though there is a diversity of opinion as to the pro- pria y of this restriction, especially as to the lower mem- ber, which is very commonly placed with the Silurian. The commencement of the Lower or Cambro-Silurian 1 * ■ V \ ^ a with th.> Calciferous Sandrock is generally acceded to at the present day. Some prefer to write Siluro-Cam- brian instead of Cambro-Silurian, as originally proposed by Sedgwick, and quite extensively used by English geol- ogists. The word Cambrian suggests a world of conten- tion. Our representation (.overs the areas termed by authors the Potsdam, Acadian or St. Johns, Keweenian or Kewenawan, Lake Superior, St. Croix, much of the Taconic, etc., besides various mica schist groups in New England, and the itacolumites ot the Southern States. There is not entire agreement in the reference of man}- eastern terranes to the Huronian. Certain areas in Mich- igan and Wisconsin might be correlated with the gneisses of the Atlantic slope, commonly called McMitalban ; but in the present state of opinion it has not seemed best to separate them from the Laurentian. 1 understand the Montalban to represent gneissic areas in the upper part of what might very naturally be called Laurentian. They underlie the Huronian and seem to be unconformable with the Laurentian beneath. Some authors regard the Montalban as meiamorphic Silurian and Devonian, others aspost-Huronian but preSilurian. The term Upper Lau- rentian was originally applied to the Labrador or Norian series. This group is represented in Canada and New York by a special color, in accordance with the definitions of Logan and Sterry Hunt. In the West, the term Lau- rentian includes cverx thing below the Huronian. Granite, essentially eruptive, is distinguished by a separate color so far as possible. Much more of it remains to be sepa- rated from the Laurentian. The modern volcanic ejec- tions of the West are distinguished as a class without subdivision. The trap division is not represented at all. It is possible to give nii.ch fuller details of the Pale- ozoic formations in the Appalachian region, but not in 8 ff the West; and. thcrelorc, for the sake of uiiiformitv, the smaller series have beei. merged in the larg-er. In the following- text, also, certain special variations in the sii^nih- cance of the colois will be mentioned. After reducinsr the maps of adjacent States, by different authors, to our scale, it often ai)pears that the colors will not fit each other. This may be due to differences of opinion as to the proper limits of the several g-roups or to incorrect maps. To harmonize such differences is a mat- ter of irreat difficulty and often impossible, and has led us to adopt the following principle for our guidance. We assume that each geologist understands his own territory better than any one else, and therefore follow his division lines to his boundaries, where a forced connection is made with his neighbor's delineations. If great incongruities are occasioned by this course, a statement of the case will be made in the following pages. Objection is sometimes made to the attempt to prepare a geological map of the whole United States, that over large areas the character of the underlying formations is not known, and that consequently the student is perplexed by not knowing what is well determined and what is hypothetical. Some suggest that w^here great uncertainty exists. no attempt should be made to represent even what is probable. I have in some cases left blank si)aces in the entire absence of any attempt at exploration. In other cases I have used a broken instead of a solid color, thus enabling all to perceive at a glance where the structure has not been worked out satisfactorily. In some S])ecial cases the difificulties of coloration a/e particularly de- scribed. With these general remarks we proceed now to state specifically what authorities have been used for the repre- sentation of the geology of all parts of the map. Vet we A i have not space enouj^h to acknowledge many of the smaller items of information kindly furnished by our corre- spondents. DOMINION OF CANADA. Every possible facility for the acquisition of the latest information about the distribution of the formations in that part of Canada embraced in our map has been cheerfully furnished by A. R. C. Sehvyn, the accomplished Director of the Geological Survey. The sheets have been submitted to him and his assistants: particuh rly Prof. R. Bell and G. i\i, Dawson, and their suggestions of improvement have been followed. In fact, Prof. Bell colored, with his own hand, the x^gion north of the paleozoic basin, from Quebec across to the Rocky Mountains. From Lake Winnipeg to the Pacihc Ocean we follow the guidance of G. M. Daw- son. Logan's map of 1865 correctly represents the fossilifer- ous groups from Quebec to Lake Superior. For the east- ern townships region, the views of Sterry Hunt and Sel- wyn are adopted in placing the Lauzon and Sillery beneath instead of above the. Levis, the latter containing many primordial types of life. The Canadian extension of the Vermont Green Mountains is referred to the Montalban because it underlies the Huronian. East of Sherbrooke P. Q., the calcareous rocks were referred to the Upper Silurian by Logan. As they seem to merge into the Coos and Calciferous mica schist groups of Vermont, and the latter are by Dana referred to the Lower Heldcrberg, I have represented their age south of Canada as doubtful. In order to call attention to the existence of a gneissic scries m Ontario newer than the Laurentian, though its place in the column is unknown, we have r )lored the Hastings group of Vennor the same as the Montalban. lO 1 1: There is a diserepancy in the maps of the country be- tween the Lake of the Woods and Red River. Bigsby, in 1842 yQiiar. Jour. GeoL Soc, London), described Upper Silurian limestones in situ upon the west shore of the Lake of the Woods. Prof. Hind, in i860, extends this group of fossiliferous rocks westerly and southerly into Minnesota, to the latitude of 46°. Logan's maps differ. The small one makes a broad strip of Devonian extend entirely through Minnesf)ta to connect with the exposures of this age in Iowa. This is accompanied by a br(.)ader area of the Trenton from Red River to Lake of the Woods, and to Lat. 45°, where its width is much diminished and is continuous into Iowa. The larger map has the Devonian terminate abruptly about twenty-five miles south of the international boundary ; and the Trenton has less width, reaching to Todd and Douglass counties. West of the Lake of the Woods is an area of Niagara, continuous thence along the international boundary to Rainy Lake. G. M. Dawson, in the Boundary Survey, colors the en- tire area between the Lake and Red River as Paleozoic. Professor Bell divides this area midway between these points, giving half to the limestones and half totheLauren- tian ; and thinks the supposed fossiliferous outcrops about the Lake of the Woods consist of transported lioutders. Our representation shows all of northern Minnesota as un- certain — by means of broken colors — and disposes of a part of the troublesome area by giving the limits of the former glacial extension of Lake Winnipeg — called Lake Agassiz by the Minnesota Geological Survey. From Lake Traverse to the mouth of the Saskatchewan, there is hardly a rocky outcrop — so that the use of the yellow color for the Qua- ternary is eminently appropriate. To the north of the Sas- katchewan, where the ledges are plenty, the limits of the lake are also shown by suitable markings. Many of the i n II 4 enormous Huronian areas east of Lake Superior are shown in broken colors, because their limits have not yet been worked out. Concerning the representation of the coun- try west of the Rocky Mountains, remarks will be made further on in the mention of Washington Territory. NEW ENQLAND. The compiler is alone responsible for the delineation of the geology of New England— making use of all the offi- cial reports, so well known, combined with personal field- work. The map, when mounted, well shows the difficulty of calling the New England gneisses by other names than are commonly assigned to them from Alabama to the Highlands of the Hudson, /. i\, Laurentian with pre-Silu- rian accompaniments. The range is a continuous one from Alabama to Canada, consisting of gneisses, and bordered first by the Cambrian sandstones, derived from the ruins of the gneiss; thence by the great Appalachian Lower Silu- rian limestone valley. If orography is determined by stratigraphy, then the gneisses of New England are mainly of pre-Silurian age. A contour or relief map would illus- trate this position even more strongly than colors. The typical Montalban rocks in New Hampshire under- lie the Huronian ; and we understand the same to be true of all the gneisses upon the Atlantic slope colored as dis- tinct from the Laurentian. The Laurentian areas in New England are usually ovoidal in shape, and of limited ex- tent ; and in the [-ri.neval history must have formed a con- geries of islands before the interspaces became filled by the Atlantic gneisses. The more important of them are Formations K2. K3, of Percival, in western Connecticut ; Formations A and B of Percival in caste.n Connecticut, with their respective continuations into M issachusetts and Rhode Island ; the Stamford granite and gneiss east of 12 Bennins^t-on. and. the Chester gneiss range of Vermont ; gneissic areas east of Worcester, and underlying the Bos- ton Cambrian basin in Massachus'jtts; the porphyritic and Bethlehem protogene tracts in New Hampshire and the coastal gneisses east of Portland in Maine. Eruptive granites are distinguished in New England. Canada, South Carolina, Cieorgia, and to a limited extent in the far west. This is but a tithe of what will be sepa- rated from the gneisses hereafter. NEW YORK. Our authorities for this State are mainly the published map of the Geological Survey, and a manuscript map pre- pared by Prof. R. P. Whitelield, showing the improvements obtained under the directions of Prof. James Hall in the Catskill mountain region and elsewhere, and exhibited to the public in the American Museum of Natural History at Manhattan Square. East of the Hudson. Prof. Dana's recent ol)servations may authorize us to enlarge the Lau- rentian area called Ki. by Percival. We accept his the- ory of the superior position of the Westchester county gneisses to the Laurentian ; but cannot yet see the way clear to call them Silurian. Farther north we follow Mather's view of the Lower Silurian age of nearly all the rocks east of the Hudson, taking note, however, of certain limited Cambrian exposures, and anticipating a greater ex- tension of them hereafter at the expense of the clay slates and talcoid schists once referred to the Taconic system. In the Adirondacks an area of Labrador is given, as well as possible, from Prof. Emmons' limits assigned to the hyper- sthene rocks. Various hints suggest the future discovery of Huronian and Montalban terranes within this elevated district. Mather's reference of the Long Island division to the Cretaceous seems to be confirmed, while the Tertiary may also occur beneath the Quaternary. 13 i NEW JERSEY. i'n^i. G. H. Cook's latest reports are followed impli- citly. He does not state definitely in his printed reports which division of the Tertiary prevails in the low ground next to the ocean, for want of outcrops ; but authorizes us to call it ui)per Tertiary as far as Chesapeake Bay. The former extent of the Hudson River valley out to sea is shown off the coast of New Jersey bv the sub-marine con- tour lines. What the age of the formations mav be in this submerged district is doubtful. Perhaps the' discovery, by Cook, of Devonian fossils in certain Cretaceous beds as rolled pebbles may indicate the presence of Paleozoic strata in this lost Atlantis. PENNSYLVANIA. The Second Geological Sur\c\- is in progress, and its results have been utilized by us for the following counties: hne. Crawford, Mercer, Venango, Lawrence, Beaver, But- ler. Washington, Alleghany. Westmoreland, Fayette, Arm- strong, Clari(Mi, Greene, Fulton, Blair. Huntington, Adams, York, Lancaster, Lehigh, Northampton. Daui)hin. Lebanon, Northumberland, MuaUmi; Union, Snyder, Pcrrv, Clinton.' Lycoming, Sullivan, McKean. Tioga, and Potter. Else- where Rogers' map has been followed, and made to tit the new coloration somewhat arbitrarily. The members of the survey differ in their estimates of the age of the crys- tallines along the Susquehanna. Frazcr's maj) of the gneis- sic areas is so unlike that of Rogers, and of Tyson in iMary- laiul. that the forcing of a connection between them is less lelicitous than usual. It seems to us as if the lower Car- boniferous group has too great an extension in the north- eastern part of the State. uiK)n which the Second Survey liave not yet i-eported. If the CatskiU sandstone were 14 distinguished upon our map, it would display the contuiu- ation of all the Carboniferous synclinals into New York. MARYLAND, DELAWARE, VIRGINIA, WEST VIRGINIA. No chanj,^es have been made in the delineation of Mary- land and Delaware since the publication of the Census maps. For the Virginias we have had. first, the use of Prof. W. B. Rogers' manuscript ma]); second, the i)ublication of the same upon a small scale in the report of Maj. Jed. Hotchkiss ; third. Prof. Rogers' note> m Macfarlane's rail- way guide; fourth, letters from Prof. W. M. Fontaine, of the University of Virginia ; and fifth, the Virginias h\ Maj. Hotchkiss. The railway guide gives us the reference of the Fairfax gneiss areas, west of Richmond, and from Lib erty to near Lynchi)urg, to the Laurentian ; and the Meso- zoic areas south of Richmond. Prof. Fontaine named for us the Laurentian west of Lynchburg and Amherst ; and furnished us a tracing showing the Huronian limits from the Potomac to Willetts mountain. Subsecpiently he writes that these limits may be extended farther, viz., "the three counties of Floyd, Carrol, and Grayson are ccmiposed of metamorphics like those fcjund composing the Blue Ridge further north; c g. at Harper's Feny. Hence they are Huronian, if there is any Huronian in the Blue Ridge ranges. The line of junction of the jnetamorphics and primordial rocks is to be found almost always, if not always, just along the sf)utheast foot of the ranges called Pilot, Poplar-Camp, and Iron mountains. The metamorphics are hydro-mica and chlorite slates, sometimes with cpidote ; some hornblende schist ; a great deal of felsite, sometimes with copper ; also a singular gneissoid rock, having shot- like particles of bluish quartz, of a waxy lustre, etc. ^'ou will note that the range of Iron mountain near Balsam i i 15 mountain liciuls south, while it dies clown in the orif^inal southwest direction. The new ranjre, now called Iron and Smoky, is, near White Top. certainly Huronian if we have any in the Blue Rid^e." This letter ajj^rees with a map of this neij^borhood by R. O. Currey, made in 1859, and published in the Virginias for April, 1880; though the term Huronian is not used by Currey. It also seems to ajj^ree with the map of Professor Kerr in the North Carolina geological report, whose two Huronian bands correspond nearly with the position of the Virginia areas as described by Currey and Fontaine. Dr. T. Sterry Hunt, on the contrary, is (|uite positive that these two bands in North Carolina should be referred to the primordial, the eastern band extending into Georgia to merge into the itacolumite or "principal gold region" of the geological map published m White's Statistics of Georgia. Our representation of these areas follows the latter author for North Carolina, and no effort is made to separate any of the Eozoic groups in Alabama and much of Georgia. THE ATLANTIC PLAIN. Adjoining the coast from New Jersey to Florida, and thence through the Gulf States, is a low, broad country, sometimes called the Atlantic plain, underlaid by Cretaceous and Tertiaiy beds, which are commonly concealed bv the Quaternary. It is most perfect in its devel()i)ment in the Gulf States, where the upper Cretaceous line mav be sev- eral hundred feet above the sea: to the north of Georsria the rivers wind thi-ough marshy districts after leaving the crystallines. It is not dititicult to see that they are drowned lands, and entirely submerged east of New York, save the islands Long, Block, Martha's Vineyard, etc. The plain is traceable by soundings to join the Great Banks of New- i6 fouiullaiul, and the fishcniR-ii constantly l)rinfr in Teitiar\- fossils from this ])lateau cast of Ca|)c Cod. The forma- tions do not skirt the land roncentricallv over this entire plain, as several anticlinoria aiul svnclinoria are easilv made out. The first basiti is in Georji^ia, the second in South Carolina, the thirJ in the southern part of North Carolina, tin- fourth in North Carolina, merjLjinti;' into that depression into which the James, York, and Potomac rivers flow, inakinj^ Chesapeake Bay. Because of the lowness of this land, the formations are not well defined ; and ue color them, as seems best, after studyinjj^ Tysori's map of Marx- land, Roi^jers", of Virj^^inia, Kerr's, of North Carolina, Tuo- mey"s, ol South Carolina, Lvell's (^1845), ^' Cjeorj^ia. Florida is represented as wholh- Quaternary ; but Conrad has described Eocene fossils from its northern portion. Mil- i^'ard has distiny;uishcd himself bv the patient unravelling;' of the embayment of the Mississi|)pi vallev, includinj.j the demonstration of a a^reat elevation of Lower Louisiana since the Tertiarv ; and we re<^ret that we cannot present all his subdivisions; enouj^h is as patiently answered numerous cpiestions concerning the Minnesota focks; and he regards the present coloration as j)rovisional. We get, however, a great improvement over the delineations ot the earlier edi- tions. The use of Lake Agassi/ has been already men- tioned. No systematic explorations of the northern [)()r- tions of the State have been made: and the colors are broken, where the compiler would have prelerred to leave a blank space, after reading the reports ol School- craft. Nicollet. Owen, Logan. Dawsor, Bell. Hind, aiul WincheU. W'rv few ledges occur, the countrx being cov- ered b\- drift. The areas of Silurian. Dexonian and Cam- brian east of Lake Agassiz may possibly ha\e no better tenure than the presence of erratic blocks derived bom the northwest. Professor Bell has described mimilely sev- eral bands of the Laurent ian and Iluronian along \\\v international boundaiw b'om the Lake ol the Woods 1o Lake Superior, and these are made to extend lar into 21 iMinnesola. Tlic Vermilion Lake terranc is traced across to Alexandria. The Lanrentian is contined to the nor- thern part ol the State; or, at least, the reference of the iiianite and i^neiss ahuii;- Minnesota ri\cr to this series is donbtfiil. The Lanrentian and Huronian rocks occnr in oval patches in Minnesota, as in Michi.^-an and Wisconsin, rather than in one hn.ad stripe, vet niakin,ir an Eozoic i)roniontorv reachin,;^ nearly thronijh the State, the counterpart of the Adirondack peninsnla in New ^■ork. Abrupt connections in the colorini,r between Minnesota and Canada represent dilferences of opinion as entertained bv the respective ^ovennnent ,<;-eolo,t;-ists. One of the Minnesota areas of Huronian reaches to Taylor's Falls on the St. Croix, and is su.y;,i,a"sted by Winchell as the con- tinuation ot the same rock a tew miles distant in Wiscon- sm. Only a thin coveiiii;^- of I'otsdam conceals it between the known outcrops. The (piart/ites. etc.. of the i)ipestone region are rejrarded as Potsdam. Ouite an CAtensive area of {juartzite <,nieiss and granite is covered by the Cretaceous in the southwest part of the State. If it were possible to use both the pink and <,n-een colors lor the same area we should do so here, as the country is essentiallv a Creta- ceous ])lain showiiiij: the crystallines where it has been deeply cut by rivers. Winchell lestricts the Fotsd.im to narrower limits than those represented (after Belli wl. en- it passes into the Dominion adjoininij^ Lake Superior. NEBRASKA, DAKOTA, WYOMINa, MONTANA. The foundation to our kuovled^e of these districts, was ^-iven us by Ilayden in the map accomjjanvini^ the Reynolds expedition, and the final report upon Nebraska. The changes consist in callini;- the Lignite Tertiarv Lara- mie, i^dving some data from the notes of E. S. Dana and G. B. Grinnell, forthe Yellowstone Army Exiiedition. and from the 22 Black Hills map ot Newton, prepared under the direction of J. VV. Powell. Prof. Havden's maps and repoits have afforded us the principal data for the delineation of the immense areas of Wyoming- and Montana. Permission was given iis to cop)' from several of his maps in advance of their publication. In Hayden's map, illustratm^ the Revnolds expedition, the whole of Montana is colon.'d with much precision. That which lies east of the crvstallines has been modihed considerably by Hayden's later ex])editions. He ijives notes of the rocks at Jefferson, Helena, and at the Forks, also panoramic views, but ver\- scanty maj^s. We there- fore follow the Reynolds map, save whciC it has been differently described in later publications. The maps, in the reports of 1877, 1878, for the Yellowstone Park and farther south, are of great value for the northwest part of Wyoming. In the earlier map, all the volcanic and crys- talline rocks were not distinguished from each other; and hence the use of a similar color for the entirelv unexplored region of the west part of Montana and the east part of Idaho must be regarded mereh- as a cover for ignorance. The principal part of Wyoming is likewise taken from the Reynolds map. GOVERNMENT SURVEYS OF TERRITORIES. The elaborate (geological mai)s of the Fortieth Parallel Survey under Clarence King; of Colorado and much of Wyoming under Prof. F. \'. Flavden ; of the Geographical and Geological Surveys under Lieut. Wheeler, espcciallv in New Mexico, Arizona, Utah, and Nevada; of the vari- ous reports prepared under tiie direction ol Major J. W. Powell, as Button's High Plateaus of Utah, the Colorado River and Uintah Mountains, the Henry Movmtains bv G. K. Gilbert, the unpublished map of the Black Hills bv H. 23 Newton, etc., have all been consulted, and so far as prac ticable transferred to our sheets. For New Mexico the data have not been so complete. Our sources of information are J. Marcou's Pacific Railroad and other reports, 1857; Prof. J. S. Newberry's report in connection with the Macomb Expedition ; annual reports by Prof. E. D. Cope and H. Loew to Lieut. Wheeler, 1874; the extension of the coloring? of Hayden's Colorado atlas for about hfteen miles into the territory ; and Prof. J. .T. Stevenson's observations made for Lieut. Wheeler, in a tract south of the north line of New Mexico to hit. 35° 15', and between loui;. 104" 15' and 106^. Cope and Stevenson agree that the Carboniferous strata east of Santa Fe should be referred to the Coal Measures rather tlian the Lower en- Sub-Carboniferous ; and it is likelv that much of what we have referred to the Lower Carbonifenuis in the south- eastern part of the territory and in Texas is of the same age. Prof. Stevenson rtnds gyi)sum beds, similar to those in the Indian Territory and referred to the Tri;'.s, appar- ently situated in the Dakota group of the Cretaceous ; and thus suggests a problem for future study, analogous to that propounded by Mudgc in Kansas, lie also has de- fined for us the eastern limit of the Laramie gnjup, bring- ing it to the Raton Mountains to the southeast of Trinidad, Col. The delineation of the northwest i)art of Arizona and of southern Utah was taken from tlie maps of the Wheeler Survey. Since then Messrs. Powell, Howell, Gilbert and Duttcm have fashioned elegant relief majis of the same regions, |)iesenting differences in detail from the the origin.al Wheeler sheets. I have followed the later authorities in the coloration of the volcanic masses in N. W. Arizona, and in minor changes about the Acpiarius plateau in Utah. The Permian in Arizona is given ap- l)roximately from information furnished by C. D. Walcott. 24 The Huronian is ^-iven for the Black Hills, but not tor any other ])art ot the territories, although supposed bv Kin^ to exist extensively in them, especially in the more eastern portions. North of the Fortieth Parallel Survey, in Wyomino- and Nevada, are extensive blank areas, for which we can hnd no data of representation. It would have been better jierhaps to leave a i^reater ])art of southern Nevada in the same condition. In Western Nevada, California, Orci^on, Montana, and Idaho, the tint for Lower Carboniferous is intended to sij^nifv Paleozoic strata in general, though the Carboniferous is well defined in Northern California. Likewise the older Tertiary tint in the same State signifies Tertiary strata of anv age. CALIFOB,NIA. The California portion of the map is colored from mate- rial furnished chieHy by Prof. VVm. P. Blake, using as a basis his geological map of May, 1857, in the fifth volume of the Pacific Railroad Reports our census maps, and the results of recent explorations. The crest of the Sierra Nevada consists mainlv of granite and crystalline schists of pre-Silurian age, and believed to be in part, at least, Huronian. For a part of the length of the range these rocks are Hanked on the west bv Paleozoic limestones, quartzites, and slates traversed bv auriferous veins. Lower down the slope, serpentine rocks are fre- quent, and there is a broad belt of slates, also auriferous, referable to the Mesozoic period and believed to include the Triassic and Jurassic formations. These formations disappear at the southern end of the range, while at the north they occupy a greater breadth, but are largelv cov- ered by volcanic overflows. Upon the eastern side of the range, especially from Mono Lake southwards, there is a well-marked line of volcanic vents in the form of extinct 25 conical craters surrounded by lava streams. There are also some extensive lava Hows on the opposite and western slope, such as Table Mountain in Tuolumne County, and upon the Upper San Joaciuin. The chiet area of former volcanic outHow is, however, at the north, toward the Ore^ron line, joining the vast volcanic area of the Cascade ran-e. In this part of the State, Lassens Peaks, Shasta Mcnmtain, and the Marysvillc Buttes are pominent volca- nic centres. The Cretaceous and Tertiary formations are largely developed in the Coast Me Gibbs in Washiui^ton. Thev seem to be the metamorphic rocks of the Coast and Gold rana^es. Between the two areas mentioned, lies the Cache Creek ijroup of Selwyn, much like the Vancouver Island series and including^ some Triassic strata. This distinction into Cascade and Cache Creek grou])S wasnot recognized bv Gibbs south of the in- ternational boundarv line. East of the Kootenay, the rocks are certainly Paleozoic, largely of Carboniferous age, as determined bv Dawson, and the indigo tint is used to represent them. The Crystalline rocks mentioned were called granite and Huronian by Dr. James Hector, geolo- gist of Capt. J. Palliser's expedition in 1857-60. He calls the Rocky Mountain limestones east of the Kootenay Devonian. WASHINGTON TERRITOEY. Tiic remotest corner of our map is one of the most dififi- cult to color satisfactorily, and is based upon the informa- tion turnished for Coluinliia by Sclwvn and Dawson. 37 Geofirc Gibbs. and Thomas Condon, State Geolojrist of Orejron. It is supposed that the Olympic mountains con- sist of the Vancouver Island crystalline njcks, which, in their extension southwards, are much covered bv volcanic overflows. It is thou