=== m — "~~ ^ p i a MBL/WH 111 m a □ ^^= □ ^^ m □ ^= /*>': 1HP 1 DEPARTMENT OF THE INTERIOR R E I3 O R T V * UNITED STATES GEOLOGICAL SURVEY THE TERRITORIES F. V. HAYDEN, UNITED STATES OEOLOGIST-IN-CHARGE, VOLU ME VI. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1 8 7 4 . LETTER TO THE SECRETARY. Office U. S. Geological Survey of the Territories, Washington, D. C, March 1, 1874. Sir : I have the honor to transmit for publication the very valuable report of Prof. Leo Lesquereux on the Fossil Flora of the Cretaceous Dakota Group. This division, lying at the base of the Cretaceous series, forms a most important link in the physical history of the western portion of the continent, containing as it does the first proofs of the introduction on the earth of a vegetation allied to our fruit and forest trees. The formation also has a vast geographical extension, being exposed along the flanks of the various mountain-ranges, from a point far north of our northern boundary, and extending far south to Mexico. Nearly all the fossil forms, however, vegetable or animal, that it has yielded up to this time, have been found on the jjlains in the eastern portions of Kansas and Nebraska. This elaborate memoir of Professor Lesquereux will be indispensable to every student of the geology of the West, and will reflect great credit on the survey at home and abroad, and its immediate publication is earnestly requested. Very respectfully, your obedient servant, F. V. HAYDEN, United States Geologist. Hon. C. Delano, Secretary of the Interior. UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. CONTRIBUTIONS v\<3\ THE FOSSIL FLORA WESTERN TERRITORIES, F^VRT I THE CRETACEOUS FLORA By LEO LESQUEREUX. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1874. TABLE OF CONTENTS. Page. §1. Discovery of the fossil plants of the Dakota group 3 2. Surface-distribution of the Dakota group 10 3. Stratigraphical distribution of the Dakota group 13 4. The Dakota group considered as a marine formation 25 5. Distribution of the leaves in the composition of the Dakota group 28 G. Generic characters of the flora of the Dakota group 31 7. Disconnection of the flora of the Dakota group from antecedent types 35 8. The flora of the Dakota group in relation to climate 38 9. Description of species 42 10. On the general characters and the relation of the flora of the Dakota group 116 11. Conclusion 130 ERRATA. Page 31, gamsB. Pago 31, gamre. Page 32, Page 32, Page 32, Page 33, Page 39, Page 46, 5, 5b. Page 48, Page 49, line 20, for Cryptogamia? read Crypto- liue 30, for Phanerogamia! read Phanero- line 3, for Pbyllodadus read Phyllocladus. line 14, for 2 read 1. line 16, for 4 read 3. line 12, for Diospiios read Diospyros. line 32. for 30° read 35°. line 22, for XXX, Fig. 12b, read XXIX, Figs. line 37, for PI. IV and V read PI. IV. line 13, for 97 read 91. Page 49, lino 25, for p. 139 read I, p. 139. Page 51, line 29, for p. 8 read p. 7. Page 55, line 11, for (p. 62, PI. XXIII, Figs. 2, 3,) read (I, p. 62, PI. XXIII, Figs. 8, 9, 11.) Page 57, liue 2, for p. 442 read 422. Page 59, line 5, for p. 704, read II, p. 704. Page 62, line 7, for Kanseaua read Kansaseana. Page 65, line 17, for Ellswortbiauus read Ellswortb- iana. Page 69, line 19, for read 98. Page 79, line 8, for former read following. Page 91, liue 19, for darted read parted, Columbus, Ohio, February 12, 1874. Dear Sir : I send you herewith my report on the fossil flora of the Cre- taceous Dakota group. Allow me to gratefully acknowledge the assistance received from you in the preparation of this memoir. The opportunity offered to me of exploring the more interesting localities where the materials for this work have been obtained was especially of great advantage. It enabled me to become ac- quainted with the geological distribution of the formation; to study the vege- table remains, and to compare their various forms in places where they were more abundant ; to recognize their local disposition, and thus to solve many questions which, without this advantage, would have been left indefinite. Very respectfully, yours, L. LESQUEREUX. Prof. F. V. Hayden, United States Geologist, Washington, D. C. 1 L ON THE FOSSIL PLANTS OF THE CRETACEOUS DAKOTA GROUP OF THE UNITED STATES. § 1. — The discovery of the fossil plants. From the beginning of his explorations for the Geological Survey of the Western Territories, Dr. F. V. Hayden had remarked a formation of reddish and yellow sandstone, with variously colored clays, seams of impure lignite, and remains of fossil plants, the whole group holding a position at the base of the Cretaceous series of the Northwest. Already in 1853 he had obtained a number of specimens of leaves of exogenous and dicotyledonous plants, referable, according to his statements of that time, if not to species, at least to genera still represented in our Jlora, or, as he said,1 closely resembling those of some of the higher types among our existing dicotyledonous forest-trees. In 1856 and 1857 the same geologist, then assisted by Professor Meek, found new specimens of these fossil plants in Nebraska; and later in their explora- tions of Kansas, undertaken in common for the purpose of studying the same formation which some geologist had referred to the Trias,2 they still discov- ered in that State a number of leaves of the same kind. They moreover as- certained that the Kansas formations are in exact correlation, in all their geo- logical characters, with No. 1 of their Nebraska section, now bearing the name of the Dakota Group. From a number of specimens these dicotyledonous leaves of Kansas were recognized as identical with some which had been formerly seen in abundance in strata of this Dakota group at the mouth of the Big Sioux River and at the Blackbird Hills, on the Missouri River, in Nebraska. Among these leaves especially were specimens of a trilobate leaf, mentioned by Mr. Hawes, as found in the measures which he referred to the Trias of Kansas, and which had been exhibited at the Baltimore meeting of the Association for the Advancement of Science. In the discussion on the age of the formation where these fossil plants had been recognized, the dis- coverers, Messrs. Meek and Hayden, remark, in the same paper, that these 1 American Journal of Science and Arts, vol. xxvii, No. 79, 1859, p. 32. a Trias of Kansas, by F. Hawn, Trans. Saint Louis Academy of Science, vol. I, \>. 171. leaves certainly belong to a higher and more modern type of dicotyledonous trees than has yet been found even in Jurassic rocks, and that therefore the formation could not be of Triassic age. And though they recognized it in imme- diate superposition to Upper Carboniferous or Permian rocks, they persisted in the former opinion of Doctor Hayden, that the red sandstones of the Dakota group were of Cretaceous age. Some sketches of these plants had been sent to Prof. O. Heer, of Switzerland, and in the meanwhile the whole collec- tion of the leaves had been subjected to the examination of Doctor Newberry, who wrote, "that they did include so many highly organized plants, that were there not among them several genera exclusively Cretaceous, he should be disposed to refer them to a more recent era.'' After remarking that these plants did not represent any vegetable type older than Cretaceous ones, he says that the species, though probably all new, are closely allied to the Cre- taceous species of the Old World. He refers them to the following genera : Sphenopteris, Abietites, Acer, Fagns, Populus, Cornus, Liriodcndron, Pyrus, Alnus, Salix, Magnolia, Credneria, and Ettingshausenia ; this last represented by that peculiar trilobate leaf mentioned above, which from better and more numerous specimens has been since admitted as referable to the genus Sassafras. The discussion on the age of the Dakota group, which was then con- sidered as Triassic by Messrs. Swallow and Hawn, and as Jurassic by Professor Marcou, was then complicated by the opinion of Professor Heer, who, answering Doctor Hayden's letter after the examination of the sketches sent to him, stated : That although one of the outlines resembles a Cretaceous genus, (Credneria,) the nervation being obscure, and the others more like Tertiary forms than anything known in the Cretaceous of the Old World, he was inclined to the opinion that they represent Tertiary species. From what is now known of the characters of the flora of the Dakota group, it is clear that, judging from mere sketches, the celebrated professor of Switzerland could scarcely come to a different conclusion. But this has nothing to do with the discovery of the fossil plants of the Dakota group, and with the history of the Cretaceous flora as we know it now. The above remarks merely tend to prove that the first discovery of the vegetable Cretaceous re- mains of this western section is due to Dr. F. V. Hayden, who first by him- self, and afterward in connection with Professor Meek, studied the formations where these remains have been discovered, first in Nebraska and afterward in Kansas; marking exactly the limits and the characters of this group, now generally admitted as the lower member of the American Cretaceous forma- tion. Vegetable paleontology has been too often considered as of little import- ance in regard to the determination of the age of geological divisions. In this case at least we have an evident proof of its value as a guide ; for, indeed, without the fossil leaves of Nebraska, the. relation of the Dakota group either to the Trias, the Jurassic, or the Cretaceous, would be still uncertain and subject to dispute ; especially for the reason that the few animal remains rec- ognized in the red sandstones of this group have been, as yet, too scant and of too little distinct characters to afford sufficient evidence on this point. This proves the importance of the first collection of fossil plants of Prof. Hayden. For now, as a result of his care in collecting them; in publishing geological facts marking the exact relative position of the Dakota group to the Permian rocks which underly it, and to the Cretaceous strata above it, and at the same time forcing the examination and comparative study of these fossil plants, which most of the geologists of the time would have passed as unworthy of regard ; new researches have been induced; specimens have been obtained, more nu- merous, more perfect; and we have not only full geological evidence in regard to the lithology and geological distribution of the strata, but the first pages of what may be called a new chapter of our geological history. To it have been added the records furnished by the materials afterward brought up in abund- ance from various points. The first contribution to these materials appears to have been furnished by Doctor Newberry. In reporting his opinion on the general character of the leaves submitted to his examination by Messrs. Meek and Hayden, he adds this paragraph i1 " I may say in confirmation of the assertion that your fossil plants are Cretaceous, that I found near the base of the yellow sand- stone series in New Mexico, a very similar flora to that represented by your specimens, one species at least being identical with yours, associated with Gryjrficea, Inoceramus, and Ammonites of Lower Cretaceous species." And in his report on Doctor Hayden's fossil plants, he also remarks:2 "That he subsequently went himself to the region where the vegetable remains had been obtained, and that he spent some years in the study of the geology of the interior of the Continent, exploring a large area occupied by Cretaceous 1 American Journal of Science anil Arts, vol. xxvii, No. 71), p. 33. -Notes on the later extinct floras of North America, p. A. rocks in Kansas, Colorado, Arizona, New Mexico, and Utah. That during these explorations he obtained from the Cretaceous strata, at a great number of localities, angiosperm-leaves, consisting of some of the species obtained by Doctor Hayden, with many others, all of which are described in the re- port of the San Juan expedition, not yet published." Unhappily for paleontological science, nothing is known as yet of these vegetable remains but what is said above, and they cannot be taken into con- sideration now as truly representing Cretaceous species. For the reason, especially, that except from the Cretaceous strata of Nebraska, Kansas, and Minnesota, we do not know as yet any fossil plants positively referable to a Cretaceous formation from the western territories named above, and traversed by Doctor Newberry in his survey. All our plants from these countries are referable to the Tertiary, like those of Colorado, Wyoming, and of California. In 1856, being on a tour of exploration on the southwestern limits of the State of Minnesota, I remarked, above the mouth of the Big Waraju, or Cot- ton-wood, which enters the Minnesota River, near the present town of New Ulm, some exposures of a yellow-reddish sandstone bearing a few vege- table impressions, apparently representing leaves of willow. By reason of the generic identity of these leaves, I considered the rocks as of Ter- tiary age. I was the more disposed to admit this conclusion, as I found near by, in the bottom of the river, pieces of lignitic coal, evidently Tertiary, which I supposed to have been taken out by the water, from beds underlying the sandstone, somewhere in the vicinity ; for I was not then aware that in the Big "Waraju, as in the Smoky Hill River and many affluents of the Mis- souri and the Minnesota, these pieces of lignite coal are carried by the current from the upper part of the riveiis, where they cross the Tertiary formation, hundreds of miles above.1 As I did not have then any instrument with me, not even a hammer, and no means of transportation, I was unable to get specimens of these fossil plants, and regretted many times thereafter the im- possibility of comparing these Minnesota leaves with those of Doctor Hayden, and especially with some referable to Salix, which I have since obtained in abundance from Nebraska and Kansas. In 1867, at the meeting of the Na- tional Academy at Northampton, Prof. Jas. Hall, who had just returned from a geological exploration in Western Minnesota, exhibited, among a number of 1 These lignites arc different from the sbaly, friable, carbonaceous matter seen in the bluffs of the same river. They correspond by general aspect and chemical compound with the Tertiary lignite found, too, in the bed of the Blue Earth River above Saint Peter, in the Missouri, the Smoky Hill River, &c. other specimens, some fossil leaves taken from a red sandstone at about the same locality which I had formerly visited. From my impression in regard to the geological distribution of the rocks which I had seen in place, and from the preseuce of two species of leaves recognizable among these specimens — one Salix, one Laurus, with apparently a Comus, I then considered them as pertaining to a Tertiary formation. By the kindness of Professor Hall I have now these specimens for examination, and, comparing them with those of the Dakota group ofNebraska, recognize them easily as from the same Cretaceous formation. Some of the species are identical with those of the Blackbird Hills, and the compound of the stone is of exactly the same kind. It is coarser, however, forming a rough-grained sandstone, which renders some- what difficult the study of the specimens, on account of the obliteration of the veins. Some of these leaves are described and figured in this paper. In 1863 another geological exploration in the same field of research had also contributed new and interesting materials for the study of our Creta- ceous flora. As has been stated already, the reference of the Nebraska fossil leaves to a Cretaceous formation caused a difference of opinion between some American and European geologists concerning the true age of the Dakota group. The details of the discussion on this subject are given at length in Dr. Newberry's Extinct Floras, (Joe. cit.) Professors Marcou and Capellini, two European geologists of celebrity, wishing to obtain for them- selves full evidence on the conclusions of Doctor Hayden, undertook an exploration in Nebraska to visit the localities where the fossil plants had been discovered and to review the stratigraphical records on which these conclusions had been based. They obtained in their tour, especially in the vicinity of Tekamah, as also from the Indian reservation in the Blackbird Hills, a number of specimens, which were delivered to Professor Heer for examination. From these materials the Phyttites du Nebraska were pre- pared and published — a very interesting paper, 22 pages quarto, describing seventeen species, all new ones, with four plates of illustrations. This memoir gives us the first authentic and reliable record of our North American Cre- taceous fossil plants, and is the more valuable on account of the high scientific attainments of the author, of the accuracy of his descriptions of the leaves, and of the figures by which they are exemplified.1 Of course the explora- 1 Three leaves from the Dakota group are figured in Journal of Sciences and Arts, vol. xxvii, No. 80, pp. 222 and 223, 1869. They are, however, without description. The first has been considered a leaf of Liriodendron, the second a Crcditcria, the third a Sassafras. 8 tions of Messrs. Marcou and Capellini could but corroborate the facts already known from the reports of Dr. Hayden. They recognized the accuracy of the statements concerning the stratigraphical distribution of the members of the Dakota group, as also the conclusions advanced on its age. They even acknowledge that after ascertaining that the American geologists were right, they had been unable to pursue their explorations to as successful a result as had been done by Dr. Hayden, having failed to discover the line of super- position of the Benton group with its animal fossils to the red-sandstone bearing plants. In the mean while the interest awakened by the discussions in regard to these plants and to their positive relation to the age of Nebraska sandstones had incited new researches, and the result was the discovery of a large number of better specimens, representing some species already known, and many new ones, too. In the same year (1863) Prof. F. B. Mudge, of Manhattan College, Kansas, collected, as State geologist, some splendid specimens of Cretaceous fossil plants, which were sent to Prof. F. B. Meek and to the Smithsonian Institution. In 1867 Dr. John Leconte, while connected with the survey of the Union Pacific Railway, obtained also a number of fine specimens of fossil leaves from the same red shales of the Dakota group, near Fort Harker; and about the same time, Mr. Charles Sternberg, who was domiciled in that vicinity, discovered some localities rich in remains of fossil plants, and sent many specimens of them to the Smithsonian Institution and to Dr. Newberry. From the examination of specimens furnished to me by Dr. Hayden, Dr. Leconte, and Professor Mudge, I prepared a paper entitled On Some Creta- ceous Fossil Plants from Nebraska, the first paper published in America de- scribing fossil plants of the Dakota group. This memoir1 gives an account of fifty-three species, eight of which were known already from the Phyllites du Nebraska, by Professor Heer, three referable with doubt to others already published, and the balance, forty-one species, considered as new. Soon after, a second paper, partly on the same subject, was published by Doctor New- berry and distributed in pamphlet form.2 This very interesting memoir, 1 American Journal of Sciences and Arts, vol. xlvi, No. 136, pp. 91-104. 2 Though I do not attach any importance whatever to the right of priority of authorship for species of fossil plants, known from mere descriptions, I take this opportunity of fixing dates in order to show that my paper had precedence in distribution, if not of publication, to that of Dr. Newberry, and that therefore if a few identical species are described in both memoirs, under different names, I am in no way accountable for it. My own report, as seen from its datnm, was delivered to Dr. Hayden 19th March, 1868, and published in the Journal (loc. cit.) July, 1868. Dr. Newberry's paper is marked by him as read the 9 The Late Extinct Floras of North America, describes, besides Tertiary plants, twenty-one species of fossil plants from the same Dakota group. Later still, in Dr. F. V. Hayden's annual report for 1871, eight new species are described by the writer, with mention of two already known, all from specimens furnished by Dr. B. F. Mudge. And from my own explora- tions of 1872 over the Dakota group of Kansas I obtained a large number of fine specimens, serving to better illustrate some species already described from insufficient materials, and adding to our list of Cretaceous species twelve new ones for the American flora, three of which, however, were known from Europe and European publications. All these species, already briefly described by myself either in the Jour- nal of Sciences and Arts, or in the annual reports of Dr. Hayden, together with the new ones recognized from specimens collected in a tour of field explorations in Kansas and Nebraska, (1873,) constitute the materials from which the present memoir is made. I must remark, also, that in order to complete, as far as it was in my power, the history of the flora of the Dakota group, I have added to the materials mentioned above, the description and figures of five species which I had published, as an appendix to the Tertiary plants of the Mississippi, in the Transactions of the American Philosophical Society, vol. xiii, and also of a few new species recognized in the specimens kindly lent to me by Prof. Jas. Hall, which are described and figured with his approval.1 I do this especially in order to have all together the materials pertaining to our Cretaceous flora. With Professor Newberry's Report on the Ancient Floras, which is to have also descriptions and figures of all his species of Cretaceous plants, we have nearly the whole of what is known as yet oi this interesting group of fossil plants. The only species which have been described by Professor Heer and have not been published out of the Phyllites du Nebraska are : Salix nervillosa, Ficus primordialis, Magnolia capellini, and Cissites insignis. These, however, are remarked upon in the text of this memoir. 22d of April, 1867, and reprinted from the Lyceum of Natural History of New York, vol. ix, April, 1868. It was mentioned in the Journal of Sciences and Arts November, 1868, and distributed at the same time in pamphlets, the copy sent me being received 7th November, 1868. As far as I am informed, no copies of this paper had been distributed at au earlier date. 'By the kindness of the industrious and untiring investigator of the Cretaceous measures of Kansas Prof. B. F. Mudge, I have recently received, after the preparation of this paper, a new contribution of specimens, which has enabled me to add two new plates to the flora of the Dakota group, representing, among others, ten species not described before. 2l 10 § 2. — Surface distribution of the dakota group. In order to illustrate the geological relation of the species of fossil plants described in this memoir, it is convenient to make some remarks on the distri- bution of the group wherein they have been discovered. In doing this it will be advisable to record facts already published by geologists who have formerly explored this formation — by Dr. Hayden especially, by Professors Meek, Mudge, Conrad, Marcou, Capellini, Hall, &c. These records and quotations are rendered necessary by the scattering of the materials referring to this group in scientific journals which are rarely accessible to paleontologists. The eastern limits of the surface area of the Dakota group are marked in the Geological Report of Iowa, by Prof. C. H. White, who recognizes the most easterly deposits of this formation, which he calls the Nishnabotany sandstone, in the southeast part of Guthrie County, and as far south as the southern part of Montgomery County. To the north it passes under the Woodbury sandstone, overlaid by the Inoceramus, or chalky beds. The north- western counties of Iowa have not been yet surveyed in detail, and owing especially to the few exposures of the rocks underlying the drift, and the prairies which cover this region, the exact limits of the group are not here distinctly recognized. The direction, however, is, in Iowa, from near Council Bluffs north and somewhat east to the point where the Des Moines River leaves Minnesota, and hence due north to the mouth of the Big Cotton- wood River, near New Ulm, where the red sandstone is exposed in the bank of the river. From this locality Professor Hall has recognized it one hundred and thirty miles farther north. From Council Bluffs, or from above the mouth of the Platte, in Nebraska, the border of the belt passes in the same direction, south a little westward, across the western part of Cass and Otoe Counties ; thence to the middle of Gage County, near Beatrice ; then through Marshall County, entering Kansas in the eastern corner of Clay. It descends farther south to the mouth of Solomon River, and reaches the Arkansas River west of the line of the Atchison, Topeka and Santa Fu Rail- road, near the mouth of Cow Creek. I can find no data marking the borders of the belt, nor even recording its appearance in the Indian Territory, between Kansas and Texas. But subsequent geological investigations cannot fail to recognize it in that country, as its connection cannot be broken in that, as yet unexplored, region alone. The records of the geological surveys of Texas and of Arkansas indicate it 11 in those States, in the same direction which it is following in Kansas, or nearly clue south. In a note in the proceedings of the Academy of Science of Saint Louis, Professor Shumard, after remarking,1 "that they had not be- fore succeeded in finding dicotyledonous leaves in the Lower Cretaceous marls and sandstone of Texas, as had been done by Meek and Hay den in Nebraska and Kansas, and that they supposed they would probably be found in this position," adds : "I have now the pleasure to inform you that further explo- rations in Lamar County, near Red River, have resulted in the discovery, by Dr. G. G. Shumard, of numerous impressions of leaves in alternations of yellowish sandstone and bluish shales which are believed to occupy a position below the marly clay, or Red River group of my section, and which we re- gard as being on a parallel with the lower beds of No. 1 of the Nebraska section. The collection made by Dr. Gr. G Shumard contains several species of dicotyledonous leaves which appear to belong to the genera Salix, Ilex, Laurus, &c." At the time of the discovery of these fossil plants, I corresponded with Doctor Shumard, desiring that they should be sent to me for examination, and I was promised communication of them. To my regret the promise was not fulfilled, owing especially to modifications in the corps of the geological sur- vey of Texas. There can be no doubt, however, from the description of the position of the strata, of their compound, and also of the generic relation of the leaves, that they are referable to species of the flora of the Dakota group, or that this Cretaceous group is represented in the northern counties of Texas. The chalk-beds of the Cretaceous equivalent of the Benton group are predominant not only in Texas, but also in the southwestern corner of Arkansas, and have been recognized in the whole extent of Sevier, Pike, and Hempstead Counties, &c. According to Dr. D. Dale Owen's report on the geological survey of Arkansas, this chalk limestone is seen in these counties, almost everywhere near the bottom of the creeks, under the loam. On account of its lower station, of course the red sandstone of the Dakota group was not observed, the beds of the river being nowhere deep enough to expose it to view. From North Texas, the Cretaceous formation passes to the south, under wide prairies mostly of loam and Tertiary deposits. It is not positively ascertained if it reaches the Gulf of Mexico, but it is 'Vol. ii, No. 1, (1863,) p. 14(1. 12 more than probable, as Hayden and Hall suppose, that it extends further south to the sea. In tracing the eastern borders of the Dakota group, the length of its area from north to south is recognized from the northern limits of the State of Minnesota to North Texas, on about 20° of latitude. That this group ex- tends farther north into British America maybe hypothetically admitted ; and as the fossil leaves received from Greenland by Professor Heer, and consid- ered by this author as Upper Cretaceous, represent some genera and, perhaps, some species too, identical with those of the Dakota group, it would seem that this formation has been continuous from the Gulf of Mexico to the Arctic lands, Greenland, Melville, &c, over 35° of latitude. As far as it is known, in the States of Iowa, Kansas, and Nebraska, the average width of the belt occupied by the Dakota group from east to west, varies from sixty to one hundred miles. It has been seen that the red sandstone of this formation is exposed in the southeast part of Guthrie County, in Iowa, which is already ninety to one hundred miles east of De Soto, on the Missouri River. In following up this river, the same formation is still exposed to thirty miles above the mouth of the Big Sioux, where it passes under the bed of the river.1 This, in a direct line, is at least one hundred and thirty miles. In Nebraska State, the width of the belt is, ac- cording to Doctor Hayden, from sixty to eighty miles.2 In Kansas I have followed this formation along the Kansas Pacific Railroad, from the mouth of Solomon River, for seventy-five miles to the west. Professor Mudge has col- lected specimens of its fossil plants around Fort Larned, and recognized the sandstone of the Dakota group, up the Arkansas River, to the limits of the State. He says that the average breadth of this sandstone formation in the northern half of the State is about forty miles, (northwest and south- east,) or about sixty miles in a diagonal line running due east and west. But when it reaches the bluffs of the Arkansas Valley the strike is westerly, and instead of a westerly extension of sixty miles, it covers the whole country from thirty miles east of Pawnee Rock to the western line of the State, a distance of about two hundred miles.3 It may be that it enlarges still far- ther southwestward, for, according to Dr. Newberry's statement, it reaches 1 P. V. Hayden's remarks on the Cretaceous rocks of the West. American Journal Science and Arts, vol. xliii, p. 172. - Report, United States Geological Survey, (1867,) 2d edition, p. 52. 3 Transactions Kansas State Board of Agriculture, (1872,) p. 408. 13 New Mexico and the Rocky Mountains. I have not been able to find any trace of it in that country, however, and as all the specimens of fossil plants either found by myself south of Colorado or sent to me for examination from the Rocky Mountains or their eastern slopes, are species representative of the Tertiary formations, as remarked already, I am still uncertain if the Da- kota group is really extended farther west than Kansas. The western strata bearing plants which are now recognized as of Eocene age, were formerly considered as Cretaceous, and the leaves found in great abundance in connec- tion with the Tertiary formation, though of a different character, may have been inadvertently referred to species of the Dakota group. However it may be, this Cretaceous group has not been positively recognized by Dr. Hayden in his explorations to and along the Rocky Mountains, and from the nature of its compounds, which, as it will be seen hereafter, induces me to consider it as a beach formation, I doubt whether it is of a much wider extent west- ward, as it has been reported, or whether it is to be found west of the borders of Kansas. § 3. StRATIGRAPHICAL DISTRIBUTION OP THE DAKOTA GROUP. The section of the Cretaceous rock of the West, published in Dr. Hayden's Report of the Geological Survey of the Territories, 1870, p. 87, gives the best possible illustration of the relation of the groups of the Amer- ican Cretaceous from its base, in connection with the Permian, to its top, over which the Eocene sandstone is superposed. It is here copied in full as a necessary exemplification of the details which are given in this chapter : 14 General section of the Cretaceous roclcs of the Northwest Divisions and subdivisions. Localities. S 3 £ .2 -S to p t-j '» 5 ■p fc 3 g 2 H .= £ S h CO ft ci to n ■ g o a a hi a ■? « H s £ fe ,_■ P. 6 H fc & s « '-3 "^ = a .a a R^t 'Gray, ferruginous, and yellowish sandstone, and arenaceous clays, containing Belcmnitella bullosa, Nautilus dekayi, Ammonites placenta. A. lobatus, Scapkites conradi, S. ni- colletti, Baeulites grandis, Busycon bairdi, Fusus culbert- son, F. newberryi, Aporrkais amcricana, Pseudo-buccinum, nebrascensis, Mactra warrenana, Cardium subquadratum, and a great number of other molluscous fossils, together with bones of Mosasaurus missouriensis, d\c. Dark-gray and bluish plastic clays, containing, near the up- per part, Nautilus dekayi, Ammonites placenta, Baeulites ovatus, B. compressus, Scai^hites nodosum, Dentalium gracile, Crassatella evansi, Ouculloea nebrascensis, Inoceramus sagensis, I. nebrascensis, I. vanuxemi, bones of mosasau- rus missouriensis, dc. Middle zone nearly barren of fossils Lower Fossiliferous zone, containing Ammonites complexus, Baeulites ovatus, B. compressus, Helioceras mortoni, H. tor- turn, M. umbilieatum, H. cochleatum, Ptychoceras mortoni, Fusus vinculum, Anisomyon borealis, Amauropsis paludi- niformis, Inoceramus subloevis, I. tenui-lineatus, bones of Xlosasaurus missouriensis, d-c. Dark bed of very fine unctuous clay, containing much car- bonaceous matter, -with veins and seams of gypsum, masses of snlphuret iron, and numerous small scales, fishes, local, filling depressions in the bed below. Lead-gray calcareous marl, weathering to a yellowish or whitish chalky appearance above, containing large scales and other remains of fishes, and numerous species of Ostrea congesta attached to fragments of Inoceramus. Passing down into light yellowish and whitish limestone, containing great numbers of Inoceramus problematicus, I. pseudo-mytiloides, I. aviculoidcs, and Ostra congesta, fish scales,