dication, according to the crystallogenic views which are rapidly being generally adopted at the present day, of the agency of water, at or near the ordinary temperature, in its formation. Considering, for the sake of simplicity, as Breithaupt, von Kobell, Frankenheim and Rammelsberg have done,* that pyrrhotine is protosulphid of iron, the action of oxygeniferous water upon it in the formation of pyrites and limonite, may be represented by the rather simple equation

3FeS+2 HO+20=FeS2+Fe2О3, 1†HO+HS,

the sulphohydric acid formed entering into solution in the water, and subsequently either undergoing oxydation in its turn, or issuing in sulphur springs.t

ART. VI. On the so-called Triassic Rocks of Kansas and Nebraska; by F. B. MEEK and F. V. HAYDEN.

In several of our publications on the geology of Nebraska, we have mentioned a formation (No. 1 of the Nebraska Section) consisting of reddish and yellow sandstones, and various colored clays, with seams and beds of impure lignite, holding a position at the base of the Cretaceous series of the northwest. Although entertaining some doubts respecting the exact age of this formation, we have always placed it provisionally in the Cretaceous system, in our published sections.

Having learned through Mr. Hawn that a precisely similar group of strata, holding apparently the same position, occurs in northeastern Kansas, we placed these latter beds on a parallel with No. 1 of the Nebraska section, in a paper read before the Phila. Acad. Nat. Sci., May, 1857. Soon after the publication of this paper, however, a few fossils Mr. Hawn had shipped to us some time before, from a bed near the base of a section of the Kansas rocks he had furnished us for publication, came to hand. On examining these fossils, we at once discovered they were not, as had been supposed, Cretaceous forms, but similar to those of the Permian of the Old World. From this it became. manifest that in drawing a parallel between the Kansas and Nebraska formations, we had carried No. 1 too low in Kansas, by bringing it down so as to include the bed from which these fossils had been obtained.

* Handwörterbuch der Chem. Lieb. Pogg. and Woehler, v, 62.

These views will be recurred to in a future communication, to be presented whenever I shall have been able to complete my chemical examinations of the minerals collected in this section, and in which I propose to bring forward some general considerations regarding the metamorphism of the crystalline schists of the United States, and the nature and origin of the included metalliferous veins.

This misunderstanding in regard to the lower limits of No. 1, in Kansas, also led us to place on a parallel with that formation, all the lower two-hundred feet of Mr. Marcou's Pyramid Mountain section, (New Mexico) referred by him to the Trias. Suspecting however, that No. 1, as thus defined, might possibly include beds not properly belonging to it, we distinctly stated in the closing remarks of the same paper, that we yet wanted positive evidence, we might not be making it include beds older than any part of the Cretaceous system.

Although we are now aware that in drawing this parallel between the Nebraska rocks and those of Kansas and New Mexico, we carried No. 1, too low, we yet regard all, or nearly all of Mr. Marcou's Pyramid Mountain section, referred by him to the Jurassic System, as equivalent to the Cretaceous formations No. 1, 2 and 3, of Nebraska; while the lower two hundred feet of the Pyramid Mountain referred by Mr. Marcou to the Trias, we think equivalent to the Kansas deposits between the base of No. 1, as we now understand it, and the beds containing the Permian fossils.

In our paper on the collections brought in by Lieut. Warren's expedition to the Black Hills, read before the Acad. Nat. Sci., Philad., March, 1858, we remarked that in consequence of the occurrence in No. 1, of the genus Baculites, and numerous leaves closely resembling those of some of the higher types amongst our existing dicotyledonous forest trees, we thought we were hazarding little in referring it to the Cretaceous epoch.

More recently Mr. Hawn has published a paper in the Transactions of the St. Louis Acad. Sci. in which he places this formation in Kansas and New Mexico (as we had done), on a parallel with No. 1, of the Nebraska section, but refers the whole to the Trias.*

This difference of opinion caused us to examine with no little interest, during our recent expedition to Kansas, some of the localities mentioned by Mr. Hawn, near the junction of the Grand Saline and Smoky Hill branches of Kansas river, with the view of determining definitely whether or not the formation regarded by him as Triassic, could really be the same as No. 1 of the Nebraska section. In this we were particularly successful, for we not only found these Kansas formations agreeing exactly in all the details of their lithological characters, with No. 1, in Nebraska, but we also discovered in them several good specimens of the same dicotyledonous leaves so abundant in No. 1, at the mouth of Big Sioux river, and at Blackbird Hill, on the Missouri, in Nebraska. Associated with these leaves we likewise found specimens of the same peculiar trilobate leaf

* Trias of Kansas, by F. Hawn, Trans. St. Louis Acad. Sci., vol. i, p. 171.

(Ettingshausinia) mentioned by Mr. Hawn* as occurring in the formation referred by him to the Trias, thus establishing beyond the possibility of a reasonable doubt, the identity of the sup posed Triassic deposits of Kansas, and No. 1, of the Nebraska

section.

In regard to the leaves here referred to, we would merely remark that they are quite abundant in this formation, both in Nebraska and Kansas, and certainly belong to higher and more modern types of dicotyledonous trees, than have yet been found even in Jurassic rocks. Dr. J. S. Newberry our excellent authority in fossil botany, to whom we have submitted the whole collection, decidedly concurs with us in the opinion that the rocks in which they occur cannot be older than lower Cretaceous. In a communication recently received from him respecting these remains he says: "They include so many highly organized plants, that were there not among them several genera exclusively Cretaceous, I should be disposed to refer them to a more recent era.'

"A single glance is sufficient to satisfy any one they are not Triassic. Up to the present time no angiosperm dicotyledonous plants have been found in rocks older than the Cretaceous, while of the eighteen species which comprise your collection sixteen are of this character." ****

"The species of your fossil plants are probably all new; though generally closely allied to the Cretaceous species of the Old World. From the limited study I have given them I have referred them to the following genera:

"Of these the last two are exclusively Cretaceous, and highly characteristic of that formation in Europe.

"I may say in confirmation of the assertion that your fossil plants are Cretaceous, that I found near the base of the yellow sandstone series in New Mexico, considered Jurassic by Mr. Marcou, a very similar flora to that represented by your specimens, one species at least being identical with yours, associated with Gryphaea, Inoceramus, and Ammonites of lower Cretaceous species."

*Prof. Swallow exhibited a specimen of this species at the Baltimore meeting of the Am. Association.

SECOND SERIES, VOL. XXVII, No. 79.-JAN., 1859.

We have only to add in regard to the formation under consideration that we think it will no longer be doubted that it really belongs where we have always placed it, in the Cretaceous System.*

*

Between the base of No. 1 and the beds from which the Permian fossils are obtained in Kansas, there is a considerable thickness of red, blue, green and whitish clays, with a few beds of sandstone, and near the base gypsum deposits. This series may, at least in part,-be Jurassic or Triassic or both, (much more probably the former), but until we have some reliable palæontological evidence, it would only be groping in the dark to attempt to define its age; knowing as we do that lithological characters are of no value whatever, as a guide in drawing a parallel between these formations and those of the Old World.

As we expect soon to publish a paper giving in more detail the results of our examinations amongst the rocks in which so many Permian fossils have been found in Kansas, we would merely remark here that the coal measures of that region pass upwards by imperceptible gradations into an extensive series of rocks, consisting usually of rather impure more or less magnesian limestones, alternating with generally much thicker beds of blue, green, red and ash-colored laminated clays or very soft shales, with occasional beds of sandstone. Into this series, nearly all the species of fossils found in the middle and intermediate coal measures pass in great numbers.† Associated with these however, we occasionally meet with fossils belonging to types regarded in the Old World as characteristic of the Permian epoch.

*After the reception of a brief preliminary report by us, published last winter in the National Intelligencer, on the collections brought in from the Black Hills by Lieut. Warren, Mr. Marcou published a paper in the Archives des Sciences de la Bibliotheque Universelle of Geneva (a translation of which has recently appeared in the New York Mining Journal) in which after speaking of some points of difference in our opinions respecting the geology of the far west, he says, "in other respects the series of Messrs. Meek and Hayden agrees perfectly with mine, and it is with great pleasure I see that these learned geologists admit not only the existence of the New Red Sandstone (Permian and Trias) and Jurassic, but that they are led to regard as Jurassic, formation No. 1, of their Nebraska Cretaceous Series, a formation which from their description, I have no hesitation in regarding as Jurassic."

It was perhaps owing to the necessary brevity of our preliminary statement of the Jurassic and other discoveries in the Black Hills, seen by Mr. Marcou in the Intelligencer, that he misunderstood us. We have no where said we had recognized the Trias in the northwest; nor have we admitted in any of our publications that No. 1, of the Nebraska section is Jurassic. We stated that in consequence of the similarity between the lithological characters of No. 1, and the Jurassic deposits in the Black Hills, and the absence of organic remains near the junction, we were in doubt respecting the particular horizon at which the line should be drawn between them. At the same time, we stated that the beds from which the Jurassic fossils, described by us were obtained, hold a position below No. 1, of the Nebraska section.

Amongst these we recognize nearly all the Carboniferous fossils figured by Mr. Marcou in his "Geology of North America."

As we ascend in this group of strata, which comprises, nearly or quite all the lower Permian, and much of the upper coal measures of Prof. Swallow's and Mr. Hawn's section we find the Carboniferous forms very gradually diminishing in numbers to be replaced by Permian types, or others rather intermediate in their affinities, between those of the Permian and Carboniferous epochs.

Still higher in the series, without passing any horizon of unconformability, or meeting with any abrupt change, either in the fossils, or the lithological characters of the rocks, we find, when fairly up into the Upper Permian of Prof. Swallow's and Mr. Hawn's section, that we have lost sight of nearly, or quite, all the coal measure types, and meet only with Permian forms.

From these facts, we are inclined to the opinion that the entire series, from near the top of the Lower Permian of Prof. Swallow's and Mr. Hawn's section, down even lower than the horizon where they draw the line between the coal measures and the lower Permian,† should be regarded as intermediate in age, and as filling the hiatus between the Permian and upper coal measures of the Old World; while we think only the Upper Permian of their section really represents the Permian rocks, as developed on the other side of the Atlantic.

This intermediate series might be very appropriately termed the Permo-Carboniferous group, to indicate its relations both to the Permian and Carboniferous rocks. In case however, it may be thought best, in order to avoid the inconvenience of introdu cing a new name into our nomenclature, to class it along with either the Permian or Carboniferous, we would certainly place it in the latter, since Carboniferous types greatly predominated in its fauna.

In conclusion we would state that there is no unconformability so far as our knowledge extends, amongst all the rocks of Nebraska and northeastern Kansas, from the coal measures to the top of the most recent Cretaceous. The whole series in N. E. Kansas, and along the Missouri, as far up as Heart river in Nebraska, where the latest Cretaceous deposits pass beneath the water level, dip to the northwest. Consequently the elevating forces that produced this inclination of these various formations, must have been called into play-as in the region of the Black Hills,-after the close of the Cretaceous epoch, and previous to the deposition of the Miocene Tertiary formations of the north

west.

* Transactions St. Louis Acad. Sci., vol. i, p. 171.

We found the genus Monotis ranging down several hundred feet below the base of what we understand to be the lower Permian in Prof. Swallow's and Mr. Hawn's section.