NATURAL SCIENCES OF PHILADELPHIA. 129 



Triassic Rocks. 



At several localities east of Lake Utah, near the tributaries of Uintah River, 

 extensive deposits of fine red, more or less arenaceous material were seen oc- 

 cupying considerable areas, and from the accounts of various explorers, this 

 formation is greatly developed along the Wahsatch Mountains south of Lake 

 Utah. At these latter localities we have accounts of numerous beds of gypsum, 

 and deposits of rock salt. These beds where seen near Uintah River are not 

 known to contain gypsum or salt, but from the occurrence of gypsum in similar 

 formations a little farther south, and their proximity and relations to Jurassic 

 strata to be mentioned hereafter, there is little room for doubting that they 

 are the same red gypsum-bearing deposit seen by Dr. Hayden beneath Jurassic 

 rocks at the Black Hills. (See paper by Meek & Hayden, Proceed. Acad. Nat. 

 Sci., Phil'a, March, 1858, p. 44.) 



From the statement of Mr. Marcon, Dr. George Shumard, Mr. Blake, and 

 more recently of Dr. J. S. Newberry, it is evident this formation is developed on 

 a grand scale in New Mexico. The only organic remains yet found in it, so far 

 as we know, were some plants (Zamites, Pterophyllum, c.) and Saurian bones, 

 discovered by Dr. Newberry during his important investigations in the South- 

 West, as geologist of the exploring expeditions under the command of Lieut. 

 Ives, in 1858, and Capt. M'Comb, Top. Engrs., U. S. Army, in 1859. These 

 fossils led Dr. N. to refer this series to the New Red or Triassic epoch,* which 

 view was also maintained by Mr. Marcon, though the latter gentleman seems 

 not to have had a very clear idea of its limits, since he included other rocks 

 in the Trias as defined by him. 



This formation is well exposed on the North Platte at Red Butte, above Fort 

 Laramie, where it also contains several beds of gypsum, and again on La- 

 Bonte Creek, nearer Fort Laramie. It likewise occurs on Smoky Hill River, 

 and at other localities in Kansas, where it has been referred (along with some 

 lower Cretaceous rocks, and possibly some Jurassic strata) to the Trias, by Mr. 

 F. Hawn. All the facts that have been accumulating for some time past, seem 

 to render it more than probable that this series really represents the Trias of 

 the Old World. 



Jurassic Rocks. 



At the localities already mentioned where the red beds were seen near 

 Duchesne River, a tributary of Uintah River, heavy deposits were also observed 

 of grayish and whitish calcareous rock, and light, red and whitish sandstones 

 and shales. Some portions of the same formation were also met with further 

 to the north-west on the east branch of Weber River. At both of these places 

 in the calcareous beds, fragments of Peclen, Ostrea and portions of the columns of 

 Pentacrinus, undistinguishable from those of the Jurassic species P. asteriscus, 

 Meek and Hayden, were found. From the presence of these fossils, taken together 

 with all the other circumstances, we have scarcely room to doubt that these 

 deposits are of Jurassic age. 



Well marked Jurassic strata occur at Red Buttes, on the North Platte, at 

 the same locality already referred to in speaking of the red gypsum bearing 

 rocks. They were not seen in direct contact with the gypsum formations, but 

 under circumstances showing that they must hold a higher stratigraphical 

 position. Here they consist of sandstones, shales and slates, more or less lam- 

 inated calcareous sandstones, and gritty limestones of various colors, altogether 

 of considerable thickness. Some of the lower of these beds are quite fossilifer- 

 ous. The specimens collected consist of Pentacrinus asteriscus, Meek and Hayden, 

 a Gryphaa probably identical with G. calceola, Quenstredt, a plicated oyster. 



*See Am. Journ., vol. 28, 2d ser., p. 299: 



I860.] 8 



