GEOLOGICAL KEPOKT. 2o3 



they form the bed of the river. On the Platte, they dip under ground near the 

 mouth of Elkhorn River. Farther south, however, a considerable thickness of strata 

 is observed above this series, which, h)' their organic remains, are characterized as 

 "members of the same Upper Carboniferous formation. In their upper portions, gradu- 

 ally Permian types of fossils appear, thus forming a transition between the strata of 

 the Carboniferous and Permian periods, apparently tilling the break which exists 

 between the two in the eastern hemisphere. I have myself observed these strata, 

 which we may provisionally call Permo-Carboniferous, on the Republican River, 

 extending as far as o2 miles above its mouth. (See Explorations of Lieut. F. T. 

 Bryan, T. E., 1856. Report of Secretary of War, 1857). The highest strata of 

 this series, in that locality, appear to be identical with No. 11 of Messrs. Meek and 

 Hayden's Kansas section. (Proceedings of the Academy of Natural Sciences of 

 Philadelphia, January, 1859). My collection then only contained ( Jarboniferous types 

 of fossils, which were determined by Dr. B. F. Shumard. Still farther south these 

 upper formations seem to be considerably more developed. 



Beyond Fort Leavenworth, on the road to Fort Kearney, the compact limestones 

 Of the upper members of the Missouri section form prominent belts of drl.rls near the 

 top of the hills, the sides of which, corresponding to a series of argillaceous shales, 

 soft sandstones, and slialy limestones, are mostly covered with detritus. Farther on 



The compact, siliceous gray and buff limestones were thus noticed near Salt 

 Creek, and again at our first camp, some 8 miles from the fort There they contain 



Crinohlra, and various Un/o.zoa. Some miles farther on, near the head of a drain, the 

 same Fusulina limestone is exposed, and below it some argillaceous shales, and a cal- 

 careous, micaceous sandstone, with impressions of long, narrow leaves, and a few 

 particles of coal. Near Mount Pleasant, I again found such limestone, while on the 

 branches of Independence Creek, only shales were noticed. Some limestones on the 

 East Fork of Grasshopper Creek still present the same lithological character, but con- 

 tain numerous Ftmilhut cylhirtrka of the ventricose variety , and max . perhaps, occupy 

 a higher geological horizon than the Leavenworth rocks. On Clear Creek, 43 miles 

 from the fort, they again appear to be exactly like No. 1. 



At the next branch, 2 miles further on, a similar stratum crops out, some 40 feet 



limestone are exposed, quite fetid from the large number of organic remains, among 

 which I noticed several Proihidus, Orthis, Allorisnm, Mti«Vn«L Lidkrophoii, stems of 

 CYnwhka, &v,, all decidedly Carboniferous forms. 



Only on the top of the hill east of Walnut Creek, about 50 miles from the fort, 

 I found the first rock which presents an appearance decidedly dim-rent from any 1 had 

 seen farther east. It is a yellowish limestone, altogether composed of small bivalves 

 of the genera Pcdvu, MtiaVu,«, Plettrophonu (!), &c. About 40 feet lower down, 10 

 feet of gray and yellowish friable, micaceous sandstone are exposed, above which I 

 found fragments of compact gray limestone, with numerous remains of Brachiopoda. 

 Similar limestones continue up Walnut Creek, north of the road. 



