213 



bases are of the Niobrara. Farther west it forms the whole of the visible 

 outcrop, and the inouiuls are not so promiuent. 



On Prairie Dog Creek, in Norton Ooimty, it is 400 feet in thickness, 

 and in the extreme northwestern part of tlie State we have reason to 

 believe it is still thicker. The various strata are not clearly defined or 

 regular in line of deposit, and the continued thickness cannot be easily 

 discovered. The formation, like all others in the State, appears to dip 

 slightly to the northwest. It is conformably, or nearly so, upon the 

 Cretaceous. 



In the southern portion of the Pliocene, in the vicinity of Fort Wallace 

 and Sheridan, the hill-tops are covered with a stratum about 8 feet in 

 thickness, very hard and siliceous. The material varies from coarse 

 iiint-quartz to chalcedony. The latter mineral shades from milk-white 

 to transparent, sometimes presenting a semi-opal appearance. The so- 

 called moss agate is found in the upper few inches of the stratum. 



Over a considerable portion of the Pliocene no fossils are to be seen ; 

 but at other points they are somewhat abundant. They are of modern 

 type, represented by bones of deer, beaver, a large animal of the ox 

 kind, two species of the. horse, less in size than small Indian ponies, a 

 wolf, ivory from the elephant or mastodon, bones of the rhinoceros and 

 camel, and also remains of uudertermined character. In addition to 

 these mammalia, we find the bones and carapace of a large fresh-water 

 turtle 5 feet in length. 



All the bones are firmly fossilized, and most of them changed to a 

 hard, compact silica. The most interesting of these is the ivory. In 

 the process of petrifaction, the tusk must have been so softened as to 

 admit the intermixture of black oxide of manganese in solution, which 

 then crystallized in delicate sprigs. The ivory was next silicified into 

 nearly -pnre quartz, with the usual hardness of that substance. Thus 

 we have the ivory converted into the so-called moss agate. Some frag- 

 ments could not be detected, by the ordinary observer, from the usual 

 specimens of that gem. 



This ivory is found in fragments in the extreme upper portion of the 

 deposit, and we were at first inclined to call it Post-Tertiary ; but the 

 peculiar fossilization, similar to some of the other bones, induces me to 

 think that it belongs to the close of the Pliocene. 



The remains of the horse are apparently the most common, the teeth 

 and jaws being found from Smith County to the vicinity of Ellis, in 

 Ellis County. One is a species of the celebrated three-toed horse, hav- 

 ing three hoofs coming to the ground. In the northern part of Ellis 

 County, our party, in 1S75, found the feet, with the three toes in excel- 

 lent preservation. 



In most cases the bones are badly broken, and much of the skeleton 

 missing. A full and careful examination of the Pliocene of Kansas 

 will undoubtedly furnish some valuable fossils, illustrating the mamma- 

 lia of the period, and give to science some new species. 



The Eocene and Miocene have not yet been discovered in Kansas, 

 unless the specimen of the three-toed horse, found in Ellis County, 

 should prove to be the Anchitherium of the Miocene. It was imbedded 

 in the lowest part of the deposit, within 10 feet of the Niobrara lime- 

 stone. Further examination of this formation is desirable. 

 No. 3 2 



