110 GEOLOGICAL SURVEY OF THE TERRITORIES. 



The surface of the country is sometimes weathered by atmospheric 

 agencies into peculiar fantastic shapes. The rock formations are en- 

 tirely composed of the whitish and yellowish-white clays, marls, and 

 sandstones of the more recent beds of the great tertiary lake basin. 



Fig. 6. 



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Fort Mitchell— Scott's Bluff". 



The most striking examples are in the vicinity- of Scott's Bluff and 

 Chimney Bock, which have been noted landmarks for years. The 

 surface is here washed out into the form of domes, towers, churches, and 

 fortifications, and it is hardly possible to persuade oneself that the 

 hand of art has not been busy here. Chimney Bock shoots up its 

 tall, white spire from one hundred to one hundred and fifty feet. The 

 strata are perfectly horizontal, and, therefore, we may infer that the 

 surface of the whole country was originally on a level with the summit 

 at least, and that these landmarks are monuments left after erosion. 

 These picturesque views south of White Biver are not extensive, although 

 on both sides the north and south forks of the Platte they occur in cer- 

 tain localities. A few fossil turtles and the bones of some huge animal, 

 probably the elephant or mastodon, have been washed from the bluffs. 

 At Antelope Station, near Pine Bluffs, about four hundred and seventy 

 miles west of Omaha, a collection of curious boues was taken out of a 

 well sixty-eight feet below the surface, which were at once regarded by 

 the people in the vicinity as human remains. These bones were dis- 

 tributed throughout the country and furnished many a sensational par- 

 agraph for the daily press. About two years ago, Professor Marsh, in 

 visiting this country, made inquiry for them, and succeeded in obtaining 

 a few fragments, from which he determined the existence of a small 

 species of horse, which must have been originally about two or two and 

 a half feet high. 



From a mass of sediment sixty-eight feet below the surface, ten feet in 

 diameter and six feet thick, Professor Marsh obtained a quantity of 

 fragments of bones belonging to seventeen different species of animals. 

 In it were those of four varieties of the horse family, one of which was 

 as large as the liviug domestic horse; one or two species of rhinoceros; 



