290 ANNUAL OF SCIENTIFIC DISCOVERY. 



and extending several hundred miles northerly, there was a cretaceous form- 

 ation, the most prominent fossils of which were Ammonites and Baculites. 

 All had shown that this existed on a largely developed scale, but, with the 

 exception of Nicolay, no attempt was made to establish subdivisions. In 

 1847 we had for the first time a published notice of the existence of an ex- 

 tensive tertiary formation in that region, given by Dr. Prout, of St. Louis. 

 This was, however, to the west of Missouri. Subsequently Mr. Culbertson 

 brought collections, and Dr. Owen directed Mr. Evans to make collections, 

 from which we had a pretty good knowledge of the tertiary formation and its 

 fossils. Mr. Hall's object in making collections was not to make discoveries 

 of new species, but the investigations of Dr. Owen did not tell us whether 

 there were distinct formations or not, and moreover it seemed an important 

 consideration that the flora corresponding to the ancient fauna should be 

 known. That was not accomplished by the expedition sent out under the 

 charge of Mr. Meeks ; but we had some more details with regard to the 

 tertiary and cretaceous formations. In the neighborhood of the mouth of the 

 Platte the carboniferous formation terminated. Passing up the Missouri we 

 found that the carboniferous passed into cretaceous. At their junction was a 

 sancl-stone, which might perhaps be older than the cretaceous. Upon it lay 

 a buff calcareous rock, which would mark like chalk, containing scales and 

 jaws of fishes. Above this was a great thickness of clays which contained 

 most of the species that had been brought from this part of the country. A 

 thinner bed above the clay was characterized by a large baculites. Those 

 subdivisions extended over the western country, and we had yet to seek their 

 characteristic fossils. The species already described already amounted to 

 between thirty and forty, and he had about an equal number of new species. 

 At a considerable distance west of the Missouri, the cretaceous beds began to 

 dip slightly to the west. Above the bed characterized by baculites, and 80 

 miles west of the Missouri, commenced the tertiary, at first containing no 

 fossils, but about 80 miles further on there were paljeotherium and fossil tur- 

 tles within twenty feet of the cretaceous, although the tertiary nearer the 

 river was 50 or 60 feet high. They concluded, therefore, that the beds were 

 unconformable, the cretaceous dipping westward, and the tertiary being de- 

 posited horizontally upon it so that the eastern tertiary began to be deposited 

 when the western was already 250 feet thick. The Mauvaises Terres were 

 formed of this tertiary extensively denuded. Two new species of mammals 

 had been discovered, one of them allied to the musk deer, and the other a 

 small, carnivorous animal. The shortest term to express the character of 

 Nebraska was to say that it was a perfect desert, incapable of supporting men 

 or animals, except in a migratory condition. The buffaloes came in the 

 spring with the grass, and went away in midsummer when it was gone, and 

 the Indians followed them. There was almost no wood ; some few shrubby 

 willows, and a cotton- wood a foot in diameter was always known as the big 

 cotton-wood, and now that it was gone, the place was still called Big Cotton- 

 wood Spring, Pure water was rarely met with. There were occasionally 

 some springs in the baculite formation which commenced 75 miles west of 

 the Missouri. The deep clay beneath it was almost impassable. In the 



