Douglass: A Geological Reconnaissance. 237 



Some scutes of crocodiles were found. Toward the top the beds 

 become less sandy and contain more clay and fine-grained " silicified 

 rock." 



The Middle White River ( Oreodon) Beds. — The Oreodon beds are 

 somewhat thicker than at White Butte, and are a little different in 

 minor details. The color is greenish on fresh exposure, but the mass 

 of the deposits weathers to a light buff and the nodules to a chocolate- 

 brown. Both contain darker irregular fragments scattered through 

 the mass. These weather out at the surface of the harder nodules and 

 give to the latter a cellular appearance. In the lower portion of the 

 beds are many bones, teeth, and skulls of extinct animals — insec- 

 tivores, rabbits, mice, horses, rhinoceroses, merycoidodonts (oreo- 

 donts), etc. There are also turtles and a few bones of mammals near 

 the top. 



The Upper Beds. — Above the nodular beds are clays and sand- 

 stones, which in part resemble the upper beds at White Butte, and 

 they are undoubtedly of nearly the same age. The clays contain re- 

 mains of three-toed horses, merycoidodonts with large ear-capsules, 

 lizards, turtles, etc. ; and in the sandstone part of the skull of a 

 rhinoceros {Aceratherium) was found. 



From Medora, North Dakota, to Glendive, Montana. 



As we proceed on our way westward from Medora on the Northern 

 Pacific Railroad, we ascend a branch of the Little Missouri River. It 

 is a small winding stream, which has made cut-banks in modern alluvial 

 deposits and in Fort Union strata. The sage-brush flats, through 

 which it flows, are shut in on either side by hills and bluffs one 

 hundred feet or more in height. As the road rapidly ascends, the 

 valley becomes broadly V-shaped, the hills are relatively lower and 

 more grassy, and are scored by shallow depressions called "buffalo- 

 wallows." The cut-banks and other exposures of the strata become 

 less and less numerous. Soon we are on the high rolling prairie on 

 which are large buttes. In some of these buttes are exposed the rocks 

 of which they are composed. 



Sentinel Butte is a conspicuous landmark, which lies to the south- 

 ward of the station of that name. Like Black Butte it is a remnant 

 of higher strata, the greater portions of which have been removed by 

 erosion. Seams of coal are still seen in the exposures of the rocks 

 along the railroad. The general surface of the country consists of 



