8 



WATER REPTILES OF THE PAST AND PRESENT 



over the denuded rocks in which they occur. Methods of search 

 and collection will best be understood by the following description 

 of the noted fossil-bearing rocks of western Kansas. 



About the middle of Cretaceous times, there extended from the 

 Gulf of Mexico on the south to or nearly to the Arctic Ocean on 

 the north a narrow inland ocean or sea, a few hundred miles in 

 width, covering what is now the western part of Kansas and the 

 eastern part of Colorado, and separating the North American 



Fig. I. — A characteristic chalk exposure in western Kansas, a hundred acres or 

 more in extent. 



continent into two distinct bodies of land. This ocean, because of 

 its location, bordered on both sides by low-lying lands — the Rocky 

 Mountains had not then been pushed up — doubtless was compara- 

 tively calm and placid, free from violent storms and high tides. 

 That the climate, in the region of Kansas at least, was warm or 

 even subtropical is fairly certain, since plants alhed to those now 

 living in w^arm, temperate, or subtropical regions were then living 

 much farther to the north; and since the animals which then 



