io8 Introduction to Life of the Lakes. 



clams, but the place to look for land animals 

 is in some old lake bed, and this lake bed 

 being absent from any land region, no matter 

 how abundant the life on its hillside, the geo- 

 logical record is lost; for the hills are them- 

 selves dying and Nature writes no geological 

 records on dying hills. The reason for this is 

 not far to seek. If a bone or tooth is dropped 

 on a hillside beyond the reach of a stream, it 

 at once begins a process of decay that in a 

 few years reduces its form to dust and it is 

 thenceforth lost. These hills on which it fell 

 are themselves wasting away with all that rests 

 upon their surfaces. Geological records are 

 only preserved in the sediments of water. 

 Now, in the light of these facts, we see at once 

 the great geological advantages conferred 

 upon our Shoshone region by an extensive 

 lake of not less than one hundred thousand 

 square miles in area, extending from Shoshone 

 island westward to where the DesChutes river 

 now runs, and continuing through the whole 

 length of Miocene time. This lake of Eastern 

 Oregon continued to receive into its waters 



