66 



CARNEGIE INSTITUTION OF WASHINGTON. 



As the history of Lake Lahontan is largely to be determined by our 

 knowledge of the origin of its calcareous deposits, the evidence bearing 

 on the history of this lake has been reviewed and conclusions differing 

 somewhat from those of Professor Russell have been reached. It 

 seems highly probable that Lahontan has never been completely desic- 

 cated and that Pyramid Lake is a remnant of the older lake. 



An estimate of the age of Pyramid Lake, based on its present saline 

 content, indicated that Lahontan originated about 4,500 years ago. 

 The finding of the bones of a horse, lion, and camel, similar to those 



1907 



1908 



1909 



1910 



1912 



1913 



1914 



Fig. 1. — Curves showing the amounts of summer rainfall at the Desert Lab- 

 oratory (solid line) and at an elevation of 8,000 feet in the Santa Catalina 

 Mountains (broken line), covering a period of eight years. The amounts 

 for 1914 are to the end of July only. 



