THE BIOGRAPHY OF AN ANCIENT AMERICAN LAKE » 



By WiLMOT H. Bradley 

 Geologist, U. S. Geological Survey 



[With 4 plates] 



As in olden times, when Kiiblai Khan held absolute rule over a vast 

 domain and progressively amassed great wealth by reason of the 

 tribute that flowed in from outlying provinces, so in a far remoter 

 epoch, long antedating human history, a great lake held sway over a 

 vast area in the Rocky Mountain region and gradually accumulated 

 in tremendous volume a potential natural resource derived from the 

 sun's unfailing supply of energy and from the mineral burden that 

 flowed in from adjoming lands through its tributaries. 



So remote was this epoch that could we go back to it in time we 

 would be compelled to gage our progress by the slow evolution of 

 animal hfe and the gradually changing expression of the earth's face. 

 We would have to go backward with undreamed-of speed past a 

 pageant of animals that inherited the earth in slow succession as 

 evolution molded them. So short is man's history that it would flit 

 by too quicldy to be perceived. Passing backward in a brief moment 

 through the silent ice age, we would see man's primitive ancestors, 

 together with giant sloths, giant bears and beavers, and the woolly 

 mammoth. Farther back we would meet small elephants and, on the 

 plains, bands of horses, wild asses, and camels. Farther back in 

 time's flight we would flnd their smaller and ever smaller precursors. 

 Suddenly would appear the hippopotamusUke titanotheres and a 

 host of other strange creatures, each leading a succession of smaller 

 and less specialized ancestors. Finally we would come to the time 

 of the diminutive four-toed horses, which dwelt in the forests and 

 grassy parks of that epoch of long ago when the ancient lake came 

 into its regency. 



This great lake, ImouTi as "Lake Uinta," occupied a long, shallow 

 basin or downwarp of the earth's crust about a hundred miles south- 

 east of Utah's present Great Salt Lake. The record it left is pre- 



> Published by permission of the Director, U. 8. Geological Survey. Reprinted by permission from the 

 Scientific Monthly, vol. 42, pp. 421-430, May 1936. 



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