c;eolc)c.ic history 209 



These latter-day events were all parts and reflections 

 of the greater isostatic history of the Pacific Ocean 

 Basin — a history as yet unwritten and which will re- 

 veal much when done. 



SOUTHERN CALIFORNIA DURING THE GLACIAL 



EPOCHS 

 The four or more great ice loads which in Glacial 

 times covered much of the northern portions of our 

 continent and of Eurasia are not known to have ex- 

 tended as far south as California, although mountain- 

 top glaciation was much more in evidence then 

 than now. The abundance of ill-sorted, fragmental 

 rocks distributed over the foothills and margins of the 

 valley plains by outwash from the highlands has led 

 many to associate these phenomena with wide-extend- 

 ing glacial deposits, but they are mistaken. Neverthe- 

 less great geologic events were taking place in South- 

 ern California during the glacial epochs, as will be 

 shown. 



CAUSES OF EARTH MOVEMENTS IN THE 

 GLACIAL EPOCHS 

 The fact is that almost incalculable weights and quan- 

 tities of water were gathered from the surface of the 

 ocean, transported and redeposited as loads of snow 

 and ice upon restricted, continental areas during the 

 Glacial Epochs, and that they must have constituted 

 great earth loads of vast isostatic potentiality. Billions 

 upon billions of tons of water were transferred from 

 the ocean to the lands thereby lowering the surface of 

 the latter and lightening the load above the bottoms 

 of the former. These loads, unless the theory of 

 isostasy fails us, must have caused great sinkings of 

 those portions of the crust immediately beneath them 



