GEOLOGIC HISTORY 213 



east-west trending ranges of the Channel Archapelago 

 arose across the path of the older northwest ranges 

 mentioned; while a former valley plain of the land 

 subsided to make the Santa Barbara Channel. 



In fact it was during the earliest of the Pleistocene 

 epochs that the great Transverse structures arose 

 across the continent and separated Northern and 

 Southern California, like the "earth was divided" in 

 Peleg's day. 



Climate is the servant of geology, and temperatures 

 and precipitation in Southern California during the 

 Pleistocene epoch likewise reflected the presence or 

 absence of the northern ice sheets. Life, too, then re- 

 sponded to the great structural and climatic changes, 

 as is witnessed by the presence and extinction of pecu- 

 liar forms such as have been found at La Brea and 

 other places, for here camels, elephants, horses, sabre 

 toothed tigers, lions and peacocks flourished. 



It is even probable that in the last days of this Pleis- 

 tocene epoch early man may have appeared upon 

 the scene in California. The writer believes that 

 the human remains of La Cienega Basin at Los An- 

 geles are of the latest days of this epoch. 



And, finally, it was during these epochs that the 

 great fault and earthquake-producing movements com- 

 parable to those now active on the west side of the 

 Pacific Basin, here attained their maximum and be- 

 gan to diminish before the present time of comparative 

 quiet and moderate seismicity. 



The collective details of this story of Southern Cali- 

 fornia in Pleistocene time is one of the most fascinat- 

 ing of all the annals of geologic history, and one which 

 overshadows all others in relation to this particular 

 region. 



