S2 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 



temporary camping places, of objects scattered over the surface 

 of the ground, and the results of mining exploitation. 



And, further, by a continued search for, and study of, the 

 animal life of the region, from its earliest appearance to the pres- 

 ent time, especially with a view to ascertaining what species of 

 animals occupied the region anterior to, or, contemporaneous 

 with, our "oldest inhabitants." The correct answers to these 

 cjuestions throw much light upon the subject under considera- 

 tion, as will hereafter become apparent. 



TOPOGRAPHY. 



In order that we may be able to realize something of the 

 great changes in the topography of California which preceded 

 the advent of its human inhabitants, it is deemed necessary to 

 go back in the world's history to the close of the Cretaceous or 

 Reptilian Age, at which time the region now known as California 

 — with the exception of the Sierra Xevada ]yIountain Range, and 

 portions of the Coast Range — was lying at the bottom of the 

 ocean. 



It is probable that some portions of the Coast Range, as 

 well as of the Sierras, formed detached islands in the Cretaceous 

 ocean. 



During the Cretaceous Age a large portion of the present 

 continent of Xorth America, including the Rocky ^Mountain Re- 

 gion, was under water, as shown bv the marine and fluviatile 

 deposits now found in the regions which, at that time, formed 

 the ocean's bed. 



The Gulf of INIexico extended northward along what is now 

 the Valley of the Mississippi to the confluence of the Ohio and 

 Mississippi rivers, where a great bay received the waters of 

 those rivers. 



Westward it extended to the region of the Colorado River, 

 and probably to the Pacific Ocean, and from the southern por- 

 tion of California -a cretaceous sea flanked the eastern slope of 

 the Sierra Nevadas, extending northerly to the Arctic Ocean, 

 where the Mackenzie River and its tributaries are now found. 



It also covered the present watershed of the Missouri and, 

 Yellowstone rivers. Cretaceous seas covered the ''Great Plains" 

 Prairie region and the summits of parts of the Rocky Moun- 

 tains, to where the eastern slope ol the AA'ahsatch ^Mountains 

 now are. 



These lofty ranges have since been raised, and in part the 

 elevation took place before the epoch of the Tertiary, whose ma- 

 rine beds lie at their base.^ 



Abundant evidences of this extensive submersion during 

 the Cretaceous Ag-e are found throuo'hout California. 



I. See Dana's "Manual of Geology," pps. 490 and 503. 



