lindghkn.J NEOCENE EIVERS OF THE SIERRA NEVADA. 65 
region of the eastern slope. The gravels and the covering volcanic 
material are to he discussed from a geological and petrographical 
standpoint; and much space will he given to the question of the con- 
nection of the isolated gravel areas with Neocene river systems, 
a question which also includes a physiographical description of the 
Sierra Nevada during the Neocene period. As a general result the 
Neocene Sierra Nevada will be shown to have existed at that time as 
a well-defined range, similar to though lower than the present moun- 
tains. The rivers headed near the present divide, and flowing in a 
general westerly direction, emptied into the bay or marshes of the 
Sacramento and San Joaquin valleys. Finally, the probable char- 
acter of the orographic disturbance to which the range owes its 
present elevation will be discussed. 
Bull. 2i:J— 03 5 
