8 University of California Publications in Zoology [Vol.22 



The differences in gradient partly cause an asymmetery of the 

 valley floor which is made prominent by the differences of the streams 

 on the two sides. Since the streams on the east side are larger, they 

 have built larger deltas with a wider spread as they cross the lighter, 

 longer slopes. Deltas from the two sides have united across the valley, 

 cutting off the Tulare basin. For this reason water from the large 

 streams at the head of the valley does not reach the San Joaquin River, 

 except in years of unusual rainfall. Thus about one-fourth of the 

 main basin is practically separated from the rest and this southern 

 area rarely has any influence on northern conditions. 



FOEEST ABE AS 



There is no important forest cover in the main valley. Some of the 

 higher ground in the Coast Range bears shrubbery and light timber. 

 The Sierra foothills are usually well covered with grass, brush and 

 scattering trees. Above the foothills is heavy timber to 10,000 feet, 

 above which none occurs. The famous Sequoias occur in this region. 

 National forests occupy about 65 per cent of the Sierra slopes. 



EAINFALL 



The annual rainfall varies from five to twenty inches from south 

 to north along the valley. The west slope has light rainfall with simi- 

 lar increase northwest. The Sierra slopes show heavier precipitation 

 according to altitude, but with similar increase to northward. 



IMPOKTANT TRIBUTARIES OF SAN JOAQUIN DRAINAGE AREA 



In addition to the foregoing consideration of the main river and 

 the basin as a whole it is worth while to include some points concern- 

 ing three or four of the principal tributaries which may have some 

 recognizable influence at Stockton. 



The Kings River 

 The King's River is the most southerly tributary that has any 

 ordinary connection witli the San Joaquin. Its relation is rather 

 peculiar since its delta forms a large part of the barrier cutting off 

 the Tulare Lake Basin from the main valley. This delta has been built 

 in such a way as to carry the entire flow of the Kings River to the San 

 Joaquin during low water, but most of the flood waters go to Tulare 

 Lake. The altitude near the entrance of the San Joaquin is about 175 

 feet according to Clapp and Henshaw (1911). 



