Lawson.] 



The Upper Kern Basin. 



319 



Toowa Valley. — Falling within the hypsometric limits of the 

 High Valley Zone is the valley occupied by Volcano Creek in its 

 western part and, in its eastern extension toward the Summit 

 Divide, by the South Fork of the Kern. It will be referred to as 

 the Toowa Valley from the neighboring range of that name, 

 since, being occupied by two distinct streams, it cannot be 

 referred to by the name of either without some confusion. This 

 valley is a scarcely less remarkable feature of the mountains than 

 the Chagoopa plateau. It is a high valley, geomorphicly 

 mature, which extends across the southern Sierra Nevada from 

 the caiion of the Kern to a gap in the crest of the Summit 

 Divide, about six miles west from the south end of Owen's Lake. 

 The relations of Volcano Creek and the South Fork of Kern 

 River to this valley are peculiar and merit a brief mention before 

 entering upon a consideration of its more general features. 



Volcano Creek rises on the southern slope of Cirque Peak 

 and flows southerly for about eight miles, as a small brook in a 

 mature valley, with a grade of probably 200 to 250 feet per mile. 

 It then enters Toowa Valley and flows westerly to the Kern. 

 The South Fork of the Kern heads in the Summit Divide about 

 three miles southeast of Cirque Peak and flows southwest for six 

 miles as a similarly small brook, entering Toowa Valley at the 

 same point as the upper stretch of Volcano Creek. But instead 

 of flowing west to the Kern it makes an acute bend and flows 

 southeasterly through the eastern part of the valley. The divide 

 between the two streams, where they thus enter the valley, is a 

 low ridge of alluvium so narrow as to have suggested the attempt, 

 which was successfully made, of connecting the two streams by a 

 tunnel, and so diverting the waters of Volcano Creek into the 

 South Fork. These two brooks were at one time clearly tributa- 

 ries of one stream, which occupied the Toowa Valley, and the 

 separation of the drainage into two distinct streams, one flowing 

 west and the other east in the same valley, is an interesting 

 problem which has its bearing upon the geomorphy of the region, 

 and will be again referred to in a later part of the paper. 



The low alluvial divide between Volcano Creek and the South 

 Fork, at the place where they enter Toowa Valley, is about 8,600 

 feet above sea level; and the general altitude of the meadows of 



