3G6 



University of California. 



[Vol. 3. 



buttresses from the canon walls, and the ridges of the multiple 

 kernbuts from one another, being called kerneols. 



With the initiation of the down cutting of the Kern, below the 

 floor of the High Valley, Toowa Valley was beheaded. This 

 resulted from the capture of the drainage of Chagoopa Plateau 

 by a stream heading up the rift line from the point where the 

 present Kern bends to the east below Lower Lake. 



After the canon of the Kern had been cut very nearly to its 

 present depth certain volcanic vents opened on the floor of 

 Toowa Valley and in the trench which had dissected it. These 

 built up cones, which are still perfectly intact, and caused lava 

 streams to flow down Volcano Creek nearly to the level of the 

 Kern, filling up the trench which had been cut in the floor of 

 Toowa Valley by that stream. Since then the lower end of this 

 lava coulee has been cut away by the Kern and Volcano Creek 

 has cut back an incisive gorge in the lava for a couple of miles. 



Very late in Quaternary time the region was subjected to 

 Alpine glaciation. At its maximum a trunk glacier reached 

 down Kern Canon as far as Coyote Creek, 24 miles from the head 

 of the canon. The stay of the ice front at this point was brief. 

 It receded a mile up the canon and remained stationary for a 

 very much longer time ; and then vacated the canon at a uniform 

 rate of retreat. The sculpture of the high mountains by the ice 

 streams which fed this trunk glacier has completely transformed 

 the aspect of maturity which the mountains possessed in pre- 

 glacial time, and which is still splendidly displayed by the 

 unglaeiated southern portion of the region about Toowa Valley; 

 which maturity, of course, had been preserved from the time of 

 the High Valley cycle of degradation. 



The complete evacuation of the region by the ice is a very 

 recent event, and glaciers still linger in the cirques of the summit 

 divide but a short distance north of the head of the Kern.* 



The post-glacial degradation of the region has been very 

 slight. Atmospheric erosion is almost negligible and is measured 

 only in terms of small talus accumulations at the base of some of 



*This interesting fact has been communicated to the writer by Mr. J. N. 

 LeConte as the result of his observations in this part of the Sierra Nevada last 

 summer. 



