Lawson.] 



The Upper Kern Basin. 



307 



At the base of the steep slopes of the high mountains, which 

 thus encircle the Upper Kern Basin from the southern end of 

 the Great Western Divide to Cirque Peak, there spreads out in 

 the central part of the basin a broad valley land of very subdued 

 relief. This valley land is known as the Chagoopa Plateau. 

 From the mountains on either side of the basin it slopes gently 

 with a remarkably uniform surface toward the Kern. Its upper 

 limit at the base of the high mountain peaks and crests is about 

 10,500 feet, while its lowest part at the brink of the Kern Canon 

 is from 8,400 feet in the southern part to about 9,000 feet in the 

 northern part, above sea level. Through the central part of this 

 high valley runs the profound canon of the Upper Kern, a 

 meridional trough sunk in the valley floor to a maximum depth 

 of about 2,500 feet and bordered by almost vertical walls for a 

 large part of its course. The streams which drain the high 

 mountains on either side flow through similarly deep, steep- 

 walled trenches as they cross the Chagoopa Plateau on their way 

 to the Kern, but in no case have they cut as deeply as the master 

 stream . 



It thus appears that within the Kern Basin there are three 

 hypsometric zones, distinguished by such marked differences in 

 the character of their relief as to constitute three distinct geo- 

 morphic zones. These may be called for convenience, (1) The 

 High Mountain Zone; (2) Tlie High Valley Zone; and (3) The 

 Cation Zone. 



THE HIGH MOUNTAIN ZONE. 



The Summit Upland. — This zone has been characterized in the 

 sketch of the rim of the basin as consisting essentially of high 

 peaks and crests. This, however, does not sufficiently describe 

 the geomorphic character of these mountains, and some of their 

 more striking features must be noted particularly. Several of 

 the culminating portions of the summit divide are either flat 

 topped, or have slopes which are so gently inclined as to be in 

 sharp contrast to the more precipitous slopes which abound in 

 the region. The best illustrations of such flat, or gently sloping, 

 summits is that afforded by the summit range from Sheep 

 Mountain to Circpie Peak. The summit of Mt. Whitney itself is 



