Lawson.] 



The Upper Kern Basin. 



Haviug pointed out the analogies between Toowa Valley and 

 Chagoopa Plateau and correlated them on that basis, it remains 

 to indicate some interesting differences. These lie chiefly in the 

 character of the slopes which border and confine these high 

 valleys. In the ease of the Chagoopa Plateau, as we vise from 

 the back of the valley into the High Mountain Zone we enter at 

 once, in almost all directions, info a zone of intensely glaciated 

 country; while, from points which afford the most commanding 

 views of Toowa Valley and the higher country drained by it, no 

 trace of glaciation can he detected, but only those forms of relief 

 which are clearly and unquestionably referable to atmospheric 

 and stream erosion. But since Toowa Valley is hypsomef rically 

 and geomorphicly, and, therefore, also chronologically, the 

 equivalent of Chagoopa Plateau, it is evident that the slopes 

 which encircled Chagoopa Plateau, in time anterior to the 

 glaciation of the region, must have reached the same general 

 stage of geomorphie development as had the slopes which confine 

 Toowa Valley. In the mature geomorphy of the High Mountain 

 Zone bordering Toowa Valley with its rounded forms, its flaring 

 valleys, its sloping divides and its low grades, we have presented 

 to us, therefore, in but slightly modified form, the geomorphie 

 character of the High Mountain Zone about Chagoopa Valley at 

 the time of the inauguration of the Sierran glaciation. The 

 fierce and preeipitoiis forms of the relief of the High Mountain 

 Zone in the northern three-fourths of the upper Kern Basin 

 have, for the most part, been evolved from a geomorphy almost 

 as mature as that we see in the country tributary to Toowa 

 Valley. 



The modifications referred to above which necessitate the 

 introduction of the word "almost" in the last sentence are due to 

 three causes. (1) The hypsometric range of the High Mountain 

 Zone about Chagoopa Plateau is greater than that above Toowa 

 Valley. This implies, of course, that more erosional work would 

 have to be done in that part of the basin in order to arrive at 

 maturity than in the somewhat lower country to the south. 

 Still, the time necessary for the reduction of the country 

 about Toowa Valley to maturity could not fail of the same 

 general result in the country encircling Chagoopa Plateau. The 



