Lawson.] 



The Upper Kern Basin. 



339 



wall of the defile rises rapidly again in height, and is in places 

 1000 feet or more above the floor of the defile. This wall is in 

 places precipitous and cliff-like. It is the western edge of the 

 semicircular area of mountainous country which is circumscribed 

 by the bend of the Kern above referred to. There are no streams 

 entering the defile from either side, and the only water found in 

 it is seepage from underground waters, and this only at one or 

 two places. This seepage flows southerly and accumulates at 

 Trout Meadows, and is the cause of the formation of the meadows. 

 The defile shows no evidence of ever having been occupied by a 

 stream flowing through it. Its floor is mantled with the waste 

 of the granite from the slopes on either side and is chiefly a coarse 

 arkose sand. The width of the defile is least at its northern end, 

 where, at the bottom, it is not much more than 200 feet. This 

 portion of the defile is shown in Plate 40a. Toward the south it 

 gradually widens to about 1000 feet near Trout Meadows. The 

 floor and sides of the defile are generally timbered, but in this 

 timber there are occasional open glades, one of which is shown 

 in Plate 40 b. 



This remarkable defile in the mountains can scarcely be 

 explained in any other way than as having been determined by a 

 rift line along the west wall of Kern Canon. It is structurally 

 the extension of Kern Canon, though it is not now, and may never 

 have been, functional as a stream course. 



This rift hypothesis which thus seems to be forced upon us 

 embraces two possibilities: either, that the defile is a simple graben, 

 or, that it is an erosional feature controlled or originated by a rift 

 line. The absence of stream features and of stream gravels in 

 the defile and the fact, not before stated, that at its southern 

 end it is lower than the Little Kern Plateau, which is clearly a 

 stream-cut terrace, militate against the erosional phase of the 

 hypothesis and impel us to accept the graben phase as the most 

 probable explanation of this most interesting geomorphic feature. 

 But if we accept this view for the defile it establishes the hypoth- 

 esis of rifting as a factor in the morphogeny of the whole of the 

 canon of the Upper Kern; for the west wall of the defile is iden- 

 tical with the west wall of the canon above the bend. 



Thus the difficulty which presented itself on attempting to 



