Lawson.] 



The I '/>})(' r Kern Basin 



335 



But the material of which the kernbut is composed is not 

 plastic, and lias suffered no observable plastic deformation, and 

 a fairer comparison would be with known rock-slides. For- 

 tunately for such a comparison we have, in this case, not far to 

 seek. On the east side of Kern Canon, immediately below Lower 

 Lake, there is a colossal rock-slide nearly a mile in length and 

 about 2,000 feet high. This rock-slide differs from ordinary 

 landslides in this important respect, that the slipped mass, being 

 of rigid materials incapable of plastic deformation under the 

 stresses induced by gravity, broke to pieces as it slid, and is 

 now a chaotic aggregation of huge spauls of rock. The same 

 general profile has, however, resulted from the smashing up of 

 the mass and the readjustment of the fragments as is attained by 

 rotation and plastic deformation in more yielding materials; and 

 there is a distinct, though rude, landslide terrace at the top of 

 the fallen mass. 



We have here, therefore, an excellent basis of comparison of 

 the kernbuts with an unequivocal rock slide in the canon of the 

 Kern itself, in the same kind of rock and under the same general 

 conditions that may be supposed to have affected the canon walls 

 at the time when the kernbuts were formed. The comparison, it 

 is scarcely necessary to point out, is adverse to the hypothesis 

 that the kernbuts are of the nature of landslides. This adver- 

 sity, however, does not disprove the hypothesis. It may be 

 urged, with good reason, that the rock-slide, which has just been 

 cited, may be only one phase of the results which arise from this 

 process. It is possible that the rock-slide on the east side of the 

 Kern Canon below Lower Lake has been a sudden slip, a catas- 

 trophic event , and that the smashing up of the mass is due to the 

 rapidity of the movement. If such a slide were a slow process, 

 the slipped block might in time descend to the bottom of the 

 canon without the shattering of the mass. But landslides and 

 rock-slides are in general habitually sudden in their movements;* 

 and the assumption that the kernbuts are the result of slowly 

 moving slides of the landslide type would reverse their habit in 



♦There are, however, certain exceptions to this general rule, and under special 

 conditions a land-slide may move comparatively slowly. An instance of this kind 

 is described by Gilbert in the Bull. Philos. Soc. of Wash., Vol. XII, p. 244. 



