Lawson.] 



The Upper Kern Basin 



295 



the biotite, into hornblende- granite with much less quartz. 

 From these there appear to be gradations into quartz- diorite 

 and diorite in which plagioelase can be recognized easily in 

 hand specimens. These more basic facies, however, appeal' to 

 be quite subordinate in extent as compared with the common 

 biotite- granite. In this type of granite, dykes or veins of peg- 

 matite are rare; but on the canon walls above the meadows there 

 are numerous small dykes of a reddish, or flesh tinted, fine- 

 grained granite, with but very little admixture of ferro-magnesian 

 minerals. The rock may be perhaps conveniently classed with 

 the aplites, although its structure, as judged by hand specimens, 

 appears frequently to be granular. These dykes were observed 

 in several instances to be from three to five feet wide, but the 

 width of most of them probably does not exceed one foot. They 

 appear to have had little or no influence in giving direction to 

 differential erosion. 



The biotite- granite of this portion of the basin, together with 

 its dioritic facies, is characterized by the presence of a great 

 abundance of angular, sub-angular and rounded inclusions of a 

 darker gray, finer grained, porphyrinic rock. These appear 

 usually to be slightly more resistant to disintegration than the 

 granite which holds them. In some instances, where such 

 inclusions are particularly abundant, it was estimated that there 

 might be one cubic foot of inclusion for every cubic yard of 

 granite. On the average, however, where these inclusions 

 occur, there is probably not more than one cubic foot of inclu- 

 sion to every four or five yards of granite. In size the inclusions 

 range from a few inches to several feet in diameter and probably 

 average about one foot. 



In this biotite-granite there are, also, in the canon of the 

 Kern comparatively small areas of coarse-grained gabbro-like rock, 

 in which, however, the proportions of feldspar and ferro-magnesian 

 silicate vary. This gabbro may be assumed, in the light of 

 current doctrines on magma differentiation, to be genetically 

 connected with the granite ; but the transitions from the gabbro 

 to the granite, so far as they were observed, are abrupt, and 

 more suggestive of an intrusive relationship than of a gradual 

 transition of one rock into the other. These gabbro areas are 



