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University of California. 



[Vol. :j. 



devoid of the inclusions which abound in the adjacent granite. 

 The gabbro, where exposed to the weather, shows the etching of 

 the feldspar and the relief of the pyroxene. 



Dykes. — In addition to these more intrinsic characters of the 

 granitic rocks in the vicinity of the canon of the Kern, it may be 

 stated that near the Kern Lakes and for some little distance 

 above Coyote creek the granite is cut rather frequently by small 

 dykes of black, fine grained lamprophyre. These are rarely 

 more than a few feet, sometimes only a few inches, in width, 

 and have all attitudes from nearly horizontal to quite vertical. 

 Some of them are multiple dykes. These dykes appear to be 

 particularly abundant on the east side of Kern Canon below 

 Lower Lake, on a scar formed by a great rock-slide, where they 

 dip northeasterly at low angles. The dykes above the mouth of 

 Coyote Creek strike E.N.E. and dip southerly at an angle of 70° 

 from the horizon. A multiple dyke of three members was here 

 observed. The most northerly is from four to five feet wide; 

 the next parallel dyke to the south, 10 feet distant, is about two 

 and a half feet wide; and the next, about 10 feet farther south, 

 is six inches wide. The rock is here a dark gray, porphyritic 

 rock with phenocrysts of feldspar and hornblende, the latter 

 predominating. The groundmass is fine grained but apparently 

 holocrystalline. The texture on the chilled edges against the 

 granite is finer than in the middle of the dykes. A little to the 

 south of this multiple group another dyke of the same rock was 

 observed with a strike at right angles to that above recorded. 

 These dykes are somewhat more resistant to the weather than 

 the granite which they cut, and are, therefore, somewhat prom- 

 inent as a shoulder on the steep mountain slope. They break 

 down into angular blocks, while the granite on disintegration 

 crumbles to a coarse sand. 



Such dykes, though locally abundant in the southern part of 

 the basin, in the Kern Canon, do not appear to be at all common 

 throughout the basin and cannot be said, even where they 

 abound, to have exercised an important influence upon the gen- 

 eral morphogenic process, by determining lines of either maxi- 

 mum or minimum erosion; unless we assume that the association 

 of an exceptional number of such dykes with the large rock-slide 



