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University of California. 



[Vol. 2. 



Endomorpliism of the Granite. — The relation of the granite of 

 the peninsula to other formations will be more fully stated in the 

 succeeding paragraphs, yet it may be incidentally referred to here 

 for the fuller discussion of the granite itself. Lacroix has 

 described the occurrence in the Pyrenees of an acid biotite granite 

 which has been intruded into a series of calcareous and siliceous 

 sedimentary rocks. Among the metamorphic alterations effected 

 in the zone of contact was the development of more basic phases 

 in the granite itself where it was found in contact with limestone. 

 Quite similar relations are to be seen on the peninsula. Imme- 

 diately beneath a zone of crystalline schist developed in the sedi- 

 mentaries is a zone of granite different from any other that was 

 found in the field. A thorough study of this interesting occurrence 

 was not undertaken, although there can be no doubt that it would 

 be well rewarded. 



The character of the granite at this contact is not uniform. It 

 seems, in fact, to be quite variable. Much of it is a very dark, 

 rather fine-grained, hornblende-bearing rock, containing only a little 

 quartz and not a large amount of feldspar. The hornblende is of 

 the green variety and considerably more abundant than the dark 

 grains of biotite. The feldspars are similar to those of the normal 

 granite in which orthoclase predominates. Oligoclase is common 

 and andesine is occasionally seen. These are the only idiomorphic 

 elements found in the rock. Magnetite occurs in scattered grains 

 resulting apparently from the alteration of hornblende. Another 

 phase of the granite which is perhaps less basic than this is a light- 

 colored garnetiferous variety which contains no hornblende and a 

 smaller amount of biotite than most of the normal granite. In 

 other respects it may rank with the normal variety, except that it 

 contains great numbers of small pinkish-colored garnets resembling 

 some of the lime-iron varieties. This rock was found not far from 

 the preceding variety below the zone of crystalline schist. Other 

 basic phases are common but were not sufficiently studied to make 

 definite statements in regard to them. 



Relation to Other Massifs. — The geological relation of the 

 granites of the Coast Ranges of central California to those of other 

 parts of the state, or of the coast, is a very interesting question. 



