146 H. W. TURNER 



diorite, in actual use the term in some of my own folios has been 

 applied to all the rocks of which analyses are given in the table, 

 so far as field mapping is concerned, although as a rule gabbro, 

 even when genetically related to granodiorite proper, has been 

 separated. Since the term has been so extensively used for 

 quartz-diorites containing orthoclase, it is thought better to 

 restrict the term to this usage and to call the rocks which are 

 strictly intermediate between granite and diorite, quartz-mon- 

 zonite. 



While there is some doubt as to all of the areas called 

 granodiorite in the folios being actually all portions of one 

 magma, yet there is so great a variation within so many of these 

 areas that the fact that the magma is a greatly variable one is 

 established independently of the consideration of the batholith 

 as a whole. 



The evidence that the areas ascribed to this great batholith 

 were intruded at nearly the same time is not altogether satisfac- 

 tory, but at all places it points in the same direction. That is 

 to say, wherever the granolites composing the batholith come 

 into contact with other rocks, excepting those of post-Jurassic 

 age, it is usually evident that they have metamorphosed those 

 rocks, indicating that they are intrusive in them and are of later 

 age. West of Mariposa the granodiorite has cut off and meta- 

 morphosed the Jurassic Mariposa slates into chiastolite- and 

 mica-schists. At Mineral King - , in the heart of the Sierra 

 Nevada, to the west of Mt. Whitney, is a lens of Juratrias sedi- 

 ments which has been metamorphosed by granodiorite. The 

 evidence is good that the great bulk of the pyroclastic meta- 

 augite-andesites of the foothills are of Juratrias age. That the 

 granodiorite is intrusive in these rocks at some points, and has 

 metamorphosed them, is evident in the field, as for example, 

 north and east of Mormon Bar in Mariposa county, where the 

 meta-augite-andesite-tuffs have undergone a thorough recrys- 

 tallization. In Plumas county, southeast of Sierra City, the 

 Juratrias rocks of the Milton formation have likewise been 



