NOTES ON SOME IGNEOUS, METAMORPHIC, AND 
SEDIMENTARY “ROCKS OF THE COAST RANGES 
OF CAL INOR INIA 
The metabasalts and diabases of the Coast Ranges.—There are 
very abundant masses of greenish rocks in the Coast Ranges 
which are often massive, but sometimes form distinct breccias. 
The microscopic investigation of these rocks show them to be 
of igneous origin, and to largely represent old lavas. Many such 
rocks were supposed by Professor Whitney, the former state 
geologist of California, to be metamorphic sandstones. Dr. 
Becker, in his investigation of the quicksilver deposits? of the 
Pacific slope, regarded some of them as metamorphic sandstones, 
and gave such the name “ pseudo-diabase”’ and ‘“ pseudo-diorite.”’ 
In an investigation of the geology and petrography of Mt. 
Diablo,3 I found that some of the so-called metamorphic sand- 
stone of Whitney was true diabase and unquestionably of 
igneous origin. In this conclusion, Dr. Becker concurred. 
More recently Dr. Ransome,* in a study of the rocks at Pt. 
Bonita, California, found there similar rocks, which he called 
basalt and diabase. Still later, Ransome, in an investigation of 
the geology of Angel Island, found certain greenstones which he 
considered as allied to fourchite, although admitting that feld- 
spar might have been present in the rock, as indicated by the 
great abundance of a zoisite-like mineral in some thin sections. 
In 1897, in company with Mr. J. S. Diller, I visited Angel 
Island and collected there specimens of the so-called fourchite, 
and of other rocks. Some of these specimens show plenty of 
fresh plagioclase and there is therefore no doubt that some of 
™ The author, doubtless due to absence in the field, has been unable to read the 
proof of this article. 
? Mon. XIII, U.S. Geol. Sury. 3Bull. Geol. Soc. Am., Vol, II, pp. 383-414. 
4 Bull. Dept. Geol., University of California, Vol. I, pp. 71-114. 
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