No. 384.] REVIEWS OF RECENT LITERATURE. 967 
occurs in two varieties, a reddish brown and a dark green one, the 
latter only as zonal growths around the former. The hornblende- 
gabbros are occasionally porphyritic through the development in them 
of phenocrysts of brown hornblende. The peridotites include wehrlite, 
cortlandtite, and other types that grade into one another and into gab- 
bro. In some of the peridotites the olivines are surrounded by rims 
of orthorhombic pyroxene, and these by rims of hornblende. 
All these various rocks are regarded as belonging to one geological 
unit, the order of succession of its parts being gabbro, peridotite, and 
diorite, and, finally, possibly granite 
Analyses: Mica-diorite (I), homablende-gabbrds (II), bronzite-no- 
rite (III), and peridotite (IV). 
SiO, TiO, AlO; Fe,03 FeO CaO MgO K,O NaO H,O P,Os CO, Toni 
I 58.51 16.32 4-43 3-92 3-73 pi 2.23 «30 = 99.46 
II 49-80 .79 19.96 6.32 49 1033 705 6 232 18 07 15 = 100.63 
III 48:17 roo 25.260 1.13 6.10: 053 3 Ly aw 07 43 = 100.17 
IV. 44-99 -97 sór ¥.4e Syo 579 38. 74 OF 362 205 tr, 99-1 
The peridotite contains also .25 per cent Cr2Q3. 
California Rocks. — In an article discussing the geology of the 
coast ranges in California, Turner’ gives some interesting informa- 
tion concerning the igneous and the metamorphic rocks of the dis- 
trict, and corrects some erroneous notions heretofore held concerning 
the latter. The*metabasalts and diabases were thought by Whitney 
to be metamorphosed sandstones — a view also held by Becker con- 
cerning some of them. These are all igneous rocks of the usual char- 
acter of altered basalts and diabases. The “ fourchite ” of Ransome 
from Angel Island is also a metabasalt (altered basalt). The serpen- 
tines, regarded by Whitney and by Becker as altered sandstones, are 
also shown by Turner to be altered igneous rocks in which olivine, 
or orthorhombic pyroxene, was an original constituent. The idea that 
the serpentine is a changed sandstone was due to the fact that some 
of the sandstones associated with it contain some igneous material, 
and that this has changed in part to serpentine. 
The amphibole-schists and the blue amphibole-schists of the 
Golden Gate series were looked upon by Ransome and by Lawson 
as contact metamorphosed rocks. The author urges reasons for 
believing them to be regionally metamorphose volcanic masses. 
Adirondack Gneisses.—Some interesting facts concerning the 
gneisses associated with the crystalline limestones in St. Lawrence 
1 Journ. of Geol., vol. vi (1898), p. 483- 
