284 The American Geologist. May, 1902. 
The ‘“granodioryte” as in the Sierra Nevada region is ap- 
parently not a true granite as its feldspars are mainly plagio- 
clase, but the pink variety seems to more nearly approach the 
composition of a true granite. The two are a complementary 
series and represent the same magma at different stages. The 
pink granite bears the same relation to the granodioryte as the 
aplytes of the north. Although so sharply delimited and so 
strongly contrasted, there is no very great difference in their 
ages. This granite mass is part of the great grano-dioryte 
batholith of the Sierra Nevada region which has been proved 
to be of later age than the Mariposa slates which belong to the 
latest recognized epoch of the Jurassic period. The main bath- 
olith of Mohave desert sends long arms and outlying smaller 
batholiths into the Coast range region where they are known to 
be older than the Knoxville shales, as in Piru cafon. The in- 
trusion of this granite series, therefore, occurred sometime 
during the interval between the deposition of the latest fos- 
siliferous Jurassic sediments and the earliest, positively iden- 
tified, fossiliferous Cretaceous sediments. It may be presumed 
with reason that the same granite series is that which under- 
lies and is older that the Franciscan series a little farther west 
than I carried my investigations. 
THE RAVENNA PLUTONIC SERIES. 
The western. end of the Sierra Madre range in the vicinity 
of Lang and Ravenna stations seems to be composed largely 
of a plutonic series of a peculiar and rather unusual composi- 
tion. Just east of Lang station, Soledad canon is entered on 
the south by a deep, narrow cafion which extends far back 
into the high mountains. The creek brings out crystalline 
rocks of a great variety, from a very acid to a very basic. 
Several small specimens were selected from the rock in place 
near the mouth of the cafon and submitted to Dr. A. C. Law- 
son, who has kindly furnished me the following notes in ref- 
erence to them: 
A. A coarse-grained allotriomorphic granular aggregate of plagio- 
clase, green hornblende and magnetite. The plagioclase is charac- 
terized by prevailingly low symmetrical extinction angles not exceed- 
ing 30° and has a sp. g. of 2.67. It is therefore andesine and the rock 
is a hornblende dioryte. 
B. A coarse-grained allotriomorphic granular aggregate of plagio- 
clase having symmetrical extinctions of albite lamella ranging in value 
