282 The American Geologist. Mav, 350%. 
From Mint Canyon to Soledad pass there is a succession of 
small batholiths of the light pink granite andthe railroad 
crosses the summit in a valley excavated in this granite. Ad- 
joining it on the south is an east-west belt occupied by a rather 
basic granitic rock of gray color, somewhat like certain 
phases of the Sierra Nevada granodiorytes. Both biotite and 
hornblende are important constituents. Its areas are of a uni- 
form light brown color, strongly contrasted with the comspic- 
uously light colored acid granite on the north. 
The main mass of granite occupies the western portion of 
Mohave desert. It outcrops in low, undulating belts several 
miles in width and abounding in knolls and low mountain 
masses. Antelope valley is a structural depression occupied 
by a great thickness of Tertiary and Quaternary deposits, but 
the country north of it to the Tehachapai range, except for a 
_narrow belt of rhyolyte resting on granite and the broad, al- 
luvium-floored basins, should be mapped as granite. It is the 
-outhward extension of the great grano-dioryte belt of the 
Sierra Nevada region. It has a well-defined eastern boundary 
trending north-south about ten miles west of Barstow, with 
many reentrants and dike-like arms. 
Most of the granite forming the low mountains of Mohave 
desert and giving them their uniform light brown color is of 
the light pink variety occurring in Tehachapai mountain at 
Gorman’s Station. It consists of quartz and pink or flesh-col- 
ored feldspar, with relatively unimportant constituents of dark 
minerals (biotite and some hornblende). It is of medium tex- 
ture in mass, but just east of the railroad about two miles 
north of Rosamond it abounds in large vein-like masses of 
coarse pink pegmatyte or graphic granite, very abundant in 
fragments on many small knolls. Similar pegmatyte dikes are 
common throughout this main granite area and are always 
connected with the acid variety of granite, although occurring 
in a darker granite as intrusives. 
At Bissell Station occurs an outcrop of light gray biotite- 
hornblende granite or grano-dioryte. The Santa Fe Railway 
company once quarried similar gray granite on the south shore 
cf Rogers dry lake-bed, although the neighboring range of 
hills seems to be composed mainly of the light qink variety. 
Vive miles east of Kramer, grano-dioryte of a typical Sierra 
Nevada variety appears in the crest of a low smooth ridge. 
