Geology of Eastern California. — Fairbanks. 73 
large grayish crystals of orthoclase, biotite, hornblende, and 
little quartz. Titanite is quite common in the granite of the 
region described. 
The almost entire absence of basic intrusives is a rather 
remarkable feature. One single occurrence was noted near 
the Eclipse mine, east of Independence. This is a coarse 
rock with a granitic structure but related to the gabbros. 
(2). Volcanic Rocks. Tuffs of volcanic origin are very wide 
spread along the line extending eastward from Tehachapai to 
Pilot knob. Andesite seems to be the prevailing type. It 
occurs as flows and dikes about Black mountain. 
Volcanic activity has been very pronounced in the western 
part of the Coso range, two or more periods of eruption being 
noted. To the older belong the liparites and andesites, while 
the younger consist of basalt. Extensive flows, so recent in 
origin that their surfaces have been but slightly modified, 
extend southward in long arms into Salt Wells valley. In 
the vicinity of Little lake and eastward several volcanic cones 
are sharply defined. 
Southeast of Owen’s lake there are extensive areas of lava, 
chiefly basalt, which are older than the similar rock in the 
Coso range. 
Numerous flows of andesite and basalt are met with through 
the Argus range. Their surfaces generally form inclined 
plateaus on the slopes of the mountains. The superficial 
extent of these flows must have once been much greater, .judg¬ 
ing from the position which they now occupy with reference 
to the canons. Argus gulch and its tributaries have cut 
through several basalt flows, one of which shows beneath an 
ancient river channel filled with clay and gravel. 
One of the most ancient lavas observed in the region is a 
body of liparite forming the highest portion of the Panamint 
range for a number of miles. 
The volcanic flows about Fish springs are perhaps of the 
same age as the basalts of the Coso range which they much 
resemble. They have been described by W. A. Goodyear.* 
From Bishop creek northward toward Mono lake volcanic 
activity has been very intense. The most of the region for 
many miles south of the lake has been covered by flows of 
* Report of Cal. State Mining Bureau, vol. viii, pp. 271-272. 
