306 The American Geologist. Tune; Sane. 
7. Light brown coarse sandstone; much granite debris and 
rhyolyte; occurs in limited patches capping knolls,.. 100 feet. 
LE Ot all wae ek ees ola ae Cee ee -.... 1650 feet. 
This is preéminently a series of rhyolitic volcanics al- 
though some of the dark lava may be trachytic and some thin 
layers may be basic enough to be andesyte. The prevailing 
purple color of the hills is due to rugged outcrops of the 
dark red lava and the irregular strips of yellow and white 
to the rhyolyte tuffs. 
Four miles west and one mile north of Rosamond sta- 
tion is a low mountain whose colors are light red and pink. 
It is between two purple ranges and separated from them 
by detrital slopes. It is continuous by a low ridge with the 
Willow Springs Mountain, northwest of it probably two miles 
and of similar material. This short range of mountains 
represents a narrow northwest-southeast belt of granite capped 
with rhyolyte, apparently brought up from under the purple 
and yellow series by a fault with upthrow on the southwest. 
The first bright red mountain comprises the Rosamond 
mining © district and contains the Fairview and Hamilton 
mines and several prospects. Narrow branching dikes of 
white rhyolyte occur in the granite deep in the mountain, but 
the main mass of rhyolyte seems to be in the form 
of a thick sheet resting on the granite and thrown 
down into it by many, small faults. Much of this 
rhyolyte contains porphyritic quartzes. Some of it has a sort 
of shaly structure and other is a massive breccia. Under 
ground it is white but on the surface it is much stained 
with iron oxide, giving the.mountain its bright light-red 
color. The granite is stained to a dark red in many places 
under the rhyolyte. I think we are here an the site of one of 
the rhyolyte volcanoes. 
This volcanic belt seems to be represented in isolated 
patches along a line trending nearly due west along the north- 
ern border of Antelope valley to its extreme western end. 
The purple and white lavas occurring in patches faulted down 
into the granite along the southern base of the Tehachapat 
range near Gorman’s station are on this same line, are of 
similar composition and general appearance and doubtlessly 
belong to the same series. They go under the Upper Pliocene 
