California Tertiary Formations.—Hershey. 305. 
THE ROSAMOND SERIES. 
Antelope valley is a structural depression about 20 miles 
wide. On the south side there goes down under its floor the 
Escondido series with basic lavas. On the north side from a 
point two miles east of Rosamond station on the Southern 
Pacific railway to an indefinite distance west, there emerges 
from under it a rhyolyte series. Remnants of this constitute 
an east-west range of hills from 500 to 1000 feet high,: re- 
-markable for their colors of brilliant dark purple streaked 
with white and yellow. They are almost bare of soil and 
very rugged. They have a wide distribution on Mohave des- 
ert and may be distinguished many miles awav from the uni- 
form light brown ridges of granite. 
West of the railroad, a mile and a half north of Rosa- 
mond station, the lava belt, here about one mile wide, bends 
to the northwest and a range of purple and yellow hills ex- 
tends for over five miles in that direction. The strike is 
northwest and the dip to southwest at angles of 10° to 20°. 
Sections are much complicated by faulting and by the orig- 
inal inequalities, but I continued to roughly measure the fol- 
lowing sections (in ascending order) just west of the railroad 
where the sequence is fullest: 
Type Section of the Rosamond Series near Rosamend Siation. 
Granite. Thickness. 
1. Coarse and fine white sandstone, composed of granite 
debris and rhyolyte tuff, thin-bedded, regularly strat- 
ified and dipping westerly at angles of 10 to 20 de- 
ROE f HEA a art tA Wilda a. See ie PE Se BTU AT rE 500 feet. 
2. Bright, light red, stratified sandstone containing granite 
debris, some cobbles and boulders (waterworn) of 
granite and many angular and subangular fragments 
Se TREC TARE Sie an c's 23 av * rnd Siohnge Mita eee es ar ea 5 a 50 feet. 
3. Light yellow tuff mainly of rhyolyte with an occasional 
pebble of granite; roughly stratified and dipping south- 
RON elton Adina na Sn 4a via's Dire he ae Sale Cale ak gl wget 200 feet. 
4. Massive dark red lava (apparently rhyolyte); varies 
much in thickness, averaging about ................ 100 feet. 
5. Light greenish and yellow rhyolyte tuff, coarse in layers; 
contains abundant and large angular fragments of the 
underlying red lava and an occasional pebble and 
small boulder of granite; roughly stratified and dips 
Southerly Onto 30) Goarees, usa cu sewceeeidnl ae « 400 feet. 
6. White rhyolyte, brecciated in layers, ................ 300 feet. 
