SANTA CLARA VALLEY: ELSMERE FIELD. 
97 
GEOLOGY AND STRUCTURE. 
At Fernando Pass, the low point between the Santa Snsana and 
San Gabriel mountains, there is a break in geologic continuity. The 
Elsmere anticline, described below, forms another step in the en eche¬ 
lon development exhibited by the Torrey, Tapo, and Pico anticlines 
farther west. The Elsmere fold, however, is hardly more than a 
secondary flexure of gentle curvature on the western flank of the San 
Gabriel Range. 
The formations involved in the Elsmere field include a vast body of 
granite and schist, probably of Jurassic age; chocolate-colored shale, 
sandstone, and minor beds of conglomerate bearing characteristic 
fossils of the Vaqueros formation; the Fernando (Pliocene) con¬ 
glomerate, sandstone, and clay; and certain Pleistocene gravel, sand, 
and clay, already mentioned in the description of the Pico anticline, 
that occupy what appears to have been an old lake basin coincident 
with the present valley of the Santa Clara in the vicinity ofNewhall 
and Saugus. 
The granite and schist occupy the heart of the San Gabriel Range; 
the other formations, except the lake beds, encircle its west end. 
Although the San Gabriel Range is probably the result of faulting 
there is in the encircling Tertiary rocks at least one anticlinal flexure, 
the Elsmere. This anticline has been developed in somewhat unsym- 
metrical form, the axis lying well toward the southern side of the fold. 
(See PI. IV, sec. The elevation of the strata north of the 
axis is maintained by minor flexures, until at a distance of a mile or 
more the beds drop beneath the level of the lower hills and pass to the 
east, with a N. 70° E. strike and a dip of 25°-30° N. The syncline 
separating the Elsmere anticline from the Pico fold is suggested in the 
curves of the strata in the creek southwest of Newhall and in one or 
two minor crumples in the Fernando formation higher in the hills. 
In the Vaqueros beds on the Santa Susana side there are two folds 
having a general trend of N. 60°-70° W. One is the eastern terminus 
of the Pico anticline and the other of the svncline to the south. These 
folds do not appear east of the Southern Pacific Railroad, their trend 
carrying them at this point into the San Fernando Valley, beneath the 
level of which the anticline sinks. The Fernando formation, lying 
between the two bodies of Vaqueros east of the railroad, maintains a 
southwesterly to southerly dip, except immediately north of the axis 
of the Elsmere anticline, in proximity to the more northerly body of 
Vaqueros. The relations of the Fernando to the underlying strata are 
extremely irregular and the details of the unconformity have not been 
worked out. About the northern base of the San Gabriel Range, 
however, east of the railroad, this unconformity is readily discernible. 
