Page 19 - muehlberger1954

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"The borders of the gneissic block southwest of
Palmdale reservoir may be fault contacts. No
fault zone was observed, no geomorphic evidence
of faulting was found, and little other than that
the strike of the contacts is parallel to the large
branch faults suggested that the contacts are
faults. In fact, one road cut near the south con-
tact of the gneissic body exposed numerous
granitic dikes intruded into the gneiss thus
suggesting that the contact is an intrusive con-
tact. 11

Thus Wallace casts doubt on the interpretation of the Pelona fault as

a branch of the San Andreas fault.

Purpose and nature of study

Reconnaissance studies by Simpson in the northern Soledad

basin show a set of southwest-trending faults that branch southward

from the east-trending Pelona fault. The Pelona fault, in turn, is shown

as branching from the San Andreas fault, which evidently is regarded as

the "master fault" of the region. However, recent detailed studies

(Jahns, 1940; Wallace, 1944) that have touched on this problem seem to

cast doubt on the validity of this concept.

The purpose of this study is twofold:

(1) To decipher the structural features of the northern

Soledad basin and to determine the genetic relationships, if any, of

the deformations recorded to movements along the nearby San Andreas

fault; and

(2) To integrate the general conditions of formation of the

Tertiary sediments with structural history of this region.