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The investigations have been concerned mainly with the

unraveling of the geologic history of the Vasquez series, which pro-

vides a large amount of detailed information concerning the early

Tertiary history of this region. This study also shows what happens

around the fringes qf a major sedimentary basin in southern California.

These events either may not be recorded or only indirectly recorded in

the stratigraphic record in the center of the basin where economic

reserves of oil may be found.

Field work

Field work was carried on from April to August in 1952,

from May to July in 1953, and intermittently during the intervening

period. Mapping was done on a scale of one inch to 1, 000 feet on

enlarged copies of U. S. Geological Survey maps published at a scale

of one inch to 2, 000 feet. The results of most of this geological mapping

are shown in plate 2. Plate 1 also shows the results of this work, as

well as information compiled from the published and unpublished

sources that are indicated on the map.

III CRYSTALLINE ROCKS

General statement

Schists, gneisses, and granites compose the "basement" rocks

of this region. The Pelona schist, which consists of muscovite schist,