Geologic Map Database of the El Mirage Lake Area, San Bernardino and Los Angeles Counties, California

This geologic map database for the El Mirage Lake area describes
geologic materials for the dry lake, parts of the adjacent Shadow
Mountains and Adobe Mountain, and much of the piedmont extending
south from the lake upward toward the San Gabriel Mountains.
This area lies within the western Mojave Desert of San Bernardino
and Los Angeles Counties, southern California. The area is
traversed by a few paved highways that service the community of
El Mirage, and by numerous dirt roads that lead to outlying
properties. An off-highway vehicle area established by the
Bureau of Land Management encompasses the dry lake and much of
the land north and east of the lake. The physiography of the
area consists of the dry lake, flanking mud and sand flats and
alluvial piedmonts, and a few sharp craggy mountains.
This digital geologic map database, intended for use at 1:24,000-
scale, describes and portrays the rock units and surficial
deposits of the El Mirage Lake area. It was prepared as part of
a water-resource assessments of the area, describing and
interpreting surface geology that provides information to help
understand distribution and extent of deeper groundwater-bearing
units. The area mapped covers the Shadow Mountains SE and parts
of the Shadow Mountains, Adobe Mountain, and El Mirage 7.5-minute
quadrangles. The map database includes detailed geology of
surface and bedrock deposits, which represent a significant
update from previous bedrock geologic maps by Dibblee (1960) and
Troxel and Gunderson (1970), and the surficial geologic map of
Ponti and Burke (1980); it incorporates a fringe of the detailed
bedrock mapping in the Shadow Mountains by Martin (1992).