Preliminary Surficial Geologic Map of a Calico Mountains Piedmont and Part of Coyote Lake, Mojave Desert, San Bernardino County, California

This 1:24,000 scale detailed surficial geologic map and digital database of a
Calico Mountains piedmont and part of Coyote Lake in south-central California
depicts surficial deposits and generalized bedrock units. The mapping is part
of a USGS project to investigate the spatial distribution of deposits linked to
changes in climate, to provide framework geology for land use management
(http://deserts.wr.usgs.go), to understand the Quaternary tectonic history of
the Mojave Desert, and to provide additional information on the history of Lake
Manix, of which Coyote Lake is a sub-basin. Mapping is displayed on parts of
four USGS 7.5 minute series topographic maps. The map area lies in the central
Mojave Desert of California, northeast of Barstow, Calif. and south of Fort
Irwin, Calif. and covers 258 km2 (99.5 mi2). Geologic deposits in the area
consist of Paleozoic metamorphic rocks, Mesozoic plutonic rocks, Miocene
volcanic rocks, Pliocene-Pleistocene basin fill, and Quaternary surficial
deposits. McCulloh (1960, 1965) conducted bedrock mapping and a generalized
version of his maps are compiled into this map. McCulloh's maps contain many
bedrock structures within the Calico Mountains that are not shown on the
present map.

This study resulted in several new findings, including the discovery of
previously unrecognized faults, one of which is the Tin Can Alley fault. The
north-striking Tin Can Alley fault is part of the Paradise fault zone (Miller
and others, 2005), a potentially important feature for studying neo-tectonic
strain in the Mojave Desert. Additionally, many Anodonta shells were collected
in Coyote Lake lacustrine sediments for radiocarbon dating. Preliminary results
support some of Meek's (1999) conclusions on the timing of Mojave River inflow
into the Coyote Basin.

The database includes information on geologic deposits, samples, and
geochronology. The database is distributed in three parts: spatial map-based
data, documentation, and printable map graphics of the database. Spatial data
are distributed as an ArcInfo personal geodatabase, or as tabular data in the
form of Microsoft Access Database (MDB) or dBase Format (DBF) file formats.
Documentation includes this file, which provides a discussion of the surficial
geology and describes the format and content of the map data, and Federal
Geographic Data Committee (FGDC) metadata for the spatial map information. Map
graphics files are distributed as Postscript and Adobe Acrobat Portable
Document Format (PDF) files, and are appropriate for representing a view of the
spatial database at the mapped scale.

[Summary provided by the USGS.]