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Geologic map of the East of Grotto Hills Quadrangle, California: a digital database

Open-File Report 99-35

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Abstract

The East of Grotto Hills 1:24,000-scale quadrangle of California lies west of the Colorado River about 30 km southwest of Searchlight, Nevada, near the boundary between the northern and southern parts of the Basin and Range Province. The quadrangle includes the eastern margin of Lanfair Valley, the southernmost part of the Castle Mountains, and part of the northwest Piute Range. The generally north-trending Piute Range aligns with the Piute and Dead Mountains of California and the Newberry and Eldorado Mountains and McCullough Range of Nevada. The southern part of the Piute Range adjoins Homer Mountain (Spencer and Turner, 1985) near Civil War-era Fort Piute. Adjacent 1:24,000-scale quadrangles include Castle Peaks, Homer Mountain, and Signal Hill, Calif.; also Hart Peak, Tenmile Well, and West of Juniper Mine, Calif. and Nev. The mapped area contains Tertiary (Miocene) volcanic and sedimentary rocks, interbedded with and overlain by Tertiary and Quaternary surficial deposits. Miocene intrusions mark conduits that served as feeders for the Miocene volcanic rocks, which also contain late magma pulses that cut the volcanic section. Upper Miocene conglomerate deposits interfinger with the uppermost volcanic flows. Canyons and intermontane valleys contain dissected Quaternary alluvial-fan deposits, mantled by active alluvial-fan deposits and detritus of active drainages. The alluvial materials were derived largely from Early Proterozoic granite and gneiss complexes, intruded by Mesozoic granite, dominate the heads of Lanfair Valley drainages in the New York Mountains and Mid Hills (fig. 1; Jennings, 1961). Similar rocks also underlie Tertiary deposits in the Castle Peaks, Castle Mountains, and eastern Piute Range.

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geologic map of the East of Grotto Hills Quadrangle, California: a digital database
Series title:
Open-File Report
Series number:
99-35
Year Published:
1999
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
Geology, Minerals, Energy and Geophysics Science Center
Description:
1 Plate: 33.10 x 29.17 inches; Pamphlet: 19 p.; Geology; Structure; Sample localities; Scanned topo base; All coverages; Import; Database explanation
Country:
United States
State:
California
Other Geospatial:
Grotto Hills
Datum:
National Geodetic Datum of 1929
Projection:
Universal Transverse Mercator projection
Scale:
24000