70 72
24
30
62
77
35
5540
6038
30
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QofQa
Qyf
Qof
Kgr
af
QofKgr
Qof
Qyf
Qa
QofQyf
Qa
Qyf
af
}db
af
QyfsQa
}pos}db
}pos
}pos
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Qyfs Qf
Qa
Qa
Qe
Qa
Qe
af
Qf
Qe
Qw
af
af
Qya
Qyf
af
af
Qf
Qyfc
Qyp
Qf
af
af
af
Qf
af
af
Qa
Qf
Qf
Qyfc
Qf
Qa
Qf
af
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Qyp
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Qyfc
}pos
}db
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Qyf
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118°15'34°45'00"
34°37'30"118°15'
34°37'30"118°07'30"
118°07'30"34°45'00"
STATE OF CALIFORNIA - ARNOLD SCHWARZENEGGER, GOVERNORTHE NATURAL RESOURCES AGENCY - LESTER A. SNOW, SECRETARY FOR NATURAL RESOURCES
DEPARTMENT OF CONSERVATION - DEREK CHERNOW, ACTING DIRECTOR CALIFORNIA GEOLOGICAL SURVEYJOHN G. PARRISH, Ph.D., STATE GEOLOGIST
Topographic base from U.S. Geological Survey Lancaster West 7.5-minute Quadrangle, 1958, Photorevised 1974UTM projection, Zone 11, North American Datum 1927
This geologic map was funded in part by the USGS National Cooperative Geologic MappingProgram, Statemap Award no. G09AC00193
GEOLOGIC MAP OF THELANCASTER WEST 7.5' QUADRANGLE
LOS ANGELES COUNTY, CALIFORNIA: A DIGITAL DATABASEVERSION 1.0
ByJanis L. Hernandez
Digital Database by
Janis L. Hernandez, Carlos I. Gutierrez and George J. Saucedo
2010
Copyright © 2010 by the California Department of ConservationCalifornia Geological Survey. All rights reserved. No part ofthis publication may be reproduced without written consent of theCalifornia Geological Survey.
"The Department of Conservation makes no warranties as to thesuitability of this product for any given purpose."
65 Strike and dip of metamorphic foliation.
35 Strike and dip of igneous joint.
Vertical igneous joint.
Vertical igneous foliation
MAP SYMBOLS
27
Fault - Solid where accurately located, dashed where where approximately located; short dash where inferred; dotted where concealed, queried where uncertain. Arrow and number indicate direction and angle of dip of fault plane.
Contact between map units - Solid where accurately located; long dash where approximately located; short dash where inferred; dotted where concealed, queried where uncertain.
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?
SELECTED REFERENCESBarrows, A.G., Kahle, J.E., and Beeby, D.J., 1985, Earthquake hazards and tectonic history of the San Andreas Fault Zone, Los Angeles County, California: California Division of Mines and Geology Open-File Report 85-10LA, 236 p., 21 plates, scale 1:12,000.
Dibblee, T.W., Jr., 1960, Geologic map of the Lancaster quadrangle, Los Angeles County, California: U.S. Geological Survey Miscellaneous Field Studies Map MF-76, scale 1:62,500.
______, 1967, Areal geology of the western Mojave Desert, California: U.S. Geological Survey Professional Paper 522, 153 p., scale 1:125,000.
Evans, J.G., 1966, Structural Analysis and movements of the San Andreas Fault Zone near Palmdale, southern California, Ph.D. thesis, University of California, Los Angeles, scale 1:12,000.
Evans, J.G., 1978, Postcrystalline Deformation of the Pelona Schist bordering Leona Valley, southern California: U.S. Geological Survey Professional Paper 1039, 17 p., scale 1:10,000.
Hoirup, D.F., and Hernandez, J.L., 2004, Earthquake-Induced landslide zones of required investigation in the Lancaster West 7.5-minute quadrangle, Los Angeles County, California: California Geological Survey Seismic Hazard Zone Report 95, Section 2, pp. 21-38.
Loyd, R.C., 2004, Liquefaction zones of required investigation in the Lancaster West 7.5-Minute quadrangle, Los Angeles County, California: California Geological Survey Seismic Hazard Zone Report 95, Section 1, pp. 3-20.
Miller, F.K., and Morton, D.M., 1980, Potassium-argon geochronology of the eastern Transverse Ranges and southern Mojave Desert, south ern California: U.S. Geological Survey Professional Paper 1152, 30 p.
Orme, A.R., 2008, Lake Thompson, Mojave Desert, California: The late Pleistocene lake system and its Holocene dessication: Geological Society of America, Special Paper 439, pp. 261-278.
Ponti, D.J., 1985, The Quaternary alluvial sequence of the Antelope Valley, California, in Weide, D.L., and Faber, M.L., editors, Soils and Quaternary geology of the southwestern United States: Geological Society of America, Special Paper 203, p. 79-96.
______, 1980, Stratigraphy and engineering characteristics of upper Quaternary sediments in the eastern Antelope Valley and vicinity, California: M.S. thesis, Stanford University, California, 157 p., Plates 1-4, scale 1:62,500.
Ponti, D.J., Burke, D.B., and Hedel, C.W., 1981, Map showing Quaternary geology of the central Antelope Valley and vicinity, California: U.S. Geological Survey Open-File Report 81-737, scale 1:62,500.
Ross, D.C., 1976, Metagraywacke in the Salinian block, central Coast Ranges, California – and a possible correlative across the San Andreas Fault: U.S. Geological Survey, Journal of Research, v. 4, no. 6, p. 683-696.
Silver, L.T., 1971, Problems of crystalline rocks of the Transverse Ranges: Geological Society of America Abstracts with Programs vol. 3, p. 193-194.
Streckeisen, A.L., 1973, Plutonic rocks – Classification and nomenclature recommended by the IUGS Subcommission on Systematics of Igneous Rocks: Geotimes, v. 18, p. 26-30.
______, 1976, To each plutonic rock a proper name: Earth Science Reviews, v. 12, p. 1-33.
0°40'12 MILS
13°231 MILS
GNMN
UTM GRID AND 2010 MAGNETIC NORTHDECLINATION AT CENTER OF SHEET
0
0
0
1
1
1.5
.5 2
2
2Thousand Feet
Kilometers
Miles
Scale 1:24,000
Contour Interval 5 feetNational Geodetic Vertical Datum of 1929
5
COTTONWOODCR
SANTA CLARA R
99
Bouquet Res
Elderberry Forebay
Castaic Lake
R o s a m o n d L a k e
Buckhorn Lake
Piru Lake
Santa Clara River
Pyramid Lake
Little Rock Wash
Fillmore
Gorman
LakeHughes
Lebec
LeonaValley
Littlerock
Mojave
Piru
QuartzHill
Rosamond
Saugus
Valencia
Acton
AguaDulce
Castaic
48
166
58
126
14
138
118°0'0"W118°30'0"W119°0'0"W35
°0'0
"N34
°30'
0"N
5Kilometers
5Miles
GRAPEVINE
PASTORIA
RIDGE
TWINS
TYLERHORSE
WILLOW
SOLEDAD
BISSELL
ROSAMOND
ROSAMOND
LITTLE
FAIRMONT
NEENACH
LA LIEBRE
LEBEC
FRAZIER
MOUNTAIN
BLACKMOUNTAIN
BURNT
LAKE SUR
LANCASTER
PALMDALE
SLEEPY
GREEN
WARM
WHITAKER
COBBLESTONE
PEAK
WINTERS
LIEBRE
CANYON
SPRINGS
MOUNTAIN
MOUNTAIN
SCHOOL
RANCH
BUTTE
BUTTES
LAKEEAST
DEL
HUGHES
PEAK
LIEBRE
MOUNTAIN
ALAMO
HEARTDEVILS
MOUNTAIN
PEAK
SPRINGS
MOUNTAIN
VALLEY
VALLEY
RIDGERITTER
CREEK
LANCASTER
WEST
QuartzSyenite
QuartzMonzonite
QuartzMonzodiorite
Syenite Monzonite Monzodiorite
Granite
Alka
li-fe
ldsp
ar G
rani
te
Tonalite
Diorite
Syen
ogra
nite
Granodioriteno
Mnargoz
eti
Quartz
Diorite
90 65 35 10
5
20
60Q Q
A P
60
20
5
Classification of plutonic rock types (from Streckeisen, 1973; 1976). A, alkali feldspar; P, plagioclase feldspar; Q, quartz.
CORRELATION OF MAP UNITS
af Qw Qa QeQc
Qya Qyp Qyfs Qyf
Qof
Qf
Qyfc
}db
Kgr
}pos
Holocene
}Pleistocene
}
Paleocene
} }}
}QUATERNARY
CENOZOIC
MESOZOIC
TERTIARY
CRETACEOUS
afArtificial fill and disturbed areas (Holocene, historic) – Surfaces intensely modified by human construction and grading activities. Consists of man-made deposits of earth-fill soils derived from local sources. Mapped specifically along the California Aqueduct structure, debris catchment basins, and includes fill soils along freeway/road alignments.
QaModern alluvium (Holocene) – Unconsolidated to weakly consolidated, fluvial gravel, sand, and silt. Loose, yellowish-gray to brown (10YR 4/3) sand, silt, and pebble-cobble gravel. Consists predominately of moderately sorted medium- to very coarse-grained arkosic sand.
Colluvium (Holocene to late Pleistocene) – Unconsolidated sand, gravel, and rock fragments flanking bedrock slopes. Deposited by down-slope creep or rain wash. Mapped where thick and continuous enough to obscure underlying bedrock.
Qc
Younger alluvium (Holocene to Late Pleistocene) – Unconsolidated, dark-yellowish-brown (10YR 4/4) sand and gravel of slightly dissected alluvial fans and associated washes.Qya
Qyf Younger alluvial fan deposits (Holocene to late Pleistocene) – Unconsolidated to weakly consolidated, dark- yellowish-brown (10YR 4/4), fine- to medium-grained arkosic sand with fine gravel. Gravels are primarily from a granitic source, with many subangular quartz fine gravel clasts. Unit is exposed as slightly dissected, elevated alluvial fans.
Qyfs Younger alluvial fan deposits, silt rich (Holocene to late Pleistocene) – Consolidated, brown (10YR 4/3) to dark- yellowish-brown (10YR 4/6), silty, fine arkosic sand. Some clay coatings on roots and rootlets. Deposits are generally distal fan sediments.
Qyp Younger playa deposits (Holocene to late Pleistocene) – Moderate to well consolidated, clay with some silt. Soils generally light-grayish-brown to brown when moist, 10YR 5/3, with upper soil profile showing laminations, and occasional pinhole porosity. Lacustrine silt and clay deposits with minor loose, well-sorted sand and fine gravel deposited in the shallow-water regions of the last pluvial lake that filled the lowland parts of Antelope Valley up to about 12,000 years ago. Deposits are generally covered with a veneer of loose sand and silt.
}dbDiabase dikes (early Tertiary to Mesozoic?) – Black to dark-brown diabase dikes. Common in Portal Schist unit, especially within Quartz Hill in the south central map area. Fine-grained groundmass, with fine phenocrysts of plagioclase and hornblende. Resistant outcrops cross-cut Portal Schist. Occasionally seen in unit Kgr, too small to map.
Kgr Granitic rocks (Late Cretaceous) – Monzogranite to quartz-monzonite in composition, light-tan to light-gray, medium- grained, some what incoherent where weathered. Moderately foliated. Late Cretaceous age assumed from r egional work by Miller and Morton, 1980. Mapped as quartz monzonite by Dibblee (1960), and granodiorite by Evans (1978).
}posPortal Schist (Late Cretaceous - earliest Tertiary) – Quartzo-feldspathic and biotite schist; schist is partially re-crystallized, and has strong foliation with quartz augen layering and quartz veins parallel to foliation. Amphibolite, marble, vein quartz and quartzite layering are common, with minor talc-actinolite schist and graphite. Unit is fine-grained, composed largely of albite, plagioclase and biotite. Noted as typical amphibo lite facies of metamorphism. Unit is highly folded, with detached intrafolial folds common.
Qyfc Younger alluvial fan deposits, clay rich (Holocene to late Pleistocene) – Consolidated, dark-yellowish-brown (10YR 4/3 to 4/4), silty, fine arkosic sand with clay and calcium carbonate content. Carbonate likely deposited during fluctuating groundwater conditions of former pluvial Lake Thompson stands. Deposits are generally distal fan sediments near edges of former lake shoreline.
Older alluvial fan deposits (late Pleistocene) – Moderately consolidated, strong brown (7.5YR 4/6 to 5/6), medium dense, fine- to medium-grained arkosic sand with fine to medium gravel. Gravels predominately fine to medium, sub-rounded granitic clasts. Clay coatings on grains and clasts predominant. Crude bedding observed with basal gravel layers.
Qof
SURFICIAL UNITS
METAMORPHIC AND INTRUSIVE ROCKS
DESCRIPTION OF MAP UNITS
Wash deposits (late Holocene) – Unconsolidated fine- to medium-grained sand, with some coarse sand and fine gravel, and silt. Deposits are generally pale-brown (10YR 5/3), angular to sub-angular grains, derived from local bedrock, or reworked from other local Quaternary sources. Subject to localized reworking and new sediment deposition during storm events.
Qw
Eolian deposits (Holocene) – Unconsolidated windblown deposits of very fine- to medium-grained, subangular, arkosic sand with some silt. Deposits are loose, generally light-gray where predominately sand, to dark- yellowish-brown (10YR 4/4) with increased silt content. Thickness estimated up to 2 m.
Qe
Qf Modern alluvial fan deposits (Holocene) – Unconsolidated to weakly consolidated, poorly sorted, rubble, gravel, sand, and silt deposits forming active, essentially undissected, alluvial fans. Includes small to large cones at the mouths of stream canyons and broad aprons of coarse debris adjacent to mountain fronts.
Preliminary Geologic Map available from:http://www.conservation.ca.gov/cgs/rghm/rgm/preliminary_geologic_maps.htm
Revised: 09/24/2010