Geologic Map and Digital Database of the Porcupine Wash 7.5 minute Quadrangle, Riverside County, California, USGS OFR 01-30
Entry ID:
USGS_OFR01-30
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Summary
Abstract:
The data set for the Porcupine Wash quadrangle has been prepared by the Southern California Areal Mapping Project (SCAMP), a cooperative project sponsored jointly by the U.S. Geological Survey and the California Division of Mines and Geology. The Porcupine Wash data set represents part of an ongoing effort to create a regional GIS geologic database for southern California. This regional digital ... database, in turn, is being developed as a contribution to the National Geologic Map Database of the National Cooperative Geologic Mapping Program of the USGS. The Porcupine Wash database has been prepared in cooperation with the National Park Service as part of an ongoing project to provide Joshua Tree National Park with a geologic map base for use in managing Park resources and developing interpretive materials. The digital geologic map database for the Porcupine Wash quadrangle has been created as a general-purpose data set that is applicable to land-related investigations in the earth and biological sciences. Along with geologic map databases in preparation for adjoining quadrangles, the Porcupine Wash database has been generated to further our understanding of bedrock and surficial processes at work in the region and to document evidence for seismotectonic activity in the eastern Transverse Ranges. The database is designed to serve as a base layer suitable for ecosystem and mineral resource assessment and for building a hydrogeologic framework for Pinto Basin. This data set maps and describes the geology of the Porcupine Wash 7.5 minute quadrangle, Riverside County, southern California. The quadrangle, situated in Joshua Tree National Park in the eastern Transverse Ranges physiographic and structural province, encompasses parts of the Hexie Mountains, Cottonwood Mountains, northern Eagle Mountains, and south flank of Pinto Basin. It is underlain by a basement terrane comprising Proterozoic metamorphic rocks, Mesozoic plutonic rocks, and Mesozoic and Mesozoic or Cenozoic hypabyssal dikes. The basement terrane is capped by a widespread Tertiary erosion surface preserved in remnants in the Eagle and Cottonwood Mountains and buried beneath Cenozoic deposits in Pinto Basin. Locally, Miocene basalt overlies the erosion surface. A sequence of at least three Quaternary pediments is planed into the north piedmont of the Eagle and Hexie Mountains, each in turn overlain by successively younger residual and alluvial deposits. The Tertiary erosion surface is deformed and broken by north-northwest-trending, high-angle, dip-slip faults and an east-west trending system of high-angle dip- and left-slip faults. East-west trending faults are younger than and perhaps in part coeval with faults of the northwest-trending set. The Porcupine Wash database was created using ARCVIEW and ARC/INFO, which are geographical information system (GIS) software products of Environmental Systems Research Institute (ESRI). The database consists of the following items: (1) a map coverage showing faults and geologic contacts and units, (2) a separate coverage showing dikes, (3) a coverage showing structural data, (4) a scanned topographic base at a scale of 1:24,000, and (5) attribute tables for geologic units (polygons and regions), contacts (arcs), and site-specific data (points). The database, accompanied by a pamphlet file and this metadata file, also includes the following graphic and text products: (1) A portable document file (.pdf) containing a navigable graphic of the geologic map on a 1:24,000 topographic base. The map is accompanied by a marginal explanation consisting of a Description of Map and Database Units (DMU), a Correlation of Map and Database Units (CMU), and a key to point-and line-symbols. (2) Separate .pdf files of the DMU and CMU, individually. (3) A PostScript graphic-file containing the geologic map on a 1:24,000 topographic base accompanied by the marginal explanation. (4) A pamphlet that describes the database and how to access it. Within the database, geologic contacts , faults, and dikes are represented as lines (arcs), geologic units as polygons and regions, and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify each geologic datum and link it to other tables (.rel) that provide more detailed geologic information. Map nomenclature and symbols Within the geologic map database, map units are identified by standard geologic map criteria such as formation-name, age, and lithology. The authors have attempted to adhere to the stratigraphic nomenclature of the U.S. Geological Survey and the North American Stratigraphic Code, but the database has not received a formal editorial review of geologic names. Special symbols are associated with some map units. Question marks have been added to the unit symbol (e.g., QTs?, Prpgd?) and unit name where unit assignment based on interpretation of aerial photographs is uncertain. Question marks are plotted as part of the map unit symbol for those polygons to which they apply, but they are not shown in the CMU or DMU unless all polygons of a given unit are queried. To locate queried map-unit polygons in a search of database, the question mark must be included as part of the unit symbol. Geologic map unit labels entered in database items LABL and PLABL contain substitute characters for conventional stratigraphic age symbols: Proterozoic appears as 'Pr' in LABL and as '<' in PLABL, Triassic appears as 'Tr' in LABL and as '^' in PLABL. The substitute characters in PLABL invoke their corresponding symbols from the GeoAge font group to generate map unit labels with conventional stratigraphic symbols.
Related URL
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Description:
Access to documentation and data for OFR 01-030
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Multimedia Sample
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Description:
Non-navigable .gif image of the geologic map, topographic base, Correlation of Map and Database Units, Description of Map and Database Units and key to point and line symbols. 64 kilobytes.
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Geographic Coverage
(Click for Interactive Map)
Spatial coordinates
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N: 33.88
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S: 33.75
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E: -115.75
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W: -115.88
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Data Set Citation
Dataset Originator/Creator:
Robert E. Powell; Pamela M. Cossette (digital cartography)
Dataset Title:
Geologic map and digital database of the Porcupine Wash 7.5 minute quadrangle, Riverside County, California
Dataset Series Name:
U.S. Geological Survey Open-File Report
Dataset Release Date:
2001
Dataset Release Place:
Menlo Park, California
Dataset Publisher:
U.S. Geological Survey
Version:
Version 1.0
Data Presentation Form:
Vector digital data
Online Resource:
http://geopubs.wr.usgs.gov/open-file/of01-030/
Temporal Coverage
Start Date:
1973-01-01
Stop Date:
2000-12-31
Data Resolution
Latitude Resolution:
0.000001 m
Longitude Resolution:
0.000001 m
Access Constraints
None
Use Constraints
Spatial Resolution. Use of this digital geologic map should not violate the spatial resolution of the data. The Porcupine Wash geologic map and database was developed using digital orthophotograph quarter quadrangles (DOQQs) as a base. DOQQs have a pixel resolution of 1 m and are accurate to a scale of 1:12,000 (1 in = 1,000 ft). Any ... enlargement beyond 1:12,000 exceeds the spatial resolution of the geologic data and should not be used in lieu of a more detailed site-specific geologic evaluation. Similarly, the digital topographic base map is derived from the U.S. Geological Survey, 1:24,000-scale Porcupine Wash 7.5 minute quadrangle (provisional edition, 1986); any enlargement beyond 1:24,000 exceeds the spatial resolution of the topographic data. Plotting or viewing of the data at scales larger than 1:12,000 on the DOQQ base, or larger than 1:24,000 on the topographic base, will not yield greater real detail, although it may reveal fine-scale irregularities below the intended resolution of the database. Where the geologic data is used in combination with the topographic data, the resolution of the combined output is limited by the lower resolution of the topographic data. Where this database is used in combination with other data of higher resolution, the resolution of the combined output will be limited by the lower resolution of these data. Content. This database, identified as "Geologic map and digital database of the Porcupine Wash 7.5 minute quadrangle, Riverside County, California" has been approved for release and publication by the Director of the U.S. Geological Survey. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on the condition that neither the USGS nor the United States Government may be held responsible for any damages resulting from its authorized or unauthorized use. This database is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Faults. The Porcupine Wash database is sufficiently detailed to identify and characterize many actual and potential geologic hazards represented by faults, but it is not sufficiently detailed for site-specific determinations or evaluations of these features. Faults shown do not take the place of fault-rupture hazard zones designated by the California State Geologist (see, for example, Hart, 1988; Hart and Bryant, 1997). Hart, E. W., 1988, Fault-rupture zones in California; Alquist-Priolo Special Studies Zones Act of 1972 with index to special studies zones maps (revised, 1988): California Division of Mines and Geology Special Publication 42. Hart, E. W., and Bryant, W.A., 1997, Fault-rupture zones in California; Alquist-Priolo Special Studies Zones Act of 1972 with index to special studies zones maps (revised, 1997): California Division of Mines and Geology Special Publication 42. 
Data Set Progress
COMPLETE
Distribution
Distribution Media:
online
Distribution Size:
5.5 megabytes
Distribution Format:
Arc/Info export
Fees:
none
Personnel
Role:
TECHNICAL CONTACT
Phone:
(509) 368-3120
Fax:
(509) 368-3199
Email:
rpowell at usgs.gov
Contact Address:
U.S. Geological Survey
904 West Riverside Avenue, Rm. 202
City:
Spokane
Province or State:
WA
Postal Code:
99201-1087
Country:
USA
Role:
DIF AUTHOR
Phone:
(509) 368-3123
Fax:
(509) 368-3199
Email:
pcossette at usgs.gov
Contact Address:
Western Earth Surface Processes Team
U.S. Geological Survey
Federal Building
U. S. Post Office
W. 904 Riverside Ave, Ste. 202
City:
Spokane
Province or State:
WA
Postal Code:
99201-1011
Country:
USA
Publications/References
Powell, R.E., 1981, Geology of the crystalline basement complex, eastern Transverse Ranges, southern California: Constraints on regional tectonic interpretation [Ph.D. thesis]: Pasadena, California Institute of Technology, 441 p. USGS, 1973, True color aerial photographs labeled GS-SE. Photographs taken along northwest-southeast oriented flight lines covering the eastern Transverse Ranges south of the Pinto Mountain fault. Lines flown at moderate to low sun-angle in October 1973; scale 1:36,000.
Powell, R.E., 1993, Balanced palinspastic reconstruction of pre-late Cenozoic paleogeology, southern California: Geologic and kinematic constraints on evolution of the San Andreas fault system, in Powell, R.E., Weldon, R.J., II, and Matti, J.C., eds., The San Andreas fault system: Displacement, palinspastic reconstruction, and geologic evolution: Geological Society of America Memoir 178, p. 1-106.
A complete description of the polygon, line, and point data coding schemes is available in U.S. Geological Survey Open-File Reports 97-859, OFR 97-860, and OFR 97-861 (full source citations follow):
Matti, J.C., Miller, F.K., Powell, R.E., Kennedy, S.A., Bunyapanasarn, T.P., Koukladas, Catherine, Hauser, R.M., and Cossette, P.M., 1997b, Geologic-point attributes for digital geologic-map databases produced by the Southern California Areal Mapping Project (SCAMP), Version 1.0: U.S. Geological Survey Open-File Report 97-859
Matti, J.C., Miller, F.K., Powell, R.E., Kennedy, S.A., and Cossette, P.M., 1997c, Geologic-polygon attributes for digital geologic-map databases produced by the Southern California Areal Mapping Project (SCAMP), Version 1.0: U.S. Geological Survey Open-File Report 97-860
Matti, J.C., Powell, R.E., Miller, F.K., Kennedy, S.A., Ruppert, K.R., Morton, G.L., and Cossette, P.M., 1997a, Geologic-line attributes for digital geologic-map databases produced by the Southern California Areal Mapping Project (SCAMP), Version 1.0: U.S. Geological Survey Open-File Report 97-861
Creation and Review Dates
DIF Creation Date:
2001-02-23
Last DIF Revision Date:
2005-04-12
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