This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border, and is located approximately 9.0 km (5.6 mi) west-southwest of Parker, CA, immediately south of the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border, and is located approximately 9.0 km (5.6 mi) west-southwest of Parker, CA, immediately south of the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border and includes the community of Parker, AZ, and the southeastern part of the Whipple Mountains, where the prominent Whipple Mountains Detachment Fault separates lower plate Cretaceous and older gneisses from upper plate crystalline, volcanic, and sedimentary rocks. The Whipple Mountains are surrounded by numerous Neogene sedimentary units that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene, as well as Quaternary alluvial fan processes on the southern flank of the Whipple Mountains and in lower Vidal Valley.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border and includes the community of Parker, AZ, and the southeastern part of the Whipple Mountains, where the prominent Whipple Mountains Detachment Fault separates lower plate Cretaceous and older gneisses from upper plate crystalline, volcanic, and sedimentary rocks. The Whipple Mountains are surrounded by numerous Neogene sedimentary units that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene, as well as Quaternary alluvial fan processes on the southern flank of the Whipple Mountains and in lower Vidal Valley.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border and includes the community of Parker, AZ, and the southeastern part of the Whipple Mountains, where the prominent Whipple Mountains Detachment Fault separates lower plate Cretaceous and older gneisses from upper plate crystalline, volcanic, and sedimentary rocks. The Whipple Mountains are surrounded by numerous Neogene sedimentary units that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene, as well as Quaternary alluvial fan processes on the southern flank of the Whipple Mountains and in lower Vidal Valley.

This digital map shows the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 under the Front Range Urban Corridor Geology Program. Colton used his own geologic mapping and previously published geologic maps to compile one map having a single classification of geologic units. The resulting published color paper map (USGS Map I-855-G, Colton, 1978) was intended for land-use planning and to depict the regional geology. In 1997-1999, another USGS project designed to address urban growth issues was undertaken. This project, the USGS Front Range Infrastructure Resources Project, undertook to digitize Colton's map at 1:100,000 scale, making it useable in Geographical Information Systems (GIS). That product is described here. In general, the digitized map depicts in its western part Precambrian igneous and metamorphic rocks, Pennsylvanian and younger sedimentary rock units, major faults, and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The central and eastern parts of the map (Colorado Piedmont) show a mantle of Quaternary unconsolidated deposits and interspersed outcrops of sedimentary rock of Cretaceous or Tertiary age. A surficial mantle of unconsolidated deposits of Quaternary age is differentiated and depicted as eolium (wind-blown sand and silt), alluvium (river gravel, sand, and silt of variable composition), colluvium, and a few landslide deposits. At the mountain front, north-trending, Paleozoic and Mesozoic formations of sandstone, shale, and minor limestone dip mostly eastward and form folds, fault blocks, hogbacks and intervening valleys. Local dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area.

This digital map shows the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 under the Front Range Urban Corridor Geology Program. Colton used his own geologic mapping and previously published geologic maps to compile one map having a single classification of geologic units. The resulting published color paper map (USGS Map I-855-G, Colton, 1978) was intended for land-use planning and to depict the regional geology. In 1997-1999, another USGS project designed to address urban growth issues was undertaken. This project, the USGS Front Range Infrastructure Resources Project, undertook to digitize Colton's map at 1:100,000 scale, making it useable in Geographical Information Systems (GIS). That product is described here. In general, the digitized map depicts in its western part Precambrian igneous and metamorphic rocks, Pennsylvanian and younger sedimentary rock units, major faults, and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The central and eastern parts of the map (Colorado Piedmont) show a mantle of Quaternary unconsolidated deposits and interspersed outcrops of sedimentary rock of Cretaceous or Tertiary age. A surficial mantle of unconsolidated deposits of Quaternary age is differentiated and depicted as eolium (wind-blown sand and silt), alluvium (river gravel, sand, and silt of variable composition), colluvium, and a few landslide deposits. At the mountain front, north-trending, Paleozoic and Mesozoic formations of sandstone, shale, and minor limestone dip mostly eastward and form folds, fault blocks, hogbacks and intervening valleys. Local dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area.

The Blythe 30' x 60' quadrangle in southeastern California and southwestern Arizona displays complex geology that includes Mesozoic contractional deformation, metamorphism, and magmatism and Cenozoic extensional deformation and magmatism. The scope of the present map is limited to bedrock units of Miocene and older age because the younger deposits have not been mapped in sufficient detail across the quadrangle to support a systematic compilation. Mapping and topical studies by previous investigators (refer to accompanying pamphlet) resulted in recognition of the following regionally significant geologic features: (1) variably metamorphosed and deformed Paleozoic to early Mesozoic sedimentary rocks stratigraphically correlative with cratonal platform strata of the Colorado Plateau region; (2) Jurassic plutonic and volcanic rocks; (3) thick sequences of moderately to weakly metamorphosed sedimentary rocks of the Jurassic to Cretaceous McCoy Basin; (4) ductile folds and faults of the Late Cretaceous Maria Belt; and (5) Miocene detachment faults in the Big Maria and Plomosa Mountains. A major recent discovery is the recognition of the Late Cretaceous to Paleogene Orocopia Schist structurally below undated gneiss in the northern Plomosa Mountains. This northernmost outcrop area of Orocopia Schist yet found in western Arizona demonstrates that the entire Blythe quadrangle likely is underlain by this extensive, tectonically underplated subduction complex. In addition, post-middle Miocene transtensional deformation has been documented in the northern La Posa Plain, including recognition of left-lateral motion on two northeast-striking faults in the northern Plomosa Mountains and at Mesquite Mountain.

The Blythe 30' x 60' quadrangle in southeastern California and southwestern Arizona displays complex geology that includes Mesozoic contractional deformation, metamorphism, and magmatism and Cenozoic extensional deformation and magmatism. The scope of the present map is limited to bedrock units of Miocene and older age because the younger deposits have not been mapped in sufficient detail across the quadrangle to support a systematic compilation. Mapping and topical studies by previous investigators (refer to accompanying pamphlet) resulted in recognition of the following regionally significant geologic features: (1) variably metamorphosed and deformed Paleozoic to early Mesozoic sedimentary rocks stratigraphically correlative with cratonal platform strata of the Colorado Plateau region; (2) Jurassic plutonic and volcanic rocks; (3) thick sequences of moderately to weakly metamorphosed sedimentary rocks of the Jurassic to Cretaceous McCoy Basin; (4) ductile folds and faults of the Late Cretaceous Maria Belt; and (5) Miocene detachment faults in the Big Maria and Plomosa Mountains. A major recent discovery is the recognition of the Late Cretaceous to Paleogene Orocopia Schist structurally below undated gneiss in the northern Plomosa Mountains. This northernmost outcrop area of Orocopia Schist yet found in western Arizona demonstrates that the entire Blythe quadrangle likely is underlain by this extensive, tectonically underplated subduction complex. In addition, post-middle Miocene transtensional deformation has been documented in the northern La Posa Plain, including recognition of left-lateral motion on two northeast-striking faults in the northern Plomosa Mountains and at Mesquite Mountain.

The Digital Geologic Map of the Point Loma Quadrangle and area immediately west, California is composed of GIS data layers complete with ArcMap 9.3 layer (.LYR) files, two ancillary GIS tables, a Map PDF document with ancillary map text, figures and tables, a FGDC metadata record and a 9.3 ArcMap (.MXD) Document that displays the digital map in 9.3 ArcGIS. The data were completed as a component of the Geologic Resources Inventory (GRI) program, a National Park Service (NPS) Inventory and Monitoring (I&M) funded program that is administered by the NPS Geologic Resources Division (GRD). Source geologic maps and data used to complete this GRI digital dataset were provided by the following: California Division of Mines and Geology. Detailed information concerning the sources used and their contribution the GRI product are listed in the Source Citation sections(s) of this metadata record (polm_metadata.txt; available at http://nrdata.nps.gov/cabr/nrdata/geology/gis/polm_metadata.xml). All GIS and ancillary tables were produced as per the NPS GRI Geology-GIS Geodatabase Data Model v. 2.1. (available at: http://science.nature.nps.gov/im/inventory/geology/GeologyGISDataModel.cfm). The GIS data is available as a 9.3 personal geodatabase (polm_geology.mdb), and as shapefile (.SHP) and DBASEIV (.DBF) table files. The GIS data projection is NAD83, UTM Zone 11N. That data is within the area of interest of Cabrillo National Monument.