The Elsinore quadrangle is located in the northern part of the Peninsular Ranges Province and includes parts of two structural blocks, or structural subdivisions of the province. The active Elsinore Fault Zone diagonally crosses the southwest corner of the quadrangle, and is a major element of the right-lateral strike-slip San Andreas Fault system. The Elsinore Fault Zone separates the Santa Ana Mountains block west of the fault zone from the Perris block to the east. Internally both blocks are relatively stable and within the quadrangle are characterized by the presence of widespread erosional surfaces of low relief. Within the quadrangle the Santa Ana Mountains block is underlain by undifferentiated granitic rocks of the Cretaceous Peninsular Ranges batholith, but to the west, includes widespread pre-batholithic Mesozoic rocks. The Perris block is underlain by a combination of batholithic and prebatholithic rocks, the latter consisting of metasedimentary rocks of low metamorphic grade; sub-greenschist grade. The most abundant lithology is phyllite but includes locally thick sections of impure quartzite. Minor sills, dikes, and small elongate plutons of fine-grained hornblende gabbro intrude the phyllite. Thin layers of tremolite-bearing marble occur locally. Also local are thin layers of manganese-bearing rocks. Both rhodonite and manganese oxides occur in these layers. The phyllite has a regular northwest strike throughout the main body of metamorphic rock giving rise to a homoclinal section over 25,000 feet thick. The layering-schistocity of these rocks is transposed bedding and is not stratigraphic thickness. In the northwest corner of the quadrangle is a series of Cretaceous volcanic and associated sedimentary rocks in the northwest corner of the quadrangle contain widespread primary sedimentary structures and appear to post date the metamorphism of the phyllite. The volcanic rocks are part of the Estelle Mountain volcanics of primarily rhyolitic composition. The sedimentary rocks are well indurated, perhaps incipiently metamorphosed, siliceous rocks containing local conglomerate beds. Parts of three plutonic complexes are included within the quadrangle, all part of the composite Peninsular Ranges batholith. In the southeast corner is the northwest part of the Paloma Valley ring complex, which is elliptical in plan and consists of an older ring-dike and two subsidiary short-arced dikes that were emplaced into gabbro by magmatic stoping. Small to large stoped blocks of gabbro are common within the ring-dikes. A younger ring-set, made up of hundreds of thin pegmatite dikes, occur largely within the central part of the complex. Only the northern part of the older ring dike occurs within the quadrangle. Stoped gabbro masses occur near the southeast margin of the quadrangle. In the northern part of the quadrangle is the southern part of the composite Gavilan ring complex of mostly tonalite composition. Hypersthene, although not usual in tonalite in the batholith, is a characteristic mineral of most of the rock of this complex. The Gavilan ring complex is a shallow intrusive that appears to be tilted up to the northeast. Fabric of the rocks changes in texture from hypauthomorphic-granular in the east to semiporphyritic in the west. The main part of the complex appears to have been emplaced by magmatic stoping. Several inactive gold mines, Goodhope, Gavilan, and Santa Rosa, are located within the complex. Within the Gavilan ring complex is the south-half of the Arroyo del Toro pluton. This near circular-in-plan pluton consists of massive-textured granodiorite that is essentially devoid of inclusions, and at one time was quarried for building stone. The Elsinore Fault Zone forms a complex series of pull-apart basins. The largest and most pronounced of these pull-apart basins forms a flat-floored closed depression, La Laguna, which is partly filled by Lake Elsinore. This basin forms the terminus for the San Jacinto River. During excessively wet periods the La Laguna fills and the overflow passes through Warm Springs Valley into Temescal Wash which joins the Santa Ana River at Corona. La Laguna, bounded by active faults, is flanked by both Pleistocene and Holocene alluvial fans emanating from both the Perris block and the Santa Ana Mountains. North of La Laguna are exposures of the Paleocene Silverado Formation. Clay beds of the Silverado Formation have been an important source of clay. Overlying the Silverado Formation are discontinuous exposures of conglomeratic younger Tertiary sedimentary rocks that are tentatively correlated with the Pauba Formation.

This layer is a component of Address Grid.

This data set maps and describes the geology of the Devore 7.5' quadrangle, San Bernardino County, California. Created using Environmental Systems Research Institute's ARC/INFO software, the data base consists of the following items: (1) a map coverage containing geologic contacts and units, (2) attribute tables for geologic units (polygons), contacts (arcs), and site-specific data (points). In addition, the data set includes the following graphic and text products: (1) A PostScript graphic plot-file containing the geologic map, topography, cultural data, a Correlation of Map Units (CMU) diagram, a Description of Map Units (DMU), an index map, a regional geologic and structure map, and a key for point and line symbols; (2) PDF files of this Readme (including the metadata file as an appendix), Description of Map Units (DMU), and the graphic produced by the PostScript plot file. The Devore quadrangle straddles part of the boundary between two major physiographic provinces of California, the Transverse Ranges Province to the north and the Peninsular Ranges Province to the south. The north half of the quadrangle includes the eastern San Gabriel Mountains and a small part of the western San Bernardino Mountains, both within the east-central part of the Transverse Ranges Province. South of the Cucamonga and San Andreas Fault zones, the extensive alluviated area in the south half of the quadrangle lies within the upper Santa Ana River Valley, and represents the northernmost part of the Peninsular Ranges Province. There are numerous active faults within the quadrangle, including right-lateral strike-slip faults of the San Andreas Fault system, which dominate the younger structural elements, and separate the San Gabriel from the San Bernardino Mountains. The active San Jacinto Fault zone projects toward the quadrangle from the southeast, but its location is poorly constrained not only within the quadrangle, but for at least several kilometers to the southeast. As a result, the interrelation between it, the Glen Helen Fault, and the probable easternmost part of the San Gabriel Fault is intrepretive. Thrust faults of the Cucamonga Fault zone along the south margin of the San Gabriel Mountains, represent the rejuvinated eastern end of a major old fault zone that bounds the south side of the western and central Transverse Ranges (Morton and Matti, 1993). Rejuvenation of this old fault zone, including the Cucamonga Fault zone, is apparently in response to compression in the eastern San Gabriel Mountains resulting from initiation of right-lateral slip on the San Jacinto Fault zone in the Peninsular Ranges.The structural grain within the San Gabriel Mountains, as defined by basement rocks, is generally east striking. Within the Devore quadrangle, these basement rocks include a Paleozoic (?) schist, quartzite, and marble metasedimentary sequence, which occurs as discontinuous lenses and septa within Cretaceous granitic rocks. Most of the granitic rocks are of tonalitic composition, and much of them are mylonitic. South of the granitic rocks is a complex assemblage of Proterozoic (?) metamorphic rocks, at least part of which is metasedimentary. The assemblage was metamorphosed to upper amphibolite and lower granulite grade, and subsequently remetamorphosed to a lower metamorphic grade. It is also intensely deformed by mylonitization which is characterized by an east striking, north dipping foliation, and by a pronounced lineation that plunges shallowly east and west. East of Lytle Creek and west of the San Andreas Fault zone, the predominant basement lithology is Mesozoic Pelona Schist, which consists mostly of greenschist grade metabasalt and metagraywacke. Intruding the Pelona Schist, between Lytle Creek and Cajon Canyon, is the granodiorite of Telegraph Peak of Oligocene age (May and Walker, 1989). East of the San Andreas Fault in the San Bernardino Mountains, basement rocks consist of amphibolite grade gneiss and schist intermixed with concordant and discordant tonalitic rock and pegmatite. Tertiary conglomerate and sandstone occur in the Cucamonga Fault zone and in a zone 200 to 700 m wide between strands of the San Andreas Fault zone and localized thrust faults northeast of the San Andreas. Most of the conglomerate and sandstone within the Cucamonga Fault zone is overturned forming the north limb of an overturned syncline. Clasts in the conglomerate are not derived from any of the basement rocks in the eastern San Gabriel Mountains. Clasts in the conglomerate and sandstone northeast of the San Andreas Fault zone do not appear to be locally derived either. The south half of the quadrangle is dominated by the large symmetrical alluvial-fan emanating from the canyon of Lytle Creek, and by the complex braided stream sediments of Lytle Creek and Cajon Wash. The San Andreas Fault is restricte... Visit https://dataone.org/datasets/c536e13d-c687-4b4e-afcd-decdcdbf8ecb for complete metadata about this dataset.

description: The Yucaipa 7.5' quadrangle is located at the southeastern margin of the San Bernardino Basin, an extensional region situated within a right-step-over zone between the San Jacinto and San Andreas Fault zones. The quadrangle is traversed by several faults of the San Andreas system, including (from oldest to youngest) the Banning Fault and the Wilson Creek, Mission Creek, Mill Creek, and San Bernardino Strands of the San Andreas Fault. The Mill Creek Strand of the San Andreas Fault is the easternmost strand of the San Andreas in the Yucaipa quadrangle. It separates granitic and metamorphic rocks of the San Bernardino Mountains block from a thin slice of similar rocks on Yucaipa Ridge, and thus has only a small amount of strike-slip displacement. The Wilson Creek Strand traverses Yucaipa Ridge and converges toward the Mlll Creek Strand in the Santa Ana river Canyon. The fault has juxtaposed an igneous and metamorphic complex (Wilson Creek block) and overlying nonmarine sedimentary rocks (Mill Creek Formation of Gibson, 1971) against rocks of San Bernardino Mountains-type, and thus has significant strike-slip displacement. The Mission Creek Strand is inferred to lie beneath Quaternary surficial deposits along the southwestern base of the San Bernardino Mountains. This fault is the major strand of the San Andreas Fault zone, and has juxtaposed crystalline rocks of San Gabriel Mountains-type (including Pelona Schist overlain by the Vincent Thrust and associated upper-plate crystalline rocks) against the Wilson Creek block and the San Bernardino Mountains. The San Bernardino Strand defines the modern trace of the San Andreas Fault. The strand forms primary fault features in all but the youngest Quaternary surficial units, and is thought to have evolved in the last 125,000 years or so based on regional fault relations. Complications within the San Andreas Fault system over the last several hundred thousand years have created a landscape setting in which Quaternary surficial materials of the Yucaipa quadrangle have accumulated. Crustal extension throughout the San Bernardino Basin region led to uplift of the Crafton Hills block and down-dropping of the Yucaipa Valley region on faults of the Crafton Hills and Chicken Hill complex. Subsequent middle and late Quaternary streamflows deposited several generations of axial-valley and alluvial-fan sediment in the down-dropped lowlands. These deposits and the older San Timoteo beds they overlie record the history of Quaternary fault movements, and form reservoirs for ground water in the Yucaipa quadrangle. Digital Data: The geologic database of the Yucaipa 1:24,000-scale 7.5' quadrangle, San Bernardino and Riverside Counties, California, was prepared by the Southern California Areal Mapping Project (SCAMP), a regional geologic-mapping project sponsored jointly by the U.S. Geological Survey and the California Geological Survey. The database was created in ARC/INFO (Environmental Systems Research Institute, ESRI), and includes the following files: (1) a readme.txt file, (2) this metadata file, (3) coverages containing geologic data and station-location data, (4) associated INFO attribute data files, (5) a browse graphic (.pdf) of the geologic-map plot and map-marginal explanatory information, (6) a PostScript graphics file of the geologic-map plot with map-marginal explanatory information, and (7) .pdf text files describing the map units of the Yucaipa quadrangle (Description of Map Units) and their geologic age and correlation (Correlation of Map Units).; abstract: The Yucaipa 7.5' quadrangle is located at the southeastern margin of the San Bernardino Basin, an extensional region situated within a right-step-over zone between the San Jacinto and San Andreas Fault zones. The quadrangle is traversed by several faults of the San Andreas system, including (from oldest to youngest) the Banning Fault and the Wilson Creek, Mission Creek, Mill Creek, and San Bernardino Strands of the San Andreas Fault. The Mill Creek Strand of the San Andreas Fault is the easternmost strand of the San Andreas in the Yucaipa quadrangle. It separates granitic and metamorphic rocks of the San Bernardino Mountains block from a thin slice of similar rocks on Yucaipa Ridge, and thus has only a small amount of strike-slip displacement. The Wilson Creek Strand traverses Yucaipa Ridge and converges toward the Mlll Creek Strand in the Santa Ana river Canyon. The fault has juxtaposed an igneous and metamorphic complex (Wilson Creek block) and overlying nonmarine sedimentary rocks (Mill Creek Formation of Gibson, 1971) against rocks of San Bernardino Mountains-type, and thus has significant strike-slip displacement. The Mission Creek Strand is inferred to lie beneath Quaternary surficial deposits along the southwestern base of the San Bernardino Mountains. This fault is the major strand of the San Andreas Fault zone, and has juxtaposed crystalline rocks of San Gabriel Mountains-type (including Pelona Schist overlain by the Vincent Thrust and associated upper-plate crystalline rocks) against the Wilson Creek block and the San Bernardino Mountains. The San Bernardino Strand defines the modern trace of the San Andreas Fault. The strand forms primary fault features in all but the youngest Quaternary surficial units, and is thought to have evolved in the last 125,000 years or so based on regional fault relations. Complications within the San Andreas Fault system over the last several hundred thousand years have created a landscape setting in which Quaternary surficial materials of the Yucaipa quadrangle have accumulated. Crustal extension throughout the San Bernardino Basin region led to uplift of the Crafton Hills block and down-dropping of the Yucaipa Valley region on faults of the Crafton Hills and Chicken Hill complex. Subsequent middle and late Quaternary streamflows deposited several generations of axial-valley and alluvial-fan sediment in the down-dropped lowlands. These deposits and the older San Timoteo beds they overlie record the history of Quaternary fault movements, and form reservoirs for ground water in the Yucaipa quadrangle. Digital Data: The geologic database of the Yucaipa 1:24,000-scale 7.5' quadrangle, San Bernardino and Riverside Counties, California, was prepared by the Southern California Areal Mapping Project (SCAMP), a regional geologic-mapping project sponsored jointly by the U.S. Geological Survey and the California Geological Survey. The database was created in ARC/INFO (Environmental Systems Research Institute, ESRI), and includes the following files: (1) a readme.txt file, (2) this metadata file, (3) coverages containing geologic data and station-location data, (4) associated INFO attribute data files, (5) a browse graphic (.pdf) of the geologic-map plot and map-marginal explanatory information, (6) a PostScript graphics file of the geologic-map plot with map-marginal explanatory information, and (7) .pdf text files describing the map units of the Yucaipa quadrangle (Description of Map Units) and their geologic age and correlation (Correlation of Map Units).

description: The Redlands 7.5' quadrangle is located in the southeastern margin of the San Bernardino Basin, an extensional region situated in a right-step-over zone within the San Andreas Fault system. The quadrangle is traversed by several important fault zones, including: (1) northwest-trending right-lateral strike-slip faults of the San Andreas system (Banning Fault, the Mission Creek and San Bernardino Strands of the San Andreas Fault, the San Jacinto Fault); (2) northeast-trending normal dip-slip faults that have downdropped the San Bernardino Basin; (3) east-trending contractional faults of the San Timoteo Canyon Fault zone. Some of these faults bound distinctive packages of crystalline basement rock. Northwest of the Mission Creek Strand of the San Andreas Fault lies an igneous and metamorphic complex characterized by textural and compositional heterogeneity. This terrane, the Wilson Creek block, is strongly gneissose but includes foliated to massive granitoid rocks intimately intermingled with the gneisses. Thin slices of the gneissose complex have been displaced a few kilometers by the San Bernardino Strand of the San Andreas, the modern trace of the San Andreas Fault in the Redlands quadrangle and elsewhere along the southwest margin of the San Bernardino Mountains. The Mission Creek strand is inferred to lie beneath Quaternary surficial deposits along the southwestern base of the San Bernardino Mountains. This fault is the major strand of the San Andreas Fault zone, has about 100 km of right-slip, and has juxtaposed distinctive crystalline rocks of San Gabriel Mountains-type against the Wilson Creek block and the San Bernardino Mountains. The Banning Fault probably demarcates an important boundary between rocks of San Gabriel Mountains-type to the north and rocks of Peninsular Ranges-type to the south. This hypothesis is difficult to test because outcrops of the two terranes are several miles apart and between them the trace of the Banning Fault must be inferred beneath surficial deposits and beneath the San Timoteo beds of Frick (1921). The rocks of Peninsular Range-type are very different from those of San Gabriel Mountains-type, and consist of massive to foliated granitoids of monzogranitic, granodioritic, and tonalitic composition. Much of the Redlands quadrangle is covered with unconsolidated Quaternary surficial deposits of sand and gravel that have accumulated over the last 600,000 years or so. These are thickest on the modern and ancestral flood plains of the Santa Ana River. In the south part of the quadrangle within the San Timoteo and Reche Canyon drainage systems, Quaternary surficial deposits are less extensive and have distribution patterns determined by displacements on the San Timoteo Canyon Fault zone (reverse faulting) and the San Jacinto Fault (strike-slip faulting). In this region, folded and faulted deposits of the San Timoteo beds of Frick, (1921) formed upwarps and downwarps that influenced the evolution of the landscape and its sedimentary deposits. Digital Data: This geologic database of the Redlands 1:24,000-scale 7.5' quadrangle, San Bernardino and Riverside Counties, California, was prepared by the Southern California Areal Mapping Project (SCAMP), a geoscience project sponsored jointly by the U.S. Geological Survey (USGS) and the California Geological Survey. The database was created in ARC/INFO (Environmental Systems Research Institute), and includes the following files: (1) a readme file, (2) this metadata file, (3) coverages containing geologic-map data and station-location data, (4) associated data tables, (5) a browse graphic of the geologic-map plot and map-marginal explanatory information (.pdf file), (6) a PostScript graphics file of the geologic-map plot with map-marginal explanatory information, and (7) .pdf files describing map units of the Redlands quadrangle (Description of Map Units) and their geologic age and correlation (Correlation of Map Units).; abstract: The Redlands 7.5' quadrangle is located in the southeastern margin of the San Bernardino Basin, an extensional region situated in a right-step-over zone within the San Andreas Fault system. The quadrangle is traversed by several important fault zones, including: (1) northwest-trending right-lateral strike-slip faults of the San Andreas system (Banning Fault, the Mission Creek and San Bernardino Strands of the San Andreas Fault, the San Jacinto Fault); (2) northeast-trending normal dip-slip faults that have downdropped the San Bernardino Basin; (3) east-trending contractional faults of the San Timoteo Canyon Fault zone. Some of these faults bound distinctive packages of crystalline basement rock. Northwest of the Mission Creek Strand of the San Andreas Fault lies an igneous and metamorphic complex characterized by textural and compositional heterogeneity. This terrane, the Wilson Creek block, is strongly gneissose but includes foliated to massive granitoid rocks intimately intermingled with the gneisses. Thin slices of the gneissose complex have been displaced a few kilometers by the San Bernardino Strand of the San Andreas, the modern trace of the San Andreas Fault in the Redlands quadrangle and elsewhere along the southwest margin of the San Bernardino Mountains. The Mission Creek strand is inferred to lie beneath Quaternary surficial deposits along the southwestern base of the San Bernardino Mountains. This fault is the major strand of the San Andreas Fault zone, has about 100 km of right-slip, and has juxtaposed distinctive crystalline rocks of San Gabriel Mountains-type against the Wilson Creek block and the San Bernardino Mountains. The Banning Fault probably demarcates an important boundary between rocks of San Gabriel Mountains-type to the north and rocks of Peninsular Ranges-type to the south. This hypothesis is difficult to test because outcrops of the two terranes are several miles apart and between them the trace of the Banning Fault must be inferred beneath surficial deposits and beneath the San Timoteo beds of Frick (1921). The rocks of Peninsular Range-type are very different from those of San Gabriel Mountains-type, and consist of massive to foliated granitoids of monzogranitic, granodioritic, and tonalitic composition. Much of the Redlands quadrangle is covered with unconsolidated Quaternary surficial deposits of sand and gravel that have accumulated over the last 600,000 years or so. These are thickest on the modern and ancestral flood plains of the Santa Ana River. In the south part of the quadrangle within the San Timoteo and Reche Canyon drainage systems, Quaternary surficial deposits are less extensive and have distribution patterns determined by displacements on the San Timoteo Canyon Fault zone (reverse faulting) and the San Jacinto Fault (strike-slip faulting). In this region, folded and faulted deposits of the San Timoteo beds of Frick, (1921) formed upwarps and downwarps that influenced the evolution of the landscape and its sedimentary deposits. Digital Data: This geologic database of the Redlands 1:24,000-scale 7.5' quadrangle, San Bernardino and Riverside Counties, California, was prepared by the Southern California Areal Mapping Project (SCAMP), a geoscience project sponsored jointly by the U.S. Geological Survey (USGS) and the California Geological Survey. The database was created in ARC/INFO (Environmental Systems Research Institute), and includes the following files: (1) a readme file, (2) this metadata file, (3) coverages containing geologic-map data and station-location data, (4) associated data tables, (5) a browse graphic of the geologic-map plot and map-marginal explanatory information (.pdf file), (6) a PostScript graphics file of the geologic-map plot with map-marginal explanatory information, and (7) .pdf files describing map units of the Redlands quadrangle (Description of Map Units) and their geologic age and correlation (Correlation of Map Units).

The data set for the Corona South 7.5' quadrangle was prepared under the U.S. Geological Survey Southern California Areal Mapping Project (SCAMP) as part of an ongoing effort to develop a regional geologic framework of southern California, and to utilize a Geographic Information System (GIS) format to create regional digital geologic databases. These regional databases are being developed as contributions to the National Geologic Map Database of the National Cooperative Geologic Mapping Program of the USGS.

This data set maps and describes the geology of the Corona South 7.5' quadrangle, Riverside and Orange Counties, California. Created using Environmental Systems Research Institute's ARC/INFO software, the data base consists of the following items: (1) a map coverage containing geologic contacts and units, (2) a coverage containing structural data, (3) a coverage containing geologic unit annotation and leaders, and (4) attribute tables for geologic units (polygons), contacts (arcs), and site-specific data (points). In addition, the data set includes the following graphic and text products: (1) a postscript graphic plot-file containing the geologic map, topography, cultural data, a Correlation of Map Units (CMU) diagram, a Description of Map Units (DMU), and a key for point and line symbols, and (2) PDF files of the Readme (including the metadata file as an appendix), and the graphic produced by the Postscript plot file.

The Corona South quadrangle is located near the northern end of the Peninsular Ranges Province. Diagonally crossing the quadrangle is the northern end of the Elsinore Fault zone, a major active right-lateral strike-slip fault zone of the San Andreas Fault system. East of the fault zone is the Perris block and to the west the Santa Ana Mountains block. Basement in the Perris block part of the quadrangle is almost entirely Cretaceous volcanic rocks and granitic rocks of the Cretaceous Peninsular Ranges batholith. Three small exposures of very low metamorphic grade siliceous rocks correlated on the basis of lithology with Mesozoic age rocks are located near the eastern edge of the quadrangle. Exposures of batholithic rocks is restricted to mostly granodiorite of the Cajalco pluton that underlies extensive areas to the east and north. There are limited amounts of undifferentiated granitic rock and one small body of gabbro. The most extensive basement rocks are volcanic shallow intrusives and extrusives of the Estelle Mountain volcanics. The volcanics, predominantly latite and rhyolite, are quarried as a source of crushed rock.

West of the Elsinore Fault zone is a thick section of Bedford Canyon Formation of Jurassic age. This unit consists of incipiently metamorphosed marine sedimentary rocks consisting of argillite, slate, graywacke, impure quartzite, and small pods of limestone. Bedding and other primary sedimentary structures are commonly preserved and tight folds are common. Incipiently developed transposed layering, S1, is locally well developed. Included within the siliceous rocks are small outcrops of fossiliferous limestone than contain a fauna indicating the limestone formed in a so-called black smoker environment. Unconformably overlying and intruding the Bedford Canyon Formation is the Santiago Peak Volcanics of Cretaceous age. These volcanics consist of basaltic andesite, andesite, dacite, rhyolite, breccia and volcanoclastic rocks. Much of the unit has been hydrothermally altered; the alteration was contemporaneous with the volcanism. A minor occurrence of serpentine and associated silica-carbonate rock occurs in association with the volcanics.

Sedimentary rocks of late Cretaceous and Paleogene age and a few Neogene age rocks occur within the Elsinore Fault zone. Marine sandstone of the middle Miocene Topanga Formation occurs within the fault zone southeast of Corona. Underlying the Topanga Formation is the nonmarine undivided Sespe and Vaqueros Formation that are predominantly sandstone. Sandstone, siltstone, and conglomerate of the marine and nonmarine Paleocene Silverado Formation extends essentially along the entire length of the fault zone in the quadrangle. Clay beds in the Silverado Formation have been an important source of clay. In the northwest corner of the quadrangle is a thick, faulted, sedimentary section that ranges in age from Cretaceous to early Pliocene-Miocene.

Emanating from the Santa Ana Mountains is an extensive alluvial fan complex that underlies Corona and the surrounding valleys. This fan complex includes both Pleistocene and Holocene age deposits.

The Elsinore Fault zone at the base of the Santa Ana Mountains splays in the northwestern part of the quadrangle; beyond the quadrangle boundary the name Elsinore Fault is generally not used. The southern splay takes a more western trend and to the west of the quadrangle is termed the Whittier Fault, a major active fault. The eastern splay continues on strike along the east side of the Chino (Puente) Hills north of the quadrangle where it is termed the Chino Fault. The Chino Fault appears to have very limited displacement.

The geologic map data base contains original U.S. Geological Survey data generated by detailed field observation recorded on 1:24,000 scale aerial photographs. The map was created by transferring lines from the aerial photographs to a 1:24,000 scale topographic base. The map was digitized and lines, points, and polygons were subsequently edited using standard ARC/INFO commands. Digitizing and editing artifacts significant enough to display at a scale of 1:24,000 were corrected. Within the database, geologic contacts are represented as lines (arcs), geologic units are polygons, and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify each geologic datum.

description: This data set maps and describes the geology of the Cucamonga Peak 7.5' quadrangle, San Bernardino County, California. Created using Environmental Systems Research Institute's ARC/INFO software, the database consists of the following items: (1) a map coverage containing geologic contacts and units, (2) a coverage containing site-specific structural data, (3) a coverage containing geologic-unit label leaders and their associated attribute tables for geologic units (polygons), contacts (arcs), and site-specific data (points). In addition, the data set includes the following graphic and text products: (1) A PostScript graphic plot-file containing the geologic map, topography, cultural data, a Correlation of Map Units (CMU) diagram, a Description of Map Units (DMU), an index map, a regional geologic and structure map, and a key for point and line symbols; (2) PDF files of this Readme (including the metadata file as an appendix) and the graphic produced by the PostScript plot file. The Cucamonga Peak quadrangle includes part of the boundary between two major physiographic provinces of California, the Transverse Ranges Province to the north and the Peninsular Ranges Province to the south. The north part of the quadrangle is in the eastern San Gabriel Mountains, and the southern part includes an extensive Quaternary alluvial-fan complex flanking the upper Santa Ana River valley, the northernmost part of the Peninsular Ranges Province. Thrust faults of the active Cucamonga Fault zone along the the south margin of the San Gabriel Mountains are the rejuvenated eastern terminus of a major old fault zone that bounds the south side of the western and central Transverse Ranges (Morton and Matti, 1993). Rejuvenation of this old fault zone, including the Cucamonga Fault zone, is apparently in response to compression in the eastern San Gabriel Mountains resulting from initiation of right-lateral slip on the San Jacinto Fault zone in the Peninsular Ranges. Within the northern part of the quadrangle are several arcuate-in-plan faults that are part of an antiformal, schuppen-like fault complex of the eastern San Gabriel Mountains. Most of these arcuate faults are reactivated and deformed older faults that probably include the eastern part of the San Gabriel Fault. The structural grain within the San Gabriel Mountains, as defined by basement rocks, is generally east striking. Within the Cucamonga Peak quadrangle, these basement rocks include a Paleozoic schist and gneiss sequence which occurs as large, continuous and discontinuous bodies intruded by Cretaceous granitic rocks. Most of the granitic rocks are of tonalitic composition, and many are mylonitic. South of the granitic rocks is a comple assemblage of Proterozoic(?) metamorphic rocks, at least part of which is metasedimentary. This assemblage is intruded by Cretaceous tonalite on its north side, and by charnockitic rocks near the center of the mass. The charnockitic rocks are in contact with no other Cretaceous granitic rocks. Consequently, their relative position in the intrusive sequence is unknown. The Proterozoic(?) assemblage was metamorphosed to upper amphibolite and lower granulite grade, and subsequently to a lower metamorphic grade. It is also intensely deformed by mylonitization characterized by an east-striking, north-dipping foliation, and by a pronounced subhorizontal lineation that plunges shallowly east and west. The southern half of the quadrangle is dominated by extensive, symmetrical alluvial-fan complexes, particularly two emanating from Day and Deer Canyons. Other Quaternary units ranging from early Pleistocene to recent are mapped, and represent alluvial-fan, landslide, talus, and wash environments. The geologic map database contains original U.S. Geological Survey data generated by detailed field observation and by interpretation of aerial photographs. This digital Open-File map supercedes an older analog Open-File map of the quadrangle, and includes extensive new data on the Quaternary deposits, and revises some fault and bedrock distribution within the San Gabriel Mountains. The digital map was compiled on a base-stable cronoflex copy of the Cucamonga Peak 7.5' topographic base and then scribed. This scribe guide was used to make a 0.007 mil blackline clear-film, from which lines and point were hand digitized. Lines, points, and polygons were subsequently edited at the USGS using standard ARC/INFO commands. Digitizing and editing artifacts significant enough to display at a scale of 1:24,000 were corrected. Within the database, geologic contacts are represented as lines (arcs), geologic units as polygons, and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify each geologic datum.; abstract: This data set maps and describes the geology of the Cucamonga Peak 7.5' quadrangle, San Bernardino County, California. Created using Environmental Systems Research Institute's ARC/INFO software, the database consists of the following items: (1) a map coverage containing geologic contacts and units, (2) a coverage containing site-specific structural data, (3) a coverage containing geologic-unit label leaders and their associated attribute tables for geologic units (polygons), contacts (arcs), and site-specific data (points). In addition, the data set includes the following graphic and text products: (1) A PostScript graphic plot-file containing the geologic map, topography, cultural data, a Correlation of Map Units (CMU) diagram, a Description of Map Units (DMU), an index map, a regional geologic and structure map, and a key for point and line symbols; (2) PDF files of this Readme (including the metadata file as an appendix) and the graphic produced by the PostScript plot file. The Cucamonga Peak quadrangle includes part of the boundary between two major physiographic provinces of California, the Transverse Ranges Province to the north and the Peninsular Ranges Province to the south. The north part of the quadrangle is in the eastern San Gabriel Mountains, and the southern part includes an extensive Quaternary alluvial-fan complex flanking the upper Santa Ana River valley, the northernmost part of the Peninsular Ranges Province. Thrust faults of the active Cucamonga Fault zone along the the south margin of the San Gabriel Mountains are the rejuvenated eastern terminus of a major old fault zone that bounds the south side of the western and central Transverse Ranges (Morton and Matti, 1993). Rejuvenation of this old fault zone, including the Cucamonga Fault zone, is apparently in response to compression in the eastern San Gabriel Mountains resulting from initiation of right-lateral slip on the San Jacinto Fault zone in the Peninsular Ranges. Within the northern part of the quadrangle are several arcuate-in-plan faults that are part of an antiformal, schuppen-like fault complex of the eastern San Gabriel Mountains. Most of these arcuate faults are reactivated and deformed older faults that probably include the eastern part of the San Gabriel Fault. The structural grain within the San Gabriel Mountains, as defined by basement rocks, is generally east striking. Within the Cucamonga Peak quadrangle, these basement rocks include a Paleozoic schist and gneiss sequence which occurs as large, continuous and discontinuous bodies intruded by Cretaceous granitic rocks. Most of the granitic rocks are of tonalitic composition, and many are mylonitic. South of the granitic rocks is a comple assemblage of Proterozoic(?) metamorphic rocks, at least part of which is metasedimentary. This assemblage is intruded by Cretaceous tonalite on its north side, and by charnockitic rocks near the center of the mass. The charnockitic rocks are in contact with no other Cretaceous granitic rocks. Consequently, their relative position in the intrusive sequence is unknown. The Proterozoic(?) assemblage was metamorphosed to upper amphibolite and lower granulite grade, and subsequently to a lower metamorphic grade. It is also intensely deformed by mylonitization characterized by an east-striking, north-dipping foliation, and by a pronounced subhorizontal lineation that plunges shallowly east and west. The southern half of the quadrangle is dominated by extensive, symmetrical alluvial-fan complexes, particularly two emanating from Day and Deer Canyons. Other Quaternary units ranging from early Pleistocene to recent are mapped, and represent alluvial-fan, landslide, talus, and wash environments. The geologic map database contains original U.S. Geological Survey data generated by detailed field observation and by interpretation of aerial photographs. This digital Open-File map supercedes an older analog Open-File map of the quadrangle, and includes extensive new data on the Quaternary deposits, and revises some fault and bedrock distribution within the San Gabriel Mountains. The digital map was compiled on a base-stable cronoflex copy of the Cucamonga Peak 7.5' topographic base and then scribed. This scribe guide was used to make a 0.007 mil blackline clear-film, from which lines and point were hand digitized. Lines, points, and polygons were subsequently edited at the USGS using standard ARC/INFO commands. Digitizing and editing artifacts significant enough to display at a scale of 1:24,000 were corrected. Within the database, geologic contacts are represented as lines (arcs), geologic units as polygons, and site-specific data as points. Polygon, arc, and point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify each geologic datum.