Riverside County's GIS web viewer that supplies various datasets containing parcel, transportation, environmental, and boundary layers and more.

Vector polygon map data of property parcels from Riverside County, California containing 846, 890 features.

Property parcel GIS map data consists of detailed information about individual land parcels, including their boundaries, ownership details, and geographic coordinates.

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Property parcel data can be used to analyze and visualize land-related information for purposes such as real estate assessment, urban planning, or environmental management.

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Available for viewing and sharing as a map in a Koordinates map viewer. This data is also available for export to DWG for CAD, PDF, KML, CSV, and GIS data formats, including Shapefile, MapInfo, and Geodatabase.

APN refers to Assessor's Parcel Number FLAG refers to a special designation for the parcel

The California Department of Fish and Game (CDFG) contracted with the California Native Plant Society (CNPS) and Aerial Information Systems (AIS) to produce an alliance-level, vegetation classification and map of Western Riverside County, California. The resulting classification and map products will be used to help establish a monitoring basis for the vegetation and habitats of the Western Riverside County Multi-Species Habitat Conservation Plan (MSHCP). The plan aims to conserve over 500,000 acres of land out of the 1.26 million acre total. This area is the largest MSHCP ever attempted and is an integral piece of the network of Southern California Habitat Conservation Plans and Natural Community Conservation Planning (Dudek 2001, Dudek 2003). Riverside County is one of the fastest growing counties in California, as well as one of the most biodiverse counties in the United States. A wide array of habitats are found within the non-developed lands in Western Riverside County, including coastal sage scrub, vernal pools, montane coniferous forest, chaparral, foothill woodland, annual grassland, and desert. In the CNPS contract, vegetation resources were assessed quantitatively through field surveys, data analysis, and final vegetation classification. Field survey data were analyzed statistically to come up with a floristically-based classification. Each vegetation type sampled was classified according to the National Vegetation Classification System to the alliance level (and association level if possible). The vegetation alliances were described floristically and environmentally in standard descriptions, and a final key was produced to differentiate among 101 alliances, 169 associations, and 3 unique stands (for final report, see https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=18245). In a parallel but separate effort by AIS (as reported in this dataset), vegetation mapping was undertaken through interpretation of ortho-rectified, aerial photographs for vegetation signatures in color infrared (CIR) and in natural color (imagery flown in winter or summer). A detailed map has been produced through the following process: 1) hand-delineation of polygons on base CIR imagery, 2) digitization of polygons, and 3) attribution of the vegetation types and overstory cover values. The map was created in a Geographic Information System (GIS) digital format, as was the database of field surveys. The dataset was produced through an on-screen photo interpretation procedure using three sets of geo-referenced imagery. The data is classified to a floristic classification derived through clustering analysis procedures based on species dominance and significance. The classification is based on the MCV (Manual of California Vegetation) in which 103 alliances and 169 floristic associations have been defined for the study area. Over 3300 full plot and reconnaissance points have been used in helping classify the mapped polygons. Mapped polygons are classified to either an association, alliance or mapping unit which may be an aggregation of associations or alliances. The dataset encompasses the western portions of Riverside County from the county boundary on the west eastward to the summit of the San Jacinto Mountains and Anza valley.

This data set of polygon features represents the official Riverside County's Supervisorial districts.

This layer contains the Township and Range data for the County of Riverside.

The Cahuilla Valley and Terwilliger Valley groundwater basins, 9-006 and 7-026 respectively (California Department of Water Resources 2016) located approximately 25 miles southwest of Palm Springs, are the sole-source for groundwater supply for the rural disadvantaged community and two Native American Tribes, the Ramona Band of Cahuilla and the Cahuilla. The characteristics and sustainable yield of the Cahuilla Valley and Terwilliger Valley groundwater basins are not well understood and are threatened by increasing water use and potential changes in water sustainability related to climate change. Previous USGS studies of the Cahuilla-Terwilliger Valley groundwater basins defined the thicknesses and characteristics of the alluvial sediments that constitute the main water-bearing unit of the aquifer system and identified where wells completed in the underlying fractured bedrock are located (Moyle, 1976; Landon and others, 2015; Woolfenden and Bright, 1988). However, although the fractured bedrock is an important part of the aquifer system for domestic and some irrigation supply, the thickness and hydraulic characteristics of the fractured bedrock are not well understood (Landon and others, 2015; Moyle 1976). Existing gravity data identified a possible conduit for groundwater flow beneath Cahuilla Creek in the Cahuilla and Durasno Valleys (Landon and others, 2015). Electrical resistivity tomography (ERT) data was collected in August 2018 to evaluate the cross-sectional depth to bedrock underlying a narrow section of Durasno Valley, and to help select locations for groundwater monitoring wells. Data from two transects were collected perpendicular to Cahuilla Creek, and offset by approximately 600 meters (m).

This data set of polygon features represents Riverside County's specific plans. A specific plan is used to facilitate effective implementation of the general plan. The specific plan must specify in detail the land uses, public and private facilities needed to support the land uses, phasing of development, standards for the conservation, development, and use of natural resources, and a program of implementation measures, including financing measures.Maintained by Stella Spadafora, 2/2016

This is SCAG 2019 Regional Land Use dataset developed for the final 2024 Connect SoCal, the 2024-2050 Regional Transportation Plan/Sustainable Communities Strategy (RTP/SCS), including general plan land use, specific plan land use, zoning code, and existing land use at parcel-level (approximately five million parcels) for 197 local jurisdictions in the SCAG region.The regional land use dataset is developed (1) to aid in SCAG’s regional transportation planning, scenario planning and growth forecasting, (2) facilitate policy discussion on various planning issues, and (3) enhance information database to better serve SCAG member jurisdictions, research institutes, universities, developers, general public, etc. It is the most frequently and widely utilized SCAG geospatial data. From late 2019 to early 2020, SCAG staff obtained the 2019 parcel boundary GIS file and tax roll property information from county assessor’s offices. After months of data standardization and clean-up process, SCAG staff released the 2019 parcel boundary GIS files along with the 2019 Annual Land Use dataset in February 2021. In December 2021, SCAG staff successfully developed the preliminary dataset of the 2019 regional land use data and released the draft SCAG Data/Map Book in May 2022. The preliminary land use data was reviewed by local jurisdictions during the Local Data Exchange (LDX) process for Connect SoCal 2024. As a part of the final 2019 regional land use data development process, SCAG staff made every effort to review the local jurisdictions’ inputs and comments and incorporated any updates to the regional land use datasets. The products of this project has been used as one of the key elements for Connect SoCal 2024 plan development, growth forecasting, scenario planning, and SCAG’s policy discussion on various planning issues, as well as Connect SoCal key growth strategy analysis.Note: This dataset is intended for planning purposes only, and SCAG shall incur no responsibility or liability as to the completeness, currentness, or accuracy of this information. SCAG assumes no responsibility arising from use of this information by individuals, businesses, or other public entities. The information is provided with no warranty of any kind, expressed or implied, including but not limited to the implied warranties of merchantability and fitness for a particular purpose. Users should consult with each local jurisdiction directly to obtain the official land use information.2019 SCAG Land Use Codes: LegendLand Use Description Single Family Residential1110 Single Family Residential 1111 High Density Single Family Residential (9 or more DUs/ac) 1112 Medium Density Single Family Residential (3-8 DUs/ac) 1113 Low Density Single Family Residential (2 or less DUs/ac)Multi-Family Residential1120 Multi-Family Residential 1121 Mixed Multi-Family Residential1122 Duplexes, Triplexes and 2- or 3-Unit Condominiums and Townhouses1123 Low-Rise Apartments, Condominiums, and Townhouses1124 Medium-Rise Apartments and Condominiums1125 High-Rise Apartments and CondominiumsMobile Homes and Trailer Parks1130 Mobile Homes and Trailer Parks1131 Trailer Parks and Mobile Home Courts, High-Density1132 Mobile Home Courts and Subdivisions, Low-DensityMixed Residential1140 Mixed Residential1100 ResidentialRural Residential 1150 Rural ResidentialGeneral Office1210 General Office Use 1211 Low- and Medium-Rise Major Office Use 1212 High-Rise Major Office Use 1213 SkyscrapersCommercial and Services1200 Commercial and Services1220 Retail Stores and Commercial Services 1221 Regional Shopping Center 1222 Retail Centers (Non-Strip With Contiguous Interconnected Off-Street Parking) 1223 Retail Strip Development1230 Other Commercial 1231 Commercial Storage 1232 Commercial Recreation 1233 Hotels and MotelsFacilities1240 Public Facilities1241 Government Offices1242 Police and Sheriff Stations1243 Fire Stations1244 Major Medical Health Care Facilities1245 Religious Facilities1246 Other Public Facilities1247 Public Parking Facilities1250 Special Use Facilities1251 Correctional Facilities1252 Special Care Facilities1253 Other Special Use FacilitiesEducation1260 Educational Institutions1261 Pre-Schools/Day Care Centers1262 Elementary Schools1263 Junior or Intermediate High Schools1264 Senior High Schools1265 Colleges and Universities1266 Trade Schools and Professional Training FacilitiesMilitary Installations1270 Military Installations1271 Base (Built-up Area)1272 Vacant Area1273 Air Field1274 Former Base (Built-up Area)1275 Former Base Vacant Area1276 Former Base Air FieldIndustrial1300 Industrial 1310 Light Industrial1311 Manufacturing, Assembly, and Industrial Services1312 Motion Picture and Television Studio Lots1313 Packing Houses and Grain Elevators1314 Research and Development1320 Heavy Industrial1321 Manufacturing1322 Petroleum Refining and Processing1323 Open Storage1324 Major Metal Processing1325 Chemical Processing1330 Extraction1331 Mineral Extraction - Other Than Oil and Gas1332 Mineral Extraction - Oil and Gas1340 Wholesaling and WarehousingTransportation, Communications, and Utilities1400 Transportation, Communications, and Utilities 1410 Transportation1411 Airports1412 Railroads1413 Freeways and Major Roads1414 Park-and-Ride Lots1415 Bus Terminals and Yards1416 Truck Terminals1417 Harbor Facilities1418 Navigation Aids1420 Communication Facilities1430 Utility Facilities1431 Electrical Power Facilities1432 Solid Waste Disposal Facilities1433 Liquid Waste Disposal Facilities1434 Water Storage Facilities1435 Natural Gas and Petroleum Facilities1436 Water Transfer Facilities 1437 Improved Flood Waterways and Structures1438 Mixed Utilities1440 Maintenance Yards1441 Bus Yards1442 Rail Yards1450 Mixed Transportation1460 Mixed Transportation and UtilityMixed Commercial and Industrial1500 Mixed Commercial and IndustrialMixed Residential and Commercial1600 Mixed Residential and Commercial 1610 Residential-Oriented Residential/Commercial Mixed Use 1620 Commercial-Oriented Residential/Commercial Mixed UseOpen Space and Recreation1800 Open Space and Recreation 1810 Golf Courses 1820 Local Parks and Recreation 1830 Regional Parks and Recreation 1840 Cemeteries 1850 Wildlife Preserves and Sanctuaries 1860 Specimen Gardens and Arboreta 1870 Beach Parks 1880 Other Open Space and Recreation 1890 Off-Street TrailsAgriculture2000 Agriculture2100 Cropland and Improved Pasture Land2110 Irrigated Cropland and Improved Pasture Land2120 Non-Irrigated Cropland and Improved Pasture Land2200 Orchards and Vineyards2300 Nurseries2400 Dairy, Intensive Livestock, and Associated Facilities2500 Poultry Operations2600 Other Agriculture2700 Horse RanchesVacant3000 Vacant3100 Vacant Undifferentiated3200 Abandoned Orchards and Vineyards3300 Vacant With Limited Improvements3400 Beaches (Vacant)1900 Urban VacantWater4000 Water4100 Water, Undifferentiated4200 Harbor Water Facilities4300 Marina Water Facilities4400 Water Within a Military Installation4500 Area of Inundation (High Water)Specific Plan7777 Specific PlanUnder Construction1700 Under ConstructionUndevelopable or Protected Land8888 Undevelopable or Protected LandUnknown9999 Unknown

Cook County GIS Dept map of Proviso, River Forest and Riverside Townships in a pdf format. Includes streets and municipalities.

The Cahuilla Valley and Terwilliger Valley groundwater basins, 9-006 and 7-026 respectively (California Department of Water Resources 2016) located approximately 25 miles southwest of Palm Springs, are the sole-source for groundwater supply for the rural disadvantaged community and two Native American Tribes, the Ramona Band of Cahuilla and the Cahuilla. The characteristics and sustainable yield of the Cahuilla Valley and Terwilliger Valley groundwater basins are not well understood and are threatened by increasing water use and potential changes in water sustainability related to climate change. Previous USGS studies of the Cahuilla-Terwilliger Valley groundwater basins defined the thicknesses and characteristics of the alluvial sediments that constitute the main water-bearing unit of the aquifer system and identified where wells completed in the underlying fractured bedrock are located (Moyle, 1976; Landon and others, 2015; Woolfenden and Bright, 1988). However, although the fractured bedrock is an important part of the aquifer system for domestic and some irrigation supply, the thickness and hydraulic characteristics of the fractured bedrock are not well understood (Landon and others, 2015; Moyle 1976). Existing gravity data identified a possible conduit for groundwater flow beneath Cahuilla Creek in the Cahuilla and Durasno Valleys (Landon and others, 2015). Electrical resistivity tomography (ERT) data was collected in August 2018 to evaluate the cross-sectional depth to bedrock underlying a narrow section of Durasno Valley, and to help select locations for groundwater monitoring wells. Data from two transects were collected perpendicular to Cahuilla Creek, and offset by approximately 600 meters (m).

This Digital Raster Graphic (DRG) was created using scanned U.S. Geological Survey 7.5-minute 1 to 24,000 scale maps georeferenced in Universal Transverse Mercator (UTM) grid. DRGs can be acquired with or without collar information for use in Geographic Information System (GIS) environment. Collarless DRGs can be edge matched creating a continuous collection of topographic maps.

This shapefile contains tax rate area (TRA) boundaries in Riverside County for the specified assessment roll year. Boundary alignment is based on the 2017 county parcel map. A tax rate area (TRA) is a geographic area within the jurisdiction of a unique combination of cities, schools, and revenue districts that utilize the regular city or county assessment roll, per Government Code 54900. Each TRA is assigned a six-digit numeric identifier, referred to as a TRA number. TRA = tax rate area number

Riverside County 2012 images. 1 foot resolution. Projected to California State Plane Zone VI

The Geologic Map of the Perris 7.5? Quadrangle, Riverside County, California contains a digital geologic map database of the Perris 7.5? quadrangle, Riverside County, California that includes: 1. ARC/INFO (Environmental Systems Research Institute, "http://www.esri.com") version 7.2.1 coverages of the various elements of the geologic map.

The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Geologic Investigations Series (I-series) maps but has not been edited to comply with I-map standards. Within the geologic map data package, map units are identified by standard geologic map criteria such as formationname, age, and lithology. Where known, grain size is indicated on the map by a subscripted letter or letters following the unit symbols as follows: lg, large boulders; b, boulder; g, gravel; a, arenaceous; s, silt; c, clay; e.g. Qyfa is a predominantly young alluvial fan deposit that is arenaceous. Multiple letters are used for more specific identification or for mixed units, e.g., Qfysa is a silty sand. In some cases, mixed units are indicated by a compound symbol; e.g., Qyf2sc.

[Summary provided by the USGS.]

This shapefile contains tax rate area (TRA) boundaries in Riverside County for the specified assessment roll year. Boundary alignment is based on the 2017 county parcel map. A tax rate area (TRA) is a geographic area within the jurisdiction of a unique combination of cities, schools, and revenue districts that utilize the regular city or county assessment roll, per Government Code 54900. Each TRA is assigned a six-digit numeric identifier, referred to as a TRA number. TRA = tax rate area number

This shapefile contains tax rate area (TRA) boundaries in Riverside County for the specified assessment roll year. Boundary alignment is based on the 2017 county parcel map. A tax rate area (TRA) is a geographic area within the jurisdiction of a unique combination of cities, schools, and revenue districts that utilize the regular city or county assessment roll, per Government Code 54900. Each TRA is assigned a six-digit numeric identifier, referred to as a TRA number. TRA = tax rate area number

The data set for the Corona North 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 North 7.5' quadrangle, Riverside and San Bernardino 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 North quadrangle is located near the northern end of the Peninsular Ranges Province. All but the southeastern tip of the quadrangle is within the Perris block, a relatively stable, rectangular in plan area located between the Elsinore and San Jacinto fault zones. The southeastern tip of the quadrangle is barely within the Elsinore fault zone.

The quadrangle is underlain by Cretaceous plutonic rocks that are part of the composite Peninsular Ranges batholith. These rocks are exposed in a triangular-shaped area bounded on the north by the Santa Ana River and on the south by Temescal Wash, a major tributary of the Santa Ana River. A variety of mostly silicic granitic rocks occur in the quadrangle, and are mainly of monzogranite and granodioritic composition, but range in composition from micropegmatitic granite to gabbro. Most rock units are massive and contain varying amounts of meso- and melanocratic equant-shaped inclusions. The most widespread granitic rock is monzogranite of the Cajalco pluton, a large pluton that extends some distance south of the quadrangle. North of Corona is a body of micropegmatite that appears to be unique in the batholith rocks.

Diagonally bisecting the quadrangle is the Santa Ana River. North of the Santa Ana River alluvial deposits are dominated by the distal parts of alluvial fans emanating from the San Gabriel Mountains north of the quadrangle. Widespread areas of the fan deposits are covered by a thin layer of wind blown sand.

Alluvial deposits in the triangular-shaped area between the Santa Ana River and Temescal Wash are quite varied, but consist principally of locally derived older alluvial fan deposits. These deposits rest on remnants of older, early Quaternary or late Tertiary age, nonmarine sedimentary deposits that were derived from both local sources and sources as far away as the San Bernardino Mountains. These deposits in part were deposited by an ancestral Santa Ana River. Older are a few scattered remnants of late Tertiary (Pliocene) marine sandstone that include some conglomerate lenses. Clasts in the conglomerate include siliceous volcanic rocks exotic to this part of southern California. This sandstone was deposited as the southeastern-most part of the Los Angeles sedimentary marine basin and was deposited along a rocky shoreline developed in the granitic rocks, much like the present day shoreline at Monterey, California. Most of the sandstone and granitic paleoshoreline features have been removed by quarrying and grading in the area of Porphyry north to Highway 91. Excellent exposures in highway road cuts still remain on the north side of Highway 91 just east of the 91-15 interchange and on the east side of U.S. 15 just north of the interchange.

South of Temescal Wash is a series of both younger and older alluvial fan deposits emanating from the Santa Ana Mountains to the southeast. In the immediate southwest corner of the quadrangle is a small exposure of sandstone and pebble conglomerate of the Sycamore Canyon member of the Puente Formation of early Pliocene and Miocene age and sandstone and conglomerate of undivided Sespe and Vaqueros Formations of early Miocene, Oligocene, and late Eocene age.

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.

Approximate locations of faults crossing the California Aqueduct, Coastal Branch, North Bay Aqueduct, and South Bay Aqueduct. Taken from "State Water Project, California Aqueduct Fault Crossings" report (PG Report 50-00-06) and supplemental maps (PG Report 50-00-06A) dated November 18, 1965. Fault crossings were collected before and during construction of the State Water Project (SWP) to inform design, and have been compiled in this database for future use in repairs and design. This compilation covers the SWP from North of San Francisco Bay in Solano County to Riverside County, and includes the California Aqueduct, North and South Bay Aqueducts, Coastal Branch, and West Branch.

Riverside County 2011 images. 1 foot resolution. Projected to Web Mercator.

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.