Entry_ID: (required) Entry_Title: Geologic Map of the Riverside West 7.5' Quadrangle, Riverside County, California Group: Data_Set_Citation Originator(s): Douglas M. Morton; Brett F. Cox Title: Geologic Map of the Riverside West 7.5' Quadrangle, Riverside County, California Publication: U.S. Geological Survey Open-File Report Publication_Date: 2001 Publication_Place: Menlo Park, California Publisher: U.S. Geological Survey Edition: Version 1.0 Data_Presentation_Form: vector digital data URL: http://geopubs.wr.usgs.gov/open-file/of01-451/ End_Group Keyword: geologic map Keyword: geology Keyword: bedrock geology Keyword: alluvial geology Keyword: Cretaceous tonalite and granodiorite Keyword: Quaternary deposits Keyword: Cretaceous Keyword: Quaternary Group: Temporal_Coverage Start_date: 2001 Stop_date: 2001 End_Group Data_Set_Progress: Complete Group: Spatial_Coverage Southernmost_Latitude: 33.87498306 Northernmost_Latitude: 34.00000046 Westernmost_Longitude: -117.5000914 Easternmost_Longitude: -117.3749086 End_Group Location: California Location: Riverside County Location: Riverside West 7.5' quadrangle Group: Data_Resolution Latitude_Resolution: 1.000380039215 Longitude_Resolution: 1.000380039215 End_Group Access_Constraints: None Use_Constraints: The Riverside West 7.5' geologic-map database should be used to evaluate and understand the geologic character of the Riverside West 7.5' quadrangle as a whole. The data should not be used for purposes of site-specific land-use planning or site-specific geologic evaluations. The database is sufficiently detailed to identify and characterize many actual and potential geologic hazards represented by faults and landslides and posed by ground subsidence and earthquake-generated ground shaking. However, 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 Hart, 1988). Use of this digital geologic-map database should not violate the spatial resolution of the data. Although the digital form of the data removes the constraint imposed by the scale of a paper map, the detail and accuracy inherent in map scale are also present in the digital data. The fact that this database was compiled and edited at a scale of 1:24,000 means that higher resolution information may not have been uniformly retained in the dataset. Plotting at scales larger than 1:24,000 will not yield greater real detail, although it may reveal fine-scale irregularities below the intended resolution of the database. Similarly, although higher resolution data is incorporated in most of the map, the resolution of the combined output will be limited by the lower resolution data. Originating_Center: (required) Group: Data_Center Data_Center_Name: U.S. Geological Survey Information Services Dataset_ID: USGS Open-File Report 01-451 Group: Data_Center_Contact Last_name: U.S. Geological Survey Information Services First_name: N/A Phone: (303)202-4700 Group: Address Box 25286 Denver Federal Center Denver, Colorado 80225 USA End_Group End_Group End_Group Storage_Medium: SunOS, 5.8, sun4m UNIX ARC/INFO version 7.2.1 Group: Distribution Distribution_Media: online Distribution_Format : ArcInfo export Distribution_Size: 1.8 megabytes Fees: none End_Group Group: Multimedia_Sample URL: http://geopubs.wr.usgs.gov/open-file/of01-451/images/rsw.jpg Format: JPEG Group: Description Reduced-size image of the map, 400x548 pixels, 32-bit RGB true color 95 kbytes. End_Group End_Group Group: Multimedia_Sample URL: http://geopubs.wr.usgs.gov/open-file/of01-451/rsw_map.pdf Format: PDF Caption: Printable map sheet, 1.6 megabytes End_Group Group: Reference Citation_Information: Originator: Morton, D.M. Publication_Date: 1999 Title: Preliminary digital geologic map of the Santa Ana 30'x60' quadrangle, southern California, version 1.0. Geospatial_Data_Presentation_Form: vector digital data Series_Information: Series_Name: U.S. Geological Survey Open-File Report Issue_Identification: 99-172 Publication_Information: Publication_Place: California Publisher: U.S. Geological Survey Online_Linkage: http://geopubs.wr.usgs.gov/open-file/of99-172/ End_Group Group: Summary The data set for the Riverside West 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 Riverside West 7.5' quadrangle, Riverside 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) 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 Riverside West quadrangle is located in the northern part of the Perris block, a relatively stable, rectangular-in-plan area located between the Elsinore and San Jacinto fault zones in the northern Peninsular Ranges Province. Most of the quadrangle is covered by a variable thickness of Quaternary alluvial material deposited on Cretaceous and older basement rocks. In the southern part of the quadrangle, northwest trending amphibolite grade biotite-bearing schist of Mesozoic or older age separates massive textured granitic rocks to the west from foliated and layered granitic rocks to the east. In the northern part of the quadrangle, scattered exposures of amphibolite grade biotite schist, impure quartzite, marble, calc-silicate rock, and skarn are probably Paleozoic. In the northeast corner of the quadrangle probable Paleozoic marble, which was quarried for local use, is intruded by tonalite, producing pyroxene-hornfels grade garnet-pyroxene skarn. The wide variety of mafic to silicic Cretaceous plutonic rocks in the quadrangle, are part of the composite Peninsular Ranges batholith. Hornblende and pyroxene gabbro, oldest of the plutonic rocks, occurs as a number of scattered small bodies. The relatively large gabbro body located at the south edge of the quadrangle extends for some distance south into the Lake Mathews quadrangle. On both sides of this body, the granodiorite of the Cajalco pluton contains numerous stoped masses of gabbro. Most of the granitic rock in the quadrangle is tonalitic with a faint to pronounced planar fabric produced by oriented biotite and hornblende. This planar structure in the northern two-thirds of the quadrangle typically strikes east, distinct from the northwest strike of planar structures common to most of the Peninsular Ranges batholith. The northwest part of the extensive, relatively uniform medium-to coarse-grained biotite-hornblende tonalite the Val Verde pluton underlies the southeast corner of the quadrangle. Relatively mafic hornblende and biotite-hornblende quartz diorite occurs in the central part of the quadrangle, and heterogeneous tonalite underlies most of the Pedley Hills in the north part of the quadrangle. In the southwestern part of the quadrangle, the northeastern extent of the lesser amounts of biotite-hornblende granodiorite. Common to this part of the Cajalco pluton are concentrated large and small stoped blocks of gabbro, most too small to be mapped at 1:24,000-scale. Numerous, massive to foliated, leucocratic biotite granite bodies are scattered thoughout the quadrangle. At Mount Rubidoux, very distinctive, dark colored, massive, coarse-grained granite contains hypersthene and fayalitic olivine in addition to biotite and hornblende. Located along the southwest boundary of the quadrangle is a very small occurrence of Paleocene? conglomerate that consists of exotic welded-tuff clasts and a few exotic bedded quartzite clasts. Several small areas of late Pliocene or early Pleistocene, slightly indurated fluvial sand, gravel, and cobbles occur in the Arlington area. Clasts in the deposits north of State Highway 91 consist entirely of San Bernardino Mountains lithologies. The deposits south of State Highway 91 consist of an upper section composed of slightly indurated bouldery gravel and sand derived from nearby Peninsular Ranges basement rocks and a lower section composed of clasts of San Bernardino Mountains lithologies. The patches of sediments containing San Bernardino Mountains lithologies are interpreted as being erosional remanants of paleo-Santa Ana River deposits, deposited when the river course was further south than its present day course. Most of the lower elevation areas of the quadrangle are covered by Pleistocene alluvial fan deposits. These fans were graded to the location of the present day course of the Santa Ana River but at a slightly higher elevation than the elevation of the present day river grade. The eastern part of the Santa Ana River includes a relatively broad young fluvial expanse and the western part is a relatively narrow alluvial channel incised into bedrock. 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. End_Group Group: Related_URL URL_Type: URL: http://geopubs.wr.usgs.gov/open-file/of99-172/ Group: Description Originator: Morton, D.M. Publication_Date: 1999 Title: Preliminary digital geologic map of the Santa Ana 30'x60' quadrangle, southern California, version 1.0. Geospatial_Data_Presentation_Form: vector digital data Series_Information: Series_Name: U.S. Geological Survey Open-File Report Issue_Identification: 99-172 Publication_Information: Publication_Place: California Publisher: U.S. Geological Survey Online_Linkage: http://geopubs.wr.usgs.gov/open-file/of99-172/ End_Group End_Group Group: DIF_Author Last_name: Alvarez First_name: Rachel Middle_name: M.H. Email: rhauser@usgs.gov Phone: (909) 276-6397 Group: Address U.S. Geological Survey Department of Earth Sciences University of California, Riverside Riverside, California 92521 USA End_Group End_Group DIF_Revision_Date: 20011002 Science_Review_Date: