Preliminary geologic map of the Elsinore 7.5' quadrangle, Riverside County, California

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What does this data set describe?

Preliminary geologic map of the Elsinore 7.5' quadrangle, Riverside County, California
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.
Supplemental_Information: None
  1. How might this data set be cited?
    Morton, Douglas M., and F. Harold Weber, Jr., 2003, Preliminary geologic map of the Elsinore 7.5' quadrangle, Riverside County, California: U.S. Geological Survey Open-File Report 03-281, U.S. Geological Survey, Menlo Park, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -117.37509053
    East_Bounding_Coordinate: -117.24990947
    North_Bounding_Coordinate: 33.74999995
    South_Bounding_Coordinate: 33.62498421
  3. What does it look like? (GIF)
    Reduced-size image of the entire map sheet, 450x312 pixels, 44k bytes (PDF)
    Printable version of the entire map sheet, 4.4 megabytes.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2003
    New data
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: vector digital data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Point (296)
      • String (749)
      • GT-polygon composed of chains (297)
    2. What coordinate system is used to represent geographic features?
      The map projection used is Polyconic.
      Projection parameters:
      Latitude_of_Projection_Origin: 33.625
      Longitude_of_Central_Meridian: -117.3125
      False_Easting: 0.00000
      False_Northing: 0.00000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      Planar coordinates are specified in Meters
      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    Version 1.0 of the Elsinore 7.5' quadrangle comprises three ARC/INFO coverages, of which two contain geologic data, and one contains cartographic features: els_geo (geology), els_str (structural data), and els_ano (annotation and leaders).
    Geologic data represented by line entities and the polygons they delineate are contained in the coverage ELS_GEO. For display purposes, the annotation coverage contains one annotation subclass: anno.geo contains unit labels.
    Geological point data includes site-specific information describing the types and the orientation of bedding and foliation. Annotation is respective dip and plunge values associated with individual point data.
        1  AREA                   8    18     F      5
        9  PERIMETER              8    18     F      5
       17  ELS_GEO#               4     5     B      -
       21  ELS_GEO-ID             4     5     B      -
       25  LABL                  35    35     C      -
       60  PLABL                 35    35     C      -
       95  NAME                 100   100     C      -
      195  SHD                    3     3     I      -
      198  SHDFIL                 3     3     I      -
        1  FNODE#                 4     5     B      -
        5  TNODE#                 4     5     B      -
        9  LPOLY#                 4     5     B      -
       13  RPOLY#                 4     5     B      -
       17  LENGTH                 8    18     F      5
       25  ELS_GEO#               4     5     B      -
       29  ELS_GEO-ID             4     5     B      -
       33  LTYPE                 35    35     C      -
       68  L-SYMB                 3     3     I      -
    Geologic units (LABL) and their corresponding names (NAME) identified in the Elsinore 7.5' quadrangle
    geologic map unit label, in plain text
    QafArtificial fill
    QwVery young wash deposits
    QfVery young alluvial-fan deposits
    QlVery young lacustrine deposits
    QywYoung alluvial-wash deposits
    QyfYoung alluvial-fan deposits
    Qyf1Young alluvial-fan deposits, Unit 1
    QyaYoung alluvial-channel deposits
    QyvYoung alluvial-valley deposits
    QofOld alluvial-fan deposits
    Qof1Old alluvial-fan deposits, Unit 1
    QoaOld alluvial-channel deposits
    QvofVery old alluvial-fan deposits
    QvoaVery old alluvial-channel deposits
    QpfPauba Formation
    QpfsPauba Formation, sandstone member
    TsiSilverado Formation
    KgtGavilan ring complex, massive textured tonalite
    KghGavilan ring complex, hypabyssal tonalite
    KatgGranodiorite of Arroyo del Toro pluton
    KgbfFine grained hornblende gabbro, Railroad Canyon area
    KpvgPaloma valley ring complex
    KgdGranodiorite, undifferentiated
    KhgHeterogeneous granitic rocks
    KvspSantiago Peak Volcanics
    KvemEstelle Mountain volcanics of Herzig
    KvsIntermixed Estelle Mountain volcanics of Herzig(Cretaceous) and sedimentary rocks(Cretaceous)
    KsvIntermixed Estelle Mountain volcanics of Herzig(Cretaceous) and sedimentary rocks(Mesozoic)
    MzuMetasedimentary rocks, undifferentiated
    MzqQuartz-rich rocks
    Geological map unit label used to generate plot labels with relevant stratigraphic symbols. The geologic units with LABL designating Mesozoic (Mz) have keystroke substitute characters, }, that call their corresponding symbols from the Geoage Font Group. Geologic map unit labels will plot on derivative map plots with appropriate stratigraphic symbols if PLABL is used as the source for unit labels.
    polygon color (as integer value) from shadeset alc1.shd
    polygon fill pattern (as integer value) from shadeset geology2.shd
    Geologic name of map unit (see list under LABL attribute)
    Geologic features such as contacts and faults that bound rock-unit polygons
    Description of types of lines on the geologic map (contact, fault).
    contact, certain 
    fault, certain 
    fault, approx. located 
    fault, concealed 
    Geological point data includes site-specific information describing the types and the orientation of bedding, foliation, joints, and lineations. One annotation subclass is included in the geologic points coverage, ELS_STR which displays the respective dip and plunge values associated with individual point data.
    Describes type of point data (bedding, foliation)
    sedimentary bedding 
    igneous foliation 
    metamorphic foliation 
    vertical metamorphic foliation 
    Coded integer value that relates point to cartographic point symbol in markerset geoscamp2.mrk
    Azimuthal strike of planar feature
    Dip of planar feature
    Annotation leaders
    Description of types of lines in coverage (annotation leaders)
    Coded integer value (1) that relates arcs to cartographic line symbol in lineset, geoscamp2.lin

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Douglas M. Morton
    • F. Harold Weber, Jr.
  2. Who also contributed to the data set?
    Geologic mapping and digital preparation of this report were sponsored jointly by (1) the National Cooperative Geologic Mapping Program of the U.S. Geological Survey, (2) the California Geological Survey, and (3) the Southern California Areal Mapping Project (SCAMP).
  3. To whom should users address questions about the data?
    Douglas M. Morton
    U.S. Geological Survey, Western Region, Earth Surface Processes Team
    Project Geologist
    U.S. Geological Survey
    Riverside, California

    (909)276-6397 (voice)
    (909)276-6295 (FAX)

Why was the data set created?

The data set for the Elsinore 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.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 1978 (process 1 of 6)
    Field mapping and aerial photograph interpretation; iterative process (D.M. Morton).
    Date: 1973 (process 2 of 6)
    Field mapping and aerial photograph interpretation; iterative process (F.H. Weber, Jr.).
    Date: 1999 (process 3 of 6)
    Digitization of geologic linework and point data from a scale-stable cartographic base of quadrangle. ARC/INFO database established; cleanup of artifacts; polygon, arc, and point attribute tables established. Digitizing and editing artifacts significant enough to display at a scale of 1:24,000 were corrected (R.M. Alvarez and Diane Burns).
    Date: 2003 (process 4 of 6)
    Description of map units and correlation of map units (R.M. Alvarez).
    Date: 19-Mar-2003 (process 5 of 6)
    First draft of metadata created by R.M. Alvarez using FGDCMETA.AML ver. 1.2 05/14/98 on ARC/INFO data set on /scamp27/elsinore/els_geo
    Date: 19-Mar-2003 (process 6 of 6)
    Creation of original metadata record Person who carried out this activity:
    U.S. Geological Survey
    Attn: Rachel M. Alvarez
    U.S. Geological Survey
    Riverside, California

    (909)276-6397 (voice)
    (909)276-6295 (FAX)
  3. What similar or related data should the user be aware of?
    Morton, D.M., 1999, Preliminary digital geologic map of the Santa Ana 30'x60' quadrangle, southern California: U.S. Geological Survey Open-File Report 99-172, U.S. Geological Survey, Menlo Park, California.

    Online Links:

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Geologic-map units in the Elsinore quadrangle database were described using standard field methods. Consistent with these methods, the database author has assigned standard geologic attributes to geologic lines, points, and polygons identified in the database.
    Nation-wide geologic-map accuracy standards have not been developed and adopted by the U.S. Geological Survey and other earth-science entities. Until such standards are adopted, the SCAMP project has developed internal map-accuracy standards for 1:24,000-scale geologic maps produced by the project.
    Geologic lines and points on 1:24,000 scale geologic maps are judged to meet SCAMP's internal map-accuracy standards if they are located to within +/-15 meters, relative to topographic or cultural features on the base map.
    On any derivative geologic-map plot, line data that are judged to meet the SCAMP internal map-accuracy standard are denoted by solid lines; line data that may not meet the SCAMP internal map-accuracy standard are denoted by dashed or dotted lines. There is no cartographic device for denoting the map-accuracy for geologic-point data (e.g., symbols representing bedding, foliation, lineations, etc.).
  2. How accurate are the geographic locations?
    The maximum transformation RMS error acceptable for a 7.5' quadrangle transformation and data input is 0.003 (1.8 meters). Horizontal positional accuracy was checked by visual comparison of hard-copy plots with base-stable source data.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    The geologic map database of the Elsinore 7.5' quadrangle contains new data that have been subjected to rigorous review and are a substantially complete representation of the current state of knowledge concerning the geology of the quadrangle.
  5. How consistent are the relationships among the observations, including topology?
    Polygon and chain-node topology present.
    The areal extent of the map is represented digitally by an appropriately projected (polyconic projection), mathematically generated box. Consequently, polygons intersecting the lines that comprise the map boundary are closed by that boundary. Polygons internal to the map boundary are completely enclosed by line segments which are themselves a set of sequentially numbered coordinate pairs. Point data are represented by coordinate pairs.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None
The Elsinore 7.5' geologic-map database should be used to evaluate and understand the geologic character of the Elsinore 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.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey Information Services
    Box 25286 Denver Federal Center
    Denver, Colorado

    (303) 202-4700 (voice)
    (303) 202-4693 (FAX)
  2. What's the catalog number I need to order this data set? USGS Open-File Report 03-281
  3. What legal disclaimers am I supposed to read?
    The U.S. Geological Survey (USGS) provides these geographic data "as is." The USGS makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. The USGS further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for use lies entirely with the user. Although these data have been processed successfully on computers at the USGS, no warranty, expressed or implied, is made by the USGS regarding the use of these data on any other system, nor does the fact of distribution constitute or imply any such warranty.
    In no event shall the USGS have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data or arising out of the delivery, installation, operation, or support by USGS.
    This digital geologic map database of the Elsinore 7.5' quadrangle, 1:24,000 map-scale, and any derivative maps thereof, is not meant to be used or displayed at any scale larger than 1:24,000 (e.g., 1:12,000).
  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 12-Apr-2016
Last Reviewed: 27-Jul-2004
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse,
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA

703-648-6533 (voice)
703-648-6252 (FAX)
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

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