Preliminary geologic Map of the Perris 7.5' Quadrangle, Riverside County, California

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What does this data set describe?

Preliminary geologic Map of the Perris 7.5' Quadrangle, Riverside County, California
This data set maps and describes the geology of the Perris 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 Perris quadrangle is located in the northern part of the Peninsular Ranges Province within the central part of the Perris block, a relatively stable, rectangular in plan area located between the Elsinore and San Jacinto fault zones.
The quadrangle is underlain by Cretaceous age and older basement rocks. The Cretaceous plutonic rocks are part of the composite Peninsular Ranges batholith. A wide variety of intermediate composition granitic rocks are located in the quadrangle. These rocks are mainly of tonalitic composition but range from monzogranite to diorite. Most rock is faintly to intensely foliated. Many are heterogenous and contain varying amounts of meso-and melanocratic discoidal-shaped inclusions. Some rocks are composed essentially of inclusion material and some are migmatitic. Included within these granitic rocks are a few septa of Paleozoic(?) schist of upper amphibolite metamorphic grade.
Metamorphic rocks of probable Mesozoic age occur in the southwest corner of the quadrangle. Most of these rocks are well-foliated phyllite of Mesozoic age. The metamorphic grade of these rocks is greenschist or sub-greenschist. Rocks of probable Paleozoic age occur as scattered masses within plutonic rocks in the northern part of the quadrangle. These rocks are of amphibolite grade and include cordierite and sillimanite biotite schist.
In the center and southeast quarter of the quadrangle, biotite-hornblende tonalite of the Lakeview Mountains pluton is characterized by ubiquitous schlieren and by a lack of potassium feldspar. Masses of leucocratic and melanocratic rock occur scattered throughout the pluton. Mesocratic-to melanocratic discoidal-shaped inclusions are oriented parallel to the schlieren. A small body of comb-layered gabbro is located with the tonalite near the southern margin of the pluton. The tonalite contains rare-earth bearing, zoned pegmatite dikes.
Biotite-hornblende tonalite located in the southwest part of the quadrangle is part of the Val Verde pluton. This tonalite is similar to that of the Lakeview Mountains pluton but lacks the ubiquitous schlieren and contains potassium feldspar.
Diagonally crossing the quadrangle is the channel and flood plain of the ephemeral San Jacinto River. Most of the alluviated area west of the San Jacinto River consists of Pleistocene age fluvial deposits, which have a degraded upper surface that is preserved in some places near the contact with granitic rocks. The upper part of these deposits form the Paloma surface of Woodford and others (1971). A modern-to Holocene-age drainage channel is within these older Pleistocene deposits. Younger Pleistocene alluvial fans emanate from the Lakeview Mountains east of the San Jacinto River.
Supplemental_Information: none
  1. How might this data set be cited?
    Morton, Douglas M., 2003, Preliminary geologic Map of the Perris 7.5' Quadrangle, Riverside County, California: U.S. Geological Survey Open-File Report 03-270, U.S. Geological Survey, Menlo Park, California.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -117.25009084
    East_Bounding_Coordinate: -117.12490892
    North_Bounding_Coordinate: 33.87500054
    South_Bounding_Coordinate: 33.7499832
  3. What does it look like? (GIF)
    Reduced-size image of the entire map sheet, 500x346 pixels, 56k bytes. (PDF)
    Printable representation of the map sheet, 3.3 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 (92)
      • String (247)
      • GT-polygon composed of chains (93)
    2. What coordinate system is used to represent geographic features?
      The map projection used is Polyconic.
      Projection parameters:
      Latitude_of_Projection_Origin: 33.75
      Longitude_of_Central_Meridian: -117.1875
      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 Perris 7.5' quadrangle comprises three ARC/INFO coverages, of which two contain geologic data, and one contains cartographic features: per_geo (geology), per_str (structural data), and per_ano (annotation and leaders).
    Geologic data represented by line entities and the polygons they delineate are contained in the coverage PER_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 foliation, joints and lineations. 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  PER_GEO#               4     5     B      -
       21  PER_GEO-ID             4     5     B      -
       25  LABL                  35    35     C      -
       60  SHD                    3     3     I      -
       63  PLABL                 35    35     C      -
       98  SHDFIL                 3     3     I      -
      101  NAME                 200   200     C      -
        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  PER_GEO#               4     5     B      -
       29  PER_GEO-ID             4     5     B      -
       33  LTYPE                 45    45     C      -
       78  L-SYMB                 3     3     I      -
    Geologic units (LABL) and their corresponding names (NAME) identified in the Perris 7.5' quadrangle
    geologic map unit label, in plain text
    QafArtificial fill
    QwActive-wash deposits
    QvActive valley deposits
    QyfYoung alluvial-fan deposits
    QyaYoung axial-valley floor deposits
    QyvYoung alluvial-valley deposits
    QofOld alluvial-fan deposits
    QvofVery old alluvial-fan deposits
    Qvof1Very old alluvial-fan deposits, Unit 1
    QvoaVery old axial-channel deposits
    KlmtLakeview Mountains pluton, Tonalite
    KlmmLakeview Mountains pluton, Melanocratic tonalite
    KlmtgLakeview Mountains pluton, Tonalite and granodiorite, undifferentiated
    KlmcLakeview Mountains pluton, Comb-layered gabbro
    KbpgMonzogranite of Bernasconi Pass
    KbpmMigmatitic rocks within monzogranite of Bernasconi Pass
    KtbhTonalite of Bernasconi Hills
    KvtVal Verde pluton, tonalite
    KguGranite, undifferentiated
    KtTonalite, undifferentiated
    KdDiorite, undifferentiated
    KhgHeterogeneous granitic rocks
    Khg(s)Heterogeneous granitic rocks, submerged
    MzpPhyllite and schist
    KgPzMixed metamorphic rocks and granitic rocks
    PzsBiotite schist
    Perris ReservoirPerris Reservoir
    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, dike).
    map boundary 
    contact, certain 
    Kg, granite pegmatite dike 
    Kp, granite dike 
    water boundary 
    stores appropriate line symbol value from the lineset geoscamp2.lin
    Geological point data includes site-specific information describing the types and the orientation of foliation, joints, and lineations. One annotation subclass is included in the geologic points coverage, PER_STR which displays the respective dip and plunge values associated with individual point data.
    describes type of point data (foliation, joints, lineations)
    igneous foliation 
    vertical igneous foliation 
    igneous joint 
    vertical igneous joint 
    metamorphic foliation 
    vertical metamorphic foliation 
    metamorphic lineation 
    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
    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
  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) U.S. Air Force, (3) the California Geological Survey, and (4) 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
    United States of America

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

Why was the data set created?

The data set for the Perris 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: 1991 (process 1 of 5)
    Field mapping and aerial photograph interpretation; iterative process (D.M. Morton).
    Date: 1999 (process 2 of 5)
    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 (K.R. Bovard and G. Morton).
    Date: 2003 (process 3 of 5)
    Description of map units and correlation of map units (K. Bovard).
    Date: 09-Mar-2003 (process 4 of 5)
    First draft of metadata created by K.R. Bovard using FGDCMETA.AML ver. 1.2 05/14/98 on ARC/INFO data set /scamp31/kbovard/perris/per_geo
    Date: 10-Apr-2003 (process 5 of 5)
    Creation of original metadata record Person who carried out this activity:
    U.S. Geological Survey
    Attn: Kelly R. Bovard
    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, version 1.0.: U.S. Geological Survey Open-File Report 99-172, U.S. Geological Survey, 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 Perris 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 Perris 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 Perris 7.5' geologic-map database should be used to evaluate and understand the geologic character of the Perris 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?
  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 Perris 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: 10-Jun-2016
Last Reviewed: 09-May-2003
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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