Geology of Point Reyes National Seashore and Vicinity, California: A Digital Database

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Frequently anticipated questions:


What does this data set describe?

Title:
Geology of Point Reyes National Seashore and Vicinity, California: A Digital Database
Abstract:
The Point Reyes Peninsula is a roughly triangular projection of the Marin County coast with an apex at Point Reyes and a base along Tomales Bay and the rift valley of the San Andreas fault zone. This fault zone forms the active tectonic boundary between the Pacific and North American lithospheric plates and here separates Upper Cretaceous granitic and older metamorphic rocks of the Salinian block to the west from Upper Jurassic to Lower Cretaceous graywacke sandstone and melange of the Franciscan complex to the east.
  1. How might this data set be cited?
    Clark, Joseph C., and Brabb, Earl E., 1997, Geology of Point Reyes National Seashore and Vicinity, California: A Digital Database: U.S. Geological Survey Open-File Report 97-456.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -123.03
    East_Bounding_Coordinate: -122.63
    North_Bounding_Coordinate: 38.25
    South_Bounding_Coordinate: 37.88
  3. What does it look like?
    http://pubs.usgs.gov/of/1997/of97-456/pr-map.pdf (PDF)
    PDF representation of the geologic map sheet (6.4MB)
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1997
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: map
  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):
      • entity point
      • complete chain
      • GT-polygon composed of chains
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 10
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -123
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Planar coordinates are specified in meters
  7. How does the data set describe geographic features?
    PR-ARROWS.AAT
    Landslide arrows (Source: OFR-97-456)
    LTYPE
    Line type (Source: OFR-97-456)
    ValueDefinition
    arrow, certainLandslide arrow
    contact, certainLandslide contact
    PR-GEOL.PAT
    Geologic map units (Source: OFR-97-456)
    PTYPE
    Polygon type (Source: OFR-97-456)
    ValueDefinition
    QsBeach sands (Holocene)
    QdDune sands (Holocene)
    QalAlluvium (Holocene)
    QlsLandslide deposits (Pleistocene and Holocene)
    QodOlder dune sands (Pleistocene)
    QtTerrace deposits (Pleistocene)
    QocOlema Creek Formation (Pleistocene)
    QmiMillerton Formation (Pleistocene)
    QTmMerced Formation (upper Pliocene to Pleistocene)
    TwgWilson Grove Formation (upper Miocene to lower Pliocene)
    TpPurisima Formation (upper Miocene to lower Pliocene)
    TscSanta Cruz Mudstone (upper Miocene)
    TsmSanta Margarita Sandstone (upper Miocene)
    TmMonterey Formation (middle to upper Miocene)
    TlLaird Sandstone (middle Miocene)
    TprPoint Reyes Conglomerate of Galloway 1977 (lower Eocene)
    KgPorphyritic granodiorite of Point Reyes (Upper Cretaceous)
    KgrGranodiorite and granite of Inverness Ridge (Upper Cretaceous)
    KqdTonalite of Tomales Point (Upper Cretaceous)
    KJfFranciscan complex (Jurassic and Cretaceous)
    mmetamorphic rocks
    PR-GEOL.AAT
    Linear features on geologic map (Source: OFR-97-456)
    LTYPE
    Line type (Source: OFR-97-456)
    ValueDefinition
    contact, certainObserved contact
    contact, concealedConcealed geologic contact whose position is inferred
    contact, approx. locatedGeologic contact whose position is not precisely known
    contact, inferredGeologic contact whose position is inferred
    fault, certainObserved fault
    fault, concealedConcealed fault whose position is inferred
    fault, approx. locatedFault whose position is not precisely known
    fault, inferredFault whose position is inferred
    water boundaryBoundary of a body of water
    map boundaryBoundary of mapped area
    PR-GEOL.PAT
    Geologic map units at specific locations (same attributes as polygon coverage PR-GEOL.PAT) (Source: OFR-97-456)
    PR-OIL.PAT
    Oil well locations (Source: OFR-97-456)
    PTTYPE
    Point type (Source: OFR-97-456)
    ValueDefinition
    oilwelllocation of oilwell
    PR-OUTLN.AAT
    Outline of mapped area (Source: OFR-97-456)
    LTYPE
    Line type (Source: OFR-97-456)
    ValueDefinition
    map boundary,Boundary of mapped area
    PR-STRC.AAT
    Fold axes (Source: OFR-97-456)
    LTYPE
    Line type (Source: OFR-97-456)
    ValueDefinition
    f.a., anticline, approx. locatedAnticlinal fold axis whose position is not precisely known
    f.a., anticline, concealedConcealed anticlinal fold axis whose position is inferred
    f.a., syncline, approx. locatedSynclinal fold axis whose position is not precisely known
    f.a., syncline, concealedConcealed synclinal fold axis whose position is inferred
    PR-STRC.PAT
    Bedding orientation (Source: OFR-97-456)
    PTTYPE
    Point type (Source: OFR-97-456)
    ValueDefinition
    beddingbedding orientation
    flat beddingOrientation of bedding that is basically horizontal
    horz beddingHorizontal bedding orientation
    DIP
    Dip of bedding (Source: OFR-97-456)
    Range of values
    Minimum:0
    Maximum:75
    Units:degrees
    Resolution:1
    STRIKE
    Strike of bedding (Source: OFR-97-456)
    Range of values
    Minimum:0
    Maximum:359
    Units:degrees
    Resolution:1

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Joseph C. Clark
    • Earl E. Brabb
  2. Who also contributed to the data set?
    We are grateful to Don Lewis, former chief geologist of Chevron, for the release of well data and to Robert Fleisher also of Chevron for providing microfossil slides of Chevron Oil Company wells. We also are indebted to Kris McDougall for identifying and interpreting microfossils, to Martin Link for measuring and interpreting the sedimentology of the Kehoe Beach section, and to the late Clyde Wahrhaftig for enthusiastically supporting this work and for collaborating with us on two field trips in 1990 and 1991 to the Points Reyes area. LeeRoy Brock, former Chief Park Ranger of Point Reyes National Seashore, greatly facilitated our field work in 1978 and 1979.
    Carolyn Randolph, Heather Schoonover, and Carl Wentworth developed this digital version of the geologic map, and Carolyn Randolph prepared the booklet announcing the release of this database in Open Files. Partial funding was provided to Clark by USGS NEHRP award number 1434-HQ-96-GR-02741.
  3. To whom should users address questions about the data?
    Brabb, Earl E
    USGS-GEO-WRG-NGM
    Mail Stop 975, USGS
    345 Middlefield Road
    Menlo Park, CA
    US

    650-329-5140 (voice)
    ebrabb@usgs.gov

Why was the data set created?

This digital map database, compiled from previously published and unpublished data and new mapping by the authors, represents the general distribution of surficial deposits and rock units in Point Reyes and surrounding areas. Together with the accompanying text file (pr-geo.txt or pr-geo.ps), it provides current information on the stratigraphy and structural geology of the area covered.

How was the data set created?

  1. From what previous works were the data drawn?
    Galloway (1977) (source 1 of 1)
    Galloway, A.J., 1977, Geology of the Point Reyes Peninsul, Marin County, California: California Division of Mines and Geology Bulletin Bulletin 202.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 48000
    Source_Contribution:
    The most comprehensive publication on the geology of the Point Reyes Peninsula is by Galloway (1977), who summarized the previous geologic work.
  2. How were the data generated, processed, and modified?
    Date: 1991 (process 1 of 2)
    The geologic map information was digitized from stable originals of the geologic maps at 1:48,000 scale. A pencil on mylar overlay of the author manuscript were scanned using a Altek monochrome scanner with a resolution of 800 dots per inch. The scanned images were vectorized and transformed from scanner coordinates to projection coordinates with digital tics placed by hand at quadrangle corners. The scanned lines were edited interactively by hand using ALACARTE, color boundaries were tagged as appropriate, and scanning artifacts visible at 1:48,000 were removed. Base map layers were prepared from scale-stable printing negatives of the U.S. Geological Survey Point Reyes National Seashore and Vicinity, California 1:48,000 topographic map, which has an 80-foot contour interval and the U.S. Geological Survey Napa, California 1:100,000 drainage map. Scanned and vectorized images were transformed from scanner coordinates to projection coordinates with digital tics placed by hand at map corners. The images were then trimmed interactively by hand using ALACARTE to conform to the area of the geologic coverages.
    Date: 03-Aug-2000 (process 2 of 2)
    Creation of original metadata record Person who carried out this activity:
    Jennifer Lenz
    US Geological Survey
    12201 Surise Valley Drive, Mail Stop 918
    Reston, VA
    USA

    703-648-6974 (voice)
    703-648-6560 (FAX)
    pschweitzer@usgs.gov
  3. What similar or related data should the user be aware of?

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

  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Complete map of surficial deposits
  5. How consistent are the relationships among the observations, including topology?
    his digital map database, compiled from previously published and unpublished data and new mapping by the authors, represents the general distribution of surficial deposits and rock units in Point Reyes and surrounding areas. The scale of the source maps limits the spatial resolution (scale) of the database to 1:48,000 or smaller.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints: none
  1. Who distributes the data set? (Distributor 1 of 1)
    USGS Information Services
    Box 25286, Denver Federal Center
    Denver, Colorado
    USA

    1-888-ASK-USGS (voice)
    1-303-202-4695 (FAX)
    infoservices@usgs.gov
  2. What's the catalog number I need to order this data set? US Geological Survey Open-File Report 97-456
  3. What legal disclaimers am I supposed to read?
    This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
    This database, identified as "Geology of Point Reyes National Seashore and Vicinity, California: A digital database," has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.
  4. How can I download or order the data?
    • Availability in digital form:
      Data format:
      ARC/INFO export files	Description of coverage
      
      pr-geol.e00            Depositional contacts, faults, and unit labels
      pr-strc.e00            Fold axes, strike and dip information
      pr-arrows.e00          Landslide arrows
      pr-oil.e00             Oil well locations
      pr-topo.e00            Topographic contours base map
      pr-drain.e00           Drainage base map
      pr-outln.e00           Outline of map boundary
      
      in format ARCE (version 7.x) Size: 15
      Network links: http://pubs.usgs.gov/of/1997/of97-456/pr-data.tar.gz
    • Cost to order the data: none


Who wrote the metadata?

Dates:
Last modified: 05-Feb-2016
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse, http://geo-nsdi.er.usgs.gov/
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA
USA

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

This page is <https://geo-nsdi.er.usgs.gov/metadata/open-file/97-456/metadata.faq.html>
Generated by mp version 2.9.48 on Tue Jul 03 20:06:50 2018