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Metadata for GEOLOGY

 Table of Contents

Identification_Information
     Abstract
     Purpose
     Supplemental Information
Data_Quality_Information
Spatial_Data_Organization_Information
Entity_and_Attribute_Information
     Detailed Description
     Overview
Distribution_Information
Metadata_Reference_Section

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Identification_Information

Citation_Information
    Originator:
    Publication_Date:
    Title:

Description
    Abstract
    This bedrock database for the Mojave Desert Ecoregion provides data in
    ARC/INFO format that describe polygons and lines classified similarly to those
    on a typical geologic map.  The area included in this database is determined by
    Baileys modified Mojave Desert ecoregion.  It includes a wide border around
    the ecoregion to provide geologic context for areas near the edge of the
    ecosystem.  The ecosystem includes large parts of southeastern California and
    southern Nevada, and smaller parts of northwestern Arizona and southwestern
    Utah. The color coding is a generalization of geologic type and age:

  1)Surficial map units-Primarily unconsolidated deposits of Quaternary and
         Pliocene age (0-6 Ma)
    2)Bedrock map units -Volcanic and sedimentary rocks of Tertiary age (6-66 Ma)
    3)Bedrock map units-Intrusive rocks of Cenozoic and Mesozoic age (~14-250 Ma)
    4)Bedrock map units-Strata of Mesozoic, Paleozoic, and Proterozoic age 
        (~65-1400 Ma)
    5)Bedrock map units-Intrusive and metamorphic rocks of Precambrian age 
        (~1400-1700 Ma)

    Purpose
    This database is intended to provide information on bedrock materials for
    applications for ecosystem studies of a wide variety.  Examples of applications
    include:  (1) interrelations between vegetation (habitats) and geology, (2)
    locations of young faults possibly presenting a seismic hazard, and (3)
    locations of possible important geologic resources.  The database was developed
    as one of many databases that provide fundamental data on the region, with the
    goal of improving decisions on how to manage the land.  This database may also
    be used as a starting point for assembling more geologic data for scientific
    inquiries.

Supplemental_Information
    Procedures_Used
    The database was constructed from four digital vector GIS data set layers,
    or coverages, that correspond to published state geologic maps.  We first built
    a composite of these coverages that remained faithful to the original data
    sets, and then made selected small modifications in the compiling process.
    Databases were archived during the compilation at various stages.  We made
    several modifications that depart from the original published maps to build the
    current release version, 1.0.  Throughout the process we have sought to
    maintain links to the original data.  Archived compilations can be made
    available upon inquiry.

    We gathered databases that had been prepared for state geologic maps
    (Jennings, 1977; Reynolds, 1988; Stewart and Carlson, 1978; and Hintze, 1978).
    Digital databases were downloaded from web sites (Arizona, Utah), from Turner
    and Bawiec (1991) (Nevada), and from an unpublished USGS source and California
    Division of Mines and Geology (California).  Each of these databases required
    modifications, including: (1) registering polygons properly in space
    (California) using a scanned template for reference, (2) meshing line (fault)
    coverages with polygon coverages, (3) improving topology for several problems
    such as inconsistent boundaries for rivers, and (4) adding faults to the Utah
    coverage.

    The four state geologic maps were built in ARC/INFO after developing each
    in a similar format.  The four separate databases each retained original
    polygon attributes that referenced the legend descriptions originally published
    with the maps.  At this stage, each database faithfully reproduced the original
    state geologic map.  Original map units (polygon classifications) were archived
    in the database as ptype3.

    For the next version of the bedrock database, the individual state
    databases were merged into a single database and classification was homogenized
    across state borders to a modest extent.  The merging of databases required
    adopting uniform boundaries along the Colorado River, which were based on the
    latest versions of 1:100,000-scale DLGs from USGS.  Adjacent state coverages
    were clipped to these boundaries.  Overlaps and gaps between California and
    Nevada were adjusted by modifying individual polygons.  Classification was
    homogenized across state borders by correlating map units that were identical
    or very similar, although some correlations may be invalid in detail.  This
    classification was archived and is present in the database as ptype2.

    Specific changes to the classification include:  (1) We added the unit
    "Qp" in California by digitizing the polygons representing playa deposits from
    the 1:250,000-scale geologic map series published by California Division of
    Mines and Geology ; (2) We generalized most volcanic units in California
    because the original classification divided rocks according to composition and
    character of the flow, both of which are diverse and generally not useful as
    classifiers in the desert part of California; (3) We combined units TKsu and
    Ths in Nevada, following the new information provided by Stewart (1980); and
    (4) We updated unit grPz in the San Gabriel and San Bernardino Mountains to
    Triassic granite [unit TRg], after Powell (1993).

    This database had many limitations:  (1) The intended resolution of the
    information was comparable to printing at 1:500,000 scale (Utah and Nevada),
    1:750,000 scale (California), and 1:1,000,000 scale (Arizona), (2) The data
    represented geologic information that is one to three decades old, and did not
    reflect current knowledge and understanding of the geology, (3) errors may have
    been introduced unintentionally by combining map units across state borders.

    Revisions
    Version 1.0 of the bedrock database represents an enhanced revision of the
    geology represented along the state borders and a substantial modernizing of
    the geology represented in the California part of the database.  The
    information coded into the database for each polygon indicates the heritage of
    that polygon, from the initial classification on the state map (ptype3) to the
    classification in an early version (ptype2).  That heritage is not included in
    the following text description of map units.  In addition, a few map units in
    Nevada, Utah, and Arizona were grouped to minimize nearly equivalent units.

    Geology was revised along state borders in places where the features
    across the borders represented significantly different and incompatible
    interpretations of geology.  Those areas were upgraded by locating modern
    source maps of geology to reshape and classify polygons.  In two cases,
    updating the geology was accomplished by using published digital data sets
    (Miller and Wooden, 1993, and Carr and others, 1996).  In the few cases where
    modern maps were not available, geology was inferred from LANDSAT Thematic
    Mapper images.  Some polygon boundaries still coincide with map boundaries
    where polygon classifications from state to state are incompatible and cannot
    be forced to conform without wholesale remapping of one or both states.

    Geology was revised in California by using considerable published and
    unpublished mapping completed since the map was compiled in 1973.  The
    revisions are largely of three rock groups:

    * Tertiary volcanic and sedimentary rocks were for the most part revised to use
    the classification used in Nevada.
    * Mesozoic granitoid rocks were revised to reflect the primary ages of the
    rocks (Triassic, Jurassic, and Cretaceous).  A future revision could indicate
    primary lithology and include a latest Cretaceous to early Tertiary group, as
    is done in Arizona.
    * Metamorphic rocks were revised where possible.  For instance, in many places
    in the eastern Mojave Desert, metamorphic rocks previously of unknown age are
    now known to be Paleozoic metasedimentary rocks.

    In addition, limited revisions were made of:  (1) Paleozoic stratigraphy
    east of Death Valley, (2) Precambrian gneiss and granite, and (3) Mesozoic
    sedimentary rocks in the area of the Palen and McCoy Mountains.

    Reviews_Applied_to_Data

    Related_Spatial_and_Tabular_Data_Sets

    References_Cited
    Carr, M.D., Sawyer, D.A., Nimz, K., Maldonado, F., and Swadley, WC, 1996,
    Digital bedrock geologic map database of the Beatty 30 x 60-minute quadrangle,
    Nevada and California:  U.S. Geological Survey Open File Report 96-291, scale
    1:100,000.

    Hintze, L.F., compiler, 1978, Geologic map of Utah:  Utah Geological and
    Mineral Survey, scale 1:500,000.

    Jennings, C.W., compiler, 1977, Geologic map of California:  California
    Geologic map data series, California Division of Mines and Geology, scale
    1:750,000.

    Miller, D.M., and Wooden, J.L., 1993, Geologic map of the New York Mountains
    area, California and Nevada:  U.S. Geological Survey Open File Report 93-198,
    10 p., scale 1:50,000.

    Powell, R.E., 1993, Balanced palinspastic reconstruction of pre-late Cenozoic
    paleogeology, southern California:  Geologic and kinematic constraints on
    evolution of the San Andreas fault system, in Powell, R.E., Weldon, R.J., II,
    and Matti, J.C., eds., The San Andreas fault system:  Displacement,
    palinspastic reconstruction, and geologic evolution:  Geological Society of
    America Memoir 178, p. 1-106.

    Reynolds, S.J., compiler, 1988, Geologic map of Arizona:  Arizona Geological
    Survey Map 26, scale 1:1,000,000.

    Stewart, J.H., 1980, Geology of Nevada:  Nevada Bureau of Mines and Geology
    Special Publication 4, 136 p.

    Stewart, J.H., and Carlson, J.E., compilers, 1978, Geologic map of Nevada:
    U.S. Geological Survey and Nevada Bureau of Mines and Geology, scale 1:500,000.

    Turner, R.M. and Bawiec, W.J., 1991, Geology of Nevada:  A digital
    representation of the 1978 geologic map of Nevada:  U.S. Geological Survey
    Digital Data Series DDS-2.
    SYMBOLS

    Notes
    State geologic maps were developed as GIS databases by a number of
    individuals and organizations, but most were led by Gary Raines of USGS.  Our
    GIS development was aided by Barry Moring and Geoff Phelps.

    Several individuals helped by supplying information to update the maps as
    well as by performing informal reviews of the geology represented in this
    database and of the database itself.  We thank the following for this
    indispensable help:  George Billingsley, Jim Calzia, Brett Cox, Keith Howard,
    Ron Kistler, Fred Miller, Bob Powell, Paul Stone, Dick Tosdal, Doug Walker, and
    Joe Wooden.

    Collaborators within state geological surveys have helped with many
    aspects of the database development.  We especially thank George Saucedo of the
    California Division of Mines and Geology for his collaboration and support.

Time_Period_of_Content
    Currentness_Reference

Status
    Progress:
    Maintenance_and_Update_Frequency

Spatial_Domain
    Bounding_Coordinates
    West_Bounding_Coordinate: -124.52075574
    East_Bounding_Coordinate: -112.53073587
    North_Bounding_Coordinate: 42.12680773
    South_Bounding_Coordinate: 32.82656531

Keywords
    Theme
        Theme_Keyword_Thesaurus: None
        Theme_Keyword:  Geology, Mojave Desert, Faults
    Place
        Place_Keyword_Thesaurus: None
        Place_Keyword:  Mojave Desert Ecosystem as defined by Bailey (1993) plus a 50 km buffer
    Stratum
        Stratum_Keyword_Thesaurus: None
        Stratum_Keyword:
    Temporal
        Temporal_Keyword_Thesaurus: None
        Temporal_Keyword:

Access_Constraints

Use_Constraints
This database seeks to present  data for the entire ecosystem as a single
generalized database.  It is valid only at the intended resolution of the
information collected within it, which is at a nominal scale of 1:500,000.
Polygons for the most part represent data that are generalized from more
detailed geology investigations, and the more detailed maps are generally more
suitable for individual decisions based on geology.

Data_Set_Credit
Bedford and Miller at USGS.
State geologic maps were developed as GIS databases by a number of
individuals and organizations, but most were led by Gary Raines of USGS.  Our
GIS development was aided by Barry Moring and Geoff Phelps.
We thank the following for the indispensible help:
George Billingsley, Jim Calzia, Brett Cox, Keith Howard,
Ron Kistler, Fred Miller, Bob Powell, Paul Stone, Dick Tosdal, Doug Walker, and
Joe Wooden.

Collaborators within state geological surveys have helped with many
aspects of the database development.  We especially thank George Saucedo of the
California Division of Mines and Geology for his collaboration and support.

Security_Information
    Security_Classification_System: None
    Security_Classification:  UNCLASSIFIED
    Security_Handling_Description: None

Native_Data_Set_Environment: SunOS UNIX, ARC/INFO version 7.1.1

Cross_Reference
    Originator: Unknown
    Publication_Date:
    Publication_Time:
    Title:
    Edition:
    Geospatial_Data_Presentation_Form:
    Series_Information
        Series_Name:
        Issue_Identification:
    Publication_Information
        Publication_Place:
        Publisher:
    Other_Citation_Details:
    Online_Linkage:
    Larger_Work_Citation:

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Data_Quality_Information

Attribute_Accuracy
    Attribute_Accuracy_Report: See Entity_Attribute_Information

    Quantitative_Attribute_Accuracy_Assessment
        Attribute_Accuracy_Value:  See Explanation
        Attribute_Accuracy_Explanation:
           Attribute accuracy is described, where present, with each
           attribute defined in the Entity and Attribute Section.

Logical_Consistency_Report: Chain-node topology present.

Completeness_Report

Positional_Accuracy
    Horizontal_Positional_Accuracy
        Horizontal_Positional_Accuracy_Report:
        Horizontal accuracy of this database is affected by the following limitations:
        (1) The intended resolution of the  information was comparable to printing
        at 1:500,000 scale (Utah and Nevada), 1:750,000 scale (California), and
        1:1,000,000 scale (Arizona), (2) The data represented geologic information
        that is one to three decades old, and did not reflect current knowledge and
        understanding of the geology, (3) errors may have been introduced
        unintentionally by combining map units across state borders.

    Vertical_Positional_Accuracy
        Vertical_Positional_Accuracy_Report:

Lineage: See Supplemental_Information for overview.

Process_Steps
    Process_Step
    Process_Description: MOJAVE PROJECT COVER MJG MOJGEOL_FIN
    Source_Used_Citation_Abbreviation:None
    Process_Date:  19980618
    Process_Time:  1057
    Source_Produced_Citation_Abbreviation: None

Cloud_Cover

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Spatial_Data_Organization_Information

Direct_Spatial_Reference_Method: Vector

Point_and_Vector_Object_Information
    SDTS_Terms_Description
        SDTS_Point_and_Vector_Object_Type: Point
        Point_and_Vector_Object_Count: 9279
        SDTS_Point_and_Vector_Object_Type: String
        Point_and_Vector_Object_Count: 36592
        SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains'
        Point_and_Vector_Object_Count:  9280

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Spatial_Reference_Information

Horizontal_Coordinate_System_Definition
    Planar
        Grid_Coordinate_System
        Grid_Coordinate_System_Name: Universal_Transverse_Mercator (UTM)
           Zone_Number: 11
        Planar_Distance_Units: METERS
    Geodetic Model
        Horizontal_Datum_Name: North American Datum of 1983
        Ellipsoid_Name:  GRS1980

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Entity_and_Attribute_Information

Detailed_Description

 Overview_Description
    Entity_and_Attribute_Overview
    Map units (polygons) are described in the polygon attribute table (PAT).
    The attributes describe geologic and water features.  For a full description of
    the map units see the section below.

    Polygon Attribute Definitions and Descriptions for the Bedrock Geology
    Database for the Mojave Desert Ecosystem:

    ITEM NAME WIDTH     OUTPUT    TYPE N.DEC     DESCRIPTION
    -------------------------------------------------------------------------------
    --------------------------------------
    AREA        4         12       F    3
    PERIMETER   4         12       F    3
    MOJGEOL#    4          5       B
    MOJGEOL-ID  4          5       B
    PTYPE      35         35       C         Primary Polygon Attribute
    PTYPE2     35         35       C         Intermediate Polygon Attribute
    PTYPE3     35         35       C         Original Attribute from source database
    Type_age   35         35       C         Age Classification

    Notes on Polygon Attributes:

    PTYPE  is the most current geologic polygon attribute,  while the     following
    attributes are presented for archive and referencing purposes.  This field
    conforms to the ALACARTE geologic interface for  ARC/INFO standard and is
    therefore compatible with this and other
    interfaces.  See http://wrgis.wr.usgs.gov/docs/software/software.html for
    information    about and downloads of this package.
    PTYPE2 is an intermediate editing stage attribute that represents initial
    cross-state classification,
    and was archived before updating of features occurred (ie. before Mesozoic
    Granites were reclassified into Cretaceous, Jurassic, etc).
    PTYPE3 is the original polygon attribute as received from each state geologic
    map.

    Geologic lines are described int the arc attribute table (AAT).  The attributes
    describe geologic features such as contacts and faults, and other linear
    features such as water boundaries and internal (scratch) boundaries .

    Line Attribute Definitions for the Bedrock Geology Database for the Mojave
    Desert Ecosystem:

    ITEM NAME WIDTH     OUTPUT    TYPE N.DEC     DESCRIPTION
    -------------------------------------------------------------------------------
    --------------------------------------
    FNODE#      4         5        B
    TNODE#      4         5        B
    LPOLY#      4         5        B
    RPOLY#      4         5        B
    LENGTH      4         12       F    3
    MOJGEOL#    4         5        B
    MOJGEOL-ID  4         5        B
    ARC_TYPE   12        12        C         Code for Lines(Relic from Nevada Source)
    LTYPE      35        35        C         Type of line
    MODIFIER   21        21        C         Line Modifier (Nevada Relic)
    ACCURATE   16        16        C         Positional Accuracy (Nevada Relic)
    FAULT_CONT  3         3        C         Unknown (Nevada Relic)
    DOWNTHROWN  5         5        C         Fault Description (Nevada Relic)
    SOURCE     35        35        C         Source of Line (ie. Nevada geology)
    LTYPE2     35        35        C         Type of Line (Nevada Relic)

    Notes on Line Attributes:

    LTYPE   is the current line attribute, describing the type of geologic line
    (ie. contact, certain or
    fault, concealed.)  This field conforms to the ALACARTE geologic interface
    for ARC/INFO standard and is therefore compatible with this and other
    interfaces.  See  http://wrgis.wr.usgs.gov/docs/software/software.html for
    information about and downloads of this package.
    SOURCE  is a pointer to the source of the line.  In most cases it is the
    original state database, but
    also denotes which lines where added and by  whom (ie. cageol for California
    geology, or DRB for initials of lines added by David R. Bedford).
    SEL - used for some lines for plotting purposes (ie. faults that had bar-ball
    symbols on the
    printed state maps have an attribute to try to re-create that particular
    symbology on plots.)

    List of unique LTYPE values from the Bedrock Geology Database for the Mojave
    Desert Ecosystem:

    atten. fault, certain
    contact, certain
    fault, approx. located
    fault, certain
    fault, certain, high angle
    fault, concealed
    fault, concealed, queried
    map boundary, certain
    normal fault, approx. located
    normal fault, certain
    normal fault, concealed
    s.s. fault, approx. located
    s.s. fault, certain
    s.s. fault, concealed
    s.s. fault, l.l., approx. located
    s.s. fault, l.l., certain
    s.s. fault, l.l., concealed
    s.s. fault, l.l., concealed, query
    s.s. fault, r.l., approx. located
    s.s. fault, r.l., certain
    s.s. fault, r.l., concealed
    scratch boundary, certain
    thrust fault, approx. located
    thrust fault, certain
    thrust fault, concealed
    water boundary, certain

    Classification:  Description of geologic map units
    Where mapped in only a few states, those states given in italics.

    Surficial map units-Primarily unconsolidated deposits of Quaternary and
    Pliocene age (0-6 Ma)

    Qsu  Undivided surficial deposits (Holocene and Pleistocene)-Alluvium,
    colluvium, lake, and terrace deposits; locally includes sand and glacial
    deposits

    Qa   Alluvium (Holocene and latest Pleistocene)-Deposits in present-day river
    and stream channels, flood plains, and playas.  Arizona

    Qg   Glacial deposits (Pleistocene)-Till and moraines.  Found at high
    elevations mostly in the Sierra Nevada.   California

    Qls  Landslide deposits (Holocene and Pleistocene)-Deposits formed by major
    landslides, such as Blackhawk slide on north side of San Gabriel Mountains.
    California

    Qp   Playa deposits (Holocene and Pleistocene)-Playa, marsh, and alluvial-flat
    deposits consisting of silt, clay, salts, and sand; locally includes lacustrine
    deposits.   California and Nevada

    Qs   Sand (Holocene and Pleistocene)-Eolian sand deposits, generally near
    desert playas.   California

    QToa Older alluvial deposits (Pleistocene and late Pliocene)-Alluvium with
    minor talus and eolian deposits.

    QTs  Sedimentary rocks (Pleistocene and Pliocene)-Lake and alluvial deposits.

    QTb  Basalt  (Holocene to Pliocene)-Lava flows; locally includes maar deposits;
    includes rhyolite in Utah, rhyolite and andesite in Coso volcanic field,
    California.

    Bedrock map units -Volcanic and sedimentary rocks of Tertiary age (6-66 Ma)

    Tb   Youngest basaltic rocks (Pliocene to late Miocene; 4 to 8 Ma)-Basalt flows
    and associated rhyolite.     Arizona and California

    Tsy  Young sedimentary rocks (Pliocene to middle Miocene)-Alluvial, lacustrine,
    and fluvial deposits; includes Panaca, Bouse, and Muddy Creek Formations.
    Locally includes minor amounts of tuff.  Includes marine deposits in a few
    places near San Andreas fault.

    Ths  Horse Spring Formation (late to early Miocene)-Tuffaceous sedimentary
    rocks similar to unit Tsy, but includes early Miocene strata near base of unit;
    may include latest Cretaceous rocks at base.  Nevada
    Tvy  Young volcanic rocks, undivided (late to early Miocene)-Rhyolite, andesite
    and basalt lava flows; tuff; and tuffaceous sediments.   Rocks in unit span 8
    to 17 Ma in Nevada and Utah; 8 to 21 Ma in California

    Tby  Young basaltic rocks (late to middle Miocene)-Basalt lava flows and
    associated rocks, mostly 8 to 17 Ma.

    Try  Young rhyolitic flows (late to middle Miocene)-Rhyolitic flows, rhyolitic
    ash-flow tuffs, and shallow intrusive rocks.  Includes andesitic rocks in
    Arizona.

    Tty  Young rhyolitic ash-flow tuffs (late to middle Miocene)-Welded and
    nonwelded tuff.  Locally includes thin units of air-fall tuff and sedimentary
    rock.  Nevada

    Tts  Young ash-flow tuff and sedimentary rocks (late to middle
    Miocene)-Ash-flow tuffs and tuffaceous sedimentary rocks.   Nevada

    Tay  Young andesite flows (late to middle Miocene)- Flows and volcanic breccias
    composed of andesite and related rocks of intermediate composition.    Nevada

    Tbay Young andesite and basalt flows (late to middle Miocene)-Interlayered
    basalt and andesite lava flows.  Mostly in ~17 to ~ 6 m.y. age range. May
    include rocks younger than 6 m.y. in places.  Nevada and California

    Tso  Older sedimentary rocks (middle Miocene to Paleocene)-Non-marine deposits.
    Includes marine clastic rocks in Orocopia Mountains area.  Includes Goler,
    Witnet, and San Fransisquito Formations.  Locally includes minor amounts of
    tuff and caldera fill deposits

    Tsvo Older volcanic and sedimentary rocks (middle Miocene to
    Oligocene)-Non-marine sediment and volcanic rocks, undivided.   Arizona

    Tvo  Older volcanic rocks (middle Miocene to Oligocene; 15 to 38 Ma)-Undivided
    rhyolitic to basaltic lava flows and pyroclastic rocks; includes some
    subvolcanic intrusions.   Arizona

    Tto  Older welded and nonwelded rhyolitic ash-flow tuffs (middle Miocene to
    Oligocene)- Locally includes thin units of air-fall tuff and sedimentary rock
    Nevada

    Tao  Older andesite (middle Miocene to Oligocene)-Flows and volcanic breccias
    composed of andesite and related rocks of intermediate composition.  Nevada

    TKs  Continental sedimentary rocks (early Tertiary and latest
    Cretaceous)-Claron Formation (Utah) and poorly dated clastic deposits in Nevada
    and Arizona.  Includes "rim gravels" and associated finer grained rocks along
    the Mogollon Rim of Arizona.  May overlap in age with unit Tso

    Tvu  Volcanic rocks (Miocene to Eocene)-Undivided volcanic rocks.   Utah
    Tbr  Breccia-Volcanic, thrust, and jasperoid breccia and landslide megabreccia.
    Nevada

    Bedrock map units-Intrusive rocks of Cenozoic and Mesozoic age (~14-250 Ma)

    Ti   Intrusive rocks (Miocene and Oligocene)-Aphanitic, porphyritic, and
    coarsely granular rocks ranging in composition from diorite to granite

    Tg   Granitoid plutons (Miocene to latest Eocene; 14 to 38 Ma)-Mostly granite
    and granodiorite

    TKgm Granitoid plutons (early Tertiary to Late Cretaceous; 45 to 75
    Ma)-Commonly.  Arizona

    TKg  Granitoid plutons (early Tertiary to Late Cretaceous; 55 to 85
    Ma)-Generally metaluminous granite to diorite and subvolcanic porphyry;
    includes one muscovite-garnet-bearing peraluminous granite pluton.  Arizona

    MZg  Granitoid plutons (Mesozoic)-Mostly granite, granodiorite, and quartz
    diorite. Inconclusively dated or not dated radiometrically

    MZgn Gneissic and granitic rocks (Mesozoic)-Complex small plutons and deformed,
    gneissic granitoids.  California

    Kg   Granitoid plutons (Cretaceous)-Mostly granite and granodiorite

    KJd  Diorite and gabbro plutons (Cretaceous and Jurassic)

    Jg   Granitoid plutons (Jurassic)-Granodiorite, granite and more mafic rocks

    TRg  Granodiorite (Triassic)-Monzonite, granodiorite, and related rocks

    Bedrock map units-Strata of Mesozoic, Paleozoic, and Proterozoic age (~65-1400
    Ma)

    Ks   Continental strata (Cretaceous)-Continental deposits of siltstone, shale,
    conglomerate, sandstone, and tuff.  Includes units such as Willow Tank
    Formation and Baseline Sandstone.   Nevada

    Kv   Volcanic rocks (Late Cretaceous; early Tertiary near Safford)-Rhyolitic to
    andesitic volcanic rocks and locally associated sedimentary and subvolcanic
    intrusive rocks.  Arizona

    Kk   Kaiparowits Formation (Cretaceous)-Sandstone with subordinate shale. Utah

    Kws  Wahweap Sandstone and Straight Cliffs Formation (Cretaceous)-Sandstone
    with minor shale.     Utah
    Ktd  Tropic Shale and Dakota Sandstone (Cretaceous)-Shale and sandstone with
    minor coal and conglomerate.   Utah

    KJm  McCoy Mountains Formation (Cretaceous  and Jurassic)-Shale, sandstone,
    minor conglomerate, and minor pyroclastic rocks.   California

    Jm   Morrison Formation (Late Jurassic)-Shale and sandstone.   Utah

    Jec  Entrada Sandstone and Carmel Formations (Late and Middle Jurassic)-Fine-
    to medium-grained sandstone.   Utah

    Jgc  Glen Canyon Group (Early Jurassic)-Friable fine- to medium-grained
    sandstone with conspicuous large-scale cross strata.  Navajo Sandstone, Kayenta
    and Moenave Formations, and Wingate Sandstone.  Also referred to as Aztec
    Sandstone

    Jv   Volcanic rocks and metavolcanic rock (Jurassic; locally latest
    Triassic)-Andesite and rhyolite of the Sidewinder Volcanics in California and
    the Mount Wrightson Formation, part of Canelo Hills Volcanics, Mulberry Wash
    Volcanics, Black Rock Volcanics, and equivalent rocks in Arizona.   Arizona
    and California

    JTRs Shale, mudstone, siltstone, sandstone, and carbonate rock; sparse volcanic
    rock (Early Jurassic to Early Triassic)-Includes Auld Lang Syne Group,
    Nightingale sequence, and Gabbs and Sunrise Formations in western and central
    Nevada; Fairview Valley Formation and Aztec Sandstone in California.    Nevada

    TRc  Chinle Formation (Late Triassic)-Continental deposits of variegated
    bentonitic claystone, siltstone, and clayey sandstone; ledge-forming sandstone;
    and red siltstone.  Includes Shinarump Conglomerate Member

    TRm  Moenkopi Formation (Middle[?] and Early Triassic)-Marine deposits of
    siltstone, limestone, and sparse conglomerate.  May include Thaynes Formation
    in Nevada and adjacent strata in California, where local names differ

    Mzs  Schist (Jurassic protolith; Cretaceous metamorphism)-Orocopia, Pelona, and
    Rand Schists and correlatives.   California

    MzPzs     Structurally complex rocks (Mesozoic and Paleozoic)-Jurassic,
    Triassic, and Paleozoic rocks in west-central Arizona, and roof pendants in the
    Sierra Nevada batholith

    Pzmu Metasedimentary rocks, undifferentiated (Paleozoic)-Slate, marble,
    phyllite, schist, hornfels and quartzite.   Arizona and California

    Pzm  Marble (Paleozoic)-Thoroughly recrystallized limestone and dolomite.
    California

    Pzv  Metavolcanic rocks (Paleozoic)-Undivided lava flows, breccia and tuff,
    including greenstone, diabase, and pillow lavas; minor interbedded sedimentaryro

    Pc   Cherty limestone and sparse dolomite, shale, and sandstone (Upper and
    Lower Permian)-Includes units such as Toroweap Formation, Kaibab Limestone, and
    Coconino Sandstone

    Psc  Siltstone, sandstone, limestone and dolomite (commonly silty or sandy),
    and gypsum (Lower Permian)-Includes units such as Queantoweap Sandstone, Hermit
    Shale, Coconino Sandstone, Supai Group, and Pakoon Formation.   eastern Nevada
    and Utah

    Pu   Sedimentary rocks, undivided (Permian)-Limestone and dolomite, shale,
    sandstone, conglomerate, slate, and quartzite.  California

    PIPc Limestone and sparse dolomite, siltstone, and sandstone (Lower Permian to
    Lower Pennsylvanian)-Includes units such as the Bird Spring Formation and
    Callville Limestone.   eastern Nevada and Utah

    PIPs Sedimentary rocks (Permian and Pennsylvanian)-Hermit Shale, Supai Group,
    Naco Group, De Chelly Sandstone, Cutler Group, Pakoon Limestone, Callville
    Limestone, and Queantoweap Sandstone.   Arizona

    IPe  Ely and Tippipah Limestone (Lower and Middle Pennsylvanian)-Cherty
    limestone.   Nevada

    IPMu Sedimentary rocks, undivided (Pennsylvanian and Mississippian)-Shale,
    sandstone, conglomerate, limestone, dolomite, chert, marble, quartzite.
    California

    MCs  Sedimentary rocks (Mississippian to Cambrian)-Redwall Limestone, Temple
    Butte Limestone, and Tonto Group.   Arizona

    Mc   Limestone and minor amounts of dolomite and shale (Mississippian)-Includes
    units such as Rogers Spring and Monte Cristo and Redwall Limestones.   eastern
    Nevada and Utah

    MDs  Shale, siltstone, sandstone, chert-pebble conglomerate, and limestone
    (Mississippian and latest Devonian)-Includes units such as Pilot Shale, Joana
    Limestone, Chainman Shale, Diamond Peak Formation, Narrow Canyon Limestone,
    Mercury Limestone, and Eleana Formation.   Nevada

    Dc   Dolomite, limestone, and minor amounts of sandstone and shale
    (Devonian)-Includes shallow-marine units such as Sevy and Simonson Dolomites,
    Guilmette and Nevada Formations, and Devils Gate Limestone.  Also includes
    thinner cratonal strata such as Sultan and Temple Butte Limestone and Muddy
    Peak Dolomite

    DCc  Dolomite and limestone (Devonian to Cambrian)-Shallow-marine carbonate
    rocks.   eastern Nevada

    St   Platy limestone and limy siltstone with chert at base (Silurian)-Includes
    units such as Roberts Mountains and Storff Formations.  Locally includes rocks
    of Early Devonian age.   western Nevada

    Sc   Dolomite (Silurian)-Includes shallow-marine units such as Laketown and
    Lone Mountain Dolomites. Locally includes rocks of Early Devonian age at top.
    eastern Nevada

    SOu  Sedimentary rocks, undivided (Silurian and Ordovician)-Dolomite,
    sandstone, shale, conglomerate, chert, slate, quartzite, marble, phyllite.
    California

    Oc   Limestone, dolomite, shale, and quartzite (Ordovician)-Includes
    shallow-marine units such as Pogonip Group, Eureka Quartzite, and Ely Springs
    Dolomite.   eastern Nevada
    Bedrock geology database for the Mojave Desert Ecoregion

    OCc  Undivided dolomite and limestone (Ordovician and Cambrian)-Shallow-marine
    rocks in part of Clark County; mostly Cambrian.   eastern Nevada

    Cu   Sedimentary rocks, undivided (Cambrian)-Dolomite, limestone, quartzite,
    shale, and phyllite; includes some rocks that are possibly Late Proterozoic.
    California

    Cc   Limestone and dolomite (Cambrian)-Locally includes thick sequences of
    shale and siltstone.  Includes shallow-marine units such as Carrara, Bonanza
    King, and Nopah Formations; Dunderberg and Pioche Shale; and Muav Limestone.
    eastern Nevada and Utah

    Css  Sandstone and quartzite (Cambrian)-Includes Tapeats Sandstone and related
    rocks.  Rests on Precambrian metamorphic rocks.  eastern Nevada

    CZq  Quartzite (Cambrian and Late Proterozoic)-Quartzite with minor amounts of
    conglomerate, phyllitic siltstone, limestone, and dolomite.  Includes Stirling
    Quartzite, Wood Canyon Formation, and Zabriskie and Prospect Mountain
    Quartzite.   eastern Nevada and Utah

    CZs  Strata (Cambrian and Late Proterozoic)-Phyllitic siltstone, quartzite, and
    lesser amounts of limestone and dolomite.  Includes Reed Dolomite; Deep Spring,
    Campito, Poleta, Harkless, and Saline Valley Formations; and Mule Spring
    Limestone.   western Nevada

    Zw   Wyman Formation (Late Proterozoic)-Phyllite and phyllitic siltstone and
    minor amounts of limestone, dolomite, and sandstone.  western Nevada

    Zj   Johnnie Formation (Late Proterozoic)-Quartzite, phyllitic siltstone,
    conglomerate, limestone, and dolomite.   eastern Nevada

    Bedrock map units-Intrusive and metamorphic rocks of Precambrian age
    (~1400-1700 Ma)

    PzXu Undivided metasedimentary and metavolcanic rocks of great variety
    (Paleozoic to Early Proterozoic-Slate, quartzite, hornfels, chert, phyllite,
    mylonite, schist, gneiss, and minor marble. California

    ZXsg Sedimentary rocks and gneiss (Late to Early Proterozoic)-Sedimentary
    sequences largely correlative with the Pahrump Group and overlying Late
    Proterozoic strata, including in places gneiss largely derived from Early
    Proterozoic granitoids. California

    Yg   Granitoid rocks (Middle Proterozoic)-Typically porphyritic rapakivi
    granite; about 1400 Ma

    YXg  Undivided granitoid rocks (Middle and Early Proterozoic)-Granite,
    granodiorite, tonalite, quartz diorite, diorite, and gabbro.  Includes syenite,
    anorthosite, and gabbroic rocks in the San Gabriel Mountains.  Includes
    granitoids of three age groups: 1100 to 1200, about 1400, and 1650 to 1750 Ma.
    In California, includes foliated Mesozoic granitoids.  Arizona and California

    Xg   Granitoid rocks (Early Proterozoic; 1650 to 1750 Ma)-Granite,
    granodiorite, tonalite, quartz diorite, diorite, and gabbro; commonly foliated.
    Arizona and Utah

    Xm   Metamorphic rocks (Early Proterozoic; 1650 to 1800 Ma)-Undivided
    metasedimentary, metavolcanic, and gneissic rocks, including locally abundant
    amphibolite, marble, and pegmatite.  In places includes undivided Early
    Proterozoic granitoids
    Locally subdivided into:

    Xms       Metasedimentary rocks (Early Proterozoic; 1650 to 1800 Ma)-Includes
    Vishnu Schist.  Arizona and Utah

    Xmv       Metavolcanic rocks (Early Proterozoic; 1650 to 1800 Ma).  Arizona

    Entity_and_Attribute_Detail_Citation: Not Available

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Distribution_Information

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Metadata_Reference_Section

Metadata_Date: 19980618
Metadata_Contact:

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version:  19940608
Metadata_Time_Convention:  Local Time
Metadata_Security_Information:
    Metadata_Security_Classification_System:  None
    Metadata_Security_Classification:  UNCLASSIFIED
    Metadata_Security_Handling_Description:  None

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Last modified: 98-06-18.11:03:53.Thu