Geologic map of the Grand Junction quadrangle, Mesa County, Colorado

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Frequently anticipated questions:


What does this data set describe?

Title:
Geologic map of the Grand Junction quadrangle, Mesa County, Colorado
Abstract:
This 1:24,000-scale geologic map of the Grand Junction 7.5' quadrangle, in support of the USGS Western Colorado I-70 Corridor Cooperative Geologic Mapping Project, provides new interpretations of the stratigraphy, structure, and geologic hazards in the area of the junction of the Colorado River and the Gunnison River. Bedrock strata include the Upper Cretaceous Mancos Shale through the Lower Jurassic Wingate Sandstone units. Below the Mancos Shale, which floors the Grand Valley, the Upper and Lower(?)Cretaceous Dakota Formation and the Lower Cretaceous Burro Canyon Formation hold up much of the resistant northeast- dipping monocline along the northeast side of the Uncompahgre uplift. The impressive sequence of Jurassic strata below include the Brushy Basin, Salt Wash, and Tidwell Members of the Upper Jurassic Morrison Formation, the Middle Jurassic Wanakah Formation and informal "board beds" unit and Slick Rock Member of the Entrada Formation, and the Lower Jurassic Kayenta Formation and Wingate Sandstone. The Upper Triassic Chinle Formation and Early Proterozoic meta-igneous gneiss and migmatitic meta- sedimentary rocks, which are exposed in the Colorado National Monument quadrangle to the west, do not crop out here. The monoclinal dip slope of the northeastern margin of the Uncompahgre uplift is apparently a Laramide structural feature. Unlike the southwest-dipping, high-angle reverse faults in the Proterozoic basement and s-shaped fault- propagation folds in the overlying strata found in the Colorado National Monument 7.5' quadrangle along the front of the uplift to the west, the monocline in the map area is unbroken except at two localities. One locality displays a small asymmetrical graben that drops strata to the southwest. This faulted character of the structure dies out to the northwest into an asymmetric fault-propagation fold that also drops strata to the southwest. Probably both parts of this structure are underlain by a northeast-dipping high-angle reverse fault. The other locality displays a second similar asymmetric fold. No evidence of post-Laramide tilting or uplift exists here, but the antecedent Unaweep Canyon, only 30 km to the south-southwest of the map area, provides clear evidence of Late Cenozoic, if not Pleistocene, uplift. The major geologic hazards in the area include large landslides associated with the dip-slope-underlain, smectite-rich Brushy Basin Member of the Morrison Formation and overlying Dakota and Burro Canyon Formations. Active landslides affect the southern bank of the Colorado River where undercutting by the river and smectitic clays in the Mancos trigger landslides. The Wanakah, Morrison, and Dakota Formations and the Mancos Shale create a significant hazard to houses and other structures by containing expansive smectitic clay. In addition to seasonal spring floods associated with the Colorado and Gunnison Rivers, a serious flash flood hazard associated with sudden summer thunderstorms threatens the intermittent washes that drain the dip slope of the monocline.
Supplemental_Information:
Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ARC/INFO format, this metadata file may include some ARC/INFO-specific terminology.
Geospatial data files of this data set:
  gj24k: geology polygons, contacts, faults
  gjpnt: point data representing bedding attitudes
  gjline: line representing location of the cross section,
          and fold axes

Symbolsets used for plotting in ArcInfo:
  wpgcmykg.shd: shadeset
  geol_sfo.lin: lineset
  geoscamp1.mrk: markerset
  1. How might this data set be cited?
    Scott, Robert B., Carrara, Paul E., Hood, William C., and Murray, Kyle E., 2002, Geologic map of the Grand Junction quadrangle, Mesa County, Colorado: Miscellaneous Field Studies MF-2363, U.S. Geological Survey, Denver, CO.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -108.625
    East_Bounding_Coordinate: -108.500
    North_Bounding_Coordinate: 39.125
    South_Bounding_Coordinate: 39.000
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2002
    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):
      • Point (599)
      • String (1460)
      • GT-polygon composed of chains (600)
    2. What coordinate system is used to represent geographic features?
      The map projection used is Polyconic.
      Projection parameters:
      Longitude_of_Central_Meridian: -108.5625
      Latitude_of_Projection_Origin: 39
      False_Easting: 0.00000
      False_Northing: 0.00000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 10
      Ordinates (y-coordinates) are specified to the nearest 10
      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?
    Entity_and_Attribute_Overview:
    ---------------------------------------------------------------
    COVERAGE NAME: gj24k
    ---------------------------------------------------------------
    
    USER-DEFINED ITEMS IN GJ24K.PAT:
    ------------------------------------
    
    ATTRIBUTE NAME: UNIT
    DATABASE ITEM STRUCTURE: 4,4,I,0
    DESCRIPTION: unique numeric identifier for each geologic unit
    ITEM VALUES FOR 'UNIT':
    integer value in the range 1 - 38
    
    ATTRIBUTE NAME: LABEL
    DATABASE ITEM STRUCTURE: 10,10,C,0
    DESCRIPTION: geologic unit label
    ITEM VALUES FOR 'LABEL':
    (see table below)
    
    ATTRIBUTE NAME: DESC
    DATABASE ITEM STRUCTURE: 100,100,C,0
    DESCRIPTION: text description of geologic unit
    ITEM VALUES FOR 'DESC':
    (see table below)
    
    ATTRIBUTE NAME: SYMBOL
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: shade symbol used to color geology polygons
    ITEM VALUES FOR 'SYMBOL':
    integer value in the range 12 - 930
    
    RELATIONSHIP OF ITEMS 'UNIT', 'LABEL', 'SYMBOL', and 'DESC':
    UNIT    LABEL   SYMBOL   DESC
       1       af       20   Artificial fill
      32      Jeb      330   Board beds unit of the Entrada Formation
      33      Jes      591   Slickrock Member of the Entrada Formation
      34       Jk      530   Kayenta Formation
      28      Jmb      580   Brushy Basin Member of the Morrison Formation
      38      Jmb      580   Bentonite quarry located in Jmb
      29      Jms      693   Salt Wash Member of the Morrison Formation
      30      Jmt      560   Tidwell Member of the Morrison Formation
      31       Jw      890   Wanakah Formation
      35      Jwg      785   Wingate Sandstone
      27       Kb      880   Burro Canyon Formation
      26       Kd      590   Dakota Formation
      25       Km      480   Mancos Shale
       4       Qa       60   Alluvium deposited by tributary streams
      15      Qac      271   Alluvium and colluvium, undivided
       2    Qalc1       40   Youngest alluvium deposited by the Colorado
                              River
      36    Qalc1       40   Gravel pit
       5    Qalc2       80   Oldest alluvium deposited by the Colorado River
       3     Qalg      375   Youngest alluvium deposited by the Gunnison
                               River
      17     Qaso      393   Old alluvial-slope deposit
      23       Qc       30   Colluvium
      14      Qfy       51   Young fan-alluvium and debris-flow deposits
      18      Qlg      484   Local gravel deposits
      19 Qlg/Qt30      284   Local gravel deposits over terrace alluvium 30
                               of the Colorado River
      24     Qlso      190   Older landslide deposits
      22     Qlsy      899   Younger landslide deposits
      16     Qpwf       12   Pediment deposit of Walker Field
      20      Qse      151   Eolian sand and sheetwash deposits
      21 Qse/Qt30      163   Eolian sand and sheetwash deposits over terrace
                               alluvium 30 of the Colorado River
      12    Qt100       42   Terrace alluvium 100 of the Colorado River
      13    Qt170       74   Terrace alluvium 170 of the Colorado River
       8     Qt30       70   Terrace alluvium 30 of the Colorado River
       9    Qt60c       93   Terrace alluvium 60 of the Colorado River
      10    Qt60g      194   Terrace alluvium 60 of the Gunnison River
      11  Qtc/Qtg      647   Terrace alluvium of the Colorado River over
                               terrace alluvium of the Gunnison River
       7     Qtgu      696   Terrace alluvium of the Gunnison River,
                               undivided
       6      Qvf       33   Valley-fill deposits
      37     river     930   river water
    
    USER-DEFINED ITEMS IN GJ24K.AAT:
    ------------------------------------
    
    ATTRIBUTE NAME: LINECODE
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: unique numeric identifier for linear feature type
    ITEM VALUES FOR 'LINECODE':
    integer value in the range 1 - 106
    
    ATTRIBUTE NAME: SYMBOL
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: line symbol to be used to draw line entities
    ITEM VALUES FOR 'SYMBOL':
    integer value in the range 1 - 227
    
    ATTRIBUTE NAME: TYPE
    DATABASE ITEM STRUCTURE: 10,10,C,0
    DESCRIPTION: text description of line type
    ITEM VALUES FOR 'TYPE':
    boundary
    contact
    fault
    neatline
    
    ATTRIBUTE NAME: MODIFIER
    DATABASE ITEM STRUCTURE: 20,20,C,0
    DESCRIPTION: modifier, if any, for the 'type' item above
    ITEM VALUES FOR 'MODIFIER':
    approximate
    certain
    concealed
    scarp terrace
    
    ATTRIBUTE NAME: DESC
    DATABASE ITEM STRUCTURE: 100,100,C,0
    DESCRIPTION: text description of linear geologic feature
    ITEM VALUES FOR 'DESC':
    (see table below)
    
    RELATIONSHIP OF ITEMS 'LINECODE', 'SYMBOL', 'TYPE', 'MODIFIER', and 'DESC':
    LINECODE   SYMBOL   TYPE       MODIFIER        DESC
    1          1        contact    certain         contact, certain
    2          3        contact    approximate     contact, approximately
                                                      located
    3          4        boundary   approximate     gravel quarry  boundary
    6          4        boundary   approximate     bentonite quarry boundary
    106        8        fault      approximate     normal fault,
                                                      approximately located,
                                                      queried to indicate end
                                                      of recognizable feature
    102        51       fault      certain         normal fault, certain,
                                                      with bar and ball on
                                                      downthrown side
    4          172      contact    scarp terrace   contact coincident with
                                                      scarp terrace, hachures
                                                      on low side of scarp
    101        173      fault      certain         normal fault, certain
    103        175      fault      approximate     normal fault,
                                                      approximately located
    104        176      fault      concealed       normal fault, concealed
    105        185      fault      approximate     normal fault,
                                                      approximately located,
                                                      with bar and ball on
                                                      downthrown side
    5          227      neatline                   neatline to define limits
                                                      of geologic map area
    
    ---------------------------------------------------------------
    COVERAGE NAME: gjpnt
    ---------------------------------------------------------------
    
    USER-DEFINED ITEMS IN GJPNT.PAT:
    ------------------------------------
    
    ATTRIBUTE NAME: SYMBOL
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: symbol used to draw point feature
    ITEM VALUES FOR 'SYMBOL':
    2
    63
    
    ATTRIBUTE NAME: STRIKE
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: compass orientation of feature, in degrees
    ITEM VALUES FOR 'STRIKE':
    integer value in the range 0 - 360
    
    ATTRIBUTE NAME: DIP
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: inclination from vertical of feature
    ITEM VALUES FOR 'DIP':
    integer value in the range 0 -90
    
    ATTRIBUTE NAME: DESC
    DATABASE ITEM STRUCTURE: 100,100,C,0
    DESCRIPTION: text description of feature
    ITEM VALUES FOR 'DESC':
    strike and dip of inclined bedding calculated from outcrop pattern using
       3 point solution
    strike and dip of inclined bedding measured in the field
    
    ---------------------------------------------------------------
    COVERAGE NAME: gjline
    ---------------------------------------------------------------
    
    USER-DEFINED ITEMS IN GJLINE.AAT:
    ------------------------------------
    
    ATTRIBUTE NAME: LINECODE
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: unique numeric identifier for linear feature type
    ITEM VALUES FOR 'LINECODE':
    integer value in the range 107 - 120
    
    ATTRIBUTE NAME: SYMBOL
    DATABASE ITEM STRUCTURE: 3,3,I,0
    DESCRIPTION: line symbol to be used to draw line entities
    ITEM VALUES FOR 'SYMBOL':
    integer value in the range 7 - 176
    
    ATTRIBUTE NAME: TYPE
    DATABASE ITEM STRUCTURE: 10,10,C
    DESCRIPTION: text description of line type
    ITEM VALUES FOR 'TYPE':
    fold
    xsec_line
    
    ATTRIBUTE NAME: ACCURACY
    DATABASE ITEM STRUCTURE: 15,15,C
    DESCRIPTION: apparent accuracy of line type
    ITEM VALUES FOR 'ACCURACY':
    approximate
    certain
    concealed
    
    ATTRIBUTE NAME: CERTAINTY
    DATABASE ITEM STRUCTURE: 15,15,C
    DESCRIPTION: questionable or not questionable
    ITEM VALUES FOR 'CERTAINTY':
    queried
    
    ATTRIBUTE NAME: DESC
    DATABASE ITEM STRUCTURE: 100,100,C
    DESCRIPTION:
    ITEM VALUES FOR 'DESC':
    (see table below)
    
    RELATIONSHIP OF ITEMS 'LINECODE', 'SYMBOL', 'TYPE', 'ACCURACY', 'CERTAINTY', 'DESC'
    
    LINECODE   SYMBOL   TYPE        ACCURACY    CERTAINTY   DESC
    110        7        fold        concealed   queried     concealed axis of
                                                               anticline,
                                                               queried to
                                                               indicate end of
                                                               recognizable
                                                               feature
    107        64       fold        certain                 axis of
                                                               anticline,
                                                               certain
    120        173      xsec_line                           cross-section
                                                               location line
                                                               A-A'
    108        175      fold        approximate             axis of
                                                               anticline,
                                                               approximately
                                                               located
    109        176      fold        concealed               axis of
                                                               anticline,
                                                               concealed
    
    Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/mf/2002/mf-2363/mf-2363_pam.pdf

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Scott, Robert B.
    • Carrara, Paul E.
    • Hood, William C.
    • Murray, Kyle E.
  2. Who also contributed to the data set?
    Geology south of the Colorado River mapped by Robert B. Scott and William C. Hood in 1998 and 1999. Geology north of the Gunnison River mapped by Paul E. Carrara in 1999. Digital compilation by Kyle E. Murray in 2000.
  3. To whom should users address questions about the data?
    Robert B. Scott
    U.S. Geological Survey
    Geologist
    MS 913 Denver Federal Center
    Denver, CO
    USA

    303-236-1230 (voice)
    303-236-5690 (FAX)
    rbscott@usgs.gov

Why was the data set created?

To update and reinterpret earlier geologic mapping, and provide sufficient geologic information for land-use decisions for private land and for areas managed by the Bureau of Land Management and the National Park Service. Use of these data at scales greater than 1:24,000 would be inappropriate because mapping was performed at that scale.

How was the data set created?

  1. From what previous works were the data drawn?
    Scott and others (1999) (source 1 of 1)
    Scott, Robert B., Carrara, Paul E., and Hood, William C., 1999, field notes.

    Type_of_Source_Media: mylar
    Source_Scale_Denominator: 24000
    Source_Contribution: conducted field mapping
  2. How were the data generated, processed, and modified?
    Date: 1999 (process 1 of 13)
    The original map data were manually transferred to stable mylar overlays registered to a stable-base USGS 7.5 minute topographic map by use of optical corrections of PG-2 photogrammetric plotters.
    Date: 2000 (process 2 of 13)
    Mylar overlays were scanned at 300 dots per inch.
    Date: 2000 (process 3 of 13)
    Scanned image was registered to gj24k coverage and rectified with ARC/INFO software.
    Date: 2000 (process 4 of 13)
    Linework and symbology were digitized from registered and rectified mylar image using ARC/INFO software. Topology was built after digitizing was completed.
    Date: 2000 (process 5 of 13)
    Arcs, polygons, and points were attributed using ARC/INFO software.
    Date: 2000 (process 6 of 13)
    Plots were generated and checked versus the original data. Appropriate changes were made to the ARC/INFO GIS database.
    Date: 11-Aug-2000 (process 7 of 13)
    First draft of metadata created by Kyle E. Murray using FGDCMETA.AML ver. 1.32 01/11/99 on ARC/INFO data set /data9/kmurray2/grandjunc/gj24k
    Date: 2000 (process 8 of 13)
    Geologic map review performed by U.S. Geological Survey geologists Scott Lundstrom and Ric Page.
    Date: 2000 (process 9 of 13)
    Geologic name review performed by U.S. Geological Survey Central Publications Group (Tom Judkins).
    Date: 2000 (process 10 of 13)
    Revisions made to geologic map and database as suggested by reviewers.
    Date: 2000 (process 11 of 13)
    Associated GIS files and text reviewed by USGS reviewers: R. Randall Schumann and Alex J. Donatich
    Date: 2001 (process 12 of 13)
    Revisions made to associated files by Robert B. Scott and Kyle E. Murray
    Date: 27-Jul-2009 (process 13 of 13)
    Creation of original metadata record Person who carried out this activity:
    U.S. Geological Survey
    Attn: Robert B. Scott
    Geologist
    U.S. Geological Survey
    MS 913 Denver Federal Center
    Denver, CO
    USA

    303-236-1230 (voice)
    rbscott@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?
    Attributes were checked by manually comparing hard copy plots of the digital data with the source materials. Authors and USGS map editors performed separate reviews. The attributes of this geospatial dataset consist of text identifiers and numeric codes that indicate the identity of the geologic unit or type of geologic feature, and determine how each feature is colored or symbolized. To check attribute accuracy, a color check plot was visually compared to the geologist's original compilation. Discrepancies between the digital geospatial dataset and the original analog compilation were corrected as needed. Machine-created listings of unique attribute values were used to identify spelling errors or other inconsistencies, and corrections were made as needed.
  2. How accurate are the geographic locations?
    Accuracy of 95% of the horizontal coordinates are within 12 meters on the ground or 1/50th inch on the map by transfer of geologic data on aerial photographs to a stable mylar base using PG-2 photogrammetric plotters.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Data are complete: no features that could be accurately represented at the compilation scale of 1:24,000 were eliminated or generalized. The smallest area represented is approximately 600 square meters. All geospatial database elements are attributed.
  5. How consistent are the relationships among the observations, including topology?
    The neatline bounding the map area was mathematically generated in latitudinal and longitudinal coordinates and projected to polyconic projection for capturing of geologic data. ARC/INFO software was used to digitize contacts and structural features that form the perimeters of geologic map polygons. Polygons intersecting the neatline were closed along the border. Segments making up the outer and inner boundaries of a polygon tie end-to-end to completely enclose the area. Line segments are a set of sequentially numbered coordinate pairs. No duplicate features or duplicate points exist in a data string. Intersecting lines are separated into individual line segments at the point of intersection. All nodes are represented by a single coordinate pair which indicates the beginning or end of a line segment.

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. Acknowledgment of the U.S. Geological Survey would be appropriate in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Central Publications Group
    U.S. Geological Survey
    MS 902, Box 25046 DFC
    Lakewood, CO

    303-236-5486 (voice)
    webmaster@geology.cr.usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
    Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data.
    The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data, software, or related materials.
    These data are intended for use at 1:24,000 scale. Any hardcopies utilizing these data shall clearly indicate their source. If the user has modified the data in any way (s)he is obligated to describe the types of modifications they have performed on the hardcopy map. User specifically agrees not to misrepresent these data, nor to imply that changes they made were approved by the U.S. Geological Survey or the authors of this geologic map database.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 13-Jun-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/map-mf/2363/metadata.faq.html>
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