Geologic map of the Cobblestone Creek - May Creek area, east-central foothills, Brooks Range, Alaska

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What does this data set describe?

Title:
Geologic map of the Cobblestone Creek - May Creek area, east-central foothills, Brooks Range, Alaska
Abstract:
The Cobblestone Creek-May Creek area of the foothills of the Endicott Mountains is one of a series of areas selected for detailed mapping to document important structural and stratigraphic relationships at the mountain front of the east-central Brooks Range. The Cobblestone Creek-May Creek area is important in delineating the stratigraphic and structural relationships in this area because, unlike the adjacent valleys of the Itkillik and Nanushuk rivers, Cobblestone and May Creeks were not glaciated during the Pleistocene, and thus bedrock exposures are generally more continuous.
Supplemental_Information:
The layers listed below are present as ArcGIS shape files. Attribute information for the following layers (entities) is included in this metadata file under the "Entity_and_Attribution_Information" section. Each layer is listed and described in detail under its own heading starting "Entity_Type_Label." Basic unit information is also included in the geologic unit code set file "PIR2009-5_codeset.pdf". Layers include:
cob_attitude - strikes and dips of beds
cob_beds - beds traceable in outcrop or on air photos
cob_compgeo - geology polygons
cob_contacts - geologic contacts
cob_faults - fault traces
cob_folds - fold axial planes
cob_inferred - inferred geologic contacts
cob_kc - point locations of coquinoid limestone
cob_samples - sample locations (used only on appendix map)
  1. How should this data set be cited?

    Mull, C.G., Harris, E.E., Delaney, P.R., and Swenson, R.F., 2009, Geologic map of the Cobblestone Creek - May Creek area, east-central foothills, Brooks Range, Alaska: Preliminary Interpretive Report PIR 2009-5, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, Alaska - USA.

    Online Links:

    Other_Citation_Details: 40 pages, 1 sheet, 1:63,360

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -150.65249
    East_Bounding_Coordinate: -149.932958
    North_Bounding_Coordinate: 68.75955
    South_Bounding_Coordinate: 68.24027

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 2009
    Currentness_Reference: publication date

  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?

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 5
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -153.000
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000064
      Ordinates (y-coordinates) are specified to the nearest 0.000064
      Planar coordinates are specified in meters

      The horizontal datum used is D_Clarke_1866.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.978698.

  7. How does the data set describe geographic features?

    cob_beds.shp
    Object type is vector and the entity values refer to beds traceable in outcrop or on air photos . (Source: Alaska Division of Geological & Geophysical Surveys)

    cob_compgeo.shp
    Object type is vector and the entity values refer to the unit name abbreviations for each specific polygon represented on the map. (Source: Alaska Division of Geological & Geophysical Surveys)

    unit
    A unique three to four letter abbreviation given to each map unit represented on the map. (Source: Alaska Division of Geological & Geophysical Surveys)

    Formal codeset
    Codeset Name:PIR2009-5_codeset.pdf
    Codeset Source:Alaska Division of Geological & Geophysical Surveys <http://www.dggs.alaska.gov/metadata/PIR2009-5_codeset.pdf>

    cob_contacts.shp
    Object type is vector and the entity values refer to to geologic map unit contacts. (Source: Alaska Division of Geological & Geophysical Surveys)

    cob_faults.shp
    Object type is vector and the entity values refer to various faults in the mapping area. (Source: Alaska Division of Geological & Geophysical Surveys)

    fault_type
    Type of fault. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    alloc_conallochthon boundary, concealed
    alloc_con?allochthon boundary, concealed and queried
    allochallochthon boundary thrust
    alloch?allochthon boundary thrust, queried
    alloch_conallochthon boundary thrust, concealed
    left_con?left-lateral fault, concealed, queried
    n_thru_conbackthrust, concealed
    n_thrust?queried backthrust
    thrustthrust
    thrust?apxthrust fault, approximately located, queried
    thrust?conthrust fault, concealed, queried
    thrust_apxthrust fault, approximately located
    thrust_conthrust fault, concealed
    transversetrace of a transverse fault, relative motion unknown

    cob_folds.shp
    Object type is vector and the entity values refer to fold axial traces. (Source: Alaska Division of Geological & Geophysical Surveys)

    fold_type
    Type of fold. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    antconcealanticline, concealed
    antiaxial trace of anticline
    antidashapproximate anticline
    arrowarrow symbol to show plunge
    concealedtrace of fault, concealed; relative motion unknown
    otantioverturned anticline
    synsyncline
    synconcealconcealed syncline

    cob_inferred.shp
    Object type is vector and the entity values refer to inferred geologic contacts. (Source: Alaska Division of Geological & Geophysical Surveys)

    cob_samples.shp
    Object type is point and the entity values refer to sample locations (used only on appendix map in booklet as Figure A1) (Source: Alaska Division of Geological & Geophysical Surveys)

    sample_type
    Type of sample. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    AFTApatite fission track sample
    micro_chemsample for micropaleontology and geochem

    station_id
    Unique number assigned to each station. (Source: Alaska Division of Geological & Geophysical Surveys)

    00XXYY; 00=year, XX=Geologist's initials, YY= unique sample identifier.

    map_id
    Unique number assigned to each sample on the map. (Source: Alaska Division of Geological & Geophysical Surveys)

    XX

    x
    latitude (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:-150.0266899
    Maximum:-150.595395
    Units:degrees

    y
    longitude (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:68.3942
    Maximum:68.73016822
    Units:degrees

    cob_attitude.shp
    Object type is point and the entity values refer to strikes and dips of beds. (Source: Alaska Division of Geological & Geophysical Surveys)

    strike
    The azimuth of the strike of the bed. (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:1
    Maximum:360
    Units:degrees

    dip
    The dip value of the bed, measured clockwise from strike. (Source: Alaska Division of Geological & Geophysical Surveys)

    Range of values
    Minimum:0
    Maximum:90
    Units:degrees

    type_
    Type of surface. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    appxbedapproximate bedding surface
    appxotbedapproximate overturned bedding surface
    beddingbedding surface
    horizontalhorizontal bedding surface
    otbedoverturned bed
    verticalvertical bedding surface - approximated
    vertvertical bedding - certain

    cob_kc.shp
    Object type is point and the entity values refer to point locations of coquinoid limestone. (Source: Alaska Division of Geological & Geophysical Surveys)

    unit
    A unique three to four letter abbreviation given to each map unit represented on the map. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    kccoquinoid limestone


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)

  2. Who also contributed to the data set?

    This Geologic Map was fundedby DGGS Energy Section. Geologic field investigations by: C.G. Mull (1982, 1985, 1986, 1987, 1989, 1990, 1991, 1992, 1993, 1999, 2000, 2001); E.E. Harris (1985, 1999, 2000, 2001); Paige R. Peapples (2001); D.L. LePain, R.A. Kirkham, and R.R. Reifenstuhl (1999, 2000, 2001); Jerry Siok (1983, 1985); D.A. Bodnar (1983); K.E. Adams and M.L. Buckingham (1985); D.W. Houseknecht, C.J. Schenk, and T.J. Ryherd (2001); M.D. Myers (1989, 1999); M.T. Whalen and M.B. Mickey (2000).Digital cartography by Paige R. Delaney.

  3. To whom should users address questions about the data?

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    GIS Data Manager/Cartographer
    3354 College Road
    Fairbanks, AK 99709-3707

    (907) 451-5029 (voice)
    (907) 451-5050 (FAX)
    dggspubs@alaska.gov

    Contact_Instructions:
    You may view our web site at <http://www.dggs.alaska.gov> for the latest information on available data.Please e-mail your questions and data requests when possible since our web site and e-mail address will remain current even if our phone number and mailing address change.


Why was the data set created?

Local field studies by the Alaska Division of Geological & Geophysical Surveys (DGGS) began in the area in 1982 and continued intermittently in conjunction with other field studies. In recent years, interest in hydrocarbon exploration in the Brooks Range foothills has increased considerably, resulting in an opportunity to compile previous studies as well as to carry out additional field studies to address specific structural and stratigraphic problems. In addition, ongoing mapping and structural and stratigraphic studies in the Siksikpuk River - Tiglukpuk Creek area to the west (Peapples and others, 2007) have resulted in some revised structural and stratigraphic concepts that have proven to be applicable to the Cobblestone Creek-May Creek map area and the adjacent Kanayut River map area to the west (Harris and others, in press).


How was the data set created?

  1. From what previous works were the data drawn?

    Patton and Tailleur (1964) (source 1 of 3)
    Patton, W.W., Jr., and Tailleur, I.L., 1964, Geology of the Killik - Itkillik region, Alaska: Professional Paper P 0303-G, United States Geological Survey, Reston, VA.

    Online Links:

    Other_Citation_Details: p. 409-500, 3 sheets, scale 1:125,000
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 125000
    Source_Contribution: Published geologic mapping

    Pessel and Mull (1964) (source 2 of 3)
    Pessel, G.H., and Mull, C.G., 1964, Geologic Map of the Chandler Lake quadrangle.

    Other_Citation_Details:
    Unpublished mapping of Richfield Oil Corporation (Atlantic Richfield Company), by permission of Phillips Alaska, Inc.
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 250000
    Source_Contribution: unpublished reconnaissance mapping

    Sonneman and Mull (1972) (source 3 of 3)
    Sonneman, H.S., and Mull, C.G., 1972, Geologic map of the Chandler Lake Quadrangle.

    Other_Citation_Details:
    Exxon Company, USA unpublished mapping, by permission of Exxon Co., USA
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 125000
    Source_Contribution: unpublished reconnaissance mapping

  2. How were the data generated, processed, and modified?

    Date: 2002 (process 1 of 3)
    Geologic and structural information from published and unpublished mapping were compiled by C.G. Mull.

    Data sources used in this process:

    • Patton and Tailleur (1964)
    • Pessel and Mull (1964)
    • Sonneman and Mull (1972)

    Date: 2002 (process 2 of 3)
    Map Compilation - Geologic mapping took place during three-week field seasons during June-July 2004 and 2005. Mappers recorded observations in field notebooks and on the aerial photographs and topographic maps, predominantly at 1:63,360 scale. Bedrock mapping involved using aerial photographs and topographic maps on a daily basis for checking geologic contacts and units.All compilations were made by hand on stable mylar at 1:63,360 scale. Stations were located using aerial photographs, topographic maps, and altimeters. In most instances, GPS devices were used. Stations were also plotted by hand on stable mylar topographic bases and coordinates determined by digitizing. The bedrock geologic map was compiled using field notes from fieldwork process step (above), and all known geologic data from previous work in the quadrangle. Data were compiled on multiple layers of stable mylar at 1:63,360 scale. Relevant information from all mylar layers was compiled onto one stable mylar sheet with abundant control points. This mylar was then scanned and digitized.

    Date: 2009 (process 3 of 3)
    Digital Cartography - The compilation mylar was scanned as a high-resolution tiff file, which was imported into ArcGIS 9.1 and geographically registered in UTM coordinates (see spatial reference information below).Geologic polygons, linear features, and point data were digitized "on-screen" and attributed with appropriate supporting information.Editing and quality control checks took place at every process step.All final map layout and editing was done in Adobe Illustrator, Version CS2.

  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?

    Geologic point, line, and polygon data were determined visually using color infrared aerial photographs at a scale of approximately 1:63,360 and topographic maps at scales of 1:63,360 and larger. Feature attributes were checked by the geologists who conducted the field observations. To check attribute accuracy, a check plot was visually compared to the geologist's original compilation. Discrepancies between the digital geospatial dataset and the original analog or digital compilation were corrected as needed. The geologic interpretations presented in this report have undergone two technical reviews by geologists familiar with the subject of the report or geology of the map area. Reviewers' suggestions were incorporated into the final draft when deemed appropriate by the author.

  2. How accurate are the geographic locations?

    Locations were determined in the field using raster images of topographic base maps and Garmin GPS units. The estimated positional error caluclated by the GPS unit was not recorded. Bedrock geologic map data also have a horizontal positional accuracy dependent on the "on-screen" method of digital cartography. Map error is induced by: (1) transferring map data from base topography to a Mylar compilation map, with an estimated potential error due to a pen line width of approximately 0.001 inches being equivalent to approximately 1.5 meters on the ground; (2) the digitizing RMS error (30 control points on a regular grid have an average RMS error of 14.0 meters on the ground; individual control point error ranges from 2.9 to 24.0 meters on the ground); and (3) the accuracy of the human operator digitizing the geologic line work from the topographic base map, with an estimated error due to a pen line width of approximately 0.001 inches being equivalent to approximately 1.5 meters on the ground. The average potential horizontal error for bedrock geologic map features is estimated to be approximately 15 meters.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    This dataset includes geospatial information about beds traceable on air photos and/or in the field. The dataset displays: geologic units and contacts; inferred geologic contacts; fold and fault traces; strike, dip, and fold axis attitude; point locations of coquinoid limestone; manmade infrastructure such as airstrips, roads, etc.; sample locations; point elevations digitized from the raster map; and wells.

  5. How consistent are the relationships among the observations, including topology?

    Polygon topology is present and clean on the originating geospatial dataset. All polygon features were were topologically validated using the ESRI ArcGIS 9.0 software prior to export to shape file format. The logical consistency of the point and line files has been visually checked but not systematically verified.


How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints:
This report, map, and/or dataset are available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Use_Constraints:
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. User specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys.

  1. Who distributes the data set? (Distributor 1 of 1)

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    Natural Resource Technician
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    907-451-5020 (voice)
    907-451-5050 (FAX)
    dggspubs@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
    Contact_Instructions:
    Please view our Web site (<http://www.dggs.alaska.gov>) for the latest information on available data. Please contact us using the e-mail address provided above when possible.
  2. What's the catalog number I need to order this data set?

    Preliminary Interpretive Report 2009-5

  3. What legal disclaimers am I supposed to read?

    The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requester or anyone else exceed the fee paid for the electronic service or product.

  4. How can I download or order the data?

  5. What hardware or software do I need in order to use the data set?

    It is suggested that MapInfo users import ESRI shape files (if provided) due to the possibility of data loss when importing Arc Export .e00 files. Please check the MapInfo Web site (<http://www.mapinfo.com/>) for the latest documentation on importing Arc Export and/or ESRI shape files.


Who wrote the metadata?

Dates:
Last modified: 01-Jun-2009
Last Reviewed: 01-Jun-2009
Metadata author:
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
Metadata Manager
3354 College Road
Fairbanks, AK 99709-3707
USA

907-451-5020 (voice)
451-5000 (FAX)
dggspubs@alaska.gov

Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays.
Contact_Instructions:
Please contact us through the e-mail address above whenever possible.
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)


Generated by mp version 2.9.6 on Mon Jun 15 16:43:38 2009