Geologic Map of the Eastern Half of the McGrath Quadrangle, Alaska

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Frequently-anticipated questions:


What does this data set describe?

Title:
Geologic Map of the Eastern Half of the McGrath Quadrangle, Alaska
Abstract:
This map is a compilation of previously unpublished and published data, as well as from updated field mapping. This publication offers a 1:125,000-scale map sheet accompanied by a booklet containing a summary of the geology, a colored terrane map, map unit descriptions, a summary table listing selected mineral deposits and energy resources, references, and a correlation of map units. The text (in the report) describes the geology and resource potential of a highly mineralized region centered in the Farewell silver-lead-zinc district southeast of McGrath. Potentially important coal resources flanking the Alaska Range are also described in the map area.
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_Attribute_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 "RI1997-14_codeset.pdf." Layers include:
mcggeog_arc    geologic map unit contacts (arc)
mcggeog_poly    geologic map unit contacts (polygon)
mcgflt_arc    fault location traces and types
mcgglacial_arc    glacial extents
mcgcline_arc    anticline and syncline traces of axial planes
mcgdike_arc   dike locations and probable lengths
mcgstrsym_point    points for the strike, dip, and plunge of bedding planes, foliation, and various lineaments
mcgstrdip_point    point attribute table that displays strike and dip information
mcgmine_point    location of selected mineral deposits and energy resources
  1. How should this data set be cited?

    Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the Eastern Half of the McGrath Quadrangle, Alaska: Report of Investigations RI 97-14A, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, Alaska - USA.

    Online Links:

    Other_Citation_Details: 34 pp., 1 sheet, scale 1:125,000

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -154.628732
    East_Bounding_Coordinate: -152.883844
    North_Bounding_Coordinate: 63.025637
    South_Bounding_Coordinate: 61.962990

  3. What does it look like?

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

    Beginning_Date: 01-Jul-1980
    Ending_Date: 30-Jun-1997
    Currentness_Reference: June 20, 1997 (publication date)

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: map and 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: 5N
      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 0.000001
      Ordinates (y-coordinates) are specified to the nearest 0.000001
      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?

    mcggeog_arc.shp
    Object type is vector, there are 10,322 rows associated with this entity, and the entity values refer to geologic map unit contacts. (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    Line symbol for geologic map unit contacts (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    5Contact

    MERGECODE
    Used to notate contacts that are faults. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    CContact only
    FContact/fault

    mcggeog_poly.shp
    Object type is vector, there are 3221 rows associated with this entity, 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. Any unit ending with a "?" indicates uncertainty. (Source: Alaska Division of Geological and Geophysical Surveys)

    Formal codeset
    Codeset Name:RI1997-14_codeset.pdf
    Codeset Source:Alaska Division of Geological & Geophysical Surveys <http://www.dggs.dnr.state.ak.us/metadata/RI1997-14_codeset.pdf>

    MAT
    A unique three letter abbreviation given to each materials unit represented on the map. Materials units imply a hazards classification. (Source: Alaska Division of Geological and Geophysical Surveys)

    Formal codeset
    Codeset Name:RI1997-14_codeset.pdf
    Codeset Source:Alaska Division of Geological & Geophysical Surveys <http://www.dggs.dnr.state.ak.us/metadata/RI1997-14_codeset.pdf>

    mcgflt_arc.shp
    Object type is vector, there are 750 rows associated with this entity, and the entity values refer to fault location traces and types. (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    Types of faults found in the map area. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    11high-angle fault
    12Approximately located fault
    13Fault, inferred
    15Concealed fault
    17Thrust fault, sawteeth on upper plate
    33Lineament, used on small-scale tectonic maps

    MERGECODE
    Used to notate contacts that are faults. (Source: Alaska Division of Geological & Geophysical Surveys)

    ValueDefinition
    CContact only
    FContact/fault

    mcgglacial_arc.shp
    Object type is vector, there are 43 rows associated with this entity, and the entity values refer to glacial extents. (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    Ice limit advances-Increasing roman numerals depict maximum drift limits and numerical superscripts depict stages sequentially from oldest to youngest. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    42Glacial limit I, approximately located, first advance (oldest)
    44Glacial limit II, approximately located, second advance
    46Glacial limit III, approximately located, third advance
    48Glacial limit IV, approximately located, fourth advance
    50Glacial limit V, approximately located, fifth advance

    mcgcline_arc.shp
    Object type is vector, there are 319 rows associated with this entity, and the entity values refer to the anticline and syncline traces of axial planes. This coverage must be viewed with mcgstrsym layer to know what type of anticline or syncline is being represented by the arc. (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    A number representing the anticline or syncline trace. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    34Fold axis anticline or syncline.
    38Anticline or syncline, concealed.

    mcgdike_arc.shp
    Object type is vector, there are 375 rows associated with this entity, and the entity values refer to dike locations and probable lengths. (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    One of four numbers that represent dikes found in this map area. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    54Dikes
    55Dikes
    56Dikes
    57Dikes

    mcgstrdip_point.shp
    Object type is point, there are 656 rows associated with this entity, and the entity values refer to symbols for strike and dip information. (Source: Alaska Division of Geological & Geophysical Surveys)

    DIP
    Represents the dip angles used to produce the dip directions. (Source: Alaska Division of Geological and Geophysical Surveys)

    Range of values
    Minimum:0
    Maximum:90

    CODE
    Represents the symbols used to describe the strike and dips of beds, cleavage, joints, and foliation. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    1Strike and direction of dip of beds.
    4Strike and dip of overturned beds.
    5Strike of vertical beds, stratigraphic tops to north.

    X-COORD
    Represents the X-coordinates in UTM for each strike and dip location. (Source: Alaska Division of Geological and Geophysical Surveys)

    Range of values
    Minimum:422695.41
    Maximum:499879.98
    Units:meters

    Y-COORD
    Represents the Y-coordinates in UTM for each strike and dip location. (Source: Alaska Division of Geological and Geophysical Surveys)

    Range of values
    Minimum:6874551.19
    Maximum:6952135.66
    Units:meters

    mcgstrsym_point.shp
    Object type is point, there are 202 rows associated with this entity, and the entity values refer to symbols for folds, anticlines, synclines, and bedding features. This coverage must be viewed with mcgcline layer to know the trace of the anticline or syncline. (Source: Alaska Division of Geological & Geophysical Surveys)

    SYMBOL
    Used for differentiating structural symbol types. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    22Anticline and trace of axial plane.
    23Syncline and trace of axial plane.
    24Relative horizontal movement along fault
    25Relative horizontal movement along fault
    26overturned syncline, showing direction of dip of limbs
    27Overturned anticline, showing direction of dip of limbs
    39Provides direction of plunge.

    mcgmine_point.shp
    Object type is point, there are 38 rows associated with this entity, and the entity values refer to symbols for selected metallic mineral deposits and energy resources. (Source: Alaska Division of Geological & Geophysical Surveys)

    SYMBOL
    This attribute represents the location of selected mineral deposits and energy resources. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    143Specific symbol to designate sample locality.

    MINE
    Each number represents the sample location number of the selected mineral deposits and energy resources portrayed in Geologic Map of the Eastern Half of the McGrath Quadrangle, Alaska (Sheet 1). (Source: Alaska Division of Geological and Geophysical Surveys)

    These values represent the actual locality numbers given to each selected mineral deposits and energy resources. They coincide with Table 1 ("Name of Deposit") of the report Geologic Map of the Eastern Half of the McGrath Quadrangle, Alaska.


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 map synthesis was partially supported by the U.S. Geological Survey's National Mapping Program under cooperative agreement 1434-HQ-96-AG-01471. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. government. Additional Acknowledgments: Bedrock geology field investigations by T.K. Bundtzen (1980-1984,1988-1989,1993), W.G. Gilbert (1981-1984,1989), E.E. Harris (1988-1989,1993), D.N. Solie (1981-1982,1984,1988-1989), and J.T. Kline (1980-1982,1988-1989). Additional field contributions by M.S. Lockwood(1982-1983), J.G.Clough(1981,1983), T.E. Smith(1982-1983), Kate Bull (1981-1982), K.M. McDonald (1982), Kristin Kline (1981), D.B. Dickey (1981), John Ebel (1982), Larry Lueck (1980), G.M. Laird (1989), Grant Abbot (1989,1993), S.P. Gordey (1989), R.B. Blodgett (1982-1983,1989), D.J. Szumigala (1983), and Carolyn Parker (1983). Surficial geology field investigations by J.T. Kline (1980-1982,1988-89) and T.K. Bundtzen (1981-1984, 1988). Map synthesis and compilation by E.E. Harris and T.K. Bundtzen; Technical review by M.L. Miller and R.A. Combellick; Electronic digital cartography by A.M. McCarthy and G.R.C. Graham; Color design by Ann-Lillian Schell; Editing done by Paula K. Davis.

  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.dnr.state.ak.us> 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?

This project and resulting report, map and layers are intended to provide a geologic map and a geologic interpretation of the eastern half of the McGrath Quadrangle at 1:125,000 scale. Companies involved in or considering mineral exploration in the McGrath area will find this map useful, as well as persons examining the region's coal resources as a potential fuel for local heat and power development.


How was the data set created?

  1. From what previous works were the data drawn?

    Kline and Pinney, 1997 (source 1 of 7)
    Kline, J.T., and Pinney, D.S., 19970620, Derivative Map of the Geologic Materials and Hazards in the Eastern Half McGrath Quadrangle, Alaska: Report of Investigations RI 97-14B, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:125,000
    Type_of_Source_Media: paper map
    Source_Scale_Denominator: 125000
    Source_Contribution: See references cited in reports in RI 1997-14A and RI 1997-14B

    Fernald, 1960 (source 2 of 7)
    Fernald, A.T., 1960, Geomorphology of the Upper Kuskokwim Region, Alaska: U.S. Geological Survey Bulletin 1071-G B 1071-G, United States Government Printing Office, Washington, D.C..

    Online Links:

    Other_Citation_Details: p. 191-279, 2 sheets, scale 1:250,000
    Type_of_Source_Media: paper map and report
    Source_Scale_Denominator: 250000
    Source_Contribution:
    The geologic map synthesis has benefited from regional surficial geologic investigations provided in this bulletin.

    Kline and Bundtzen, 1986 (source 3 of 7)
    Kline, J.T., and Bundtzen, T.K., 1986, Two Glacial Records from West-Central Alaska: Geological Society of Alaska, Anchorage, AK, USA.

    Other_Citation_Details: p. 123-150
    This is part of the following larger work.

    T.D. Hamilton, eds., K.M. Reed, eds., and R.M. Thorson, eds., 1986, Glaciation in Alaska: the Geologic Record: Geological Society of Alaska, Anchorage, AK, USA.

    Type_of_Source_Media: book
    Source_Contribution:
    The geologic map synthesis has benefited from regional surficial geologic investigations provided in this publication.

    Reed and Lanphere, 1972 (source 4 of 7)
    Reed, B.L., and Lanphere, M.A., 1972, Generalized Geologic Map of the Alaska-Aleutian Range Batholith Showing Potassium-Argon Ages of the Plutonic Rocks: U.S. Geological Survey Miscellaneous Field Studies Map 372 MF-372, United States Government Printing Office, Washington, D.C..

    Online Links:

    Other_Citation_Details: 2 sheets, scale 1:1,000,000
    Type_of_Source_Media: paper map
    Source_Scale_Denominator: 1000000
    Source_Contribution:
    The geologic map synthesis has benefited from regional geologic mapping provided in this publication.

    Reed and Nelson, 1980 (source 5 of 7)
    Reed, B.L., and Nelson, S.W., 1980, Geologic Map of the Talkeetna Quadrangle, Alaska: U.S. Geological Survey Miscellaneous Investigations Map I-1174 I-1174, United States Government Printing Office, Washington, D.C..

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:250,000
    Type_of_Source_Media: paper map
    Source_Scale_Denominator: 250000
    Source_Contribution:
    The geologic map synthesis has benefited from regional geologic mapping provided in this publication.

    Herreid, 1968 (source 6 of 7)
    Herreid, G.H., 1968, Geological and Geochemical Investigations Southwest of Farewell, Alaska: Geologic Report GR 26, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 24 p., 2 sheets, scale 1:72,411
    Type_of_Source_Media: paper map
    Source_Scale_Denominator: 72411
    Source_Contribution:
    The geologic map synthesis has benefited from detailed mapping in the Windy Fork area provided in this publication.

    Churkin and Carter, 1996 (source 7 of 7)
    Michael Churkin, Jr., and Carter, Claire, 1996, Stratigraphy, Structure, and Graptolites of an Ordovician and Silurian Sequence in the Terra Cotta Mountains, Alaska Range, Alaska: U.S. Geological Survey Professional Paper 1555 P 1555, United States Government Printing Office, Washington, D.C..

    Online Links:

    Other_Citation_Details: 84 p., 4 sheets, scale 1:24,000
    Type_of_Source_Media: paper map and report
    Source_Scale_Denominator: 24000
    Source_Contribution:
    The geologic map synthesis has benefited from detailed mapping in the Terra Cotta Mountains provided in this publication.

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

    Date: 1997 (process 1 of 1)
    The coverages included in this project are digitized from a mylar compilation of geologic field maps produced on USGS topo bases of the area. Map unit (polygon) locations and attributes were checked by three reviewers familiar with the dominant geologic rock types and structures and/or the specific geology of the McGrath quadrangle area. Location data were determined visually using topographic maps at scales of 1:63,360 and 1:40,000 scale topographic maps using USGS map bases. Some stations were plotted on 1:63,360 scale Infra-Red and 1:40,000 scale black and white air photos during mapping. Because location information was acquired during the time period 1980-1992, GPS technology was not used to determine locations. Instead, geologic contacts, sample, and station locations were visually hand-plotted onto stable mylar bases from the field maps and in some instances, air photos.

  3. What similar or related data should the user be aware of?

    Kline, J.T., and Pinney, D.S., 1997, Derivative Map of the Geologic Materials and Hazards in the Eastern Half McGrath Quadrangle, Alaska: Report of Investigations RI 97-14B, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 1 sheet, scale 1:125,000
    Kline, J.T., and Bundtzen, T.K., 1986, Two Glacial Records from West-Central Alaska: Geological Society of Alaska, Anchorage, AK, USA.

    Other_Citation_Details: p. 123-150
    This is part of the following larger work.

    Hamilton, T.D. (ed.), Reed, K.M. (ed.), and Thorson, R.M. (ed.), 1986, Glaciation in Alaska: the Geologic Record: Geological Society of Alaska, Anchorage, AK, USA.

    Bundtzen, T.K., Kline, J.T., and Clough, J.G., 1982, Preliminary Geology of McGrath B-2 Quadrangle, Alaska: Alaska Open-File Report 149 AOF 149, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 25 pp., 1 sheet, scale 1:40,000
    Gilbert, W.G., Solie, D.N., Kline, J.T., and Dickey, D.B., 1990, Geologic Map of the McGrath B-3 Quadrangle, Alaska: Professional Report 102 PR 102, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 2 sheets, scale 1:63,360
    Bundtzen, T.K., Kline, J.T., Smith, T.E., and Albanese, M.D., 1987, Geologic Map of the McGrath A-2 Quadrangle, Alaska: Professional Report 91 PR 91, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 20 pp., 1 sheet, scale 1:63,360
    Gilbert, W.G., Solie, D.N., and Kline, J.T., 1988, Geologic Map of the McGrath A-3 Quadrangle, Alaska: Professional Report 92 PR 92, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 2 sheets, scale 1:63,360


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

  1. How well have the observations been checked?

    Data for geologic layers was digitized off of a mylar geologic compilation. This compilation was done on a stable mylar of the USGS topographic base for the McGrath Quadrangle, Alaska that was photographically enlarged to 1:125,000. (Topographic base compiled in 1965, revised in 1978, 1980, and 1982.) Geologic data included in the compilation are the field maps and notes from this project as well as data from other sources as noted in the "Sources Cited" section.

  2. How accurate are the geographic locations?

    Location data were determined visually using topographic maps at scales of 1:63,360 and 1:40,000 scale topographic maps using USGS map bases. Some stations were plotted on 1:63,360 scale Infra-Red and 1:40,000 scale black and white air photos during mapping. Because location information was acquired during the time period 1980-1992, GPS technology was not used to determine locations. Instead, geologic contacts, sample, and station locations were visually hand-plotted onto stable mylar bases from the field maps and in some instances, air photos. The lists of samples were visually checked against the lists of analyzed samples returned from the laboratories.

  3. How accurate are the heights or depths?

    Thommen TM altimeters were frequently used and calibrated daily.

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

    This data set includes coverages that contain information about geologic units, sample locations, structural features, structural measurements, dikes, selected mines, glacial limits, and materials units.

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

    Polygon topology present and clean on appropriate coverages. Other coverages are line, point, or annotation coverages and do not require topologic relationships. Chain-node topology present.


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.dnr.state.ak.us>) 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?

    Report of Investigation 97-14A

  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?

    Please check the MapInfo web site (<http://www.mapinfo.com/>) for the latest documentation on importing ESRI shape files.


Who wrote the metadata?

Dates:
Last modified: 06-May-2008
Last Reviewed: 06-May-2008
To be reviewed: 06-May-2010
Metadata author:
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
Metadata Manager
3354 College Road
Fairbanks, AK 99709-3707
USA

907-451-5039 (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 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 Tue May 06 16:56:12 2008