Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district

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Frequently-anticipated questions:


What does this data set describe?

Title:
Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district
Abstract:
The Alaska Division of Geological & Geophysical Surveys (DGGS) has conducted 1:63,360-scale geologic mapping of the Eagle A-1 Quadrangle.The area is part of the 100-year old Fortymile mining district and is located in eastern Alaska near the Alaska-Yukon border. This map illustrates the distribution of a variety of unconsolidated deposits and undifferentiated bedrock in the Eagle A-1 Quadrangle, Fortymile mining district. It was prepared by the interpretation of 1:63,360-scale, false-color, infrared aerial photographs taken from July 1978 through August 1981 and is locally verified by ground observations during field visits.The results should be considered reconnaissance in nature. The dominant unconsolidated deposit is colluvium, which mantles most surfaces other than the tops of ridges and those areas immediately adjacent to streams. Three levels of stream terrace can be traced along major drainages at elevations of roughly 200, 100, and 30 meters above modern streams. A fourth low terrace is limited to the southwest part of the map area. Pleistocene mammalian remains have been recovered from ice-rich organic silt and muck overlying placer gravels in many valleys.
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. Basic unit information is also included in the geologic unit code set file "PIR2002-1C_codeset.csv". There are two layers. Each layer is listed and described in detail under its own heading starting "Entity_Type_Label." Layers include:
eaga1srfgeo2	polygons of surficial-geologic map units
eaga1srfcont	lines showing contacts of surficial-geologic map units
eaga1pingo	points showing locations of pingos
eaga1border	outline shape of the study area
  1. How should this data set be cited?

    Stevens, D.S.P, and Burns, P.A.C., 200206, Surficial-geologic map of the Eagle A-1 Quadrangle, Fortymile mining district: Preliminary Interpretive Report PIR 2002-1C, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

    Other_Citation_Details: 1 sheet, 1:63,360 scale

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -141.504512
    East_Bounding_Coordinate: -141.000000
    North_Bounding_Coordinate: 64.250853
    South_Bounding_Coordinate: 63.999139

  3. What does it look like?

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

    Beginning_Date: 1999
    Ending_Date: 2002
    Currentness_Reference: publication date

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

    Geospatial_Data_Presentation_Form: vector digital data, 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):

      • Complete chain (4134)
      • GT-polygon composed of chains (1504)

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 7
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -141.000
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000
      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.000254
      Ordinates (y-coordinates) are specified to the nearest 0.000254
      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 1/294.978698.

  7. How does the data set describe geographic features?

    eaga1srfgeo2.shp
    Polygons of surficial-geologic map units. (Source: This report.)

    UNIT
    Geologic unit (Source: DGGS)

    Formal codeset
    Codeset Name:PIR2002-1c_codeset.csv
    Codeset Source:Alaska Division of Geological & Geophysical Surveys

    eaga1srfcont.shp
    Lines showing contacts of surficial-geologic map units. (Source: This report.)

    JUSTBED
    Geologic Unit (Source: DGGS)

    Formal codeset
    Codeset Name:PIR2002-1C_codeset.csv
    Codeset Source:Alaska Division of Geological & Geophysical Surveys

    eaga1pingo.shp
    Points showing locations of pingos. (Source: This report.)

    EAGA1PINGO
    number assigned to each pingo (Source: this report)

    populated with values 1 and 2, this is an arbritrary number assigned to each pingo locality

    eaga1border.shp
    Outline shape of the study area. (Source: This report.)


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?

    The geologic work was funded by the Alaska State Legislature through a Capital Improvement Project (Alaska Airborne Geophysical/Geological Mineral Inventory Program) and the general fund and through the U.S. Geological Survey STATEMAP program under U.S. Department of the Interior, U.S. Geological Survey, National Cooperative Geologic Mapping Program assistance award 01HQAG0054. 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. DGGS student interns and volunteers providing field assistance include Bryan A. Finseth (1999), Mark Mccrary (1999), J.C.Grady (2000), W.C. Munley (2000), and M.R. Johnson (2001).Milton A. Wiltse provided technical review of the maps. Jessica Mayer provided assistance with surficial geologic studies.

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

    State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
    geologist in the Minerals Section at DGGS
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    907-451-5010 (voice)
    907-451-5050 (FAX)
    dggspubs@dnr.state.ak.us

    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.


Why was the data set created?

The purpose of the project was to produce a series of 1:63,360-scale geologic maps for a portion of the Fortymile mining district. The geologic data is important for characterizing and distinguishing between geologic units.Previously published 1:63,360-scale geologic maps of this area have been reconnaissance-level maps or only covered portions of the quadrangle.Mapping at 1:63,360 scale or greater detail is needed to identify critical geologic features that may relate to more regional geologic units. The Fortymile project is part of DGGS's Airborne Geophysical and Geological Mineral Inventory Program (AGGMI), a special multi-year investment by the State of Alaska to produce framework geologic maps that will expand the knowledge base of Alaska's geologic and mineral resources, catalyze future private-sector mineral exploration and development, and guide government agencies' planning.


How was the data set created?

  1. From what previous works were the data drawn?

    Yeend, 1996 (source 1 of 2)
    Yeend, Warren, 1996, Gold placers of the historical Fortymile River region, Alaska: U.S. Geological Survey Bulletin B 2125, United States Government Printing Office, Washington D.C..

    Other_Citation_Details: 74 p., 1 sheet
    Type_of_Source_Media: paper
    Source_Contribution: Geologic map compilation

    Weber, 1986 (source 2 of 2)
    Weber, F.R., 1986, Glacial geology of the Yukon-Tanana Upland: Alaska Geological Society, Anchorage, AK.

    Other_Citation_Details: 20 p. 79-98
    This is part of the following larger work.

    Hamilton, T. D., Reed, Katherine M., and Thorson, R.M., 1986, Glaciation in Alaska - Tthe geologic record: Alaska Geological Society, Anchorage, AK, United States.

    Other_Citation_Details: 265 p.
    Type_of_Source_Media: paper
    Source_Contribution: Geologic map compilation

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

    Date: 2001 (process 1 of 4)
    Fieldwork - Fieldwork for surficial investigations, including traverses, roadcut investigations, and river exposures, was conducted for 60 person-days during the months of June through August in 1999 - 2001. Field notes and sediment samples were collected throughout the quadrangle for surficial investigations. Surficial mapping involved using Yeend (1996) on a regular basis for checking placer geology and general units. Surficial mappers recorded observations on co-registered acetate overlays on 1:50,000-scale (nominal) color-infrared aerial photographs, and directly on 1:63,360-scale topographic base maps. Stations were located using air photos and handheld GPS devices with location precision varying from ±3 to 15 meters.

    Data sources used in this process:

    • Yeend, 1996
    • Weber, 1986

    Date: 2002 (process 2 of 4)
    Geologic map compilation - Surficial-geologic information was interpreted using 1:50,000-scale (nominal) air-photo stereopairs, and compiled onto acetate overlays. The overlay information was transferred to a paper 1:63,360-scale USGS topographic base using a zoom transfer scope.

    Date: 2002 (process 3 of 4)
    Surficial-geologic information was digitized from the paper USGS topographic base map (above) into Arc/Info 7.0.4 GIS (ArcEdit module) using a large-format digitizing table. Surficial-geologic polygons and lines were then edited and attributed using Arc, Info, and ArcEdit. Bedrock point data (see DGGS PIR 2002-1B) of locations of structural observations (strike, dip, cleavage, jointing, etc.) and "rubblecrop" were intersected with the surficial-geologic polygon coverage using the Arc command "intersect" in order to identify locations that were mapped as surficial materials based on aerial photography but were found to have small exposures that were desireable to be mapped as bedrock.These areas were then modified in the surficial-geologic coverages to be areas of bedrock exposure. Final bedrock and surficial geology polygon coverages were merged using the Arc command "union" to generate the polygon coverage used to make PIR 2002-1a, the comprehensive geologic map.

    Date: 2010 (process 4 of 4)
    Metadata creation - metadata for this report was compiled by Patricia Gallagher, Simone Montayne, and De Anne Stevens

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

    Szumigala, D.J., Newberry, R.J, Werdon, M.B., Athey, J.E., Stevens, D.S.P., Flynn, R.L., Clautice, K.H., and Craw, P.A., 200206, Geologic map of the Eagle A-1 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2002-1a, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Szumigala, D.J., Newberry, R.J., Werdon, M.B., Athey, J.E., Flynn, R.L, and Clautice, K.H., 200206, Bedrock geologic map of the Eagle A-1 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2002-1b, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 1 sheet, 1:63,360 scale
    Werdon, M.B., Newberry, R.J., Szumigala, D.J., and Pinney, D.S., 2001, Geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3a, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Werdon, M.B., Newberry, R.J., and Szumigala, D.J., 2001, Bedrock geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3b, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Pinney, D.S., 2001, Surficial-geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3c, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Pinney, D.S., 2001, Engineering-geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, Alaska: Preliminary Interpretive Report PIR 2001-3d, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 1 sheet, scale 1:63,360
    Szumigala, D.J., Newberry, R.J., Werdon, M.B., Finseth, B.A., Pinney, D.S., and Flynn, R.L., 2000, Major-oxide, minor-oxide, trace-element, and geochemical data from rocks collected in a portion of the Fortymile mining district, Alaska, 1999: Raw Data File RDF 2000-1, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 26 p., 2 sheets, scale 1:63,360
    Werdon, M.B., Szumigala, D.J., Newberry, R.J., Grady, J.C., and Munly, W.C., 2000, Major-oxide, minor-oxide, trace-element, rare-earth element and geochemical data from rocks collected in Eagle and Tanacross quadrangles, Alaska in 2000: Raw Data File RDF 2000-4, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 27 pages, 3 sheets, 1:63,360 scale
    Szumigala, D.J., Werdon, M.B., Newberry, R.J., Athey, J.E., Clautice, K.H., Flynn, R.L., Grady, J.C., Munly, W.C., and Johnson, M.R., 200206, Major-oxide, minor-oxide, trace-element, rare-earth element, trace geochemical, and coal quality data from rocks collected in Eagle and Tanacross quadrangles, Alaska in 1999, 2000, and 2001: Raw Data File RDF 2002-1, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 33 pages, 1 sheet, 1:63,360 scale
    Burns, L.E., Dighem, and Stevens Exploration Management Corp., 1999, CD-ROM containing profile and gridded data and section lines of 1998 geophysical survey data for part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangles: Public-Data File PDF 99-9, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 2 CD-ROMs
    Pritchard, R.A., and Dighem, 1999, Project report of the 1998 geophysical survey data for part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangles: Public-Data File PDF 99-7, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 162 p., 2 sheets, scale 1:63,360
    Burns, L.E., and Liss, Shirley, 1999, Portfolio of aeromagnetic and resistivity maps of part of the Fortymile mining area, Alaska: Public-Data File PDF 99-6, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Other_Citation_Details: 20 p., 1 sheet.


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

  1. How well have the observations been checked?

    Certainty in identification of the map units varies due to the scale and interpretive nature of the mapping. The geologic unit interpretations and boundaries presented in this report result from investigative traverses throughout the map area as well as examination of roadcuts and river exposures. Surficial-geologic polygons and lines were edited and attributed using Arc, Info, and ArcEdit. Bedrock point data of locations of structural observations (strike, dip, cleavage, jointing, etc.) and "rubblecrop" were intersected with the surficial-geologic polygon coverage using the Arc command "intersect" in order to identify locations that were mapped as surficial materials based on aerial photography but were found to have small exposures that were desireable to be mapped as bedrock. These areas were then modified in the surficial-geologic coverages to be areas of bedrock exposure. See process steps for more information about the mapping and GIS methodology. This report has received two technical reviews by scientists familiar with the subject matter. We incorporated the reviewer's suggestions into the final draft when deemed appropriate.

  2. How accurate are the geographic locations?

    Surficial-geologic map data has a horizontal positional accuracy dependent on: 1) the 1:50,000-scale (nominal) aerial photographs on which it is based, with an estimated potential error due to a pen line width of approximately 0.001 being equivalent to approximately 1.5 meters on the ground; 2) the accuracy of the human zoom transfer scope operator in tracing the linework from acetate overlays to topographic base maps, with an estimated error due to a pen line width of approximately 0.001 being equivalent to approximately 1.5 meters on the ground; 3) the accuracy of the zoom transfer process itself, error magnitude highly variable and unknown but potentially large; 4) the digitizing RMS error of 0.003 inches (input coverage units), which equates to approximately 5 meters on the ground for a 1:63,360-scale map; and 5) the accuracy of the human operator digitizing the geologic linework from the topographic base maps, with an estimated error due to a pen line width of approximately 0.001 being equivalent to approximately 1.5 meters on the ground. Total potential horizontal error for surficial-geologic map features is therefore 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?

    The data set utilizes field observations and air photo interpretations to locate and characterize the geologic unit extent and features. It includes geospatial information about units traceable on air photos at a scale of ~1:65000 and/or in the field. Potential radiocarbon and tephra samples were collected in the field area but not analyzed.

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

    Polygon topology is present and clean on the original geospatial dataset. All polygon features were topologically validated using ArcInfo software prior to export to shapefile format.


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
    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?

  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. Is there some other way to get the data?

    DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media over the counter by mail, phone, fax, or email from the DGGS Fairbanks office.Turn around time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for a exact shipping ammount.


Who wrote the metadata?

Dates:
Last modified: 04-Oct-2010
Metadata author:
Metadata manager
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys
Fairbanks, AK 99709-3707
USA

907-451-5020 (voice)

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


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