Geologic Map of the Anchorage C-7 NW Quadrangle, Alaska

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Frequently-anticipated questions:


What does this data set describe?

Title: Geologic Map of the Anchorage C-7 NW Quadrangle, Alaska
Abstract:
This map is one of a series of four 1:25,000-scale quadrangle maps (Anchorage C-7 NW Quadrangle) intended to provide information on the geology and construction materials along the southern margin of the Talkeetna Mountains between Little Susitna River and Nancy Lake, Alaska. Additionally, the geologic map portrays faults, if present, as well as other lineaments that represent either faults or erosional features.
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 "RI1994-24-27_codeset.pdf." Layers include:
ancc7nwflt2_arc    fault location traces (arc)
ancc7nwflt2_point    fault location types (point)
ancc7nwgeo2_arc    geologic unit boundaries (arc)
ancc7nwgeo2_polygon    geologic units (polygon)
ancc7nwsack2_arc    sackung failure in bedrock (arc)
ancc7nwsack2_polygon    sackung failure in bedrock (polygon)
c7nwdip_point    strike and dip information
  1. How should this data set be cited?

    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Geologic Map of the Anchorage C-7 NW Quadrangle, Alaska: Report of Investigation RI 94-25, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, Alaska - USA.

    Online Links:

    Other_Citation_Details: sheet 1 of 2, scale 1:25,000

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -149.635768
    East_Bounding_Coordinate: -149.427691
    North_Bounding_Coordinate: 61.753465
    South_Bounding_Coordinate: 61.621521

  3. What does it look like?

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

    Beginning_Date: 1980
    Ending_Date: 1994
    Currentness_Reference: publication date

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

    Geospatial_Data_Presentation_Form: tabular digital data, map, 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: 6
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -147.000
      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 0.000032
      Ordinates (y-coordinates) are specified to the nearest 0.000032
      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?

    ancc7nwgeo2_arc.shp
    Object type is vector, there are 668 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
    1Contact

    ancc7nwgeo2_polygon.shp
    Object type is vector, there are 276 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:RI1994-24-27_codeset.pdf
    Codeset Source:Alaska Division of Geological & Geophysical Surveys <http://www.dggs.alaska.gov/metadata/RI1994-24-27_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:RI1994-24-27_codeset.pdf
    Codeset Source:Alaska Division of Geological & Geophysical Surveys <http://www.dggs.alaska.gov/metadata/RI1994-24-27_codeset.pdf>

    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:360979.4
    Maximum:371214.3
    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:6834746
    Maximum:6848709
    Units:meters

    ancc7nwflt2_arc.shp
    Object type is vector, there are 44 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
    1Contact
    2Contact, approximate
    3Scarp, barb on lower side
    5Trough, may be ice-marginal channel at lower elevations
    6Photolineament with no topographic expression evident in aerial photographs. Generally visible as a color or density contrast in vegetation.

    c7nwdip_point.shp
    Object type is point, there are 38 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 and foliation. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    1Strike and dip of foliation. Also shown as SYMBOL=105.
    2Dip is equal to zero. Also shown as SYMBOL=112.
    3Strike and dip of beds. Also shown as SYMBOL=101.

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

    ValueDefinition
    101Strike and dip of beds. Also shown as CODE=3.
    105Strike and dip of foliation. Also shown as CODE=1.
    112Dip is equal to zero. Also shown as CODE=2.

    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:364018.304525507
    Maximum:371181.671787229
    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:6838020.78915279
    Maximum:6848152.14758965
    Units:meters

    ancc7nwsack2_arc.shp
    Object type is vector, there are 2 rows associated with this entity, and the entity values refer to polygons showing sackung failure in bedrock. (Source: Alaska Division of Geological & Geophysical Surveys)

    CODE
    Represents the areas of the sackung failures in bedrock. (Source: Alaska Division of Geological and Geophysical Surveys)

    ValueDefinition
    0Disregard. Drawing line for boundary.
    1Polygon showing extent of sackung.

    ancc7nwsack2_polygon.shp
    Object type is vector, there 1 row associated with this entity, and the entity value refers to a polygon showing a sackung failure in bedrock. Note: This feature wasn't assigned any user defined attribute. Sackung feature shown on map as polygon outline filled with stippled pattern. (Source: Alaska Division of Geological & Geophysical Surveys)

    ancc7nwflt2_point.shp
    Object type is vector, there are 3 rows associated with this entity, and the entity values refer to fault location traces and types. There are no attributes associated with this entity. (Source: Alaska Division of Geological & Geophysical Surveys)


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?

    Preparation of these maps was supported in part by the U.S. Geological Survey through the STATEMAP component of the National Cooperative Geologic Mapping Program. Additional Acknowledgments: Field assistance provided by Cheri Daniels, Kristin Kline, and Gina Cruse. Reviewed by Jim Clough and Jeff Kline.

  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
    USA

    (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?

This series of maps supplements an earlier series of similar maps for the adjacent area to the south between Palmer and Big Lake. A separate geologic-materials map was developed to show the probable distribution of materials with certain ranges of grain sizes, and their relative abundance, because the area is rich in geologic materials that may be useful for construction. It is an important source of construction aggregates for the region, because of extensive glaciofluvial deposits in the area. Additionally, the Castle Mountain fault, which is known to be active, traverses the area of the current series of maps. Although the fault is easily distinguishable in areas immediately to the east and west of the area mapped in this series, it is largely obscured here by surficial deposits and vegetation. We present on these maps the best known surface evidence for faults and possibly fault-related lineaments.


How was the data set created?

  1. From what previous works were the data drawn?

    Clardy (1984) (source 1 of 9)
    Clardy, B.I., 1984, Bedrock Geologic Features of the Matanuska Valley:.

    Other_Citation_Details: p. 33-44, 1 sheet, scale 1:96,000
    This is part of the following larger work.

    Clardy, B.I., Hanley, P.T., Hawley, C.C., and LaBelle, J.C., 1984, Guide to the Bedrock and Glacial Geology of the Glenn Highway, Anchorage to the Matanuska Glacier and the Matanuska Coal Mining District: Alaska Geological Society, Anchorage, AK, USA.

    Type_of_Source_Media: Map and report
    Source_Scale_Denominator: 96000
    Source_Contribution: See this publication cited in the Process Step section below.

    Csejtey and others (1979) (source 2 of 9)
    Csejtey Jr., B., and Evarts, R.C., 1979, Serpentinite Bodies in the Willow Creek District, Southwestern Talkeetna Mountains, Alaska: U.S. Geological Survey Circular 804B, United States Government Printing Office, Washington D.C., Maryland.

    Other_Citation_Details: p. 92-93
    This is part of the following larger work.

    Johnson, K.M. (ed.), and Williams, J.R. (ed.), 1979, The United States Geological Survey in Alaska: Accomplishments During 1978.

    Type_of_Source_Media: paper
    Source_Contribution: See this publication cited in the Process Step section below

    Csejtey and others (1978) (source 3 of 9)
    Csejtey Jr., B., Nelson, W.H., Jones, D.L., Silberman, N.J., Dean, R.M., Morris, M.S., Lanphere, M.A., Smith, J.G., and Silberman, M.L., 1978, Reconnaissance Geologic Map and Geochronology, Talkeetna Mountains Quadrangle, Northern Part of Anchorage Quadrangle, and Southwestern Corner of Healy Quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-558A.

    Other_Citation_Details: 60 pp., 1 sheet, scale 1:250,000
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 250000
    Source_Contribution: See this publication cited in the Process Step section below

    Csejtey and others (1975) (source 4 of 9)
    Csejtey Jr., B., and Smith, J.G., 1975, Petrography, Tentative Age, and Correlation of Schist, Willow Creek, Talkeetna Mountains, Southern Alaska: U.S. Geological Survey Circular 722.

    Other_Citation_Details: p. 48
    This is part of the following larger work.

    Yount, M.E. (ed.), 1975, United States Geological Survey Alaska Program, 1975.

    Type_of_Source_Media: paper
    Source_Contribution: See this publication cited in the Process Step section below

    Madden and others (1987) (source 5 of 9)
    Madden, D.J., Silberman, M.L., and Morre-Nall, A., 1987, Ages and Geologic Relationships in the Willow Creek Gold Mining District, Southwestern Talkeetna Mountains, Southern Alaska: U.S. Geological Survey Open-File Report 87-143.

    Other_Citation_Details: 12 pp.
    Type_of_Source_Media: paper
    Source_Contribution: See this publication cited in the Process Step section below

    Magoon and others (1976) (source 6 of 9)
    Magoon, L.B., Adkison, W.L., and Egbert, R.M., 1976, Map Showing Geology, Wildcat Wells, Tertiary Plant Fossil Localities, K-Ar Age Dates, and Petroleum Operations, Cook Inlet Area, Alaska: U.S. Geological Survey Miscellaneous Investigations Map I-1019.

    Other_Citation_Details: 3 sheets, scale 1:250,000
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 250000
    Source_Contribution: See this publication cited in the Process Step section below

    Ray (1954) (source 7 of 9)
    Ray, R.G., 1954, Geology and Ore Deposits of the Willow Creek Mining District, Alaska: U.S. Geological Survey Bulletin 1004.

    Other_Citation_Details: 86 pp.
    Type_of_Source_Media: paper
    Source_Contribution: See this publication cited in the Process Step section below

    Silberman and others (1978) (source 8 of 9)
    Silberman, M.L., OLeary, R.M., Csejtey Jr., B., Smith, J.G., and Connor, C.L., 1978, Geochemical Anomalies and Isotopic Ages in the Willow Creek Mining District, Southwestern Talkeetna Mountains, Alaska: U.S. Geological Survey Open-File Report 78-223.

    Other_Citation_Details: 33 pp.
    Type_of_Source_Media: paper
    Source_Contribution: See this publication cited in the Process Step section below

    Winkler (1992) (source 9 of 9)
    Winkler, G.R., 1992, Geologic Map and Summary Geochronology of the Anchorage 1 x 3 Quadrangle, Southern Alaska: U.S. Geological Survey Miscellaneous Investigations Map I-2283.

    Other_Citation_Details: 1 sheet, scale 1:250,000
    Type_of_Source_Media: paper
    Source_Scale_Denominator: 250000
    Source_Contribution: See this publication cited in the Process Step section below

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

    Date: 1994 (process 1 of 1)
    Geologic map preparation - Data collection for this series of maps took place over approximately a 15-year period from 1980 to 1994. The geologic map was developed by first interpreting landforms and photolineaments on color and false-color infrared photographs. These deposits and features were then verified, described, and sampled during field inspections. Additionally, information on bedrock geology was compiled from the literature and verified and mapped in the field. Finally, the bedrock and surficial geology were combined into a single draft map and digitized. The geologic-materials map was derived digitally from the geologic map on the basis of field observations that indicate that each geologic unit has a definite composition or range of composition. Therefore, the delineation of materials units was interpreted from the geologic map by using a simple conversion matrix to combine and translate geologic units into materials units. Much of the initial landform interpretation and mapping of geologic contacts and lineaments resulted from analysis of color and false-color infrared vertical aerial photographs. Color aerial photographs used in this interpretation were taken in 1973, 1981, 1982, and 1986 at scales of 1:12,000, 1:18,000, and 1:24,000. False-color infrared images were collected by NASA in 1984 and 1993 at a scale of approximately 1:60,000. Bedrock-geologic data were compiled from the following sources: Clardy (1984), Csejtey and others (1978), Csejtey and others (1979), Csejtey and Smith (1975), Madden and others (1987), Magoon and others (1976), Ray (1954), Silberman and others (1978), and Winkler (1992). Field work was conducted in 1980, 1981, 1988, 1993, and 1994 to verify photointerpretation, map bedrock-unit contacts, and examine the deposits to accurately describe their content. Finally, the draft geologic map units were digitized using geographic information system (GIS) software. The resulting polygons were assigned appropriate colors, labeled, and layered with a digital image of the corresponding U.S. Geological Survey topographic quadrangle map to produce the published geologic map. The USGS topographic base map was produced in 1979 and revised in 1993.

    Data sources used in this process:

    • Clardy (1984)
    • Csejtey and others (1978)
    • Csejtey and others (1979)
    • Csejtey and Smith (1975)
    • Madden and others (1987)
    • Magoon and others (1976)
    • Ray (1954)
    • Silberman and others (1978)
    • Winkler (1992)

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

    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Geologic Map of the Anchorage C-7 NE Quadrangle, Alaska: Report of Investigation RI 94-24, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: Sheet 1 of 2 sheets, scale 1:25,000
    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Derivative Materials Map of the Anchorage C-7 NE Quadrangle, Alaska: Report of Investigation RI 94-24, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: Sheet 2 of 2 sheets, scale 1:25,000
    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Derivative Materials Map of the Anchorage C-7 NW Quadrangle, Alaska: Report of Investigation RI 94-25, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: Sheet 2 of 2 sheets, scale 1:25,000
    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Geologic Map of the Anchorage C-8 NE Quadrangle, Alaska: Report of Investigation RI 94-26, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: Sheet 1 of 2 sheets, scale 1:25,000
    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Derivative Materials Map of the Anchorage C-8 NE Quadrangle, Alaska: Report of Investigation RI 94-26, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: Sheet 2 of 2 sheets, scale 1:25,000
    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Geologic Map of the Anchorage C-8 NW Quadrangle, Alaska: Report of Investigation RI 94-27, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: Sheet 1 of 2 sheets, scale 1:25,000
    Reger, R.D., Combellick, R.A., and Pinney, D.S., 1994, Derivative Materials Map of the Anchorage C-8 NW Quadrangle, Alaska: Report of Investigation RI 94-27, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK.

    Online Links:

    Other_Citation_Details: Sheet 2 of 2 sheets, scale 1:25,000


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 in the field using 1:63,360-scale topographic maps and 1:50,000 (nominal) scale, color-infrared aerial photographs. The surficial-geologic information was transferred from acetate air-photo overlays to a paper 1:63,360-scale USGS topographic base using a zoom transfer scope. The surficial-geologic information was then digitized into Arc/Info GIS (ArcEdit module) using a large-format digitizing table with RMS registration errors constrained to be no larger than 0.003 inches (input coverage units) for each digitizing session. 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 a scale of 1:63,360 and 1:50,000 (nominal) scale, and color-infrared aerial photographs.

  3. How accurate are the heights or depths?

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

    This dataset includes geospatial information related to geologic units, age and field sample locations, structural features, structural measurements, and fault locations.

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

    Polygon topology present and clean on appropriate data. Other data are line, point, or annotation data 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 data set 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 data sets utilizing these data sets 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 data sets, 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?

    Report of Investigation 94-25

  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: 05-Mar-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

907-451-5039 (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 14:29:37 2008