Preliminary integrated geologic map databases for the United States: Digital data for the reconnaissance geologic map of the western Aleutian Islands, Alaska

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Frequently-anticipated questions:

What does this data set describe?
    Title:
    Preliminary integrated geologic map databases for the United States: Digital data for the reconnaissance geologic map of the western Aleutian Islands, Alaska
    Abstract:
    This data set represents a reconnaissance geologic map of the western Aleutian Islands, from Great Sitkin and Umak Islands to Attu Island, spanning approximately 500km. This compilation was built from geologic mapping over the past 50 years and presented in a variety of scales. This data set is presented for use at a nominal scale of 1:500,000, although individual datasets herein may contain data for use at a larger scale.

    This data set is a portion of a statewide geology database, which is being compiled by the U.S. Geological Survey's National Surveys and Analysis (NSA) project, whose goal is to compile geologic, geochemical, geophysical, and other data.

  1. How should this data set be cited?

    Wilson, Frederic H. , Mohadjer, Solmaz, Labay, Keith A. , and Shew, Nora, 2006, Preliminary integrated geologic map databases for the United States: Digital data for the reconnaissance geologic map of the western Aleutian Islands, Alaska: U.S. Geological Survey Open-File Report OFR 2006-1302.

    Online Links:

    This is part of the following larger work.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: 172.0
    East_Bounding_Coordinate: -176.0
    North_Bounding_Coordinate: 53.25
    South_Bounding_Coordinate: 51.25

  3. What does it look like?

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

    Calendar_Date: 2006
    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?

      This is a Vector 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: 59
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: 171.0
      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 0.000256
      Ordinates (y-coordinates) are specified to the nearest 0.00256
      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 1/294.9787.

  7. How does the data set describe geographic features?

    polygons
    Characteristics of the polygon features in the geology coverages are coded in the polygon attribute table. The table <cov>.pat includes the following items: CLASS, NSACLASS, NSAMOD, QCLASS (not used), SOURCE, LABEL, MIN_AGE, and MAX_AGE. (Source: This data set)

    NSACLASS
    NSACLASS is a positive integer value (4 5 B) item in the polygon attribute table. Values range discontinuously from 0 to 1153. NSACLASS is a numeric code for the geologic unit. This data set represents a generalized map, this it is possible that a geologic unit is made of multiple NSACLASS values. Each NSACLASS matches with geologic unit labels in LABEL and has a minimum (MIN_AGE) and maximum (MAX_AGE) range, given in million of years (my). Supplemental attribute tables included with this data set, contain descriptive information of each geologic unit. A user may use items SOURCE and CLASS to retrieve information about the original units from which these generalized units were formed. NOTE: Because of the limitations of common GIS fonts, the letters "Mz" are substituted for the standard symbol for "Mesozoic." (Source: This data set.)

    ValueDefinition
    98not mapped
    99bedrock unknown
    100Qs - Surficial deposits, undivided (Quaternary)
    101ice
    102water
    105Qa - Alluvium (Quaternary)
    106Qf - Alluvial fan deposits (Quaternary)
    107Qc - Colluvial deposits (Quaternary)
    108Qls - Landslide and mudflow deposits (Quaternary)
    110Qa - Alluvium (Quaternary)
    112Qa - Alluvium (Quaternary)
    113Qsw - Swamp deposits (Quaternary)
    115Qb - Beach deposits (Quaternary)
    116Qs - Surficial deposits, undivided (Quaternary)
    120Qd - Eolian deposits (Quaternary)
    125Qg - Glacial deposits, undivided (Quaternary)
    170Qa - Alluvium (Quaternary)
    282QTs - Older silt, sand, and gravel (Quaternary or Tertiary)
    284QTs - Older silt, sand, and gravel (Quaternary or Tertiary)
    290QTf - Faneto Formation (early Pleistocene or late Tertiary)
    295Qhdd - Anthropogenic deposits (Holocene)
    300Qvu - Volcanic rocks and deposits, undivided (Quaternary)
    305Qv - Younger volcanic rocks (Quaternary)
    306Qba - Basalt and andesite domes (Quaternary)
    310Qp - Pyroclastic rocks (Quaternary)
    311Qat - Ash and tephra deposits (Quaternary)
    313Ql - Lahar and debris avalanche deposits (Quaternary)
    314Ql - Lahar and debris avalanche deposits (Quaternary)
    317Qsp - Sitkin Point Formation and similar rocks (Quaternary)
    320Qvd - Vent volcanic rocks and deposits (Quaternary)
    330Qvd - Vent volcanic rocks and deposits (Quaternary)
    335Qep - East Point Formation (Quaternary)
    336Qdd - Little Sitkin Dacite and Double Point Dacite, undivided (Quaternary)
    350QTv - Basalt plugs and associated breccia (Quaternary and Tertiary)
    355Qvu - Volcanic rocks and deposits, undivided (Quaternary)
    402Qvu - Volcanic rocks and deposits, undivided (Quaternary)
    404Qvu - Volcanic rocks and deposits, undivided (Quaternary)
    450QTv - Older volcanic rocks, undivided (Quaternary and Tertiary)
    451QTv - Older volcanic rocks, undivided (Quaternary and Tertiary)
    454QTob - Olivine basalt flows (Quaternary and Tertiary)
    460QTv - Older volcanic rocks, undivided (Quaternary and Tertiary)
    462QTqk - Quartz-keratophyre dikes (Quaternary and Tertiary)
    463QTha - Hornblende andesite and dacite (Quaternary and Tertiary)
    466QTv - Older volcanic rocks, undivided (Quaternary and Tertiary)
    470QTv - Older volcanic rocks, undivided (Quaternary and Tertiary
    475QTkh - Kiska Harbor Formation (Quaternary? and late Tertiary)
    476QTkb - Kiska Harbor Formation, breccia member (Quaternary? and late Tertiary)
    477QTkf - Kiska Harbor Formation, flow member (Quaternary? and late Tertiary)
    572Tch - Chuniksak Formation and similar rocks (Miocene)
    610Tc - Chirikof Formation (Miocene?)
    650Tn - Nevidiskov Formation (early Miocene? or late Oligocene?)
    750Tgc - Gunners Cove Formation (Tertiary)
    751Tbp - Banjo Point Formation (Oligocene or late Eocene)
    800Tal - Andrew Lake Formation and similar rocks (late Eocene)
    1010Tid - Dikes and hypabysssal intrusive rocks (Tertiary)
    1011Tid - Dikes and hypabyssal intrusive rocks (Tertiary)
    1012Tid - Dikes and hypabyssal intrusive rocks (Tertiary)
    1050Tcp - Chitka Point Formation (Miocene)
    1051Tid - Dikes and hypabyssal intrusive rocks (Tertiary)
    1066Tlp - Lavas and pyroclastic deposits, undifferentiated (Tertiary)
    1080Tvb - Vega Bay Formation (Tertiary)
    1081Tvo - Finger Bay Volcanics and similar rocks (Tertiary)
    1094TMzkv - Krugloi Formation, tuff and lava (early Tertiary or late Mesozoic?)
    1095TMzkv - Krugloi Formation, tuff and lava (early Tertiary or late Mesozoic?)
    1096TMzbv - Volcanic rocks (early Tertiary or late Mesozoic?)
    1203Tagr - Albite granite (Tertiary)
    1207Td - Diabase and gabbro (Tertiary)
    1250Tqgd - Younger quartz diorite and granodiorite (Miocene)
    1292Tgd - Older granodiorite, quartz diorite, and gabbro (Tertiary)
    1530TMzk - Krugloi Formation (early Tertiary or late Mesozoic?)
    1540TMzkc - Coarse-grained and conglomeratic sedimentary rocks (early Tertiary or late Mesozoic?)
    1550TMzu - Basement rocks, undifferentiated (early Tertiary or late Mesozoic?)
    1552TMzf - Fine-grained sedimentary rocks (early Tertiary or late Mesozoic?)
    1553TMzc - Coarse-grained and conglomeratic sedimentary rocks (Early Tertiary or late Mesozoic?)

    NSAMOD
    NSAMOD is a character (8 10 C) item in the polygon attribute table. (Source: this data set)

    ALT - hydrothermal alteration HFS - contact metamorphism, hornfels Q - queried unit

    SOURCE
    SOURCE is a character (6 8 C) item found in both the arc and polygon attribute tables. The values are abbreviated codes representing the original source reference for the arc or polygon feature. The format for SOURCE is XX###, where XX is a two letter code for the 1:250,000 scale quadrangle and ### is a three digit number (with leading zeros). All source codes with '001' are unspecified sources for water and ice features, often paper topographic maps, and DRG or DLG files. (Source: this data set)

    ValueDefinition
    AD002Coats, R.R., 1956, Geology of northern Adak Island, Alaska: U.S. Geological Survey Bulletin 1028-C, p. 47-67, map, scale 1:50,000.
    AD003Fraser, G.D., and Snyder, G.I., 1959, Geology of southern Adak and Kagalaska Island, Alaska: U.S. Geological Survey Bulletin 1028-M, p. 371-408, map, scale 1:125,000.
    AD004Simons, F.S., and Mathewson, D.E., 1955, Geology of Great Sitkin Island, Alaska: U.S. Geological Survey Bulletin 1028-B, p. 21-43, Plate 5, scale 1:50,000.
    AD005Coats, R.R., 1956, Geology of northern Kanaga Island, Alaska: U.S. Geological Survey Bulletin 1028-D, p. 69-81, Plate 15, scale 1:25,000.
    AD006Fraser, G.D., and Barnett, H.F., 1959, Geology of the Delarof and westernmost Andreanof Islands, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-I, p. 211-248, Plate 28, scale 1:25,000.
    AD007Miller, T.P., Waythomas, C.F., and Nye, C.J., 2003, Preliminary geologic map of Kanaga Volcano, Alaska: U.S. Geological Survey Open-File Report 03-113, 2 sheets, scale 1:20,000.
    AD008Fraser, G.D., and Barnett, H.F., 1959, Geology of the Delarof and westernmost Andreanof Islands, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-I, p. 211-248, Plate 27, scale 1:250,000.
    AD009Waythomas, C.F., Miller, T.P., and Nye, C.J., 2003, Preliminary geologic map of Great Sitkin Volcano, Alaska: U.S. Geological Survey Open-File Report 03-36, 1 sheet, scale 1:63,360.
    AD011Scholl, D.W., Greene, H.G., and Marlow, M.S., 1970, Eocene age of the Adak "Paleozoic(?)" rocks, Aleutian Islands, Alaska: Geological Society of America Bulletin, v. 81, p. 3583-3592.
    AD012Waythomas, C.F., 1995, Surficial geologic map of northern Adak Island, Alaska: U.S. Geological Survey Open-File Report 95-128, 6 p., 1 sheet, scale 1:50,000.
    AD013Coombs, Michele, 2005, unpublished geologic mapping on Tanaga volcano, western Aleutian Islands, written commun., April 2005.
    AT002Gates, Olcott, Powers, H.A., and Wilcox, R.E., 1971, Geology of the Near Islands, Alaska, with a section on Surficial geology by J.P., Schafer: U.S. Geological Survey Bulletin 1028-U, p. 709-822, 3 maps, scale 1:63,360.
    AT003Gates, Olcott, Powers, H.A., and Wilcox, R.E., 1971, Geology of the Near Islands, Alaska, with a section on Surficial geology by J.P., Schafer (Geologic map of Shemya): U.S. Geological Survey Bulletin 1028-U, figure 115, p. 776.
    AT004Gates, Olcott, Powers, H.A., and Wilcox, R.E., 1971, Geology of the Near Islands, Alaska, with a section on Surficial geology by J.P. Schafer: U.S. Geological Survey Bulletin 1028-U, Plate 31 (Agattu Island), 1:63,360.
    GI002Coats, R.R., 1959, Geologic reconnaissance of Gareloi Island, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-J, p. 249-256, 1 plate, no. 33, approx. scale 1:50,000.
    GI003Fraser, G.D., and Barnett, H.F., 1959, Geology of the Delarof and westernmost Andreanof Islands, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-I, p. 211-248, Plates 29, 30, scale 1:250,000 and 1:25,000.
    GI005Fraser, G.D., and Barnett, H.F., 1959, Geology of the Delarof and westernmost Andreanof Islands, Alaska: U.S. Geological Survey Bulletin 1028-I, p. 2110248, Plate 27, scale 1:250,000.
    GI006Coombs, Michele, 2005, unpublished geologic mapping on Tanaga and Gareloi volcanoes, western Aleutian Islands, written commun. April, 2005.
    KK002Coats, R.R., Nelson, W.H., Lewis, R.Q., and Powers, H.A., 1961, Geologic reconnaissance of Kiska Island, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-R, Plate 71, scale 1:63,360.
    KK003Coats, R.R., 1953, Geology of Buldir Island, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 989-A, 26 p.
    RI002Coats, R.R., 1959, Geologic reconnaissance of Semisopochnoi Island, western Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-O, Plate 59.
    RI003Snyder, G.L., 1959, Geology of Little Sitkin Island, Alaska: U.S. Geological Survey Bulletin 1028-H, Plate 23, scale 1:20,000.
    RI004Lewis, R.Q., Nelson, W.H., and Powers, H.A., 1960, Geology of Rat Island, Aleutian Islands, Alaska: U.S. Geological Survey Bulletin 1028-Q, Plate 70, scale 1:63,360.
    RI005Powers, H.A., Coats, R.R., and Nelson, W.H., 1960, Geology and submarine physiography of Amchitka Island, Alaska: U.S. Geological Survey Bulletin 1028-P, p. 521-554, 1 plate, scale approx. 1:100,000
    RI006Nelson, W.H., 1959, Geology of Segula, Davidof, and Khvostof Islands Alaska: U.S. Geological Survey 1028-K, p. 257-266, 2 plates, scale 1:25,000.

    arcs
    Characteristics of the arc features in the geology coverages are coded in the arc attribute table. Table <cov>.aat includes the following items: ARC-CODE, ARC-PARA1, and SOURCE. For explanation of SOURCE, see attribute definitions for polygons. (Source: this data set)

    ARC-CODE
    ARC-CODE is a positive integer value (3 3 I) item in the arc attribute table. Values range discontinuously from 0 to 99. Values match one-for-one with geologic features (such as stratigraphic boundary, fault, etc.) Some ARC-CODE values have additional modifiers in item ARC-PARA1. (Source: this data set)

    ValueDefinition
    0hidden line
    1Stratigraphic or intrusive contact, location certain
    2Stratigraphic or intrusive contact, location approximate
    3Stratigraphic or intrusive contact, location inferred, queried
    4Normal fault, location certain; if ARC-PARA1 = 1, then upthrown side is on right from origin
    5Normal fault, location approximate; if ARC-PARA1 = 1, then upthrown side is on right from origin
    6Normal fault, location inferred or queried; if ARC-PARA1 = 1, then upthrown side is on right from origin
    7Shoreline or riverbank
    9Boundary of altered zone or hornfels; no symbol drawn
    14Caldera or crater rim; hachures on the left from origin
    15Ice contact
    22Syncline, location approximate; digitized in direction of plunge; ARC-PARA1 equals angle of plunge, 0 is no plunge, 1 is plunge of unknown dip
    30Fault, sense of displacement uncertain; location certain
    31Fault, sense of displacement uncertain; location approximate
    32Fault, sense of displacement uncertain, location inferred
    50Dikes and sills
    51Concealed contact
    52Concealed normal fault
    71Normal fault, location certain, having right lateral oblique slip
    72Normal fault, location approx., having right lateral oblique slip
    87Right lateral fault, location certain
    89Right lateral fault, location inferred, queried
    93Lineament
    99Bounding line of coverage

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 data set was prepared by Frederic H. Wilson (USGS), Solmaz Mohadjer (contractor), Keith A. Labay (contractor), and Nora Shew (USGS)

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

    U.S. Geological Survey
    c/o Frederic H. Wilson
    Geologist
    4200 University Drive
    Anchorage, Alaska 99508-4667
    U.S.A.

    907-786-7448 (voice)
    fwilson@usgs.gov

Why was the data set created?
This data set represents part of a systematic effort to release geologic map data fro the United States in a uniform manner. Geologic data in this series has been compiled from a wide variety of sources, published and unpublished, ranging from state and regional geologic maps to large-scale field mapping.

How was the data set created?
  1. Where did the data come from?

  2. What changes have been made?

    Date: 2006 (change 1 of 1)
    Linework for the geology compilation was either hand digitized on a large digitizing tablet or from a scanned image from material of various media and scale. The arcs and polygons were attributed. The spatial databases are provided in UTM projection and geographic coordinates. The native ARC/Info coverages have been exported to an interchange file format, .e00, and also converted to ArcView shape files.

    Person responsible for change:

    U.S. Geological Survey
    c/o Frederic H. Wilson
    Geologist
    4200 University Drive
    Anchorage, Alaska 99508-4667
    U.S.A.

    907-786-7448 (voice)
    fwilson@usgs.gov

How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?

    There were many types of source materials used to compile this data set. Sources include previously published maps on folded paper and unpublished digital maps. The dates of the mapping range from the 1950's to as recent as 2005. Vector features were mostly digitized on a large digitizing tablet. Vector and polygon attributes were assigned based on the original source. The digital data has been checked, and the geologic map has been technically reviewed and edited.

  2. How accurate are the geographic locations?

    This data is presented for use at a nominal scale of 1:500,000, although some data is suitable for use at a larger scale.

  3. How accurate are the heights or depths?

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

    The complete data set consists of 5 geology coverages. There is also an associated relational database of geologic units. Each coverage has the extent of a 1:250,000 scale quadrangle, except for Kiska quadrangle, which is extended to include Buldir Island. A graphic representation of the database and a report with complete geologic unit descriptions is provided in .pdf format.

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

    Each geology coverage is a network coverage containing attributed arcs and polygons. Each polygon has a coded attribute designating the mapped geologic unit. Faults, stratigraphic contacts, and other linear features are represented as arcs. When a fault is also a stratigraphic contact, only a single arc is present. Dangling arcs may be present (faults, dike, etc.)

    This data set has been compiled from a variety of sources, ranging from state and regional geologic maps to large-scale field mapping. Locally, maps from differing sources were incompatible at their boundaries, resulting in some unit boundaries shown as straight lines, reflecting the boundary of the source map.

How can someone get a copy of the data set?
Are there legal restrictions on access or use of the data?

Access_Constraints: None
Use_Constraints:
None. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data.

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

    U.S. Geological Survey
    MS 902
    Box 25286
    Denver Federal Center
    Lakewood, CO 80225
    U.S.A.

    1-888-ASK-USGS (voice)

  2. What's the catalog number I need to order this data set?

    Open-File Report 2006-1302

  3. What legal disclaimers am I supposed to read?

    This world-wide web publication was prepared by an agency of the United States Government. Neither the United States Government, nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

  4. How can I download or order the data?

Who wrote the metadata?
Dates:
Last modified: 18-Sep-2006

Metadata author:
U.S. Geological Survey
c/o Nora Shew
4200 University Drive
Anchorage, Alaska 99508-4667
U.S.A.

907-786-7445 (voice)
nshew@usgs.gov

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)

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