Preliminary integrated geologic map databases for the United States: Digital data for the geology of southeast Alaska by George E. Gehrels and Henry C. Berg

Metadata also available as - [Outline] - [Parseable text]

Frequently-anticipated questions:


What does this data set describe?

    Title:
    Preliminary integrated geologic map databases for the United States: Digital data for the geology of southeast Alaska by George E. Gehrels and Henry C. Berg
    Abstract:
    The southeast Alaska map area includes the Alaska panhandle that extends from Skagway quadrangle on the north to Prince Rupert and Dixon Entrance quadrangles on the south. This data set is a digital version of the geologic map of southeastern Alaska by Gehrels and Berg (1992). The map area includes thirteen 1:250,000 scale quadrangles; at the time of Gehrels and Berg's (1992) compilation, no geologic mapping was available in the Atlin quadrangle.

    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?

    Shew, Nora, Peterson, C. Shaun, Grabman, Nathaniel, Mohadjer, Solmaz, Grunwald, Daniel, Wilson, Frederic H., and Hults, Chad K., 2006, Preliminary integrated geologic map databases for the United States: Digital data for the geology of southeast Alaska by George E. Gehrels and Henry C. Berg: United States Geological Survey Open-File Report OFR 2006-????.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -137.7
    East_Bounding_Coordinate: -129.9
    North_Bounding_Coordinate: 59.6
    South_Bounding_Coordinate: 54.6

  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: 8
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -135.0
      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 0.000256
      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), LITH2 (not used), SOURCE ,and LABEL. (Source: This data set)

    CLASS
    CLASS is a positive integer value (4 5 B) item in the polygon attribute table. Values range discontinuously from 98 to 5400. CLASS is a numeric code for the geologic unit from Gehrels and Berg, 1992. See Gehrels and Berg, 1992, for complete geologic unit descriptions. Each map unit from Gehrels and Berg (1992) has been assigned a preliminary NSACLASS value (4 5 B). NSACLASS is a numeric code used for a compilation of geologic mapping for the state of Alaska. NOTE: Because of the limitations of common GIS fonts, the letters "Mz", "Pz", "Tr", "Pa", and "C" are substituted for the standard symbols for "Mesozoic", "Paleozoic", "Triassic", "Pennsylvanian", and "Cambrian." (Source: This data set)

    ValueDefinition
    98not mapped; NSACLASS = 98
    101ice; NSACLASS = 101
    102water; NSACLASS = 102
    4500Qs - Surficial sedimentary deposits (Quaternary); NSACLASS = 100
    4510QTv - Volcanic rocks (Quaternary and Tertiary); NSACLASS = 450
    4520QTs - Sedimentary rocks (Quaternary and Tertiary); NSACLASS = 565
    4530Tv - Volcanic rocks (Tertiary); NSACLASS = 1059
    4540Ts - Sedimentary rocks (Tertiary); NSACLASS = 500
    4550Tsv - Sedimentary and volcanic rocks, undivided (Tertiary); NSACLASS = 794
    4560Ks - Sedimentary rocks (Cretaceous); NSACLASS = 2866
    4570Kv - Volcanic rocks (Cretaceous); NSACLASS = 2891
    4580Ksv - Sedimentary and volcanic rocks, undivided (Cretaceous); NSACLASS = 2865
    4581Ksv? - Sedimentary and volcanic rocks, undivided (Cretaceous); NSACLASS = 2865
    4590KJs - Sedimentary rocks (Cretaceous and Jurassic); NSACLASS = 2820
    4591KJs? - Sedimentary rocks (Cretaceous and Jurassic); NSACLASS = 2820
    4600KJv - Volcanic rocks (Cretaceous and Jurassic); NSACLASS = 2340
    4601KJv? - Volcanic rocks (Cretaceous and Jurassic); NSACLASS = 2340
    4610KJsv - Sedimentary and volcanic rocks, undivided (Cretaceous and Jurassic); NSACLASS = 2822
    4620Trs - Sedimentary rocks (Triassic); NSACLASS = 4470
    4621Trs? - Sedimentary rocks (Triassic); NSACLASS = 4470
    4630Trv - Volcanic rocks (rhyolitic to basaltic) (Triassic); NSACLASS = 4474
    4640Trsv - Sedimentary and volcanic rocks, undivided (Triassic); NSACLASS = 4471
    4650Trc - Carbonate rocks (Triassic); NSACLASS = 4473
    4660Trb - Basaltic rocks (Triassic); NSACLASS = 4420
    4670Trsc - Clastic sedimentary and carbonate rocks, undivided (Triassic); NSACLASS = 4000
    4680Ps - Sedimentary rocks (Permian); NSACLASS = 5766
    4690Pv - Volcanic rocks (Permian); NSACLASS = 5810
    4700Pc - Carbonate rocks (Permian); NSACLASS = 5765
    4710Pas - Sedimentary rocks (Pennsylvanian); NSACLASS = 6031
    4720Pac - Carbonate rocks (Pennsylvanian); NSACLASS = 6030
    4730Mc - Carbonate rocks (Mississippian); NSACLASS = 6340
    4740MDsv - Sedimentary and volcanic rocks, undivided (Mississippian and Devonian); NSACLASS = 5930
    4750Ds - Sedimentary rocks (Devonian); NSACLASS = 6939
    4760Dv - Volcanic rocks (Devonian); NSACLASS = 7030
    4761Dv? - Volcanic rocks (Devonian); NSACLASS = 7030
    4770Dsv - Sedimentary and volcanic rocks, undivided (Devonian); NSACLASS = 7020
    4771Dsv? - Sedimentary and volcanic rocks, undivided (Devonian); NSACLASS = 7020
    4780Dc - Carbonate rocks (Devonian); NSACLASS = 6938
    4790Dcg - Conglomeratic rocks (Devonian); NSACLASS = 6937
    4800Sc - Carbonate rocks (Silurian); NSACLASS = 6960
    4810Scg - Conglomeratic rocks (Silurian); NSACLASS = 6618
    4820Ss - Sedimentary rocks (Silurian); NSACLASS = 6619
    4830Sv - Volcanic rocks (Silurian); NSACLASS = 6740
    4840SOs - Sedimentary rocks (Silurian and Ordovician); NSACLASS = 6690
    4841SOs? - Sedimentary rocks (Silurian and Ordovician); NSACLASS = 6690
    4850SOv - Volcanic rocks (Silurian and Ordovician); NSACLASS = 6712
    4860SOsv - Sedimentary and volcanic rocks (Silurian and Ordovician); NSACLASS = 6689
    4861SOsv? - Sedimentary and volcanic rocks (Silurian and Ordovician); NSACLASS = 6689
    4870SOsvc - Clastic sedimentary, volcanic, and carbonate rocks, undivided (Silurian and Ordovician); NSACLASS = 6800
    4880KPs - Sedimentary rocks (Cretaceous to Permian); NSACLASS = 5010
    4881KPs? - Sedimentary rocks (Cretaceous to Permian); NSACLASS = 5010
    4890KPv - Volcanic rocks (Cretaceous to Permian); NSACLASS = 5105
    4900KPsv - Sedimentary and volcanic rocks, undivided (Cretaceous to Permian); NSACLASS = 5011
    4910KPsvc - Clastic sedimentary, volcanic, and carbonate rocks, undivided (Cretaceous to Permian); NSACLASS = 5271
    4920JMsv - Sedimentary and volcanic rocks, undivided (Jurassic to Mississippian); NSACLASS = 5270
    4930TrPc - Carbonate rocks (Triassic and(or) Permian); NSACLASS = 4521
    4931TrPc? - Carbonate rocks (Triassic and(or) Permian); NSACLASS = 4521
    4940TrPsv - Sedimentary and volcanic rocks, undivided (Triassic and Permian); NSACLASS = 5260
    4950TrOsv - Sedimentary and volcanic rocks, undivided (Triassic to Ordovician); NSACLASS = 5200
    4960TrOc - Carbonate rocks (Triassic to Ordovician); NSACLASS = 6617
    4970PaDsv - Sedimentary and volcanic rocks, undivided (Pennsylvanian to Devonian); NSACLASS = 6095
    4980DSv - Volcanic rocks (Devonian and Silurian); NSACLASS = 7020
    4981DSv? - Volcanic rocks (Devonian and Silurian); NSACLASS = 7020
    4990DOsv - Sedimentary and volcanic rocks, undivided (Devonian to Ordovician); NSACLASS = 7200
    4991DOsv? - Sedimentary and volcanic rocks, undivided (Devonian to Ordovician); NSACLASS = 7200
    5000DOc - Carbonate rocks (Devonian to Ordovician); NSACLASS = 6616
    5010DSc - Carbonate rocks (Devonian and Silurian); NSACLASS = 6932
    5020DSsc - Sedimentary rocks (Devonian and Silurian); NSACLASS = 6953
    5040Ksvm - Melange, sedimentary and volcanic rocks, undivided (Cretaceous); NSACLASS = 2950
    5041Ksvm? - Melange, sedimentary and volcanic rocks, undivided (Cretaceous); NSACLASS = 2950
    5050Ksm - Melange, sedimentary rocks (Cretaceous); NSACLASS = 2950
    5060Kvm - Melange, volcanic rocks (Cretaceous); NSACLASS = 2953
    5080KDsd - Disrupted rocks, sedimentary rocks (Cretaceous to Devonian); NSACLASS = 2971
    5090KDvd - Disrupted rocks, volcanic rocks (Cretaceous to Devonian); NSACLASS = 2972
    5110pTmsv - Metasedimentary and metavolcanic rocks (pre-Tertiary); NSACLASS = 12500
    5111pTmsv? - Metasedimentary and metavolcanic rocks (pre-Tertiary); NSACLASS = 12500
    5120pTmc - Metacarbonate rocks (pre-Tertiary); NSACLASS = 12600
    5130pOmsv - Metasedimentary and metavolcanic rocks (pre-Ordovician); NSACLASS = 8751
    5140pOmc - Metacarbonate rocks (pre-Ordovician); NSACLASS = 8752
    5150Tgb - Gabbro (Miocene and Oligocene); NSACLASS = 1254
    5160Tgr - Granite (Miocene and Oligocene); NSACLASS = 1250
    5170Tgd - Granodiorite (Oligocene and Eocene); NSACLASS = 1273
    5171Tgd? - Granodiorite (Oligocene and Eocene); NSACLASS = 1273
    5180Tg - Granodiorite (Eocene); NSACLASS = 1305
    5181Tg? - Granodiorite (Eocene); NSACLASS = 1305
    5190Tgt - Granodiorite and tonalite (Paleocene); NSACLASS = 1350
    5191Tgt? - Granodiorite and tonalite (Paleocene); NSACLASS = 1350
    5200TKt - Tonalite (Paleocene and Cretaceous); NSACLASS = 1662
    5201TKt? - Tonalite (Paleocene and Cretaceous); NSACLASS = 1662
    5210TKg - Granodiorite (Paleocene and Cretaceous); NSACLASS = 1655
    5211TKg? - Granodiorite (Paleocene and Cretaceous); NSACLASS = 1655
    5220Kgt - Granodiorite and tonalite (Cretaceous); NSACLASS = 2480
    5221Kgt? - Granodiorite and tonalite (Cretaceous); NSACLASS = 2480
    5230Kdb - Diorite and gabbro (Cretaceous); NSACLASS = 2494
    5240Kum - Ultramafic rocks (Cretaceous); NSACLASS = 2495
    5241Kum? - Ultramafic rocks (Cretaceous); NSACLASS = 2495
    5250Kg - Granodiorite (Cretaceous); NSACLASS = 2493
    5251Kg? - Granodiorite (Cretaceous); NSACLASS = 2493
    5260Kd - Diorite (Cretaceous); NSACLASS = 2540
    5261Kd? - Diorite (Cretaceous); NSACLASS = 2540
    5270Kgb - Gabbro (Cretaceous); NSACLASS = 2550
    5280KJd - Diorite (Cretaceous and Jurassic); NSACLASS = 2990
    5281KJd? - Diorite (Cretaceous and Jurassic); NSACLASS = 2990
    5290KJgb - Gabbro (Cretaceous and Jurassic); NSACLASS = 2920
    5291KJgb? - Gabbro (Cretaceous and Jurassic); NSACLASS = 2920
    5300Jgr - Granite (Jurassic); NSACLASS = 3410
    5301Jgr? - Granite (Jurassic); NSACLASS = 3410
    5310Jt - Tonalite (Jurassic); NSACLASS = 3404
    5320JTrd - Diorite (Jurassic and(or) Triassic); NSACLASS = 3900
    5330Trgb - Gabbro (Triassic); NSACLASS = 4320
    5331Trgb? - Gabbro (Triassic); NSACLASS = 4320
    5340Trg - Granodiorite (Triassic); NSACLASS = 3620
    5350PPasy - Syenite (Permian and(or) Pennsylvanian); NSACLASS = 5875
    5360Sst - Syenite and trondhjemite (Silurian); NSACLASS = 6730
    5370SOum - Ultramafic rocks (Silurian and Ordovician); NSACLASS = 6750
    5380SOq - Quartz diorite (Silurian and Ordovician); NSACLASS = 7650
    5381SOq? - Quartz diorite (Silurian and Ordovician); NSACLASS = 7650
    5390Ogb - Gabbro (Ordovician); NSACLASS = 7670
    5391Ogb? - Gabbro (Ordovician); NSACLASS = 7670
    5400Cdg - Diorite and granodiorite (Cambrian); NSACLASS = 8500

    NSAMOD
    NSAMOD is a character (8 10 C) item in the polygon attribute table. It is used as a modifier to item CLASS. (Source: this data set)

    Q - queried unit GBS - undifferentiated intrusive and stratified rocks; item CLASS indicates predominant lithic unit (shown as stippled area in Gehrels and Berg, 1992)

    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 polygon or arc feature. The format for SOURCE is XX###, where XX is a two letter abbreviation 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)

    The following SOURCE values are used in this dataset and all refer to Gehrels and Berg, 1992: BC006, CR012, DE008, JU012, KC013, MF011, PE006, PA006, PR003, SI009, SK015, SD016, and TR008.

    arcs
    Characteristics of the arc features in the geology and lineament coverages are coded in the arc attribute tables. Table <cov>.aat includes the following items: ARC-CODE, ARC-PARA1, ARC-PARA2 (not used), 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 contact, fault, etc. Some ARC-CODE values have modifiers in item ARC-PARA1. (Source: this data set)

    ValueDefinition
    0hidden line
    2Stratigraphic or intrusive contact, location approximate
    3Stratigraphic or intrusive contact, location inferred or queried
    4Normal fault, location certain, digitized with upthrown side on the right (code of 1 added to ARC-PARA1 where up/down is designated in source)
    7shoreline or riverbank
    10Thrust fault, location certain, teeth on right from origin
    11Thrust fault, location approximate, teeth on right from origin
    12Thrust fault, location inferred or queried, teeth on right from origin
    15Ice contact
    30Fault, sense of displacement uncertain, location certain
    31Fault, sense of displacement uncertain, location approximate
    32Fault, sense of displacement uncertain, location inferred
    51Concealed contact
    52Concealed normal fault
    53Concealed thrust fault
    57Concealed right lateral fault
    58Concealed left lateral fault
    60Concealed fault displacement uncertain
    87Right lateral fault, location certain
    90Left lateral fault, location certain
    91Left lateral fault, location approximate
    93Coast Range megalineament
    99Bounding line (neatline) 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 C. Shaun Peterson (contractor), Nora Shew (USGS), Nathaniel Grabman (USGS), and Daniel Grunwald (contractor)

  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
    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 for 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?

    Gehrels and Berg (1992) (source 1 of 1)
    Gehrels, George E., and Berg, Henry C., 1992, Geologic map of southeastern Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-1867.

    Online Links:

    • www.dggs.dnr.state.ak.us/pubs/pubs?reqtype=citation&ID=12916

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 600000
    Source_Contribution: 100% of original geology compilation

  2. What changes have been made?

    Date: 2006 (change 1 of 1)
    Linework for the geology was digitized from a scanned image of the published paper map. The arcs and polygons were attributed. The spatial data bases 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 Nora B. Shew
    Geologist
    4200 University Drive
    Anchorage, Alaska 99508
    U.S.A.

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


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

  1. How well have the observations been checked?

    The original source material for this data set is a folded paper 1:600,000 scale map. The source map's base is an enlarged U.S. Geological Survey 1:2,000,000 scale National Atlas, Albers Equal Area projection map. The paper map was scanned and portions of the scanned image were registered to a digital 1:250,000 scale coastline base. All vector features were hand digitized on screen. Vector and polygon attributes were assigned based on the original source. Some obvious cartographic errors on the original map have been corrected in this digital version, such as solid line faults underwater are now coded as concealed. Other errors have been digitized as shown on the original map. One correction was provided by original author, Henry C. Berg. A single polygon of geologic unit KJgd is shown on the north side of Admiralty Island. Unit KJgd is not mentioned anywhere else in the original publication. This polygon is attributed as KJgb? (Henry C. Berg, oral commun, 2006). The digital data has been checked, reviewed, and edited.

  2. How accurate are the geographic locations?

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

  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 20 different GIS coverages and an associated relational database of geologic units. Each coverage has the extent of a 1:250,000 scale quadrangle. There are 13 geology coverages and 7 lineament coverages. This digital data set differs from the original Gehrels and Berg (1992) map in the following ways: uses a different base and projection; does not include names of faults or geographic features, the index map showing sources used in the compilation, or the correlation chart.

  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. If a fault is also a stratigraphic contact, only a single arc is present. Dangling arcs may be present (faults, dike, etc.)


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
    USA

    1-888-ASK-USGS (voice)

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

    Open-File Report 2006-????

  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.

    Although all data and software published on this web-site have been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the accuracy of the data and related materials and (or) the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.

  4. How can I download or order the data?


Who wrote the metadata?

Dates:
Last modified: 15-Sep-2006

Metadata author:
U.S. Geological Survey
c/o Nora B. Shew
4200 University Drive
Anchorage, AK 99508
USA

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

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


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