Geologic map of the Seldovia quadrangle, south-central Alaska

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. Where did the data come from?
  2. What changes have been made?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

Title:

Geologic map of the Seldovia quadrangle, south-central Alaska

Abstract:

USGS Open-File Report 99-18B is a digital representation of a paper map that is being released simultaneously, USGS Open-File Report 99-18A. The map shows the bedrock geology of the Seldovia quadrangle, Alaska, at a scale of 1:250,000, compiled from new mapping (1988-1993) and published sources. Digital files include various map coverages in Arc/Info export format, and a picture of the map plus all map-collar information in Adobe Illustrator and PDF formats. The map collar includes detailed map-unit descriptions, text on the physiography, neotectonics, geologic history, and economic geology, cross-section, correlation of map units chart, and map showing original sources of information.

Supplemental_Information:

The 1:63,360 scale geologic maps (ink or mylar topographic bases), from which the present map was compiled, are housed at the U.S. Geological Survey, 4200 University Drive, Anchorage, Alaska 99508. These show more detail than the present map, which was simplified, in places, for display at 1:250,000 scale.

1. How should this data set be cited?

   Bradley, D.C., Kusky, T.M., Haeussler, P.J., Karl, S.M., and Donley, D.T., 1999, Geologic map of the Seldovia quadrangle, south-central Alaska: U.S. Geological Survey Open-File Report OFR 99-18B.

   Other_Citation_Details:

   Bradley, D.C., Kusky, T.M., Haeussler, P.J., Karl, S.M., and Donley, D.T., 1999, Geologic map of the Seldovia quadrangle, south-central Alaska: U.S. Geological Survey Open-File Report 99-18B, 1 sheet, scale 1:250,000.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -153.0

   East_Bounding_Coordinate: -150.0

   North_Bounding_Coordinate: 60.0

   South_Bounding_Coordinate: 59.0

3. What does it look like?

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

   Calendar_Date: 1999

   Currentness_Reference: publication date

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

   Geospatial_Data_Presentation_Form: 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.

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

      Grid_Coordinate_System_Name: Universal Transverse Mercator

      Universal_Transverse_Mercator:

      UTM_Zone_Number: 5

      Transverse_Mercator:

      Scale_Factor_at_Central_Meridian: 0.9996

      Longitude_of_Central_Meridian: -153.0

      Latitude_of_Projection_Origin: 0.0

      False_Easting: 500000

      False_Northing: 0.0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 50
      Ordinates (y-coordinates) are specified to the nearest 50
      Planar coordinates are specified in meters

7. How does the data set describe geographic features?

   arc-code

   Arc-code is a positive integer value (3 3 I) item in the arc attribute table. Values range from 1-99. It codes the type of line feature. The following arc-code values are used in svgeol.aat.

   1 Stratigraphic or intrusive contact, location certain
   2 Stratigraphic or intrusive contact, location approximate or inferred
   4 Normal fault, location certain
   5 Normal fault, location approximate or inferred
   7 Shoreline or riverbank
   9 Boundary of melange zone (invisible line, used to enclose an overprinting pattern)
   11 Thrust fault, location approximate, teeth on right from origin
   15 Ice contact
   30 Fault, sense of displacement unknown, location certain
   32 Fault, sense of displacement unknown, location approximate or inferred
   49 Dike, Early Cretaceous
   50 Dike, Tertiary
   51 Stratigraphic or intrusive contact, concealed by younger deposits
   52 Fault, sense of displacement unknown, concealed by younger deposits
   53 Thrust fault, teeth on right from origin, concealed by younger deposits
   88 Right-lateral fault, location approximate or inferred
   91 Left-lateral fault, location approximate or inferred
   99 Bounding line
   

   (Source: This report.)

   class

   Class is a positive integer value (4 5 B) item in the polygon attribute table. Values range from 0-1071. The coverage has a lookup table, svgeol.lut, which contains each class value with a geologic unit label. Here is a list of class values with a brief description. See the publication for full rock unit descriptions.

   1 Ice
   10 Jsm - Seldovia metamorphic complex (Early Jurassic metamorphic age)
   32 Jc - Chinita Formation (Upper Jurassic, Callovian)
   47 Jn - Naknek Formation (Upper Jurassic, Oxfordian to Kimmeridgian)
   50 Jtu - Tuxedni Group (Middle to Upper Jurassic, Bajocian to Callovian)
   57 Water
   60 JTrp - Port Graham Formation (Upper Triassic and Lower Jurassic)
   67 Jt - Talkeetna Formation (Lower Jurassic; Hettangian to Toarcian)
   71 Kv - Valdez Group
   72 Kk - Kaguyak Formation (Upper Cretaceous, Maastrichtian)
   74 KPmc - McHugh Complex, chert and basalt (Triassic to Cretaceous)
   75 KPms - McHugh Complex, graywacke and conglomerate (Jurassic to Cretaceous)
   77 KPm - McHugh Complex, undivided (Permian to Cretaceous)
   78 Tb - Beluga Formation (Miocene)
   79 Twf - West Foreland Formation (Eocene)
   80 Ts - Sterline Formation (Miocene to Pliocene)
   81 Tt - Tyonek Formation (Oligocene to Miocene)
   82 Qs - Surficial deposits (Quaternary)
   105 Qv - Iliamna lava flows (Quaternary)
   110 Mu - Ultramafic plutonic rocks (Mesozoic)
   111 Jd - Diorite of Point Bede (Jurassic)
   112 Mg - Gabbro (Mesozoic)
   113 Tg - Granodiorite (Eocene)
   115 J(?)f - Felsite (Jurassic?)
   116 Jto - Tonalite of Dogfish Bay (Jurassic)
   1071 Kvm - Melange of Iceworm Peak (Upper Cretaceous)
   Kd - Intermediate dike (Early Cretceous) (although this is a legitimate map unit, the rock bodies are too narrow to map as polygons, hence are shown as lines with arc-code = 49)
   Td - Intermediate, felsic, and mafic dikes (Tertiary) (although this is a legitimate map unit, the rock bodies are too narrow to map as polygons, hence are shown as lines with arc-code = 50)
   

   (Source: This publication.)

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Bradley, D.C.
   • Kusky, T.M.
   • Haeussler, P.J.
   • Karl, S.M.
   • Donley, D.T.

2. Who also contributed to the data set?

   Digital representation by Kelly Brunt (Raytheon STX contractor), D. Thomas Donley, and Patti Phillips

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

   U.S. Geological Survey
   c/o Dwight C. Bradley
   Geologist
   4200 University Drive
   Anchorage, AK 99508-4667
   U.S.A.
   

   (907)561-1181 (voice)
   dbradly@usgs.gov
   

Digital representation of geologic mapping of the Seldovia quadrangle, Alaska, is to facilitate the presentation and analysis of earth-science data. Digital maps can be displayed at any scale or projection, however the geological data in this coverage is not intended for use at a scale larger that 1:250,000.

1. Where did the data come from?

2. What changes have been made?

   Date: 1999 (change 1 of 1)

   Linework was captured by hand digitizing from a stable base line drawing. The digital linework was edited and attributed using ARC/Info. The coverage was built for polygon topology, and had labels created and attributed. For the purpose of distribution, the coverage has been converted to an interchange format file using the ARC/Info export command. The following files are included:

   (1) svgeol.e00 geology (arcs and polygons)
   (2) svfold.e00 fold axial traces
   (3) svisograd.e00 metamorphic isograds
   (4) svquad.e00 outlines of 1:63,360 scale quadrangles
   (5) svsandd.e00 attitudes of bedding and foliation
   (6) svtopo.e00 vectorized contours, not shown over glaciers
   (7) svwells.e00 exploration wells
   

1. How well have the observations been checked?

   The linework was captured by hand digitizing from 1:63,360 scale mylar maps that were all in excellent condition. The arc and polygon attributes are based on field work and on previously published mapping that is cited, as appropriate, on an inset of the PDF and Illustrator files. Water bodies were digitized from the 1:63,360 scale topographic maps. Glaciers and permanent icefields were digitized from 1:63,360 scale topographic maps, but were modified as needed, based on 1978-1984 vintage air photos, where glacial retreat had been significant. The digital coastline, provided by the State of Alaska, Dept. of Natural Resources, was based on 1:63,360 topographic maps. This digital data set was prepared in the aftermath of the Exxon Valdez oil spill. The source of line- and polygon data is not coded in attribute tables. The map was checked for accuracy by visually comparing the digital product against hand-colored ozalids of the mylars. This thematic bedrock map depicts geologic units present beneath soil or relatively thin mantles of surficial deposits, not necessarily the surficial materials themselves.

2. How accurate are the geographic locations?

   Users of this digital geologic map should respect the intentions of the original mappers and the limitations of the map. The Seldovia geologic map is intended to be used at a scale of 1:250,000; it is not intended to be used at a more detailed scale.

3. How accurate are the heights or depths?

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

   This set of digital coverages contains only the information used to create the geologic map. It does not include the files used to create the information shown in collar, or margins, of the paper version and graphic versions of the complete publication.

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

   This coverage is a net coverage containing arcs and polygons. Each polygon has a class attribute classifying bedrock, surficial deposit, or water/ice body. Faults and stratigraphic contacts are represented as arcs. When a fault is also a stratigraphic contact, only a single arc is present. Dangling arcs may be present (faults, dikes, etc.)

Are there legal restrictions on access or use of the data?

Access_Constraints: None

Use_Constraints:

Acknowledgement 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)

   USGS Information Services
   Box 25286
   Denver Federal Center
   Denver, CO 80225-0046
   USA
   

   303-202-4200 or 1-888-ASK-USGS (voice)
   

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

   USGS OFR 99-18A - paper version; USGS OFR 99-18B - digital version

3. What legal disclaimers am I supposed to read?

   Although all this data has been used by the USGS, no warranty, expressed or implied, is made by the USGS as to the acccuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data, software, or related materials.

4. How can I download or order the data?

   Data format:	ARCE
   Network links:	<https://pubs.usgs.gov/of/1999/of99-018/>

   • Cost to order the data: Free

Dates:

Last modified: 03-May-1999

Metadata author:

U.S. Geological Survey
c/o Nora B. Shew
Geologist
4200 University Drive
Anchorage, AK 99508-4667
U.S.A.

(907)561-1181 (voice)
nshew@usgs.gov

Metadata standard:

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