Geologic Map of Saint Lawrence Island, 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. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
• 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 Saint Lawrence Island, Alaska

Abstract:

Saint Lawrence Island is located in the northern Bering Sea, 190 km southwest of the tip of the Seward Peninsula, Alaska and 75 km southeast of the Chukotsk Peninsula, Russia. It lies on a broad, shallow-water continental shelf that extends from western Alaska to northeastern Russia. The island is situated on a northwest-trending structural uplift exposing rocks as old as Paleozoic above sea level. The submerged shelf between the Seward Peninsula and Saint Lawrence Island is covered mainly with Cenozoic deposits (Dundo and Egiazarov, 1982). Northeast of the island, the shelf is underlain by a large structural depression, the Norton Basin, which contains as much as 6.5 km of Cenozoic strata (Grim and McManus, 1970; Fisher and others, 1982). Sparse test well data indicate that the Cenozoic strata are underlain by Paleozoic and Proterozoic rocks, similar to those exposed on the Seward Peninsula (Turner and others, 1983).

Saint Lawrence Island is 160 km long in an east-west direction and from 15 km to 55 km wide in a north-south direction. The eastern end of the island consists largely of a wave-cut platform, which has been elevated as much as 30 m above sea level. Isolated upland areas composed largely of granitic plutons rise as much as 550 m above the wave-cut platform. The central part of the island is dominated by the Kookooligit Mountains, a large Quaternary shield volcano that extends over an area of 850 sq km and rises to an elevation of 630 m. The western end of the island is composed of the Poovoot Range, a group of barren, rubble-covered hills as much as 450 m high that extend from Boxer Bay on the southwest coast to Taphook Mountain on the north coast. The Poovoot Range is flanked on the southeast by the Putgut Plateau, a nearly flat, lake-dotted plain that stands 30-60 m above sea level. The western end of the island is marked by uplands underlain by the Sevuokuk pluton (unit Kg), a long narrow granite body that extends from Gambell on the north to near Boxer Bay on the south. Headlands having rugged cliffs or narrow, boulder-strewn beaches characterize the southwestern coastline.

1. How should this data set be cited?

   Patton, Jr., William W., Wilson, Frederic H., and Taylor, Theresa A., 2011, Geologic Map of Saint Lawrence Island, Alaska: Scientific Investigations Map 3146.

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -172.0

   East_Bounding_Coordinate: -168.5

   North_Bounding_Coordinate: 63.87

   South_Bounding_Coordinate: 62.87

3. What does it look like?

   https://pubs.usgs.gov/sim/3146/images/coverthb.gif

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

   Calendar_Date: 2011

   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: 2

      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 0.000256
      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 1/294.978698.
      

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, QCLASS, SOURCE, NSACLASS, NSAMOD, NSASUB, LABEL, MIN_AGE and MAX_AGE. CLASS is used as a key to identify and label units for the Saint Lawrence geologic map. NSACLASS is used for creating the generalized geologic map of Alaska. (Source: this data set)

   LABEL

   LABEL is a character field (6 8 C) which holds the label of the geologic unit. NOTE: Because of the limitations of common GIS fonts, the letters "Mz", "Pz", "C", and "Z" are substituted for the standard symbols for "Mesozoic", "Paleozoic", "Cambrian", and "Proterozic". (Source: this data set)

   Value	Definition
   Qs	Beach, bar, and alluvial deposits (Quaternary)
   Qg	Glacial drift (Quaternary)
   Ts	Sandstone, coal, and tuff (lower Tertiary)
   Qb	Basalt (Quaternary)
   TKv	Volcanic rocks undivided (Tertiary and (or) Cretaceous)
   Tr	Rhyolitic and dacitic tuffs (early Tertiary)
   TKsr	Sodium-rich rhyolite and basalt (early Tertiary and latest Cretaceous(?))
   Kv	Andesitic volcanic rocks (Cretaceous)
   Kg	Granite and granodiorite (Late and Early Cretaceous) light pink where concealed
   Ko	Olivine-bearing monzodiorite (early Cretaceous)
   Kn	Nepheline syenite (Early Cretaceous)
   Trs	Shale, limestone, and chert (Triassic)
   Ml	Limestone (Upper Mississippian)
   Dd	Dolostone and dolomitic limestone (Devonian)
   TrPs	Graywacke, grit, and shale (Triassic and Permian(?))
   TrPg	Gabbro and diabase (Triassic and Permian(?))
   Pzu	Calc-silicate hornfels (Paleozoic(?))

   CLASS

   CLASS is a positive integer value (4 5 B) item in the polygon attribute table. Values range discontinuously from 102 to 460. CLASS is a numeric code for the geologic unit. Each CLASS matches with geologic unit labels in LABEL and has a minimum (MIN_AGE) and maximum (MAX_AGE) range, given in million of years (my). CLASS to LABEL is a one-to-one relationship. Supplemental attribute tables included with this data set contain additional 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", "Pz", "C", and "Z" are substituted for the standard symbols for "Mesozoic", "Paleozoic", "Cambrian", and "Proterozic". (Source: this data set)

   Value	Definition
   102	water
   300	Qs - Beach, bar, and alluvial deposits (Quaternary)
   310	Qg - Glacial drift (Quaternary)
   320	Ts - Sandstone, coal, and tuff (lower Tertiary)
   330	Qb - Basalt (Quaternary)
   340	Tr - Rhyolitic and dacitic tuffs (early Tertiary)
   350	TKsr - Sodium-rich rhyolite and basalt (early Tertiary and latest Cretaceous(?))
   360	TKv - Volcanic rocks undivided (Tertiary and (or) Cretaceous)
   120	Kg - Granite and granodiorite (Late and Early Cretaceous) (from source SL002)
   370	Kg - Granite and granodiorite (Late and Early Cretaceous)(from source SL003)
   371	Kg - Concealed granite and granodiorite (Late and Early Cretaceous)
   380	360 - Olivine-bearing monzodiorite (Early Cretaceous)
   390	Kn - Nepheline syenite (Early Cretaceous)
   400	Kv - Andesitic volcanic rocks (Cretaceous)
   410	Trs - Shale, limestone, and chert (Triassic)
   420	Ml - Limestone (Upper Mississippian)
   430	Dd - Dolostone and dolomitic limestone (Devonian)
   440	TrPs - Graywacke, grit, and shale (Triassic and Permian(?))
   450	TrPg - Gabbro and diabase (Triassic and Permian(?))
   460	Pzu - Calc-silicate hornfels (Paleozoic(?))

   NSACLASS

   NSACLASS is a positive integer value (4 5 B) item in the polygon attribute table. Values range discontinuously from 100 to 6982. NSACLASS is a numeric code for the geologic unit for the statewide database. These labels are not used on the Saint Lawrence geologic map. Each NSACLASS has a minimum (MIN_AGE) and maximum (MAX_AGE) range, given in million of years (my). NOTE: Because of the limitations of common GIS fonts, the letters "Mz", "Pz", "C", and "Z" are substituted for the standard symbols for "Mesozoic", "Paleozoic", "Cambrian", and "Proterozic". (Source: this data set)

   Value	Definition
   100	Qs - Beach, bar, and alluvial deposits (Quaternary)
   102	water - Water (streams, lakes, ocean)
   200	Qg - Glacial drift (Quaternary)
   640	Ts - Sandstone, coal, and tuff (lower Tertiary)
   330	Qb - Basalt (Quaternary)
   1070	Tr - Rhyolitic and dacitic tuffs (early Tertiary)
   1145	TKsr - Sodium-rich rhyolite and basalt (early Tertiary and latest Cretaceous(?))
   1295	Pzu - Calc-silicate hornfels (Paleozoic(?))
   1600	TKv - Volcanic rocks undivided (Tertiary and (or) Cretaceous)
   2330	Kv - Andesitic volcanic rocks (Cretaceous)
   2410	Kg - Granite and granodiorite (Late and Early Cretaceous)
   2535	Kn - Nepheline syenite (Early Cretaceous)
   2545	Ko - Olivine-bearing monzodiorite (Early Cretaceous)
   4110	Trs - Shale, limestone, and chert (Triassic)
   5012	Trs - Graywacke, grit, and shale (Triassic and Permian(?))
   5140	TrPg - Gabbro and diabase (Triassic and Permian(?))
   6320	Ml - Limestone (Upper Mississippian)
   6982	Dd - Dolostone and dolomitic limestone (Devonian)

   NSAMOD

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

   HFS - Contact metamorphism, nonspecific Q - queried unit

   SOURCE

   SOURCE is a character (6 8 C) item found in both the polygon and arc 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 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)

   Value	Definition
   SL002	Patton, W.W., Jr., and Csejtey, Bela, Jr., 1980, Geologic map of St. Lawrence Island, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Series Map I-1203, scale 1:250,000.
   SL003	Patton, W.W., Jr., Wilson, F.H., and Taylor, T.A., 2011, Geologic Map of Saint Lawrence Island: U.S. Geological Survey SIM 3146, 1 sheet, scale 1:250,000.

   NSASUB

   NSASUB is a positive integer value (4 5 B) item in the polygon attribute table. One value of 2410 is used in this dataset. NSASUB is a numeric code to identify underlying concealed geologic units for the statewide database. This field is used in specific cases where the author wants to represent both a bedrock unit that is not exposed in outcrop and the overlying quaternary unit. In the .pat, the NSASUB value defines the attribute of the concealed bedrock unit, while the NSACLASS and QCLASS define the attribute of the overlying unit. The CLASS value is used for classifying the solid color fill symbol. Polygons for these units are typically a lighter shade of color than the polygons for the same unit in outcrop. Concealed bedrock units are intentionally not labeled on the geologic map, instead, their geologic relationship and symbology are described in the unit description. (Source: this data set)

   Value	Definition
   2410	Kg - Granite and granodiorite (late and early Cretaceous), covered by unit, Qs - Beach, bar, and alluvial deposits (Quaternary)

   arcs

   Characteristics of the arc features in the geology, and dike coverages are coded in the arc attribute table. 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 1 to 99. Values match one-for-one with geologic features (such as stratigraphic contact, fault, etc.) Some ARC-CODE values have additional modifiers in item ARC-PARA1. (Source: this data set)

   Value	Definition
   1	Stratigraphic or intrusive contact, location certain
   7	Shoreline or riverbank
   30	Fault, sense of displacement uncertain; location certain
   51	Concealed stratigraphic or intrusive contact
   60	Concealed fault, sense of displacement uncertain
   99	Bounding line of coverage

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Patton, Jr., William W.
   • Wilson, Frederic H.
   • Taylor, Theresa A.

2. Who also contributed to the data set?

   This data set was prepared by Theresa Taylor (USGS), and Frederic Wilson (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
   

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.

1. From what previous works were the data drawn?

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

   Date: 2009 (process 1 of 1)

   Line work for the geology compilation was head's up digitized from one scanned paper map source at 1:250,000 scale using ARC\INFO version 9.3. The arcs and polygons were attributed. The spatial databases are provided in UTM projection and geographic coordinates in coverage format.

   Person who carried out this activity:
   

   U.S. Geological Survey
   c/o Theresa A. Taylor
   Physical Scientist
   4200 University Drive
   Anchorage, Alaska 99508-4667
   U.S.A.
   

   907-786-7415 (voice)
   tataylor@usgs.gov
   

1. How well have the observations been checked?

   The geologic map of Saint Lawrence Island was prepared from published and unpublished field investigations carried out between 1966 and 1971. Vector features were mostly heads up digitized from a scanned paper map of hand drafted geology over a 1:250k topographic base. 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 1:250,000, although some sources were from 1:2,500,000, 1:500,000 scale mapping.

3. How accurate are the heights or depths?

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

   The complete dataset consists of one geology network coverage (polygons and arcs), and one age coverage (points), marking the location of dated rock samples. There is also an associated relational database of geologic units. The coverage has the extent of all St. Lawrenece Island's 1:250,000 scale quadrangle. On the web page, the map will be provided as a database and a PDF; the pamphlet will be provided as a PDF.

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.)

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
   MS902 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?

   Scientific Investigations Map 3146

3. What legal disclaimers am I supposed to read?

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	ARCE
     Network links:	<https://pubs.usgs.gov/>

   • Cost to order the data: There is no cost for the download of these digital files

Dates:

Last modified: 21-Jun-2011

Metadata author:

U.S. Geological Survey
c/o Theresa Taylor
4200 University Drive
Anchorage, AK 99508-4667
U.S.A.

907-786-7415 (voice)
tataylor@usgs.gov

Metadata standard:

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