Map of glacial limits and possible refugia in the southern Alexander Archipelago, Alaska, during the late Wisconsin glaciation

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: P.E. Carrara
Originator: T.A. Ager
Originator: J.F. Baichtal
Originator: D. Paco VanSistine
Publication_Date: 2003
Title:
Map of glacial limits and possible refugia in the southern Alexander Archipelago, Alaska, during the late Wisconsin glaciation
Edition: version 1.0
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: U.S. Geological Survey Miscellaneous Field Studies Map
Issue_Identification: MF-2424
Publication_Information:
Publication_Place: Denver, Colorado
Publisher: U.S. Geological Survey
Online_Linkage: http://pubs.usgs.gov/mf/2003/mf-2424/
Description:
Abstract:
During the late Wisconsin glaciation (circa 26,000-13,000 carbon-14 yr BP) the Cordilleran glacier complex formed vast ice fields and large glaciers along the crest of the Coast Mountains. As these glaciers flowed west to the Pacific Ocean, they were joined by local glaciers originating on the higher reaches of the Alexander Archipelago (Mann and Hamiltion, 1995). This extensive volume of ice was channeled into deep troughs (present-day fiords) that formed major outlet glaciers, such as the glaciers that occupied Chatham Strait and Dixon Entrance. In several places along the coast, deep glacially scoured submarine troughs indicate that glaciers reached to the edge of the continental shelf. For instance, the glacier that extended into the Dixon Entrance trough is known to have extended to the edge of the continental shelf. Its retreat began sometime after 16,000-15,000 carbon-14 yr BP (Barrie and Conway, 1999).
The exact extent of late Wisconsin cordilleran ice in southeastern Alaska is poorly known. Small-scale maps and reports of the region commonly show or imply ice extending west to the edge of the continental shelf (Capps, 1931; Coulter and others, 1965; Flint, 1971; Pewe, 1975; Denton and Hughes, 1981; and Prest, 1984). These maps relied heavily on earlier work, much of it of a reconnaissance nature.
The map shows our interpretation of the limit of the Cordilleran ice sheet, which is more restricted than previous estimates, and possible refugium (an area that escaped the extensive glaciation of the late Wisconsin and so provided a suitable habitat for relict species) in the southern Alexander Archipelago during the late Wisconsin glaciation. In addition to the analysis of the bathymetric map, the limits of the Cordilleran ice sheet and possible refugia were also identified by analyses of aerial photographs, USGS topographic maps (1:63,360 and 1:250,000 scales), NOAA bathymetric charts (1:20,000 and 1:40,000 scales), previous literature, and reconnaissance fieldwork throughout the region. Ice-free areas that may have served as refugia include (1) high mountain nunataks (too small to show at map scale), (2) unglaciated ocean-facing slopes and forelands (Dahl, 1946), (3) the outer islands of the Alexander Archipelago (Worley, 1980), and (4) parts of the inner continental shelf exposed by the lowering of sea level during the late Wisconsin by an estimated 125 m (Bard and others, 1990).
Purpose:
This map, which shows bathymetric contours within the southern part of the Alexander Archipelago, Alaska, has been prepared to show the limits of the Cordilleran ice sheet in this region. Previous bathymetric data for this region showed only individual water depth data (NOAA nautical charts). By producing a bathymetric contour map of this region large geomorphic features are apparent and provide information regarding the glacial history of the region. For instance, large, deep glacial troughs, such as the Chatham Strait trough, indicate that the glacier that occupied this trough flowed to the edge of the continental shelf. Previous studies suggested that during the late Wisconsin glaciation Cordilleran ice overwhelmed the Alexander Archipelago and terminated in one vast ice front at the edge of the continental shelf. Our interpretation, based on the bathymetric contours, indicates that ice reached the continental shelf at only several locations, Chatham Strait and Dixon Entrance, while large areas of the exposed continental shelf and parts of the outer islands may have been ice free.
Supplemental_Information:
Arc/Info coverages and shapefiles included in this dataset: extents(.shp)--probable Cordilleran ice extents
100m_cont(.shp)--bathymetric contours below -300 meters
25m_cont(.shp)--bathymetric contours above -300 meters
Map political location: Southern Alexander Archipelago, Alaska Compilation scale: 1:500,000 Geology mapped in 2001-2003
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 2003
Currentness_Reference: publication date
Status:
Progress: complete
Maintenance_and_Update_Frequency: none planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -136.27626612
East_Bounding_Coordinate: -131.1200724
North_Bounding_Coordinate: 57.29756559
South_Bounding_Coordinate: 54.21530596

Keywords:
Theme:
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: snow and ice cover
Theme_Keyword: bathymetry
Theme_Keyword: geologic history
Theme_Keyword: geospatial datasets
Theme_Keyword: maps and atlases
Theme:
Theme_Keyword_Thesaurus: American Geological Institute (AGI) Glossary of Geology
Theme_Keyword: Glacial limits
Theme_Keyword: Bathymetry
Theme_Keyword: Cordilleran ice sheet
Place:
Place_Keyword_Thesaurus: U.S. Board on Geographic Names
Place_Keyword: United States of America
Place_Keyword: Alaska
Place_Keyword: Southern Alexander Archipelago
Place:
Place_Keyword_Thesaurus: Augmented FIPS 10-4 and FIPS 6-4
Place_Keyword: f02201 = Prince of Wales-OuterKetchikan
Place_Keyword: f02130 = Ketchikan Gateway
Place_Keyword: f02280 = Wrangell-Petersburg
Place_Keyword: f02220 = Sitka
Access_Constraints: none
Use_Constraints:
none. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Paul Carrara
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing address
Address: USGS, Denver Federal Center, MS-980, Box 25046
City: Denver
State_or_Province: Colorado
Postal_Code: 80225
Country: USA
Contact_Voice_Telephone: 303-236-1287
Contact_Electronic_Mail_Address: pcarrara@usgs.gov

Browse_Graphic:
Browse_Graphic_File_Name: http://pubs.usgs.gov/mf/2003/mf-2424/MF-2424_250_pixel_wide.gif
Browse_Graphic_File_Description:
Reduced-size image of the entire map sheet, 250x157 pixels, 13k bytes.
Browse_Graphic_File_Type: GIF

Browse_Graphic:
Browse_Graphic_File_Name: http://pubs.usgs.gov/mf/2003/mf-2424/mf-2424.pdf
Browse_Graphic_File_Description: Printable representation of map layout, 27.5 megabytes
Browse_Graphic_File_Type: PDF

Data_Set_Credit:
Scientific Fishery Systems, Inc. for providing the digital data base of depth soundings.
Native_Data_Set_Environment:
Windows_NT, 5.0, Intel ARC/INFO version 8.2
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
Data were checked by the geologist who made the observations. To check attribute accuracy, a color check plot was visually compared to the geologist's original compilation. Discrepancies between the digital geospatial dataset and the original analog compilation were corrected as needed. This map has been thoroughly reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature.
Logical_Consistency_Report:
Map elements were visually checked by the author for overshoots, undershoots, duplicate features, polygon attributes, and other errors. Automated (ARC/INFO) routines were also used to check the databases for polygon label errors, line or point attribution errors, sliver polygons, dangling arcs, intersection errors, and projection information. The map was reviewed by other geologists for consistency with basic geologic principles and general conformity to USGS mapping standards.
Completeness_Report:
Data are complete: no features were eliminated or generalized at the scale of map compilation.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Many points were determined originally by GPS and(or) Loran System. All data used from published and unpublished digital sources are limited by the accuracy of that data. All glacial extents were on- screen digitized from hand-drafted scanned versions drawn on bathymetric map at 1:500,000 scale.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator: Scientific Fishery Systems, Inc
Geospatial_Data_Presentation_Form: digital
Publication_Date: 2000
Title: Alaska Bathymetric Data
Publication_Information:
Publication_Place: Anchorage, AK
Publisher: Scientific Fishery Systems, Inc
Type_of_Source_Media: CD-ROM
Source_Time_Period_of_Content:
Source_Currentness_Reference: map
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1997
Ending_Date: 1998
Source_Citation_Abbreviation: none
Source_Contribution:
Digital bathymetric point elevations, used to create bathymetric contours.
Process_Step:
Process_Description:
Interpretations of topographic maps and aerial photos, along with field work were done by geologist.
Process_Date: 1997-2001

Process_Step:
Process_Description:
Contours were created in Arc/Info using bathymetric point data obtained from Scientific Fishery Systems, Inc., at 25-meter and 100-meter intervals.
Process_Date: 2001

Process_Step:
Process_Description:
Glacial limits were digitized in Arc/Info from bathymetric interpretations drawn by geologist/author on bathymetry map printouts.
Process_Date: 2002

Process_Step:
Process_Description:
Bathymetric countours and glacial limit arcs were attributed and given line feature descriptions.
Process_Date: 2002

Process_Step:
Process_Description:
Map printouts were submitted for technical reviews and suggestions/corrections were made to database.
Process_Date: 2003

Process_Step:
Process_Description:
First draft of metadata created by Paco VanSistine Using FGDCMETA.AML ver. 1.32 01/11/99.
Process_Date: 2003

Process_Step:
Process_Description: Creation of original metadata record
Process_Date: 2003
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: Paco VanSistine
Contact_Address:
Address_Type: mailing address
Address: USGS, Denver Federal Center, MS-980, Box 25046
City: Denver
State_or_Province: CO
Postal_Code: 80225-0046
Country: USA
Contact_Voice_Telephone: 303-236-5452
Contact_Electronic_Mail_Address: dsistine@usgs.gov
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: State Plane Coordinate System 1927
State_Plane_Coordinate_System:
Oblique_Mercator:
Scale_Factor_at_Center_Line: 0.999900
Oblique_Line_Azimuth:
Azimuth_Measure_Point_Longitude: -133.666667
Azimuthal_Angle: 36.869898
Latitude_of_Projection_Origin: 57.0
False_Easting: 16404166.666667
False_Northing: -16404166.666667
SPCS_Zone_Identifier: 6101
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 112.65703125
Ordinate_Resolution: 112.65703125
Planar_Distance_Units: Feet
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1927
Ellipsoid_Name: Clarke 1866
Semi-major_Axis: 6378206.4
Denominator_of_Flattening_Ratio: 294.98
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
The dataset consists of three coverages:
EXTENTS (probable Cordilleran ice extents)
100M_CONT (bathymetric contours below -300 meters)
25M_CONT (bathymetric contours above -300 meters)


<EXTENTS.AAT>
item explanation:
DESCRIPTION--short description of line feature

COLUMN   ITEM NAME      WIDTH   OUTPUT   TYPE   N.DEC
1        FNODE#             4        5      B       -
5        TNODE#             4        5      B       -
9        LPOLY#             4        5      B       -
13       RPOLY#             4        5      B       -
17       LENGTH             4       12      F       3
21       EXTENTS#           4        5      B       -
25       EXTENTS-ID         4        5      B       -
29       DESCRIPTION      100      100      C       -

DESCRIPTION
Chatham Strait fault
Fairweather/Queen Charlotte fault
probable late Wisconsin Cordilleran ice marginal position
probable pre-late Wisconsin Cordilleran ice marginal position
submarine slide scarp


<100M_CONT.AAT>
item explanation:
CONTOUR--bathymetric contour interval, in meters below sea level
(100-meter increments)

COLUMN   ITEM NAME      WIDTH   OUTPUT   TYPE   N.DEC
1        FNODE#             4        5      B       -
5        TNODE#             4        5      B       -
9        LPOLY#             4        5      B       -
13       RPOLY#             4        5      B       -
17       LENGTH             4       12      F       3
21       100M_CONT#         4        5      B       -
25       100M_CONT-ID       4        5      B       -
29       CONTOUR            8       14      F       0

CONTOUR
values between -300 and -3100 (100-meter increments)


<25M_CONT.AAT>
item explanation:
CONTOUR - bathymetric contour interval, in meters below sea level (25-meter increments)

COLUMN   ITEM NAME      WIDTH   OUTPUT   TYPE   N.DEC
1        FNODE#             4        5      B       -
5        TNODE#             4        5      B       -
9        LPOLY#             4        5      B       -
13       RPOLY#             4        5      B       -
17       LENGTH             4       12      F       3
21       25M_CONT#          4        5      B       -
25       25M_CONT-ID        4        5      B       -
29       CONTOUR            8       14      F       0

CONTOUR
values between 0 and -275 (25-meter increments)
Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/mf/2003/mf-2424/mf-2424_508.pdf
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Address:
Address_Type: mailing address
Address:
Central Publications Group
MS-902, Box 25046
Denver Federal Center
City: Lakewood
State_or_Province: CO
Postal_Code: 80225-0046
Country: USA
Contact_Voice_Telephone: 303-236-5486
Resource_Description: USGS Miscellaneous Field Studies Map MF-2424
Distribution_Liability:
Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data.
The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: Shapefile
Format_Version_Number: 1.0
Format_Information_Content: Bathymetric contours and limits of the Cordilleran ice sheet
File_Decompression_Technique: gzip and tar or unzip
Transfer_Size: 37
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Digital_Form:
Digital_Transfer_Information:
Format_Name: ARCE
Format_Version_Number: 8.2
Format_Information_Content: Bathymetric contours and limits of the Cordilleran ice sheet
File_Decompression_Technique: gzip and tar or unzip
Transfer_Size: 37
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Fees: none
Metadata_Reference_Information:
Metadata_Date: 20160205
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Peter N Schweitzer
Contact_Organization: USGS Midwest Area
Contact_Position:
Collection manager, USGS Geoscience Data Clearinghouse, http://geo-nsdi.er.usgs.gov/
Contact_Address:
Address_Type: mailing address
Address:
Mail Stop 954
12201 Sunrise Valley Dr
City: Reston
State_or_Province: VA
Postal_Code: 20192-0002
Country: USA
Contact_Voice_Telephone: 703-648-6533
Contact_Facsimile_Telephone: 703-648-6252
Contact_Electronic_Mail_Address: pschweitzer@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Access_Constraints: none
Metadata_Use_Constraints: none

This page is <https://geo-nsdi.er.usgs.gov/metadata/map-mf/2424/metadata.html>
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