U.S. Geological Survey 19970430 vector digital data Anchorage, Alaska U.S. Geological Survey Citation of the source map: Schumacher, G. M. 1976. Bathymetric map of the Chukchi Sea and Arctic Ocean. USGS Open-File Report 76-823. Schumacher, G. M. 1976. Bathymetric map of the Aleutian Trench and Bering Sea. USGS Open-File Report 76-821. https://cmgds.marine.usgs.gov/data/walrus/berchuk.zip Two bathymetric maps were developed by the U.S. Geological Survey, one for the Chukchi Sea and Arctic Ocean, and one for the Aleutian Trench and Bering Sea. The 2 maps overlap near the Bering Strait. Bathymetric contours were generated from several published sources. It is unclear whether new soundings were collected for these maps. The northern map extends from Wrangel Island, Russia to MacKenzie Bay, Canada, and north to 76 N latitude. The southern map extends from Shelikof Bay, Russia, to the western tip of the Alaska Peninsula, USA, and south to 48 N latitude. Bathymetric contours are at 400 meter intervals with 20, 30, 40, 50, 100, and 200 meter contours added. Contours above 50 meters are rare, and never along the Russian coast. Hard-copy maps were published by the USGS in 1976 and digitized by the Alaska Science Center in 1997. In digital format, the 2 maps have been connected where they overlap in the Bering Strait. The maps were produced to aid in geophysical research and exploration in the Bering and Chukchi Seas. The USGS Alaska Science Center created this and other digital bathymetry coverages to support marine animal research in the Bering and Chukchi Seas. The completed coverages are being stored on the Coastal and Marine Geoscience Data System (CMGDS) for archival purposes only. The coverage "Bathymetric Map of the Bering/Chukchi Sea" is titled BERCHUK_3GEO (ber=bering sea, chuk=chukchi sea, 3=polygon topology, geo=geographic projection) 1976 map publication date Complete None 154 -130 76 48 USGS Metadata Identifier USGS:88c8475f-bf4c-4aca-9089-8e6d29279750 ISO 19115 Topic Category geoscientificInformation oceans None contours Data Categories for Marine Planning distributions bathymetry and elevation USGS Thesaurus bathymetry contouring computational methods None western Alaska eastern Russia Bering Sea Chukchi Sea None Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey and Geological Society of America as the originator of the dataset. Alaska Science Center, Marine and Fresh Water Ecology Branch mailing and physical

Biological Resources Division, U.S. Geological Survey

1011 E. Tudor Road

Anchorage Alaska 99503 USA 907-786-3512 907-786-3636 8:00 am to 4:00pm Monday through Friday None Esri Arc/INFO 7.1 National Ocean Service U.S. Department of Commerce Unknown Map Washington, D.C. Department of Commerce, NOAA, NOS Bathymetric maps available for purchase from National Geophysical Data Center, E/GC3, 325 Broadway, Boulder, Colorado 80303-3228. U.S. Geological Survey 1976 Map U.S. Geological Survey Professional Paper 759-B Washington, D.C. U.S. Government Printing Office Hopkins, D.M., Nelson, C.H., Perry, R.B., and Alpha, T.R., 1976, Physiographic subdivisions of the Chirikov Basin, Northern Bering Sea (studies on the marine geology of the Bering Sea): Geological Survey Professional Paper 759-B, U.S. Government Printing Office, 7 pp, 3 plates. U.S. Geological Survey 1984 Map Miscellaneous Investigations Series Map I-1182-D Washington, D.C. U.S. Geological Survey Hill, E.R., Grantz, A., May, S.D., and Smith, M., 1984, Bathymetric map of the Chukchi Sea: U.S. Geological Survey, Miscellaneous Investigations Series I-1182-D. U.S. Geological Survey 1988 Map Open-File Report 89-548 Menlo Park, CA U.S. Geological Survey Hall, R.K., Karl, H.A., Carlson, P.R., Cooper, A.K., Gardner, J..V., Hunter, R.E., Marlow, M.S., and Stevenson, A.J., 1989, Bathymetric map of the Aleutian Basin and Bowers Basin east of the U.S.-U.S.S.R. 1867 Convention Line, Bering Sea: U.S. Geological Survey Open-File Report 89-548, 6 pp, 1 map, scale 1:2,000,000. Geological Society of America 1974 Map Boulder, CO Geological Society of America Pratt, R., and Walton, F., 1974, Bathymetric map of the Bering Sea: The Geological Society of America, Boulder, CO. Attribute accuracy was tested by manually comparing hard copy plots to the source maps. All polygon features are checked for topology using Arc/INFO software. Each polygon begins and ends with a node feature. All nodes are checked for errors so that there are no dangling features. There are no duplicate lines or polygons. All nodes well snap together and close polygons based on a specified tolerance. If the node is not within tolerance it is adjusted manually. The tests for logical consistency are performed in Arc/INFO. All contours for both maps were digitized at a high level of accuracy. After digitizing was completed , a 1:2,000,000 scale coastline (source = digital chart of the world) was added to the coverage to provide a land reference and complete the nearshore polygons. Horizontal accuracy was tested using Arc/INFO's RMS errors generated when the digitized map is converted from table inches to real world coordinates. RMS errors ranged from 0.002 to 0.004 during map registration. In addition, the joined maps were displayed with Russian and Alaska coastlines with high accuracy. There are several islands in the Aleutian chain that appear to cross the closest bathymetric contour, a problem that may be related to the resolution and accuracy of the coastline coverage as much as the bathymetry coverage. U.S. Geological Survey 1976 Open-File Report 76-821 and 76-823 Washington, D.C. U.S. Geological Survey Schumacher, G.M., 1976, Bathymetric map of the Chukchi Sea and Arctic Ocean: USGS Open-File Report 76-823. -and- Schumacher, G.M. 1976, Bathymetric map of the Aleutian Trench and Bering Sea: USGS Open-File Report 76-821. Map 1976 Publication date USGS_berchuk The map provided the bathymetric contours for the digitized vector data Two separate tic bases were created in Arc/INFO using the generate command with the fishnet option for each map area. The tic bases were projected from geographic to Albers Equal Area (projection of the source maps) and used to register maps for digitizing. Central merideans were located from the source maps' author as -158 for 76-823 and 175 for 76-821. Arcs were hand digitized. The digitized version of 76-823 was projected to a central meridian of 175 to match 76-821 and the maps were appended together. A problem a\occurred with the Arc/INFO software when trying to project across 180 degrees. Arcs that straddled 180 were clipped and had to be manually snapped together. This will be a problem whenever this coverage is reprojected until Arc/INFO resolves the problem in the software. After the map was digitized and projected into geographic, the digital chart of the world coastline (1:2,000,000 scale) was added to provide a land reference and complete the near shore polygons. Processing tolerances were: weed 40 m, grain 40 m, dangle 0.1 m, and fuzzy 0.1 m. Note that the tolerances are listed in meters and the coverage is in geographic. THESE TOLERANCES SHOULD BE SPECIFIED IN ANY FUTURE CLEAN TO MAINTAIN THE INTEGRITY OF THE COVERAGE. USGS_berchuk 199609 Alaska Science Center, Marine and Fresh Water Ecology Branch mailing and physical

Biological Resources Division, U.S. Geological Survey

1011 E. Tudor Road

Anchorage Alaska 99503 USA 907-786-3512 907-786-3636 8:00 am to 4:00pm Monday through Friday None Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. 20170214 U.S. Geological Survey Alan O. Allwardt Contractor -- Information Specialist mailing and physical address

2885 Mission Street

Santa Cruz CA 95060 831-460-7551 831-427-4748 aallwardt@usgs.gov Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. 20201019 U.S. Geological Survey VeeAnn A. Cross Marine Geologist Mailing and Physical

384 Woods Hole Road

Woods Hole MA 02543-1598 508-548-8700 x2251 508-457-2310 vatnipp@usgs.gov Edited metadata to fix validation errors and to bring it up to FGDC CSDGM current standards based on data release policies for USGS Coastal and Marine Hazards and Resources Program (CMHRP). No data were changed. The metadata available from a harvester may supersede metadata bundled within a download file. Users are advised to compare the metadata dates to determine which metadata file is most recent. 20211118 U.S. Geological Survey Susan Cochran Geologist Mailing and Physical

2885 Mission Street

Santa Cruz CA 95060 831-460-7545 scochran@usgs.gov Bathymetric contours Vector String 5380 Entity point 460 GT-polygon composed of chains 461 Entity point 11 4.1101378883467987e-005 4.1101378883467987e-005 Decimal Degrees D Clarke 1866 Clarke 1866 6378206.4 294.9786982 No correction 400 meters; 10m, 50m, and 400m contours are represented Attribute values berchuk_3geo.aat Bathymetric Map of the Bering/Chukchi Sea Arc Attribute Table (arcs) USGS; ESRI FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. FNODE# Internal node number for the beginning of an arc (from-node). ESRI Whole numbers that are automatically generated. TNODE# Internal node number for the end of an arc (to-node). ESRI Whole numbers that are automatically generated. LPOLY# Internal node number for the left polygon. ESRI Whole numbers that are automatically generated. RPOLY# Internal node number for the right polygon. ESRI Whole numbers that are automatically generated. LENGTH Length of feature in internal units. ESRI Positive real numbers that are automatically generated. BERCHUK# Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. BERCHUK-ID User-defined feature number. ESRI Sequential unique whole numbers that are automatically generated. DEPTH Depth in meters below sea level for each contour. USGS 20 8000 meters CLASS A categorical variable to define the line type. USGS Class=0 for digitized bathymetric contours; class=8 for arcs that were added to close polygons; and class=9 for the Russian and US/Canadian coastlines. There were 2 cases where class 8 arcs were used: (1) when contours ended because adjoining contours were too close, and (2) the box used as the perimeter of the coverage. berchuk_3geo.pat Bathymetric Map of the Bering/Chukchi Sea Polygon Attribute Table (polygons) USGS; ESRI FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. AREA Area of feature in internal units squared. ESRI Positive real numbers that are automatically generated. PERIMETER Perimeter of feature in internal units. ESRI Positive real numbers that are automatically generated. BERCHUK# Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. BERCHUK-ID User-defined feature number. ESRI Sequential unique whole numbers that were automatically generated. MID_DEPTH Polygon attribute calculated as the mid-point between bounding arcs, e.g. mid-depth between 50 and 100 meter contours equals 75 meters, and between 4,000 and 4,400 meter contours is 4,200 meters. Where a bathymetric contour was an "island" and there was no further depth information inside the "island", the mid-depth was coded as the bounding contour's depth. USGS 25 8000 The coverage contains two attributes pertinent for data analysis and display (depth and mid-depth, and one attribute that specifies the line type (class). Depth is an arc attribute (.aat) that specifies the ocean depth at each contour in meters. Mid-depth is a polygon attribute (.pat) calculated from the depth values of each polygon's bounding contours (e.g. a polygon with bounding contours of 30 m and 40 m would be 35 m). Class displays the type of line, 0 for digitized contours, 9 for the coastline, and 8 for arcs added to close polygons. Producer Alaska Science Center, Marine and Fresh Water Ecology Branch Mailing and physical

1011 E. Tudor Road

Anchorage Alaska 99503 USA 907-786-3512 907-786-3636 8:00am to 4:00pm Monday through Friday None Although these data have been processed successfully on a computer system at the U.S. Geological Survey (USGS) no warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. This disclaimer applies both to individual use of the data and aggregate use with other data. It is strongly recommended that these data are directly acquired from USGS server, and not indirectly through other sources which may have changed the data in some way. It is also strongly recommended that careful attention be paid to the contents of the metadata file associated with these data. The USGS shall not be held liable for improper or incorrect use of the data described and/or contained herein. ArcInfo Interchange Version 7.1 ArcInfo Interchange file (E00) and Zip (.zip) 4 https://cmgds.marine.usgs.gov/data/walrus/berchuk.zip Use internet browse or file manager application (such as Windows Explorer) to access the directory (http://cmgds.marine.usgs.gov/data/walrus/) and download berchuk.zip None, if obtained online. 20211118 U.S. Geological Survey, Pacific Coastal and Marine Science Center PCMSC Science Data Coordinator mailing and physical

2885 Mission Street

Santa Cruz CA 95060 831-427-4747 pcmsc_data@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998