Charles M. Cannon 20230616 raster digital data Reston, VA U.S. Geological Survey https://doi.org/10.5066/P9MT4FVL This digital terrain model represents historical elevations along the valley of the North Fork Toutle River upstream of its confluence with the Green River in Cowlitz and Skamania Counties, Washington. Most elevations were derived from U.S. Geological Survey 1:62,500 scale topographic quadrangle maps published from 1953 to 1958 that were derived from aerial photographs taken in 1951 and 1952. Elevations representing the bed of Spirit Lake, at the head of the valley, were derived from a bathymetric map based on survey data from 1974. Elevations are in units of meters and have been adjusted to the North American Vertical Datum of 1988. This digital terrain model was created to support analyses of landscape change caused by eruptions of Mount Saint Helens in the 1980s. 1951 1952 19741017 ground condition Complete None planned -122.590520 -122.088010 46.378415 46.152438 ISO 19115 Topic Category elevation USGS Thesaurus topography USGS Metadata Identifier USGS:6439ae77d34ee8d4ade2302d Geographic Names Information System Washington Cowlitz County Skamania County North Fork Toutle River Spirit Lake Mount Saint Helens Mt St. Helens Common geographic areas Pacific Northwest Washington Cowlitz Skamania Lower Cowlitz Mount Saint Helens National Volcanic Monument Mount Saint Helens None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Charles M. Cannon U.S. Geological Survey Geologist mailing address

1819 SW 5th Avenue #336

Portland OR 97201 United States NA ccannon@usgs.gov Funding provided by U.S. Geological Survey Volcano Hazards Program, Volcano Science Center. No formal accuracy assessment has been performed but there is considerable uncertainty owing to the nature of historical maps. Most of the source maps depict elevation by 80-foot (24 meter) contours derived using photogrammetric methods from aerial photographs of variably forested areas. Contour locations on the source maps are generally consistent with each other but in places disagree by as much as 20 meters near map edges, particularly on the Toutle (1953) and Mount St. Helens (1958) maps. Cell size of the scanned maps is about 5 meters. The shoreline of Spirit Lake shown in Bortleson and others (1976) was in places difficult to reconcile with the shoreline depicted on the Spirit Lake (1957) and horizontal uncertainty may be as much as 20 meters. Elevations are in the expected range for the map area. These data are considered complete for the map area. See Attribute Accuracy. U.S. Geological Survey 1953 1.0 Scanned Map in GeoTIFF format Reston, Virginia U.S. Geological Survey Historical Topographic Maps 15 x 15 Minute Map Series, Toutle, WA; U.S. Geological Survey Scanned Historical Quadrangle Standard, Version 1.0. Aerial photographs taken 1951. Field checked in 1953. GeoTIFF produced by scanning and georeferencing paper version of map in 2014. https://ngmdb.usgs.gov/topoview/ 62500 digital 1951 ground condition Toutle (1953) source of elevation data U.S. Geological Survey 1953 1.0 Scanned Map in GeoTIFF format Reston, Virginia U.S. Geological Survey Historical Topographic Maps 15 x 15 Minute Map Series, Elk Rock, WA; U.S. Geological Survey Scanned Historical Quadrangle Standard, Version 1.0. Aerial photographs taken 1952. Advance field checked in 1953. GeoTIFF produced by scanning and georeferencing paper version of map in 2014. https://ngmdb.usgs.gov/topoview/ 62500 digital 1952 ground condition Elk Rock (1953) source of elevation data U.S. Geological Survey 1957 1.0 Scanned Map in GeoTIFF format Reston, Virginia U.S. Geological Survey Historical Topographic Maps 15 x 15 Minute Map Series, Spirit Lake, WA; U.S. Geological Survey Scanned Historical Quadrangle Standard, Version 1.0. Aerial photographs taken 1952. Field checked in 1957. GeoTIFF produced by scanning and georeferencing paper version of map in 2014. https://ngmdb.usgs.gov/topoview/ 62500 digital 1952 ground condition Spirit Lake (1957) source of elevation data U.S. Geological Survey 1953 1.0 Scanned Map in GeoTIFF format Reston, Virginia U.S. Geological Survey Historical Topographic Maps 15 x 15 Minute Map Series, Cougar, WA; U.S. Geological Survey Scanned Historical Quadrangle Standard, Version 1.0. Aerial photographs taken 1952. Advance field checked in 1953. GeoTIFF produced by scanning and georeferencing paper version of map in 2014. https://ngmdb.usgs.gov/topoview/ 62500 digital 1952 ground condition Cougar 1953 source of elevation data U.S. Geological Survey 1958 1.0 Scanned Map in GeoTIFF format Reston, Virginia U.S. Geological Survey Historical Topographic Maps 15 x 15 Minute Map Series, Cougar, WA; U.S. Geological Survey Scanned Historical Quadrangle Standard, Version 1.0. Aerial photographs taken 1952. Field checked in 1958. GeoTIFF produced by scanning and georeferencing paper version of map in 2014. https://ngmdb.usgs.gov/topoview/ 62500 digital 1952 ground condition Mt St. Helens (1958) source of elevation data Bortleson, G.C. Dion, N.P. McConnell, J.B. Nelson, L.M. 1976 Scanned report with maps Olympia, Washington Washington Department of Ecology Bortleson, G.C., Dion, N.P., McConnell, J.B., and Nelson, L.M., 1976, Reconnaissance data on lakes in Washington, Volume 4, Clark, Cowlitz, Grays Harbor, Lewis, Pacific, Skamania, and Thurston Counties: Washington Department of Ecology Water-Supply Bulletin 43, https://apps.ecology.wa.gov/publications/documents/wsb43d.pdf. Bathymetric contour map of Spirit Lake on page 109 showing 20-foot depth contours derived from U.S. Geological Survey data acquired October 17, 1974. https://apps.ecology.wa.gov/publications/documents/wsb43d.pdf digital 19741017 ground condition Bortleson and others (1976) source of elevation data Contours, point elevations, streams, and the shoreline of Spirit lake were digitized from parts of the U.S. Geological Survey Toutle (1953), Elk Rock (1953), Spirit Lake (1957), Cougar (1953), and Mount St. Helens (1958), Washington 1:62,500 scale topographic quadrangle maps. Topography for the maps was mostly generated from aerial photographs taken in 1952. Topography for the Toutle (1953) quadrangle was based on aerial photographs taken in 1951. The maps were obtained as GeoTIFF images with embedded georeferencing information from the U.S. Geological Survey (http://ngmdb.usgs.gov/maps/TopoView/). The map images were re-projected from their native polyconic projections to Universal Transverse Mercator, Zone 10 projection, North American Datum of 1927. Map features were heads-up digitized. Along parts of the North Fork Toutle River, where there was wide spacing between contours, supplemental contours were drawn to be approximately halfway between contours depicted on the 1950s maps. Contours and point elevations were assigned elevations in feet above Mean Sea Level (equivalent to National Geodetic Vertical Datum of 1929) as depicted on the source maps. The elevations were multiplied by 0.3048 to convert to meters. Elevations were adjusted to North American Vertical Datum of 1988 by adding 1.163 meter based on a single representative point obtained from the National Geodetic Survey North American Vertical Datum Conversion tool (VERTCON, https://www.ngs.noaa.gov/cgi-bin/VERTCON/vert_con.prl, accessed December 7, 2018). A digital terrain model (DTM) of 1952 topography was generated from the digitized contours, point elevations, streams, and the shoreline of Spirit Lake using the Topo to Raster tool in ArcGIS, which is based on the ANUDEM algorithm (Hutchinson, 1989, https://doi.org/10.1016/0022-1694(89)90073-5). The DEM of 1952 topography was reprojected to North American Datum of 1983 using the NADCON transformation. Bathymetric contours for Spirit Lake were digitized from contours shown in Bortleson and others (1976) based on a survey done in 1974. A Map shown in Bortleson and others (1976) was georeferenced by matching the shoreline with the shoreline depicted on the Spirit Lake (1957) 1:62,500 topographic quadrangle map. Contours were heads-up digitized and assigned depths in feet as depicted on the source map. Depths were converted to elevations by subtracting from the 3,198-foot water surface elevation depicted on the Spirit Lake (1957) map. The contour elevations were multiplied by 0.3048 to convert to meters and adjusted to North American Vertical Datum of 1988 by adding 1.163 meter. A digital terrain model (DTM) for the bed of Spirit Lake was made from the 1974 contours using triangulated irregular network interpolation and reprojected to North American Datum of 1983 using the NADCON transformation. Elevations were adjusted to the North American Vertical Datum of 1988 by adding 1.163 meter. The DTM of 1952 topography was mosaicked with the DTM representing the bed of Spirit lake to produce the final digital terrain model. Toutle (1953) Elk Rock (1953) Spirit Lake (1957) Cougar (1953) Mt St. Helens (1958) Bortleson and others (1976) 20200318 141228 Raster Grid Cell 23165 33381 1 Universal Transverse Mercator 10 0.9996 -123.0 0.0 500000.0 0.0 row and column 2.872047316825708 2.8720473168256997 meters North_American_Datum_1983 GRS 1980 6378137.0 298.2572221010042 GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display 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. Digital Data https://doi.org/10.5066/P9MT4FVL None 20230616 Charles M. Cannon U.S. Geological Survey Geologist mailing address

1819 SW 5th Avenue #336

Portland OR 97201 United States NA ccannon@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998