2005_Glacier margins derived from 2005 NAIP imagery for the named glaciers of Glacier National Park, MT and environs

These polygon features represent digitization of the glacier margins for the 37 named glaciers of Glacier National Park (GNP) and two glaciers on U.S. Forest Service’s Flathead National Forest land, derived from 2005 NAIP imagery. The polygons represent only the main body portion of each glacier as it appeared in 2005 NAIP imagery. Disconnected patches are not included as this dataset represents only the main body features of the named glaciers in GNP and environs. Polygons were digitized from NAIP imagery acquired on the following source dates: 20050731, 20050826, 20050827. Initial digitization was completed by Kristina A Dick, Portland State University graduate student. This set of polygons represents revisions based on supplemental imagery (oblique images in USGS collection, GoogleEarth collection), and local knowledge and interpretation by Dan Fagre and Lisa McKeon (USGS) in February - August, 2016. A Wacom Pro digital tablet was used by USGS staff to digitize outlines and make revisions to the PSU margins. Glaciers were digitized at 1:2000 scale. Since multiple images in time series contribute to this analysis, if previous image showed perennial snow that was absent from the glacier (bedrock visible), then that portion was deemed "seasonal/perennial snow" in subsequent photos and not included in the digitization of 2005 glacier margins.