A comprehensive inventory of maximum glacial extent in Glacier National Park during the peak of the Little Ice Age

This data release consists of digitized glacier margins that represent the maximum extent of glaciers in Glacier National Park (GNP) and two glaciers on U.S. Forest Service's Flathead National Forest land during the peak of the Little Ice Age. Glacier margins are based on moraine deposits that result from active glaciation, and do not depict perennial snow and ice. Moraines are continuous arcuate rock deposits with distinct crests that form at the ice edge of active glaciers. The criteria used for identifying the former size and location of glaciers were a) the presence of a terminal moraine, b) the presence of one or both lateral moraines, and c) whether the identified glacier area was 0.020 km2 (five acres) or more. Previous work also included hummocky morainal debris immediately in front of well-defined moraines. This release includes a comprehensive inventory of past and present glaciers in GNP as well as a subset of the 37 named glaciers. Final digitized glacier margins, based on moraines, were subjected to independent review by other scientists.