NUMERICAL AGES OF GLACIER RETREAT AT EMMONS GLACIER, MOUNT RAINIER USING LICHENOMETRY

Lichenometric studies provide a means to study glacier fluctuations in the Cascades during the late Holocene. Accurate numerical ages of moraines can be calculated using lichenometric growth curves established for the region. Lichenometric studies have been completed near the margin of Emmons Glacier on the northeastern side of Mount Rainier, Washington. Lichens measured on multiple sets of Little Ice Age (ca. 1550-1840 AD) end moraines were used to determine the timing of retreat of Emmons Glacier. Preliminary ages are calculated using established growth curves for the southeast area of Mount Rainier near Nisqually Glacier. In an effort to establish a growth curve for the northeastern side of Mount Rainier, measurements are made on anthropogenic structures such as bridges and buildings. Little Ice Age moraines have been mapped and dated in previous studies on the southeastern side of Mount Rainier using lichenometry. The purpose of this study was to: (1) establish whether retreat of Emmons Glacier is synchronous with glaciers on the southeastern side of Mount Rainier, and (2) create a lichen growth curve for the northeastern side of Mount Rainier.