Moraines of two different age groups have been identified; the subdued, vegetated moraines of the older group have been found at 25 sites, mainly in the central part of the Lewis Range. These older moraines are in places overlain by the Mazama ash; they date from 10 000 BP or earlier. Moraines of the younger group, consisting of fresh bouldery rubble, are common throughout Glacier Park. Tree- ring analyses indicate that some of these younger moraines were deposited by advances that culminated during the mid-19th century. At that time there were more than 150 glaciers in Glacier Park. -from Author
Additional publication details
Holocene and latest Pleistocene glacial chronology, Glacier National Park, Montana.