Abstract

Waterton Lakes National Park in Alberta and Glacier National Park in Montana lie along adjacent sections of the continental divide in the Rocky Mountains. In cirques or near divides there is evidence for two ages of glacial deposits. Younger deposits are generally well preserved, poorly vegetated, and bear no tephra and no or very small lichens. Older deposits are more poorly preserved, better vegetated, bear Rhizocarpon sp. lichens at least up to 92 mm in diameter, and bear tephra. The tephra often occurs in two different coloured horizons, but both are compositionally equivalent to Mazama tephra.The older advance has a minimum age of about 6800 14C years BP and a probable maximum age of about 12 000 14C years BP. It is correlated with the pre-Mazama Crowfoot Advance of the Canadian Rockies. Deposits of the younger advance are probably not too much older than mid-19th century, because some glaciers began retreating from the deposits about then. The younger advance is correlated to the Cavell Advance of the Canadian Rockies and the Gannett Peak Advance of the American Rockies.Both advances were minor. The older advance left moraines about 1.5 km or less beyond present glacier margins and depressed ELA's an average of 40 m below modern values.

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