A Chronology of Late Holocene Glacier Fluctuations on Mount Rainier, Washington

Abstract

Lichenometric studies permit close dating for the timing of stabilization of the late Holocene moraines built by North Mowich, Carbon, Winthrop, Cowlitz, and Ohanapecosh glaciers on Mount Rainier. The moraine chronologies indicate synchronous responses among these glaciers during the past 200 yr. Periods of glacier recession began between 1768-1777, 1823-1830, 1857-1863, 1880-1885, 1902-1903, 1912-1915, and 1923-1924. Since the early 19th century, the mean equilibrium-line altitude has risen about 160 m on Mount Rainier.

Minimum ages for earlier glacier variations are based on lichenometric, dendrochronologic, and tephrochronologic data. These data indicate that recessional phases commented about 1328-1363, 1519-1528, 1552-1576, 1613-1623, 1640-1666, 1690-1695, 1720, and 1750.

Whereas the pattern of glacier fluctuations at Mount Rainier agrees with the general chronologic framework of late Holocene variations from many other areas, comparisons of the detailed moraine chronologies from Mount Rainier for the past two centuries with those from Swedish Lapland indicate several differences in the timing of moraine stabilization. These differences imply some nonsynchrony in Northern Hemisphere glacier variations during the late Holocene.