Neoglacial fluctuations of the Natazhat and Klutlan Glaciers, Yukon Territory, Canada

Abstract

The Natazhat and Klutlan Glaciers are surging valley glaciers whose present termini are located at the northern edge of the St. Elias Mountains. Both glaciers have massive ice-cored Neoglacial morainal complexes extending down-valley from their ice termini. At least six separate Neoglacial moraines adjacent the Klutlan Glacier and four adjacent the Natazhat Glacier have been identified from changes in the geomorphic, pedologic, limnologic, vegetational, dendrochronologic, and lichenometric characteristics across the morainal complexes. Dating of the individual moraines by lichenometry, dendrochronology, and 14C implies that most were constructed within the last 550 years, although both glaciers have been relatively inactive near their termini since 1947.Stratigraphy and 14C dates suggest that the initial Neoglacial advance of the Natazhat Glacier near its Neoglacial maximum occurred ca. 3300 B.P. and that of the Klutlan Glacier ca. 1520 B.P.Intervals during which the glaciers constructed a number of moraines near their Neoglacial maxima probably were caused by cool summer temperatures, even though individual moraines were formed by glacial surges. A number of factors make impossible precise dating of the intervals of cool summer temperatures.