ABSTRACT: Cirque glacier erosion rates and characteristics of Neoglacial tills, Pangnirtung Fiord area, Baffin Island, NWT Canada

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Abstract

Ten cirque glaciers and their Neoglacial deposits were studied in th Pangnirtung Fiord area of Baffin Island to determine the origin of glacial debris and the erossion rates of subpolar glaciers. The rate of debris production for glaciers was 24 to 155 mSUP-3 yrSUP--1 . Clast rounding indicates that 84 to 96% of the till may be subglacially derived, and was produced at a rate of 22 to 140 mSUP-3 yrSUP--1 . Rockfall rates were low in the Baffin Island cirques, averaging 1 to 22 mSUP-3 yrSUP--1 . Grain-size analyses of Baffin Island Neoglacial tillss indicate that they contain little silt (5%) and clay (1%). Abrasion is probably negligible at the base of the Baffin glacierss. The low amounts of silt and clay suggest the glaciers are either wholly or partly frozen to their beds. Computed rates of total erosion by the glaciers of this study range from 8 to 76 mm/1000 yr, and are one to two times lower than those for Arapaho Glacier in Colorado. Glaciers occupying cirques with the highest rockfall rates also have the highest rates of glacial erosion. The limited data also indicate that large south-facing glaciers have the highest erosion rates. The low erosion rates suggest that 2 million to 14 million years were required to erode the cirques, and/or the erosion rates have not been constant.

Bibliography of Canadian Geomorphology