The Composite Glacial Erosional Landscape of the Northern Mcmurdo Dry Valleys: Implications for Antarctic Tertiary Glacial History
- John C. Priscu
Published Online: 16 MAR 2013
Copyright 1998 by the American Geophysical Union.
Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica
How to Cite
Prentice, M. L., Kleman, J. L. and Stroeven, A. P. (1998) The Composite Glacial Erosional Landscape of the Northern Mcmurdo Dry Valleys: Implications for Antarctic Tertiary Glacial History, in Ecosystem Dynamics in a Polar Desert: the Mcmurdo Dry Valleys, Antarctica (ed J. C. Priscu), American Geophysical Union, Washington, D. C.. doi: 10.1029/AR072p0001
- Published Online: 16 MAR 2013
- Published Print: 28 JAN 1998
Print ISBN: 9780875908991
Online ISBN: 9781118668313
- Desert ecology—Antarctica—McMurdo Dry Valleys
We reassessed glacial versus non-glacial hypotheses for the excavation of the McMurdo Dry Valleys using bedrock geomorphologic evidence. We find three glacial erosional landscapes, namely, high, intermediate, and low, within the Wright-Victoria Valley system below an elevation of 1300 m. The principal evidence for glacial erosion is the molded asymmetry of paired corners on tributary-valley spurs at trunk-valley intersections. This reflects confluence of wet-based alpine and trunk-valley glaciers flowing east to southeast. Hanging glacial benches at two different elevations in numerous valley locations coupled with valley floors that exhibit classic glacial morphology delineate the three glacial landscapes. We propose progressive glacial incision by wet-based ice in separate high, intermediate, and low phases to cut the stepped glacial landscapes. Apparent continuity of each glacial surface for more than 50 km from Transantarctic Mountain (TAM) crest toward the sea requires large ice flux from either local mountain and/or continental ice sheets. The lowest elevation of definitive fluvial morphology is c. 1300 m. Erosion of trunk valleys below this level has been by glacial processes. This implies that the TAM crest was significantly broader during the high and intermediate glacial phases than at present. It follows that a linear TAM ice sheet could account for high- and intermediate-phase glaciation. The East Antarctic Ice Sheet probably dominated during the low phase. The presence of wet-based alpine glaciers during each phase indicates that the coeval climate was significantly warmer and wetter than at present.