Abstract
Glaciers often erode, transport and deposit sediment much more rapidly than nonglacial environments1, with implications for the evolution of glaciated mountain belts and their associated sedimentary basins. But modelling such glacial processes is difficult, partly because stabilizing feedbacks similar to those operating in rivers2,3 have not been identified for glacial landscapes. Here we combine new and existing data of glacier morphology and the processes governing glacier evolution from diverse settings to reveal such stabilizing feedbacks. We find that the long profiles of beds of highly erosive glaciers tend towards steady-state angles opposed to and slightly more than 50 per cent steeper than the overlying ice–air surface slopes, and that additional subglacial deepening must be enabled by non-glacial processes. Climatic or glaciological perturbations of the ice–air surface slope can have large transient effects on glaciofluvial sediment flux and apparent glacial erosion rate.
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Acknowledgements
We thank K. Cuffey for advice and for comments on this manuscript, including help with the third paragraph. We thank our many colleagues in studying the Matanuska glacier system, including S. Arcone, S. Kopczynski, R. Bigl, J. Denner, S. Ensminger, T. Johnston and J. Strasser, and we thank R. Hooke for suggestions. Discussions with B. Hallet, G. Clarke, T. Creyts, S. Tulaczyk and other colleagues helped clarify our ideas. We thank NSF and CRREL for funding.Author contributions R.B.A. led collaborative theory development and writing, D.E.L., G.J.L. and E.B.E. provided extensive data and insights on glacier processes, and G.S.B. produced new geophysical data at Matanuska glacier.
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Affiliations
Department of Geosciences and EMS Environment Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
- R. B. Alley
Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire 03755, USA
- D. E. Lawson
Department of Geological Sciences, Michigan State University, East Lansing, Michigan 48824, USA
- G. J. Larson
Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
- E. B. Evenson
Department of Geology, University at Buffalo, Buffalo, New York 14260, USA
- G. S. Baker
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The authors declare that they have no competing financial interests.
Corresponding author
Correspondence to R. B. Alley.
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