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Rapid erosion, drumlin formation, and changing hydrology beneath an Antarctic ice stream

Scientists have discovered a warehouse-sized drumlin — a mound of sediment and rock — actively forming and growing under an Antarctic ice stream. Its discovery, and the rate at which it was formed, sheds new light on ice-sheet behaviour. This could have implications for predicting how ice sheets contribute to sea-level rise.

There are abundant indications from modern and former ice-sheets that the properties of the bed can change quite quickly, affecting the velocity of glaciers and thereby influencing sea level. Year-by-year, new measurements indicate that the glacier bed is more and more complex than we had thought, with a spectrum of instabilities in temperature, water pressure and till flux from periods of days to millennia.

Drumlins are well known features of landscapes scoured by past ice sheets and can be seen in Scotland and Northern England where they were formed during the last ice age. This paper presents a spectacular example from beneath the Rutford Ice Stream in Antarctica, and highlights the value of long-term investigations. The rates of deposition and erosion are orders of magnitude greater than expected, and suggest complex coupling between water, till and ice flow. Quite apart from being the first sub-glacial observations of a well-known geomorphic feature, these findings present an even more complex picture of the sub-glacial instabilities which drive a significant, if unknown, fraction of ice-sheet variability.

Scientists have discovered a warehouse-sized drumlin — a mound of sediment and rock — actively forming and growing under an Antarctic ice stream. Its discovery, and the rate at which it was formed, sheds new light on ice-sheet behaviour. This could have implications for predicting how ice sheets contribute to sea-level rise.

Find link to the full paper in the NERC Open Research Archive

Authors

A.M. Smith, T. Murray, K.W. Nicholls, K. Makinson, G. Aðalgeirsdóttir, A.E. Behar, D.G. Vaughan

Publication

Geology Volume 35, Issue 2 (February 2007) pp. 127*130 DOI: 10.1130/G23036A.1