Proglacial Channel Systems: Change and Thresholds for Change over Long, Intermediate and Short Time-Scales

  1. J. D. Collinson and
  2. J. Lewin
  1. Judith K. Maizels

Published Online: 29 APR 2009

DOI: 10.1002/9781444303773.ch20

Modern and Ancient Fluvial Systems

Modern and Ancient Fluvial Systems

How to Cite

Maizels, J. K. (2009) Proglacial Channel Systems: Change and Thresholds for Change over Long, Intermediate and Short Time-Scales, in Modern and Ancient Fluvial Systems (eds J. D. Collinson and J. Lewin), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303773.ch20

Author Information

  1. Department of Geography, University of Aberdeen, St Mary's, High Street, Old Aberdeen AB9 2UF, UK

Publication History

  1. Published Online: 29 APR 2009
  2. Published Print: 7 FEB 1983

ISBN Information

Print ISBN: 9780632009978

Online ISBN: 9781444303773

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Keywords:

  • proglacial channel systems - change and thresholds for change over long, intermediate and short time-scales;
  • analysis of palaeochannels;
  • palaeohydrologic conditions;
  • sedimentology;
  • palaeochannel changes in proglacial areas

Summary

This paper examines the nature, direction and magnitude of change in channel pattern and form in a series of proglacial drainage systems that have experienced deglaciation of glacial fluctuation over a variety of time-scales. Simple quantitative measures are introduced to indicate the direction and magnitude of channel change, and associated changes in meltwater discharge, through the different terrace sequences. The results indicate that in areas experiencing long-term deglaciation channel systems have changed from those comprising dominantly braided, steeply graded, low-sinuosity, high width–depth ratio bedload channels to those represented by deeper, more sinuous, low-gradient, single-thread channels. In addition, channel systems observed on terrace surfaces are shown to include threshold or transitional channels, themselves closely associated with terrace formation and a change in channel equilibrium from a stable or aggradational to an erosional regime. The major channel changes observed appear to reflect factors which are associated with long-term deglaciation, including a change in water and sediment supply, in the magnitude and frequency of extreme flood events, in regional and local base-level and/or the local exceedance of internal geomorphic thresholds.