Palaeo-ice streams

The location and behaviour of ice streams is one of the most important controls on ice sheet configuration and stability. In order to reconstruct former ice sheets we need to know ice stream location and timing. Once identified, the beds of palaeo-ice streams provide an unprecedented opportunity to glean information about their basal environment, something that remains very difficult under contemporary ice streams. This paper represents the first synthesis and discussion of palaeo-ice stream research from a variety of former ice sheets and includes new insights relating their configuration and activity to the evidence they leave behind. The ambiguous use of the term 'ice stream' is addressed and four possible configurations for ice streams are presented. Diagnostic landforms and landform assemblages that we would expect an ice stream to produce are discussed and the temporal context of bedform generation is described as either a 'rubber stamped' or 'smudged' bedform imprint, resulting from isochronous or time-transgressive landform generation. In particular, we focus on the configuration of terrestrially terminating ice streams, for which there are no modern analogues. Technological advances in marine geophysics are helping to generate a convergence of interest between Antarctic glaciology and palaeo glaciology. It is suggested that investigations around the fringes of contemporary ice sheets, (i.e. West Antarctica) can provide evidence that directly links the geomorphologaical record of palaeo-ice streams with their contemporary counterparts. In addition, computational advances and modelling adaptations have permitted the incorporation of ice streams within ice sheet models. We argue that data from palaeo-ice stream beds are invaluable to ice sheet/stream modelling experiments and will help us understand ice stream operation and the linkages between climate perturbations and both palaeo and contemporary ice sheets. (C) 2001 Elsevier Science Ltd. All rights reserved.