SUBGLACIAL SEDIMENT DYNAMICS; THE LARGER PICTURE EMERGING FROM THE MICROSCOPE

The study of a large number of large thin sections of glacial sediments of many different localities and environments has led to a new model of subglacial tills. However it has also led to a re-assessment of subglacial sediment dynamics as a whole. We have studied tills that are the result of the squashing of bedrock by glaciers, but in which the sediment has not necessarily been in contact with the ice. On the other hand there are tills which completely consist of sediment that has been completely restructured by ice, without much material having been added by the ice. Both examples appear to be end members of a wide range of origins for subglacial tills. This presentation will show and discuss some of the possible origins