PARTICLE AND AGGREGATE MOBILITY IN TILL - MICROSCOPIC EVIDENCE OF SUBGLACIAL PROCESSES

Microscopic studies of tills show that the deforming bed of glaciers i s made up of minute rotational elements or wheels, consisting of a nuc leus alone or a nucleus with spiralling arms of fine grains. These fin e grains can move from one wheel to the next, providing a process of h igh grain mobility within a deforming subglacial till. Recognition of this process explains a variety of glacial distribution patterns: i.e. the mineralogical reflection of subjacent lithologies in the till mat rix; the side by side occurrence of far-travelled erratics and locally -derived matrix; and the shape of geochemical anomalies. Copyright (C) 1997 Elsevier Science Ltd.