SEDIMENTATION IN THE ICE‐CONTACT ENVIRONMENT, WITH EXAMPLES FROM SHROPSHIRE (ENGLAND)

Abstract

ABSTRACTGlacial sedimentation is assigned to two environments, the pro‐glacial and the ice‐contact. This paper is concerned with sedimentation in the ice‐contact environment. The sub‐drift topography of the area of study and the direction of ice movement are shown to be conducive to ice stagnation which is necessary for widespread ice‐contact sedimentation. Ridges of glacigenic sediment show faulted, collapsed margins and lateral kettle holes characteristic of ice‐contact landforms. The internal structure of these ridges is analysed in terms of primary and secondary sedimentary structure and texture. The spatial distribution of sedimentary structure and texture is shown to be similar to the fluvial models of Allen (1964) and Visher (1965). The absence of lateral extension of the fluvial members is interpreted as being due to stream training by ice walls preventing lateral migration. Large thicknesses of horizontal stratification and strongly unimodal palaeocurrent estimates are believed to be a result of this low sinuosity. Primary sedimentary structure and texture are used to designate facies. The distribution of the facies is thought to be diagnostic of the ice‐contact environment. Downstream facies migration is thought to have occurred as a result of changes in the ratio of sediment supply to stream power.