GGR317H5 Lecture Notes - Braided River, Syncline, Winnowing
Document Summary
Glaciers terminating on land can deposit sediment in two ways: (i) (ii) directly, that is from the ice itself; or indirectly, for example through the action of meltwater. Direct deposition by a glacier is restricted to its immediate vicinity, whereas meltwater may carry sediment far beyond the glacier margin. Glacial sediments are traditionally divided into those that are non-sorted and formed by direct glacier sedimentation, and those that are sorted or stratified and usually deposited by meltwater. In practice this is a rather artificial distinction because meltwater deposits are not always stratified. In this chapter we describe the products of direct glacier sedimentation before considering deposition from meltwater. Debris deposited directly by a glacier is known as till. A till is defined as sediment deposited by glacier ice, but one which has not been disaggregated, although it may have suffered glacially induced flow either in the subglacial or supraglacial environment.
