6. Deposited by ice

Abstract

There are two types of primary glacial sediment created by glacier beds acting as shearing zones within which a subglacial deforming layer is developed: till and glacitectonite. ‘Deposited by ice’ explains how these deposits represent a continuum of materials, the products of the various stages of sediment mixing creating diamicton. Where a glacier acts to deform and gradually mix its substrate it will create a melange or glacitectonite. At the highly deformed end of the spectrum, the material is close to being fully homogenized into a diamicton and at this point it becomes a subglacial till. Erratics—boulders carried by glacier ice, often over long distances—are also described.