Particle breakage in glacial sediments

Abstract

In most areas of glacial deposits, soils were deposited by ice sheet expansion or contraction, and produced by deformation and mixing of pre-existing soft sediments. The resulting soil (till) is well graded. In some cases the remixing and shearing of sediments by glaciers has caused a redistribution of particle sizes by abrasion and crushing. The breakage capacity of glacial sediments recovered from the foreshore of two different glaciers in Iceland, Langjokull (West) and Breidamerkurjokull (South-East), is presented. The initial gradings of the sediments are distinct, the Langjokull sediment being better graded than the Breidamerkurjokull sediment. Results from ring shear tests performed on both kinds of sediments show that the Breidamerkurjokull sediment still has capacity for breakage while particles from the Langjokull sediment do not seem to break even when the soil is sheared to very large strains. It is suggested that the latter sediment has reached a critical grading while being deposited. © 2006 Taylor & Francis Group.