Flow Signatures on the Bed and the Surface of Ice Sheets

• Main Author: Ely, Jeremy
• Format: Thesis
• Language: English
• Published: University of Sheffield 2015
• Subjects: Antarctic; Rutford; Rutford Ice Stream; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://etheses.whiterose.ac.uk/12585/; https://etheses.whiterose.ac.uk/12585/1/Thesis_Ely_nocopy.pdf

Ice flow produces morphological features at the bed and on the surface of ice sheets. These ‘flow signatures’ provide us with an insight into the mechanisms, history and characteristics of ice sheet flow. In this thesis I examine the characteristics of basal and surficial ice sheet flow signatures, as well as possible links between them. The first chapter introduces ice sheet flow signatures. At the bed, a suite of landforms known as subglacial bedforms are found. The surface of an ice sheet is home to longitudinal surface structures (LSSs) and transverse surface structures (TSSs). Whilst the two environments are mostly considered in isolation, links between the sets of flow signatures found at each have been suggested. Section A deals with basal flow signatures. Chapter 2 asks whether subglacial bedforms are patterned. Drumlins are found to be regularly placed within the landscape, and likely grow or shrink over time. Chapter 3 examines whether subglacial bedforms conform to a size and shape continuum. By collating and analysing a dataset of 96,900 measurements of size and shape it is found that 3 continua of subglacial bedforms exist: flutes, lineations and ribs. The latter two are joined by an understudied class of quasi-circular bedforms. Section B deals with surficial flow signatures. In Chapter 4 I present and analyse a map of the LSSs of the Antarctic Ice Sheet. The morphology, spatial distribution and glaciological context of LSSs leads to the proposal of a model for their formation. Chapter 5 presents the first systematic study of TSSs. Mapping and analysis reveals that TSSs are regularly spaced, differ little in their morphology between ice streams and are most likely stationary. Section C compares basal and surficial ice sheet flow signatures. In Chapter 6, morphological comparisons, a case study of the Rutford Ice Stream, analysis of ice penetrating radar and examination of ice flow modelling lead to the conclusion that the majority of basal and surficial flow signatures are separate entities. ...