Sugden, Lindsay

2018-05-22T12:48:41Z

2018-05-22T12:48:41Z

2006

The aim of this thesis is to use the geomorphic record of NE Iceland to assess the consequences of the "8.2ka event", the largest recorded climatic reversal in the Holocene. Iceland is a sensitive and strategic location in which to study the impact of the event, given the evidence that it was triggered by a North Atlantic fresh water anomaly. The research combines new high resolution empirical evidence with ice sheet modelling to assess the extent and nature of glacial activity at 8.2ka. New geomorphic evidence is presented for the Early Holocene in the BorgarfjorSur Eystri region of northeast Iceland. In total, thirteen landform 'suites' are identified which are indicative primarily of glacial activity, but also contain evidence for massmovement events. Landform suites are backed by cliffs or scree slopes, and consist, in the upper parts, of high-relief ridges and terraces interpreted as landslide deposits. The middle and lower parts are made up of longitudinal ridges and hummocky terrain, with clear terminal and lateral moraines defining former glacier margins. Phases of glacial and mass-movement activity which generated these landforms are Holocene in age, dated to between 7600-4000 Cal. Yrs. B.P. It is suggested that glacial advances represent the primary response to the 8.2ka cooling event, while the mass-movement events which occurred later were a result of paraglacial slope instabilities, and thus can be seen as a secondary response. Ice sheet modelling experiments suggest that extreme climatic conditions, involving a temperature drop of as much as 7°C, would have been necessary to initiate glaciers in the locations where Holocene activity has been observed. It is suggested that abundant debris supplies generated from the friable exposures of rhyolitic bedrock, would have inhibited the ablation of glacier ice, so that cooling may not have had to be as much as 7°C to promote and preserve the recorded glacial activity. This study presents evidence for a time-transgressive glacial and geomorphic response to the 8.2ka event in Iceland, providing a site-specific example of regional environmental response to climate change. The record can be correlated with environmental changes at this time in the North Atlantic and beyond, promoting understanding of potential response mechanisms to future rapid climate change events.

http://hdl.handle.net/1842/30802

The University of Edinburgh

Annexe Thesis Digitisation Project 2018 Block 19

Already catalogued

Glaciers, climate and the "8.2ka event" in Iceland

Thesis or Dissertation

Doctoral

PhD Doctor of Philosophy