Constraining the glacial history of the south-west Pennines: glacial landsystems, till geochemical signatures and ice-marginal positions

Turner, Angela Christine

Abstract

Palaeoglaciological reconstruction of the eastern sector of the Irish Sea Glacier, part of the Late Devensian British-Irish ice sheet, has been hampered due to a lack of natural exposures and depositional landforms which are used to determine the limit of former ice masses. A series of conflicting ice limits have been proposed, illustrating this problem.

This study aims to constrain the location of the Late Devensian ice margin in the south-west Pennine hills and the Cheshire Plain using a multiparametric approach. It combines field and geotechnical samples of glacial diamictons, resulting in a 75km NW-SE transect which crosses the proposed ice limits. It uses geomorphological, sedimentological, and geochemical techniques to investigate the provenance of till deposits, ice flow direction and ice margins.

Geomorphological mapping shows that five different Landsystem Domains are present. Within this setting, sedimentological and geochemical analysis of the major, trace and rare earth elements identified four distinct diamictons. This allowed provenance and ice flow direction to be established. The results show that incorporation and comminution of fresh bedrock into the till occurs within 6km of crossing a major bedrock boundary, influencing the geochemical provenance signature. This is evident along the entire flowline, even in ice marginal environments at the eastern extremity of the Irish Sea Glacier.

The results show that it is possible to constrain the glacial history of the southwest Pennines through the multi-parametric application of geomorphological, sedimentological, and geochemical techniques, resulting in the identification of a proposed new Late Devensian ice limit for the eastern sector of the Irish Sea Glacier. In areas where all lines of evidence align, there is high certainty regarding the position of the limit, but issues of inheritance result in a complex landscape, resulting in contradictory evidence and uncertainty in places. This illustrates the value of employing multiple lines of evidence in regions where ice limits are contested.

Citation

Turner, A. C. (2025). Constraining the glacial history of the south-west Pennines: glacial landsystems, till geochemical signatures and ice-marginal positions. (Thesis). Keele University. https://keele-repository.worktribe.com/output/1280040

• Thesis Type: Thesis
• Online Publication Date: Jun 26, 2025
• Deposit Date: Jun 18, 2025
• Publicly Available Date: Jun 27, 2025
• Public URL: https://keele-repository.worktribe.com/output/1280040
• Award Date: 2025-06