| Academic Year | 2024-2025 |
| a.ranger.24@abdn.ac.uk | |
| Institution | University of Aberdeen |
Biography
School: School of Geosciences
Pronouns: she/her
Project: Crevasse squeeze ridges: a fingerprint of unstable glacier flow?
Supervisors: Prof Brice Rea, Prof Matteo Spagnolo, Dr Andrew Newton, Dr Bartosz Kurjanski, Dr Danni Pearce, & Dr Harold Lovell
Undergraduate Education: BSc Geography, University of Exeter
Postgraduate Education: MSc Sustainable Development, University of Exeter
Research: Crevasse squeeze ridges (CSRs) are somewhat enigmatic landforms, though our understanding of their formation and preservation mechanisms are now near fully understood. Initially they were linked only with surging glaciers but with improvements in the imaging of the earth surface and sea floor it has become apparent that they are also formed beneath ice streams. Their formation is driven by high basal water pressures and fast ice flow which in combination lead to the formation of bottom-up basal crevasses that become filled with sediment sourced from the glacier bed. Once formed, preservation then requires a switch in the ice dynamics such that the ice slows down/stops and deglaciation occurs passively, otherwise they will not be preserved. Their presence in the landform record therefore provides evidence for highly dynamic and potentially unstable ice flow. Such knowledge is important for understanding the dynamics of past ice sheet deglaciation and surging glaciers. However, the reconstruction of ice dynamics from CSR networks has, to date, been underexplored.
This project will initially undertake a systematic review of the literature to compile a database on CSR distribution and formation mechanisms that will likely form the basis for an initial review paper. From this database, key CSR sites at active glacier margins and in palaeo settings will be mapped and analysed in a GIS environment, using free to access satellite imagery and DEMs, to generate datasets on their metrics, geometries and the related/inferred ice dynamics. These data will include, for example, ridge orientation, segment lengths, relief, and ice flow direction determined from subglacial lineation (flutes and MSGL). Such data will allow basal fracture patterns to be reconstructed and the exploration of how these relate to ice dynamics (e.g. ice thickness, location and patterning within flow units, sediment volume etc.) and an assessment of how their dimensions scale in relation to ice mass geometry. Various approaches will be investigated to assess the potential for deriving quantitative estimates of past ice dynamics using preserved CSR networks, e.g. estimates of ice thicknesses linked to a geotechnical assessment of potential overburden pressure, and estimations of the orientations and ratios of tensile and shear stresses derived from CSR fracture patterns.
Possible field locations for the investigation of recently exposed landforms include Svalbard and Iceland, while excellent palaeo examples can be found in areas glaciated by the Laurentide ice sheet in North America.
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