Travis Dickinson

Proglacial landform and sediment signatures of subglacial overdeepenings

Research Supervisors: Dr. Simon Cook (University of Dundee), Dr. Darrel Swift (University of Sheffield), & Dr. Martin Kirkbride (University of Dundee)

 

Research aim: To assess the proglacial sedimentological signatures of processes that operate in subglacial overdeepenings.

To achieve this research aim, the following objectives will be completed:

1. To analyze the bed topography of Alpine glaciers and identify candidate sites (i.e. terminal overdeepenings with adverse bed slope at the supercooling threshold) for field investigation.
2. To map sediment-landform distribution within the proglacial areas of glaciers with a terminal overdeepening.
3. To stratigraphically log exposures through proglacial sediment accumulations.
4. To collect and analyze sediment samples for sedimentological analyses (e.g. clast shape & roundness; particle size distribution; SEM).

Synopsis/Background:

Subglacial overdeepenings are near-ubiquitous features in glaciated environments, and have a profound influence on glacier dynamics, meltwater hydrology, and geomorphological processes. Despite their importance, overdeepenings have not yet received the same level of systematic, detailed study as other classic glacial landforms (such as U-shaped valleys, moraines, etc.). Of particular note is the lack of detailed geomorphological and sedimentological investigation of proglacial areas situated beyond terminal overdeepenings, which may preserve an important archive of processes and conditions specific to these landscapes.

Previous studies (Cook et al. 2011; Swift et al. 2018) have, for example, noted that a specific suite of processes operate in these environments (including glaciohydraulic supercooling and englacial thrusting) which gives rise to distinctive landform-sediment signatures; these signatures may be preserved in the geomorphological record of glaciation. Previous studies (Cook et al. 2011; Cook & Swift 2012; Cook et al. 2012) have noted that processes such as glaciohydraulic supercooling, which are typical of overdeepenings, tend to generate silt-dominated tills and moraines, as well as water- rounded sediments that show signs of both subglacial and fluvial wear.

However, these studies are few and focused on individual locations (mostly in Iceland) meaning that it is unclear to what extent the process ‘signature’ of overdeepenings is pervasive, nor the extent to which it can be preserved in the geomorphological record. This study seeks to address that gap by assessing the landform-sediment signature of overdeepenings at locations in the Alps, where landforms and sediments associated with overdeepenings have not been examined in detail before.