Debris Transport in Glaciers

Terms of Reference

Rationale

Historically, glaciologists, glacial sedimentologists and Quaternary (and pre-Quaternary) geologists have tended to work independently of each other. As a result, there is a lack of awareness amongst much of the geological community about recent developments in glaciology, such as the influence of thermal regime, glacier dynamics and the processes at the ice/bed interface. In particular, the processes of subglacial sediment deformation, debris entrainment, and modification of debris during flow by glaciotectonic processes (e.g. folding, foliation development, and thrusting) all remain to be fully embedded in glacial geological literature.

Better understanding of glacial processes has considerable societal value. Much of the northern hemisphere, and parts of the southern hemisphere have been influenced by glaciers, yielding sedimentary products that include sand and gravel resources. Glacigenic sediments also have an impact on slope-stability, civil engineering, aquifers, groundwater flow and pollution.

In order to bring the different communities together, it is proposed that this Working Group runs in parallel with another under the auspices of INQUA that focuses less on the ice itself, and more on the depositional processes and resulting sedimentary facies and landforms (see below).

Themes

Contemporary glacial processes

1. Subglacial processes and deformable beds.
2. Debris entrainment at the glacier bed; the basal ice layer.
3. Debris entrainment at the glacier surface, including the roles played by avalanches, rockfall, fluvial sedimentation and aeolian inputs.
4. Structural controls on debris entrainment, and modification during flow, including the roles played by thrusting, folding and foliation development.
5. Processes of sedimentation and landform development at contemporary ice margins.
6. Interaction of glaciers with the marine environment and impact on sedimentation.
7. The role of glacier thermal regime on sedimentation.
8. Influences of supraglacial, englacial and subglacial meltwater on sedimentation.
9. Quantification of sediment transport through valley glaciers.
10. Glacier-volcano interactions.

Modelling glacial depositional systems

11. Quantitative aspects of sediment delivery to continental margins by ice sheets.
12. Numerical modelling of former ice sheets and glaciers constrained by geological data
13. Modelling interaction between ice streams and subglacial environments, in particular the influence of deformable sediment on ice flow
14. Modelling subglacial erosion and sediment transport.

Activities

The following activities by the Working Group are planned:

1. International Conference on Glacial Sedimentary Processes and Products at the University of Wales, Aberystwyth, 23-27 August 2005; includes joint meeting with INQUA Workgroup on ’Glacial Sedimentary Processes and Landforms’. [Completed: see Past Events].
2. Special Publication arising from the above; publication agreed by the International Association of Sedimentologists.
3. Field-based workshops in modern glacier settings (possibly Alaska).
4. Special sessions within annual international conferences, e.g. AGU, EGU.
5. Towards end of Working Group, a second international conference on glacial processes in collaboration with partner INQUA project.
6. Set up website for Working Group activities. [Completed: this website].
7. Provide a forum for the notification and dissemination of relevant publications.
8. Promote the public understanding of science through a photograph-based website on all aspects of glaciers, hosted by the Swiss Educational website, SwissEduc. [Completed: see
   http://www.glaciers-online.net].

Collaboration with other organisations

INQUA has recently approved a complementary working group on ‘Glacial Sedimentary Processes and Landforms’ (Chair: Dr Neil Glasser, nfg@aber.ac.uk). The forthcoming conference in Aberystwyth will enable us to develop close ties with the International Association of Sedimentologists, the Quaternary Research Association and the Scientific Commission on Antarctic Research. Some themes are complementary to other IUGG/CCS activities, e.g. the Working Group on ‘Glacier and permafrost hazards in high mountains’.