Co-organized by CR4/GM7, co-sponsored by IAS
Convener: Michael SchwenkECSECS | Co-conveners: Marius BuechiECSECS, Thomas BurschilECSECS, Urs Fischer, Bernhard Salcher
| Attendance Mon, 04 May, 10:45–12:30 (CEST)

Bedrock depressions are common features of past and modern glacial landscapes. They are often referred to as overdeepenings and act as important terrestrial archives. Which processes control the formation and geometry of glacial overdeepenings? How did they evolve over time? Which chronological and environmental information can be derived from the sedimentary record? These are the questions that will be addressed in this session.

The timing, extent and driving mechanisms for the last major glacial cycle are increasingly better understood but remain poorly constrained for previous cycles. The early conceptual models, initially adopted to understand older glaciations, neglected much of the spatial and temporal complexity of glaciations. Furthermore, they suffered from a lack of constraining data, which is mainly due to the surficial incompleteness of the terrestrial records.
Some of these limitations may be overcome by studying the sedimentary infill of subglacially formed basins. It is generally accepted that glacial processes, supported by subglacial water, have carved these overdeepenings. However, considerable uncertainties remain concerning the erosional mechanisms and physical constraints.
The sedimentary record in overdeepenings is diverse, including glacial, glacio-lacustrine and fluvial sediments. Investigated records suggest that many overdeepened basins contain a multi-cycle infilling and erosion history. Overdeepenings may therefore act as sediment storages on the timescale of several glacial-interglacial cycles, and provide a valuable record of a landscape’s glacial history. The combination of sedimentological, geophysical, and chronological methods together with the application of landscape evolution models provides new insights into the development of these bedrock features and allows constraining the environmental conditions in the geological past.

This session shall stimulate discussions concerning the formation of subglacial depressions and that aim at deciphering the sedimentary fill of overdeepenings. Contributions may include investigations based on field observations and/or modelling of modern, Quaternary and pre-Quaternary glacial settings. Possible topics cover: (a) glacial and interglacial stratigraphic successions preserved in overdeepenings, (b) subglacial erosion and deposition, (c) glaciation chronology, and (d) landscape evolution.