Glacial quarrying and development of overdeepenings in glacial valleys; modelling experiments and case studies at Erdalen, Western Norway

Erdalen valley in western Norway exhibit a set of several sediment-filled overdeepened basins carved in the rock by the Quaternary glaciers. This is a common phenomenon in presently or previously glaciated regions of the world. Despite of numerous glacial erosion theories, the origin of glacial overdeepenings remains confuse. The present study attempts to take a step further in the comprehension of the underlying processes. The results of a numerical model of glacial erosion, based on shallow ice flow modelling, bed separation and glacial plucking by sub-critical crack growth in conjunction with observations on Erdalen geology and geomorphology shows that small-scale overdeepenings are mainly the expression of bedrock resistance variations and flux pattern of the glacier. Glacial plucking, as modeled in this study, mainly contributes to headwall steepening.