Estimates of Glacial Erosion Rates Based on Sediment Accumulation in Fjords and Their Inferences

The measurement of sediment yields and inferred denudation rates is critical in the analysis of regional tectonics and climate interactions in mountain belts. Of special concern are those systems that are influenced by glacial processes due to the potential of high erosion rates to enhance fjord over-deepening. Glaciers have been shown to be an efficient mode of erosion, yet questions persist about potential variations in sediment accumulation and erosion during different phases of tidewater glaciation in fjords. Sediment accumulation and by inference erosion has been suggested to be greater during the retreat phase as the calving rate and ice flow increases. As many modern measurements are made under rapid glacial retreat, this suggestion is important to assess in order to build reliable predictive models for glacial erosion, especially on longer timescales. The degree of erosion also depends on glacial regime, which appears to be a significant control on facies and ice sheet histories based on data recent Antarctic drill cores. On occasions significant and deep erosion has occurred eliminating large sections that represent significant intervals of geological time. In other instances soft interglacial sediment and even ice-proximal advance sediment is preserved below tills indicating virtually no erosion occurred during glacial overriding. When placed into a geological time perspective it can be possible to determine when major widespread continental erosion occurred versus when differential relief was formed through the history of an ice sheet, especially in fjord areas where evidence is preserved.