Rates of erosion and sediment evacuation by glaciers: A review of field data and their implications

Abstract

Diverse field data on glacial sediment yields are assembled in the context of the current interest in sedimentary basin development in glaciated regions, and in controversial linkages between global climate and topography. Attention herein is directed at sediment yields, including both overall bedrock erosion and evacuation of sediments stored in glaciated basins over several years or decades. These yields, expressed as effective rates of glacial erosion, vary by orders of magnitude from 0.01 mm yr −1 for polar glaciers and thin temperate plateau glaciers on crystalline bedrock, to 0.1 mm yr −1 for temperate valley glaciers also on resistant crystalline bedrock in Norway, to 1.0 mm yr −1 for small temperate glaciers on diverse bedrock in the Swiss Alps, and to 10–100 mm yr −1 for large and fast-moving temperate valley glaciers in the tectonically active ranges of southeast Alaska. In Alaska, current sediment yields generally increase with the extent of glacial ice cover, and are particularly high in the large heavily-glaciated basins of southern Alaska, where they exceed those of basins from other regions by about one order of magnitude. These results, supported by comparisons of sediment yields between glaciated and nonglaciated basins in Alaska, Norway and Iceland, suggest that climatic conditions favorable for the expansion of temperate valley glaciers tend to increase both mechanical and chemical denudation rates. The results are discussed in the broader context of linking erosion and climate during the ice ages of the Quaternary, and interpreting records of sedimentation from glaciated regions.