ABSTRACT
GLACIAL EROSION Glaciers form where winter snowfall exceeds summer melt; snow layers accumulate, compressed lower zones recrystallize and these are squeezed out as flowing ice. Erosion is largely by entrained rock debris scraped over the surface, locally leaving glacial striae (scratches). Most glaciers move about a metre per day. Pleistocene glaciated areas are most easily recognized by erosional landforms. Alpine glaciation: valley glaciers in mountain areas of high relief; ice further deepens U-shape valleys between high uneroded arête ridges. Sheet glaciation: thick ice moves over entire landscape; greater erosion of high ground reduces relief; ice can erode while moving uphill, to create irregular topography with over-deepened rock basins.
