What physical features of a landscape affect the erosive action of rivers and glaciers?
How? ANSWER: Glaciers and rivers need to flow downhill in order to move fast enough to erode the land. Sedimentary rock can be eroded fairly easily, but igneous or harder rock is more difficult to move or chip. Glaciers can more easily pick up and move huge rocks that cannot be crushed while rivers tend to flow around such obstacles. • How do the erosive effects of rivers and glaciers compare in relation to degree and time? ANSWER: Rivers, even large ones at flood, are not as big as glaciers. They move more quickly, although with great force. Relative to rivers, glaciers are huge, allowing them to affect larger areas; they move more slowly or ponderously than rivers. Large and small rocks, carried along by rivers, are rounded by the constant bouncing around in a river’s flow; whereas, rocks carried by glaciers show no evidence of polishing. The river’s flow sorts the deposits it makes at flood and at its alluvial plain, whereas the glacier simply carries the debris along, dropping it o
