Compare the features caused by stream erosion wind erosion and glacial erosion?

Answer 1

I only know that there are distinctly shaped valleys formed by varying types of erosion. Streams and rivers have a lot of gravitational potential energy upstream (as they often have sources in mountains or hills) and so tend to erode vertically in their upper course creating steeply sided v-shaped valleys with very little/no floodplain. As you follow the river downstream the erosional direction changes to become more latteral (horizontal) resulting in valleys with less steep sides and wider floodplains. Glacial movement, however, leads to the creation of even steeper sided u-shaped valleys which can be very wide at the bottom. These are not to be confused with gorges which are created as waterfalls on rivers retreat upstream with consequetive episodes of undercutting and collapse, which tend to be even steeper sided and normally are rather narrow, however this depends on the size and type of the original waterfall as well as the discharge of the river. Wind does not tend to form valleys but rather sculpts those which already exist, by the process of differential erosion, through which different rock types erode at different rates leading to the formation of the beautifully shaped rocks we find sticking out of the desert as well as yardangs and zeugen.