Fluvial Erosion
A stream that flows upon a uniformly erodible substrate will tend to have a steep gradient near its source, and a low gradient nearing zero as it reaches its base level. Of course, a uniform substrate would be rare in nature; hard layers of rock along the way may establish a temporary base level, followed by a high gradient, or even a waterfall, as softer materials are encountered below the hard layer.
Human dams, glaciation, changes in sea level, and many other factors can also change the "normal" or natural gradient pattern.
Read more about this topic: Stream Gradient
Famous quotes containing the word erosion:
“Inter-railers are the ambulatory equivalent of McDonalds, walking testimony to the erosion of French culture.”
—Alice Thompson (b. 1963)