Denudation is the process of wearing away the top layers of Earths landscape. Because the rate of denudation is normally too small to directly measure, it can be indirectly determined by measuring the sediment load of the streams that drain the area in question. This is possible because any material that passes through a certain point on a stream is guaranteed to have come from somewhere in the streams drainage basin upstream of that point. As topographic relief increases, the dissolved load's contribution to the total stream load decreases due to the fact that on steeper surfaces, rain is less likely to infiltrate the rocks, leading to less chemical weathering, which decreases the dissolved load.