Nutrient-rich soil is an important part of any ecosystem because all plants depend on it. When trees are removed to make paper as in the pictures above, the soil is exposed to the elements and there are no longer as many roots holding the soil in place. In clear-cut areas, when it rains or the wind blows, nutrient-rich topsoil is washed away. What's left is hard rocky soil, making it hard for new plants to grow.

The above paragraph is describing which natural process?

Most of the erosion that occurs in San Mateo County is caused by water run-off near pavement. Pavement causes lots of water to flow to one area. This flow of water often washes away topsoil in that spot, making it hard for new plants to grow.