Weathering

Weathering is the process by which rocks and minerals are broken down into simpler materials by means of physical (mechanical), chemical, and biological processes. Weathering is an extremely important phenomenon for the human species since it is the mechanism by which one of the planet's most important natural resources—soil—is formed.

The exact way in which weathering occurs in any particular situation depends primarily on two factors: the type of rock and the environmental conditions to which the rock is exposed. For example, rocky formations along a seacoast are likely to be exposed to the mechanical action of waves and tides. But rocks buried underground are more likely to be attacked by chemical reactions made possible by water that runs through them.

The presence of living organisms can also cause weathering. Imagine that a seed falls into a small crevice in a rock and begins to germinate. As the plant continues to grow and send down roots, it will work its way into the rock and eventually make the crevice grow in size. Eventually the plant's roots may actually tear the rock apart.