Do Plants & Animals Affect Rocks?

Types

• Biological weathering is one of three types of different weathering processes; the other two are chemical and physical weathering. Often these processes act in concert to break down or degrade rocks over time.

Function

• As you know if you've ever seen a sidewalk buckling over a tree root, the growth of plant roots can gradually fracture remarkably solid surfaces, including rocks. Organisms like lichen or molds secrete substances that react with minerals in rocks to break down the rock so the lichen can anchor themselves to an otherwise sheer surface. Water frozen in plant matter, or in cracks in the rock created by plants, can stress and break apart the rocks even further.

Effects

• In some cases organisms can even continue to affect rocks after their demise. Organic matter from dead or decaying organisms can form organic acids that help to accelerate the breakdown of the rock.