Biological Weathering

Allison ChoongGao Wenxin

Joelle TanSinead Tan

Wong Kwang Lin

Definition

• The weathering of rocks/landforms by plants (roots), animals and lichen.

• Can be a physical process as well as a chemical process

• Plants release chelating compounds and certain organic acids which break down some metal compounds in the ground.

• Thrives in cool and humid climates

By Plants

• As the roots of plants grow, they grow into the rock, causing cracks to appear.

• The bigger the roots grow, the deeper and bigger the cracks in the rocks become.

• Some types of plants like moss expel chemicals that dissolve minerals in the rock.

By Fungus

• Lichen chemically and physically breaks down minerals in the rocks

• A kind of fungus related to tree root systems transfers nutrients from the rocks to the trees

By Animals

• Burrowing animals create holes in the rock by breaking it to make their burrows.

• Some animals like mollusks, clams and sea urchins digest certain minerals in rocks, making holes like tiny caves

• These make the rock more susceptible to other forms of weathering

• Animals such as worms ingest the soil

By Plants

A tree growing in rocks

Pictures

The bivalve Pholad creates hollows in rocks

Lichen on rocks emit organic acids and other chemicals that weather the rocks