Processes of biological weathering typical of glacial environments

Question 1

Describe the role of tree roots in biological weathering?

Answer 1

Tree roots grow into cracks or joints in rocks and exert outward pressure. This operates in a very similar way and with similar effects to freeze-thaw weathering. When trees topple, their roots can also exert leverage on rock and soil, bringing them to the surface and exposing them to further weathering. Burrowing animals may have a similar effect.

Question 2

Describe the role of organic acids in biological weathering?

Answer 2

Organic acids produced during decomposition of plant and animal litter cause soil water to become more acidic and react with some minerals in a process called chelation. Blue-green algae can have a weathering effect, producing a shiny film of iron and manganese oxides on rocks.