Weathering

weathering

the breakdown or disintegration of rock in situ

What are the three main types of weathering?

• mechanical (physical) weathering

• biological weathering

• chemical weathering

What are the six sub-types of weathering?

• freeze thaw weathering

• insolation weathering 

• pressure release weathering

• salt weathering

• chemical weathering

• biological weathering

freeze thaw weathering

water in cracks freezing, expanding, and weakening rocks, repeatedly breaking up the rocks into smaller pieces

insolation weathering

repeated changes in temperature weakening the rock - hot and cold temperatures cause thermal fracturing

pressure release weathering

rocks formed deep down (e.g., granite) are compressed by rock and debris above them - this pressure is released when the rock is exposed by erosion, causing it to expand and break off

salt weathering

a saline solution gets into cracks or pores in rock - if the temperature changes enough for the salt to crystallise, it will expand in the cracks and may fracture the rock

chemical weathering

ordinary rain water contains a small amount of acid (pH 5.5) - when this acid comes into contact with rock, it attacks it chemically, causing the rock to rot or crumble away

biological weathering

the breakdown of rocks by the actions of living organisms, primarily plants, animals, and microorganisms