Types of Weathering

Physical Weathering: Freeze-Thaw Weathering

• This process starts when water seeps into cracks in the rock.

• At night the temperatures fall below 0 degree Celsius, the water freezes and, as ice, expands.

• This forces the cracks open.

• This process happens again and again, and breaks up the rock.

• The loose rock is called scree

Freeze-thaw is common in mountainous areas. Igneous rocks (granite) and metamorphic rocks (marble) from uplands are prone to this type of weathering.

Physical Weathering: Exfoliation

• This process happens when rocks are repeatedly subjected to heat and cold.

• Heat from the sun makes the outer layer expand.

• The cold at night makes the outer layer contract.

• The outer layer of the rocks then peels off.

• The loose rock is called scree.

This type of weathering is common in desert areas, which are hot in the day and cool at night.

Biological Weathering

• This process is caused by plants and animals.

• Burrowing animals break up the rocks.

• Plant seeds fall into cracks and germinate, breaking up the rocks.

• Tree roots grow into cracks in the rocks and then exert pressure on the cracks as they grow, causing them to widen.