Junior Certificate Geography Notes on Weathering and Erosion for the Irish Second Level Education Curriculum.

1. Weathering
Weathering and Erosion
The earth’s surface is constantly changing. This is due to the forces of Weathering,
Erosion and Deposition.
Weathering is the breaking down of rocks exposed to the elements.
Erosion means wearing away.
Deposition means dropping off.
There are twotypes of weathering- Mechanical and Chemical.
 Mechanical (Freeze-Thaw action)
 Chemical (Acid rain on Limestone)
Mechanical weathering
The main example of mechanical weathering is Freeze-ThawAction.
This happens when water gets into cracks in the rock and freezes. Water expands
when frozen and this causes the rocks to break into smaller pieces called Scree.
Freeze-Thaw Action

2. A rock affected by Freeze-Thaw Action
in a mountainous region
Chemical Weathering
Chemical weathering occurs when acid rain weathers rock, i.e. Limestone. The acid
in the rain slowly dissolves the limestone to form Calcium Carbonate. This white
liquid then makes its way down through the permeable layers of the limestone to
underground caves and caverns. As a result many features are formed. They include
Stalagtites and Stalagmites, Pillars and Curtains.

3. A statue affected by Chemical Weathering (Acid
Rain)