1. Physical Weathering:
* This process breaks down rocks into smaller pieces without changing their chemical composition.
* Examples:
* Frost Wedging: Water seeps into cracks in rocks, freezes, expands, and widens the cracks.
* Thermal Expansion/Contraction: Fluctuations in temperature cause rocks to expand and contract, weakening them and eventually causing them to break apart.
* Abrasion: Rocks rub against each other, grinding them down. This can occur from wind carrying sand, or glaciers moving rocks.
* Exfoliation: Pressure release from the removal of overlying rock can cause large sheets of rock to peel off.
2. Chemical Weathering:
* This process changes the chemical composition of rocks, leading to their decomposition.
* Examples:
* Oxidation: Oxygen reacts with minerals in rocks, often forming oxides like iron oxide (rust). This weakens the rock.
* Carbonation: Carbon dioxide in the atmosphere dissolves in rainwater, creating a weak acid that can dissolve certain minerals like limestone.
* Hydrolysis: Water reacts with minerals in rocks, breaking them down into new minerals.
* Biological Weathering: Living organisms, such as plants, lichens, and bacteria, can break down rocks by producing acids or physically growing through them.
It's important to note that both physical and chemical weathering often work together to break down rocks. Physical weathering can create more surface area for chemical weathering to act upon, and vice versa.
