Weathering

Weathering is the process of disintegration and transformation of the rock into the different minerals that form it. 

It can be:

• Physical or mechanical: refers to the occurrence of fractures and the fragmentation into rock pieces increasingly smaller that preserve the properties of the original material. It usually takes place in extreme climates.

• Frost weathering: The water is deposited in the cracks. During night that water gets frozen because of the frosts, and it increases its volume, breaking that way the stone.
• Haloclasty: Disintegration of rocks caused when saline solutions inside rock cracks evaporate, leaving salt crystals behind (dry places). Salt ruins materials and descompones rocks because of its corrosive action.
• Thermal stress:  results from expansion and contraction of rocks, due to temperature changes. Not all materials expands and contracts equally: dark areas get warmer and create tensions between the different materials of the rock.
• Biological: A simple tree has a lot of strength. It is capable of breaking the rocks as it´s growing in between them.
• Animals like rabbits and badgers dig tunnels on the floor which produces a lot of weathering.

• Chemical: Different chemical processes may alter the rocks chemical composition. These processes need water (universal solvent), so they happen in humid areas.

• Dissolution: water dissolves the rocks. There are processes of carbonation (calcium hydroxide reacts with carbon dioxide and forms insoluble calcium carbonate) and decarbonation
• Hydration: different volume and behavior with a dehydrated material (for example, clay). Hydration produces contraction cracks and dehydration, retraction cracks.
• Oxidation: Combination of materials with Oxygen. There are differences between metals and not metallic materials. For example, ochre color appears when Roussillon is mixed with Oxygen.
• Biological: For instance, lichens. They produce chemical substances that gradually dissolve the rocks. Then, organic material is formed. Other living organisms produce ammonia, we (human beings) produce CO2 and so on.