Weathering describes the breaking down or dissolving of rocks and
minerals on the surface of the Earth. Water, ice, acids, salts, plants,
animals, and changes in temperature are all agents of weathering.
Once a rock has been broken down, a process called erosion
transports the bits of rock and mineral away.
Types of weathering
Physical weathering, also known as mechanical weathering, is
a process where rocks are broken down by environmental factors
like wind, water, and temperature change. It does not alter the
chemical composition of the rock. Cold wedging, freeze-thaw
weathering, occurs in temperate humid climates where water
freezes and expands, causing pieces to fall off. Salt crystallisation
occurs in semi-arid environments, where evaporation of water
causes salt crystallisation, increasing volume and potentially
fracturing the rock. Thermal expansion or insolation occurs in arid
regions, where temperatures rise during the day and heat the rock,
leading to expansion and exfoliation.
Chemical weathering is the breakdown of rocks due to the
interaction of air, water, or acid with their chemical composition.
Oxidation, a process where oxygen reacts with minerals like calcium
and magnesium to form iron oxide, causes rock decomposition.
Hydration, where water is absorbed by minerals, creates crystals
that press on the rock, causing it to crumble. Hydrolysis, where