Chemical Weathering
- Carbonization:
- Carbonization is the dissolving of limy rocks by percolating rainwater which contains carbon dioxide from the atmosphere or the soil.
- Hydration:
- Hydration is the taking up of water and expanding by some minerals. This breaks shells from the rock containing them.
- Hydrolysis:
- Hydrolysis is the water-rock reaction whereby feldspar is turned into clay, decomposing granite to produce kaolin.
- Organic weathering:
- Organic weathering involves organic acids produced by plant organisms. The acids attack rock-forming minerals.
- Oxidation:
- Oxidation is the process whereby oxygen combines with compounds in some rocks. Oxidized iron forms rust.
- Solution:
- Solution is the process whereby water dissolves rock salt.
Physical Weathering
- Block disintegration:
- Block disintegration involves sharp temperature changes, making desert rocks expand and contract.
- Crystallization of salts:
- Crystallization of salts as a result of dissolved salts expanding as they dry split the rocks and honeycomb its surface.
- Exfoliation:
- Exfoliation is the flaking of intensely heated surface rock as it expands more than the cooler rock below. Rounded, isolated rock masses called exfoliation domes result.
- Frost action:
- Frost action causes water to freeze and expand in winter or at night, thus widening crevices. Piles of sharp-edged debris, known as talus form below steep peaks.
- Pressure release:
- Pressure release follows the removal of overlying rock and its pressure on the rock below. Expansion of that rock then forms curved joints, creating sheeting of rock shells from the inner mass.
- Slaking:
- Slaking is the crumbling of clay-rich sedimentary rocks as they dry out during drought.
- Tree roots:
- Tree roots widen cracks in rocks as they grow.
