Oxidation
Topic: Geomorphic Processes: Weathering, Mass Movement, Erosion and Soil Formation · NCERT: Class 11, Ch 5 "Geomorphic Processes"
Meaning
Oxidation is a type of chemical weathering. Minerals combine with oxygen from air or water. It affects iron most strongly. Iron turns into red, brown or yellow iron oxides, which work like rust. The change weakens the rock and makes it break down more easily. Oxidation is why laterite and red soils have their colour. It works best where air can reach the rock, above the water table (the level below which the ground is full of water).
Example
The red soils of Tamil Nadu and Karnataka owe their colour to iron oxides. These form when iron in the old crystalline rocks of the area oxidises.
Don't confuse with
- Reduction: it happens below the water table, where oxygen is missing. It gives grey-green colours instead of red.