Eluviation
Topic: Geomorphic Processes: Weathering, Mass Movement, Erosion and Soil Formation · NCERT: Class 11, Ch 5 "Geomorphic Processes"
Meaning
Eluviation is the washing down of fine material from the upper layers of soil. When there is a lot of rain, water seeps down through the soil. It carries clay, iron, aluminium, humus (dark organic matter) and dissolved minerals with it. This leaves the top layer pale and poorer in nutrients. It matters because it decides how fertile the surface soil is and helps create separate soil layers called horizons.
Example
The heavy monsoon rain on the Western Ghats in Kerala soaks through the soil. It washes bases and silica out of the upper layers. This strong washing helps form the region's laterite soils.
Don't confuse with
- Illuviation: eluviation removes material from the upper layers. Illuviation is the deposit of that same material in lower layers.
- Erosion: eluviation moves material down inside the soil. Erosion carries soil away across the surface by water, wind or ice.
Related concepts
- Soil-forming factors
- Parent material
- Residual and transported soils
- Climate as a soil-forming factor
- Illuviation
- Desilication
- Humus
- Peat