elluviivate

Elluviivation is a geomorphological process that involves the removal of fine soil particles and minerals from the upper layers of soil or rock through the action of surface runoff and precipitation. This process is a type of weathering and soil erosion that typically occurs in humid climates where rainfall is abundant. The term derives from the Latin word *eluere*, meaning "to wash out," reflecting the washing away of soluble materials and fine particles from the soil profile.

During elluviivation, water infiltrates the soil, dissolving and carrying away soluble substances such as salts, oxides, and hydroxides of iron, aluminum, and other minerals. This leaching action often results in the accumulation of these materials in lower soil horizons, a phenomenon known as illuviation. The upper layers of the soil, known as the eluvial horizon (often labeled as the A horizon in soil classification), become depleted of these fine particles, leading to a lighter-colored, more porous texture.

Elluviivation plays a significant role in soil formation and landscape evolution. It contributes to the development of distinct soil horizons, particularly in tropical and subtropical regions where intense rainfall accelerates the process. Over time, this can lead to the formation of laterite soils, which are rich in iron and aluminum oxides but depleted of silica and other soluble components. While elluviivation is a natural process, human activities such as deforestation and intensive agriculture can exacerbate soil degradation by increasing runoff and reducing soil stability.