Geological Formation of Black Cotton Soil

The black cotton soil (regur) of India was formed by the long-term weathering and denudation of basaltic lava rocks from fissure volcanic eruptions across the Deccan Trap region. These soils are rich in clay minerals like montmorillonite, which give them strong moisture-retention and self-plowing properties. > The weathering of basaltic volcanic rocks from Deccan plateau fissures formed India's fertile black cotton soils. Answer: (b).