The black soil of the Peninsular Plateau, also called regur, has developed mainly over the region known as the:

Black soil, also called regur soil or black cotton soil, is formed mainly from the weathering of basalt rocks. These rocks were formed by huge outpourings of lava about 65-66 million years ago, at the end of the Cretaceous period, covering a vast area of western and central India. This lava region is called the Deccan Trap (the word "trap" comes from the Swedish word trappa, meaning "steps", because of the step-like landscape of the lava layers).

Black soil covers about 15% of India's area. It is found mainly in Maharashtra (which has the largest area), and in parts of Gujarat, Madhya Pradesh, Karnataka, Andhra Pradesh, Telangana and Tamil Nadu.

Features of black soil:

• Its black colour comes from titaniferous magnetite, iron and humus.
• It is rich in lime, iron, magnesia, alumina and potash, but poor in nitrogen, phosphorus and organic matter.

It is clayey and has a very high water-holding capacity. It swells and becomes sticky when wet, and shrinks and develops deep cracks when dry. This allows air to enter deep into the soil, a feature called "self-ploughing".

It is ideal for growing cotton, so it is called black cotton soil. It is also good for jowar, wheat, linseed, groundnut, sugarcane and tobacco.

The name "regur" comes from the Telugu word "reguda". In international soil classification, such soils are called vertisols.

Why not the other options?

• ✗The Aravalli Range is made of very old folded rocks, mostly with sandy and red soils.
• ✗The Chota Nagpur Plateau has mainly red and laterite soils.
• ✗The Shillong Plateau has mainly red and laterite soils.