भारत का कौन सा भू-आकृतिक क्षेत्र मुख्य रूप से 'रेगुर' (काली) मिट्टी से ढका हुआ है?

Which specific soil type is widely utilized for manufacturing bricks due to its unique characteristic of hardening when exposed to air?

What is the primary cause for the characteristic red color found in Red and Yellow soils?

Which specific type of soil is characterized by its heavy nature, dark color, and high organic matter content (up to 40-50%)?