Geography of India: Relief, Climate, Vegetation and Soils
This domain tests the physical frame of India - its relief divisions, monsoon climate, natural vegetation belts and soil types - and the reasoning that links them.
Relief divisions
India has the young fold Himalayas, the alluvial Northern Plains, the stable Peninsular Plateau of old crystalline rock, the coastal plains and the island groups of Andaman–Nicobar and Lakshadweep. The Tropic of Cancer crosses eight states. The Western Ghats form a continuous escarpment, while the Eastern Ghats are discontinuous and dissected by rivers.
Climate
India has a tropical monsoon climate: south-west monsoon (June–September), retreating monsoon (October–November) bringing rain to Tamil Nadu, cool dry winter and hot dry summer. Koppen types range from Amw and As through Aw, BSh, BWh and Cwg to Dfc and E in the Himalayas. Rainfall decreases westward across the Ganga plain.
Vegetation
Tropical evergreen forests need over 200 cm rain; moist and dry deciduous forests dominate the monsoon lands; thorn forest and scrub occupy low-rainfall tracts; mangrove occurs in the Sundarbans; alpine vegetation grades upward in the Himalayas.
Soils
Alluvial soil is the most extensive and fertile, in the northern plains and deltas. Black soil (regur) derives from Deccan basalt, holds moisture well and suits cotton. Red soils develop on crystalline rock; laterite soils form under heavy leaching in high-rainfall areas; arid, forest and peaty soils complete the list.
Worked example
A dark, clayey, moisture-retentive soil on the Deccan lava plateau is black soil, formed by weathering of basalt; its swelling and cracking behaviour and high fertility make it the classic cotton soil.
Traps
- Confusing red soil (crystalline parent rock) with laterite (leached under heavy rain).
- Saying the south-west monsoon gives Tamil Nadu its main rain; that is the retreating monsoon.
- Calling alluvial soil low in fertility.