Geography of Assam

Geomorphic studies conclude that the Brahmaputra, the life-line of Assam is a paleo-river; older than the Himalayas. The river with steep gorges and rapids in Arunachal Pradesh entering Assam, becomes a braided river (at times 10 mi/16 km wide) and with tributaries, creates a flood plain (Brahmaputra Valley: 50-60 mi/80-100 km wide, 600 mi/1000 km long). The hills of Karbi Anglong, North Cachar and those in and close to Guwahati (also Khasi-Garo Hills) now eroded and dissected are originally parts of the South Indian Plateau system. In the south, the Barak originating in the Barail Range (Assam-Nagaland border), flows through the Cachar district with a 25–30 miles (40–50 km) wide valley and enters Bangladesh with the name Surma.