Land

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Assam, the eastern most state of the Indian sub-continent, extends from 22^o19' to 28^o16' North Latitude and 89^o42' to 96^o30' East Longitude between the foot hills of the Eastern Himalayas and the Patkai and Naga Ranges. Assam is bordered in the North and East by the Kingdom of Bhutan and Arunachal Pradesh. Along the south lies Nagaland, Manipur and Mizoram. Meghalaya lies to her South-West, Bengal and Bangladesh to her West. Assam is connected with the rest of the Indian Union by a narrow corridor in West Bengal that runs for 56km below the foothills of Bhutan and Sikkim. 

Physiography

The state is divided into three broad geographic units:

1. The lower and central Assam hills, known as the Shillong Plateau

2. The Barail ranges and the low hilly terrains of Mizo hills

3. The Alluvial valley of Brahmaputra, Dhansiri and the Barak river

(I) The lower and central Assam range which includes, from west to east, the Garo, Khasi, Jaintia and the outlying Mikir hills are in reality a plateau or table-land. The general height of the plateau ranges between 3,000ft and 6,000ft. The Khasi and Jaintai hill portion of the plateau are comparatively higher and flatter than the Garo and Mikir hills on the west and northeast. The highest peak of the plateau is the Shillong peak (6450 ft).

(II) The lofty Barail ranges, also known as the North Cachar hills, are separated from the Shillong plateau on the Northwest by a system of narrow valleys. Tectonically, the Barails form a south westerly extension of the mountain chain of Nagaland and western Burma. It is this chain of mountain that separates the valley of Irrawaddy and Chindwin of Burma from the valley of Brahmaputra and the Meghna. The Patkai, Naga and Manipur hills and the Mizo hills, form part of this great mountain system. The Mizo hills consist of a belt of North-South trending ridges with intricate valleys, with an average height of 3,000ft.

(III) The alluvial plains of Assam consist of two distinct parts:

a) the valley of the Brahmaputra and its tributaries and  b) the Barak valley.

These are separated from each other by the water shed of the Shillong plateau and the Barail ranges.

The Brahmaputra valley separates the sub-Himalayan foothills from the Shillong plateau and the Patkai-Naga hill ranges. The Mizo hills and the Barail ranges die out towards the west and south west into the plains of Cachar, which is a part of Surma-Kusiyara valley.