Here is your paragraph on the Brahmaputra Plain:
This is also known as the Brahmaputra valley or Assam Valley or Assam Plain as most of the Brahmaputra valley is situated in Assam.
Though often treated as the eastern continuation of the Great Plain of India, it is a well-demarcated physical unit girdled by the Eastern Himalaya of Arunachal Pradesh in the north, Patkai and Naga Hills in the east and the Garo-Khasi-Jaintia and Mikir Hills in the south.
Its western boundary is formed by the Indo-Bangladesh border as well as the boundary of the lower Ganga Plain. Extending from the easternmost end of Assam near the syntaxial bend of the Eastern Himalayas to the west of Dhubri near the Bangladesh border this plain is about 720 km long and its average-width is 60-100 km.
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The entire plain covers an area of about 56 thousand sq km. It is an aggradational plain built up by the depositional work of the Brahmaputra and its tributaries. The Brahmaputra River enters this plain near Sadiya and flows farther to Bangladesh after turning southwards near Dhubri.
The general level of the plain varies from 130 m in the east to 30 m in the west. The average gradient of the land is 12 cm per km in the N.E. to S.W. direction. The area is well demarcated by 150 m contour beyond which the surrounding hill terrain dominates the scene.
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The northern margin has steep slope from the foothills of Arunachal Pradesh but the southern margin is marked by gradual fall from the hill ranges. The innumerable tributaries of the Brahmaputra River coming from the north debouch abruptly upon the main valley and form a number of alluvial fans.
Consequently, the tributaries branch out in many channels giving birth to river mendering leading to formation of bill and ox-bow lakes. There are large marshy tracts in this area. The alluvial fans formed by the coarse alluvial debris have led to the formation of tarai or semi-tarai conditions. Some southern tributaries also have meandering course and there are a good number of bills and ox-bow lakes.