Explanation:

Alluvial plains

The northern plain of India is formed by three river systems, i.e. the Indus, the Ganga and the Brahmaputra; along with their tributaries. The northern plains are the largest alluvial tract of the world. These plains extend approximately 3200 km from west to east.The average width of these plains varies between 150 and 300 km. In general, the width of the northern plains increases from east to west (90-100km in Assam to about 500km in Punjab). The exact depth of alluvium has not yet been fully determined. According to recent estimates, the average depth of alluvium in the southern side of the plain varies between 1300-1400m, while towards the Shiwaliks, the depth of alluvium increases. The maximum depth of over 8000m has been reached in parts of Haryana.