Explanation: The alluvial soil consists of various proportions of sand, silt and clay. As we move inlands towards the river valleys, soil particles appear somewhat bigger in size.

• In the upper reaches of the river valley, i.e. near the place of the break of slope, the soils are coarse.
• Such soils are more common in piedmont plains such as Duars, Chos and Terai.

Source: NCERT