The Sub-Himalayan Range are the southernmost mountains in the Himalaya Range. Their average height varies between 600 and 1200 meters, and are not so high in altitude as compared to other mountain ranges in the Himalaya range.
Himalayan foot hills form the sub Himalayan zone and from Punjab to Assam these hills are consist of a narrow belt of folded neogene molasse type sediments (siwaliks). Southward, the folded siwaliks sequence is covered by Indo Gangetic Alluvium. An acute fault is "Himalayan front fault" cut the aluvium in foot hill region, this fault is a series of en-echlon faults which are parallel to the strike of the hills between Punjab and Assam. Northward, this sequence is terminated by MBT, which is a set of north dipping faults and forms the boundary between Southern Himalayas and Lesser Himalayas.