4. The Shiwaliks or Outer Himalayas/Sub-Himalayas

The Shiwaliks extend from Jammu Division of Jammu and Kashmir State to Assam. In width, Shiwaliks vary from 8 km in the east to 45 km in the west with an average elevation of about 900-1500 m above sea level. It is not a continuous range. It is broader in the west and narrows down in the east. Between the Shiwaliks and the Lesser Himalayas are longitudinal valleys called Doons/ Duns. Some of the important Duns are Dehra Dun, Potli, Kothri, Kathmandu, Chumbi and Kyarda. The Shiwaliks are mainly composed of sandstones, sand-rocks, clay, conglomerates and limestones, mostly belonging to the Upper Tertiary Period.