Duns are elongated valleys found between the
Himalayan and
Shivalik mountain ranges. Unlike typical river valleys, duns have a structural origin and are covered with boulders and gravel originating from the erosion of the Himalayas and the Shivalik uplands. Major duns found in the region are Dehra,
Kohtri, Chaukham, Patli and Kota. The dun of Dehra is the biggest with a length of 35 km and width of 25 km.
