Longitudinal valley lying between lesser Himalya and Shivalik are known as 'duns' in the west and 'duras' in the east.

Longitudinal valleys between Lesser Himalayas and Shivalik are known as Duns.

Duns are large longitudinal valleys that lie between the Lesser Himalayas and the Shivalik range in the Indian subcontinent. These valleys are formed by the numerous rivers and streams that flow down from the higher Himalayas and cut through the Lesser Himalayas to reach the plains. Duns are unique features of the Himalayan region and play a significant role in the geography and ecology of the area.

Formation of Duns:
Duns are formed due to the tectonic activities in the region. The Indian subcontinent is still moving towards the north and colliding with the Eurasian plate, resulting in the formation of the Himalayan mountain range. As the Indian plate pushes against the Eurasian plate, it causes the crust to buckle and fold, leading to the formation of various mountain ranges. The Lesser Himalayas and the Shivalik range are two such mountain ranges that are parallel to each other.

The rivers originating from the higher Himalayas cut through the Lesser Himalayas and create deep valleys, which are known as duns. These valleys are elongated in shape and run parallel to the mountain ranges. The rivers flowing through the duns deposit sediments, creating fertile plains suitable for agriculture. The rivers also bring down rocks and minerals from the higher elevations, enriching the soil in the duns.

Characteristics of Duns:
- Duns are generally narrow and long valleys.
- They are located at an intermediate altitude between the plains and the mountains.
- The rivers flowing through the duns have a significant erosive power, leading to the formation of steep and rugged terrain.
- Duns are known for their fertile soil, which supports agriculture and is suitable for growing crops like wheat, rice, and maize.
- Due to their relatively lower altitude, duns have a milder climate compared to the higher Himalayas.
- The duns serve as important corridors for transportation, with several highways and railways passing through them.

Significance of Duns:
- Duns are vital for agriculture, as they provide fertile land for cultivation. The rivers flowing through the duns supply water for irrigation, supporting the agricultural activities of the region.
- The duns act as natural buffers, protecting the plains from the erosive forces of the rivers coming down from the Himalayas.
- The duns are home to a diverse range of flora and fauna, including various species of plants, animals, and birds.
- The valleys offer numerous opportunities for tourism, with their scenic beauty and proximity to the Himalayas.

In conclusion, duns are longitudinal valleys that lie between the Lesser Himalayas and the Shivalik range. They are formed by the rivers cutting through the Lesser Himalayas and are characterized by their narrow shape, fertile soil, and diverse ecology. Duns play a significant role in agriculture, ecology, and tourism in the Himalayan region.