Explanation: In the context of Indian geography, particularly the Himalayan region, understanding the various ranges and the geographical features between them is crucial. The Himalayas are divided into several parallel ranges, each with distinct characteristics and geographical significance.
The Himalayan ranges, from the outermost to the innermost, are:
1. **Shiwalik Range (Outer Himalayas)**: This is the outermost range, consisting of low hills and valleys. It is composed of unconsolidated sediments and is prone to landslides and erosion.
2. **Himachal Range (Lesser Himalayas)**: This range lies between the Shiwalik and the Great Himalayas. It is characterized by a series of parallel ridges and valleys, and it includes the famous ranges such as the Pir Panjal and Dhauladhar.
3. **Himadri Range (Great Himalayas)**: This is the highest range, including the world's highest peaks like Mount Everest. It is composed of hard crystalline rocks and is the most stable part of the Himalayas.
**Duns** are the longitudinal valleys found between the Himachal and Shiwalik ranges. These valleys are flat and often fertile, making them suitable for agriculture. The term "Duns" is derived from the local language and refers to these specific types of valleys. Examples of Duns include the Dehradun valley and the Patli Dun valley.
The confusion often arises because students might mix up the different ranges and their positions. The Himadri range, being the highest, is not directly adjacent to the Shiwalik range; the Himachal range lies in between. Therefore, the Duns are specifically located between the Himachal and Shiwalik ranges.
Understanding the geographical layout of the Himalayas and the specific features like Duns is essential for comprehending the physical geography of India, particularly in the context of competitive examinations like the UPSC Civil Services and other state PSC exams. This knowledge helps in answering questions related to the geographical features and the ecological significance of these regions.