Answer: The Himalayas are young fold mountains that form the northern boundary of India.
- They were formed by the collision of the Indian plate with the Eurasian plate; they are still rising, so the region is earthquake-prone.
- They extend for about 2500 km from the Indus in the west to the Brahmaputra in the east; their width is about 400 km in the west and about 150 km in the east.
- They are divided into parallel ranges: the Trans-Himalaya (Karakoram, Ladakh and Zaskar ranges; K2 is in the Karakoram), the Greater Himalaya or Himadri (average height about 6000 m, perennial snow and glaciers, Mount Everest 8848 m, Kanchenjunga, Nanda Devi), the Lesser Himalaya or Himachal (with hill stations such as Shimla, Mussoorie, Darjeeling) and the Shiwalik (outer Himalaya, lowest range, with duns such as Dehradun). In the east they bend south as the Purvanchal hills.
- Passes such as Zoji La, Shipki La, Nathu La and Bomdi La provide routes across the mountains.
- The Indus, Ganga and Brahmaputra rise here; being fed by snow as well as rain, they are perennial.
- The Himalayas protect India from the cold winds of Central Asia, stop the monsoon winds and cause rainfall, and are a source of water, forests, hydro-electricity, medicinal plants and tourism.