In this article we’re going to learn about the geographical division of the Himalayas. To better understand the Himalayas, geologists have divided it on the basis of geography, geology and region.
Geographically Himalayas are divided into the following divisions-
The Trans Himalayas
The Trans-Himalayas are located immediately north of the Great Himalayan ranges. In the west and east extreme points, the Trans Himalayas are 40 km wide and in the middle they are 225 km wide. The average elevation of trans Himalayas is 3000 meters and the length is around 1000 km.
The rocks of the Trans Himalayas contain fossils bearing marine sediments which prove the existence of Tethys sea between Indian and Asian plate 70 million years ago.
The Zaskar, the Ladakh, the Kailas and the Karakoram are the main ranges of the trans Himalayas.
The Greater Himalayas
The Great Himalayan ranges contain the tallest peaks of the world. Mt. Everest, Kanchanjunga, Nanga-Parbat, Gasherbum, Manaslu, Dhaulagiri, Annapurna, Gosaintahn, Cho-Cyu, Nanda-Devi, Kamet, Badrinath etc lies in Greater Himalayas.
The Greater Himalayas are almost continuous range except a few gaps created by antecedent (flowing before formation of the Himalayas) rivers.
Average width is about 25 Km and the average elevation is 6,100 meters above sea level and these ranges are only 150 away from the Great Plains of northern India.
The Lesser Himalayas
The Lesser Himalayas are located between the Greater Himalayas and the Shiwalik Himalayas. It’s 60 to 80 km wide and its elevation ranges from 3,500 to 4,500 meters.
Many peaks of this range are above 5,500 meters and remain snow covered throughout the year. The main rocks found in Lesser Himalayas are slate, limestone and quartzites. The lesser Himalayas are subjected to extensive erosion due to heavy rainfall, deforestation and urbanisation.
The Shiwalik Himalayas
The Shiwalik are the outermost range of the Himalayas that’s why they are also known as Outer Himalayas. Shiwalik range has steep slope on the southern side and appear like a hogback. Flat scarps, anticlinal crests and synclinal valleys are the main characteristic features of the Shiwalik Himalayas.
Shiwaliks are composed of sandstones, sand-rocks, clay, conglomerates and limestones. Shiwalik range is 50 km wide in Himachal Pradesh and less than 15 km in Arunachal Pradesh.
Shiwalik range is almost unbroken except for a gap of 80-90 km which was formed by Tista and Raidak rivers. Between the Shiwaliks and Lesser Himalayas are longitudinal valleys called Doon/Duns. Some of the important Duns are Dehra Dun, Potli, Kathmandu, Chumbi and Kyarda.
We’ll learn about the Eastern Hills in a different article as it requires a bit different approach to understand.