The Himalayas stand as a majestic testament to Earth’s dynamic forces, shaping geography, climate, and culture. They are not just mountains; they are nature’s great divide, a cradle of rivers, and a guardian of biodiversity. In this post, we will focus on the physiographic divisions of the Himalayas.
Geographically speaking, the Himalayas consist of a series of parallel mountain ranges located in northern India. These mountains are tectonic in origin and are dissected by fast-flowing rivers in the youthful stage of mountains itself creating beautiful landscapes like gorges, v-shaped valleys, rapids, waterfalls and so on.
The Himalayas are divided into five main divisions from north to south, namely:
- The Trans-Himalaya or Tethys Himalaya or Tibetan Himalaya
- The Greater Himalayas Inner Himalayas or Himadri
- The Lesser Himalaya
- The Shiwaliks (or Outer Himalaya)
- The Eastern Hills (or Purvanchal)
This structure highlights their unique geographical and ecological characteristics.
The Trans Himalayas
The average elevation of the Trans-Himalayan ranges is about 3,000 meters above mean sea level. These ranges are typically around 40 kilometres wide, but in the central part, the width can extend up to 225 kilometres. This division, also known as the Tethys Himalaya, contains significant sediments from the ancient Tethys Sea, with rock fossils of marine origin.
Interestingly, these ranges are also called the Tibetan Himalayas due to their location.
The major ranges in this division include the Zanskar, Ladakh, Kailas, and Karakoram. The Indus River originates from the northern slopes of the Kailas range. The Karakoram Range, also known as the Krishnagiri Range, is the northernmost range. It is home to K2, also known as Godwin-Austen, which stands at 8,611 meters and is the second-highest peak in the world.
The Greater Himalayas
Also known as the Inner Himalaya, Himadri, or Central Himalaya, the Greater Himalayas have an average elevation of about 6,100 meters above sea level and an average width of about 25 kilometres. This mountain range abruptly terminates at the syntaxial bends in a southward direction. The western syntaxial bend occurs near Nanga Parbat, while the eastern syntaxial bend occurs near Namcha Barwa.
The Greater Himalayas are well known for their mountain passes, which are generally higher than 4,570 meters above sea level and remain covered in snow for most of the year.
Some important mountain passes in this range are –
- Burzil Pass and Zoji la in Jammu and Kashmir
- Bara Lacha La and Shipki La in Himachal Pradesh
- Niti Pass and Lipu Lekh in Uttarakhand
- Nathu La and Jelep La in Sikkim
Now let us shift our focus to The Lesser Himalayas
The Lesser Himalayas
Also known as the Middle Himalayas or Himachal, this range lies between the Shiwaliks and the Greater Himalayas, running almost parallel to both. Sometimes referred to as the Lower Himalayas, these ranges are 60–80 km wide and approximately 2,400 km long, with elevations ranging from 3,500 to 4,500 meters. The steep slopes of the Lower Himalayas are densely forested.
These ranges are more hospitable to humans and are home to some of the most popular hill resorts, such as Shimla, Mussoorie, Nainital, and Darjeeling.
Regionally, important mountain ranges include:
- The Pir Panjal Range in Jammu and Kashmir is located to the south of the Kashmir Valley.
- Dhaula Dhar is in Himachal Pradesh, Mussoorie and Nag Tibba are in Uttarakhand, and Mahabharat Lekh is in Nepal.
Some important passes in this region are as follows:
- Pir Panjal Pass: Also known as Pir ki Gali, it is a historic trade route in the Pir Panjal Range, connecting Kashmir Valley with the southern regions.
- Banihal Pass: A vital pass linking the Kashmir Valley with the Jammu region, now bypassed by the Jawahar Tunnel for modern transportation.
- Rohtang Pass connects the Kullu Valley with the Lahaul and Spiti Valleys in Himachal Pradesh.
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The Outer Himalayas
Also known as the Shivaliks, these ranges were the last to form among the Himalayan ranges. The Shivaliks are located between the Great Plains and the Lesser Himalayas, with elevations ranging from 600 to 1,500 meters. They span approximately 2,400 kilometers in length, similar to the Lesser Himalayas, extending from the Potwar Plateau in the west to the Brahmaputra Valley in the east.
The southern slopes are steep, while the northern slopes are gentle. The width of the Shivaliks varies significantly, from about 50 kilometres in Himachal Pradesh to less than 15 kilometres in Arunachal Pradesh. The ranges receive more rainfall in the Northeast, resulting in dense forests there, whereas the southern slopes in Punjab and Himachal Pradesh have little to no forest cover.
The Shivaliks are known by different names in various regions:
- Jammu Hills in Jammu
- Dhang and Dundwa in Uttarakhand
- Churia Ghat in Nepal
- Dafla, Miri, Abor, and Mishmi Hills in Arunachal Pradesh
Now one important characteristic of these lower ranges is Duns.
Duns
Duns are flat, fertile valleys found between the Shivalik Hills and the Lesser Himalayas. These valleys are formed by the accumulation of sediments carried down by rivers and are often highly fertile, making them ideal for agriculture. These are characterized by their gentle slopes, river systems, and rich biodiversity, making them important both ecologically and economically.
Some well-known duns include:
- Dehradun: One of the largest and most famous duns, located in Uttarakhand.
- Patli Dun: Located near the Dehradun region.
- Kotli Dun: Located in Himachal Pradesh.
Regional Classification
The Himalayas can also be divided on the basis of region into
- The Kashmir or Northwestern Himalayas
- The Himachal and Uttarakhand Himalayas
- The Darjeeling and Sikkim Himalayas
- The Arunachal Himalayas
- The Eastern Hills and Mountains
The Kashmir or Northwestern Himalayas
This region includes the Karakoram, Ladakh, Zanskar, and Pir Panjal ranges. To the east lies a cold desert, and the area is home to the Kashmir Valley.
Kashmir Valley is known for its Karewa formations. Karewas are fertile, flat-topped deposits of clay, silt, and sand in the Kashmir Valley, formed by the uplift and erosion of ancient lake sediments during the Pleistocene period. They are ideal for growing saffron, almonds, and apples.
Kashmir Himalaya has freshwater lakes such as Dal Lake and Wular Lake, as well as saltwater lakes such as Pangong Tso and Tso Moriri. The Indus River and its tributaries, Jhelum and Chenab, flow through this scenic region, which is also known for pilgrimage sites like Vaishno Devi and Amarnath Cave.
The Himachal and Uttarakhand Himalayas
This region lies between the Ravi River in the west and the Kali River in the east. It is drained by the Indus and Ganga river systems. Major tributaries of the Indus in this region include the Ravi, Beas, and Satluj and the major tributaries of the Ganga system in this region include Yamuna and Ghaghara.
The northernmost part of the Himachal Himalayas extends into the Ladakh cold desert, particularly in the Spiti region. This area features the Great Himalayas, the Lesser Himalayas, and the Shiwalik Range.
The British colonial administration developed several hill stations here, such as Shimla, Mussoorie, Dharamshala, Kasauli, and Ranikhet.
Key physiographic features include the Shiwalik range and dun formations which are basically nothing but valleys for example Dehradun.
The Darjeeling and Sikkim Himalayas
The Darjeeling and Sikkim Himalayas lie between the Nepal Himalayas in the west and the Bhutan Himalayas in the east. The Teesta River flows through this region, which is home to high peaks like Kanchenjunga. The valleys are inhabited by Lepcha tribes, as well as Nepalis, Bengalis, and other tribal groups. The British introduced tea plantations here due to the favourable climate and terrain.
Unlike other parts of the Himalayas, the Sikkim and Darjeeling Himalayas, along with the Arunachal Himalayas, lack Shiwalik formations. Instead, they feature duar formations, which are used for tea gardens. Not to mention, this region is also known for its scenic beauty, rich biodiversity, and various types of orchids.
The Arunachal Himalayas
The region is known for fast-flowing rivers such as the, river Kameng, river kameng, river Subansiri, River Dihang and Dibang and Lohit. These rivers dissect the Himalayas from north to south forming deep gorges. Rivers are perennial and have huge hydro electric potential.
Some important peaks in this region are Kanghtu and Namcha Barwa.
The valleys are inhabited by tribal groups such as Monpa, Abor, Mishmi, Nyishi and the Nagas. Most of these communities practice jhumming – shifting cultivation or a slash-and-burn kind of cultivation. Topography is rugged so locals prefer duar region for transportation.
The Eastern Hills and Mountains
The Eastern Hills and Mountains form the last part of this Himalayan division. Locally these hills are known by different names such as –
- Patkai Bum and Naga Hills in the north
- Manipur Hills
- Mizo Hills in the south
The Barak River is a key river in Manipur and Mizoram. Loktak Lake, surrounded by mountains, is a significant lake in the region. Most rivers in Nagaland flow into the Brahmaputra, while those in Mizoram and Manipur are tributaries of the Barak.
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