BPSC Geography Notes- THE HIMALAYAN MOUNTAINS
BPSC Geography Notes- THE HIMALAYAN MOUNTAINS
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Himalayas are not only the physical barrier, they are also a climatic, drainage and cultural divide.
The mountains are supposed to emerge out of ‘The Tethy’s Sea’. The altitudinal variations are greater in the eastern half than those in the western half. The Himalaya consists of three parallel ranges in its longitudinal extent. A number of valleys lie between these ranges.
Himalaya as Young Mountains –
Presence of Fossils in Shiwalik similar to Tibetan Plateau
Frequent Occurrence of Earthquakes indicates that they have still to reach isostatic equilibrium.
Himalayan Rivers are still in their youthful age with characteristic V gorges, steep water falls etc
The Himalayas along with some other peninsular mountains are young, weak and flexible in their geological structure unlike the rigid and stable Peninsular Block. These mountains are tectonic in origin, dissected by fast-flowing rivers which are in their youthful stage. Various landforms like gorges, V-shaped valleys, rapids, waterfalls, etc. are indicative of this stage.
Broad ranges of Himalayas –
I. Northern Most Range is known as the Great or Inner Himalayas or the ‘Himadri’. It is the most continuous range consisting of the loftiest peaks with an average height of 6,000 meters. It contains all the prominent Himalayan peaks. Great Himalayas are asymmetrical in nature. The ranges are mainly composed of highly compressed and altered rocks. The core of some part of Himalayas is composed of granite with outer cover as sedimentary. Its southern slope (towards India) is steep and northern slope (towards Tibet) is gentle. The altitude varies between 3,700 and 4,500 meters and the average width is of 50 Km and most of the tallest peaks lie here.
II. Mid Himalayas or Lessser Himalyas – Valley of Kashmir lies in these. These are less hostile and most of the hill resorts like Kullu, Manali, Shimla, Nainital etc are located here.
III. Shiwalik is the southernmost range and is least in Average height. Also called Outermost Himalayas. They were almost continuous and blocked the courses of rivers which in past led to formation of lakes which after drying led to formation of plains called Duns in the West and called Duars in the east.
On the basis of relief, alignment of ranges and other geomorphological features, the Himalayas can be divided into the following sub-divisions:
I. Kashmir or Northwestern Himalayas
Mountain Ranges – It comprise a series of ranges such as the Karakoram, Ladakh, Zaskar and Pir Panjal.
Glaciars – Important glaciers of South Asia such as the Baltoro and Siachen are also found in this region.
Karewa Formation – The Kashmir Himalayas are also famous for Karewa formations, which are useful for the cultivation of Zafran, a local variety of saffron. (Karewas are the thick deposits of glacial clay and other materials embedded with moraines. In Kashmiri language, they refer to lake deposits found in the flat topped terraces of the Kashmir valley and on the Pir Panjals. These deposits consist of clays, sands and silts.)
The Kashmir and northwestern Himalayas are well-known for their scenic beauty and picturesque landscape.
Some famous places of pilgrimage such as Vaishno Devi, Amarnath Cave, Charar -e-Sharif, etc. are also located here.
II. Himachal and Uttaranchal Himalayas – The two distinguishing features of this region from the point of view of physiography are the ‘Shiwalik’ and ‘Dun formations’.
River Basins – This part lies approximately between the Ravi in the west and the Kali (a tributary of Ghaghara) in the east. It is drained by two major river systems of India, i.e. the Indus and the Ganga. Tributaries of the Indus include the river Ravi, the Beas and the Satluj, and the tributaries of Ganga flowing through this region include the Yamuna and the Ghaghara.
Shiwalik – The lowest altitude portion of Himalyas
Doons –Doons are the plain areas in the river valleys formed due to alluvial deposits by the rivers. Some important duns located in this region are the Chandigarh-Kalka dun, Nalagarh dun, Dehra Dun, Harike dun and the Kota dun,etc. Dehra Dun is the largest of all the duns with an approximate length of 35-45 km and a width of 22-25 km.
Nomads – In the Great Himalayan range, the valleys are mostly inhabited by the Bhotia’s. These are nomadic groups who migrate to ‘Bugyals’ (the summer glasslands in the higher reaches) during summer months and return to the valleys during winters.
The famous ‘Valley of flowers’ is also situated in this region.
III. Darjiling and Sikkim Himalayas – They are flanked by Nepal Himalayas in the west and Bhutan Himalayas in the east. It is relatively small but is a most significant part of the Himalayas. Known for its fast-flowing rivers such as Teesta.
High Mountain Peaks – It is a region of high mountain peaks like Kanchenjunga (Kanchengiri), and deep valleys.
Tribes – The higher reaches of this region are inhabited by Lepcha tribes while the southern part, particularly the Darjiling Himalayas, has a mixed population of Nepalis, Bengalis and tribals from Central India.
Tea Plantations – The British, taking advantage of the physical conditions such as moderate slope, thick soil cover with high organic content, well distributed rainfall throughout the year and mild winters, introduced tea plantations in this region.
Duars – Duars are ‘flood plains’ and ‘foot hills’ of eastern Himalayas in North East India around Bhutan. They are plains in foothills of eastern Himalayas. Duar in Nepali means Gateway and this region form gateway to Bhutan from India. The term duar is also interchangeably used with Terai or Doon in India.
IV. Arunachal Himalayas – The general direction of the mountain range is from southwest to northeast. Some of the important mountain peaks of the region are Kangtu and NamchaBarwa. These ranges are dissected by fast-flowing rivers from the north to the south, forming deep gorges. Bhramaputra flows through a deep gorge after crossing
Namcha Barwa (It is the highest peak of Arunachal and Eastern Himalyas). Some of the important rivers are the Kameng, the Subansiri, the Dihang, the Dibang and the Lohit. These are perennial with the high rate of fall, thus, having the highest hydro-electric power potential in the country.
Tribes – An important aspect of the Arunachal Himalayas is the numerous ethnic tribal community inhabiting in these areas. Some of the prominent ones are the Monpa, Daffla, Abor, Mishmi, Nishi and the Nagas. Most of these communities practice Jhumming. It is also known as shifting or slash and burn cultivation.
Biodiversity – This region is rich in biodiversity which has been preserved by the indigenous communities. Due to rugged topography, the inter-valley transportation linkages are nominal. Hence, most of the interactions are carried through the duar region along the Arunachal-Assam border.
V. Eastern Hills and Mountains – These are part of the Himalayan mountain system having their general alignment from the north to the south direction. They are known by different local names. In the north, they are known as Patkai Bum (famous for being the boundary between India and Myanmar), Naga hills, the Manipur hills and in the south as Mizo or Lushai hills. These are low hills, inhabited by numerous tribal groups practicing Jhum cultivation. Most of these ranges are separated from each other by numerous small rivers. The Barak is an important river in Manipur and Mizoram.