Northern Mountains

Origin

Himalayas are the outcome of collision between Indian plate and Eurasian plate. During cretaceous period Indian peninsula broke away from Gondwana and started its northward journey. The Tethys present between the two plates got squeezed forming as geosyncline

As the plate moved northwards, oceanic margin of Indian plate get subducted and which led to volcanism and part of these rocks are preserved in Ladakh region.

Stage2

Around 60million year ago,northwestern part of Indian plate hit Eurasian plate led to formation of potwar plateau and then plate took anti clockwise turn,so with eastern part of plate collision created Eastern Himalayas

Stage3

Further northward movement and again compression of Tethys sea led to rising of Tethian Himalayas

Stage4

Continuous convergence of mountains lead to formations of fold mountains called Main himalayas or Greater Himalayas and south of it created Main central Thrust

As the process continued, another fold mountain emerged, Lesser Himalayas or Middle Himalayas and south of it, the Main Boundary Fault line was created.

Stage 5

With formation of Greater and Lesser Himalayas, Foredeep was created on foot hill of these mountains where deposition and further compression led to formation Shivalik mountains and new fault line emerged south of it is called Himalayan Frontal Fault

Northern Mountains

The place where convergence of two plates is taking place is called the Indus Tsangpo Suture zone.

These youthful Himalayas are still rising its height because of Isostatic adjustments

Northern Mountains

 

Structure of HImalayas

Trans Himalayas

  • The Transhimalaya is a 1,600-kilometre-long (990 mi) mountain range ,extending in a west–east direction parallel to the main Himalayan range. Located north of Yarlung Tsangpo river on the southern edge of the Tibetan Plateau
  • The Trans-Himalayas, mainly composed of granites and volcanic rocks
  • Unlike the main Himalayas, the mountains are not divided by deep river gorges and lack a definite alignment.
  • They represent Island Arc

Indus Tsangpo Suture zone

  • the Indus-Yarlung Tsangpo suture is a tectonic suture in southern Tibet and across the north margin of the Himalayas which resulted from the collision between the Indian plate and the Eurasian plate
  • The rocks of the suture zone consist of an ophiolite mélanges composed of Neotethys oceanic crustal flyschs and ophiolites; the Dras Volcanics: which are basalts, dacites

Tethian Himalayas

  • They are formed because of compression of sediments in Tethys sea
  • Sediments are of marine origin and rocks are metamorphosed because of compression
  • Zaskar and Kailash are its important ranges
  • There is no clear separation between Greater Himalayas and Tethys
  • It is called as backbone of high Asia
  • It determines India’s frontiers with Afghanistan and China

Main Himalayas

  • Its average height is 5000kms
  • It has loft peaks along with extensive snowfields of glaciers
  • Mainly composed of crystalline igneous or metamorphic rocks
  • Its core is made of Archean Rocks and i
  • It is a continuous ranges with very few gaps and antecedent rivers
  • It runs like arc from Nanga Parbat in west to Namcha Barwa in East
  • Few passes that present are Zojila, Brazil in Kashmir; Bara Lapcha La, shipki La in Himachal Pradesh;Niti pass and Lipu lekh IN Uttarakhand;Nathula and Jelep La in Sikkim

Lesser Himalayas

  • Its average height is 1300 to 5000km
  • It generally consists of unfossiliferous sediments or metamorphosed crystallines
  • Lithology is similar to Main Himalayas but arrangement is highly different, they represents very strongly folded and complicated structures
  • Important ranges are Dhauladhar,Pirpanjal,Nagatibba,Mussorie and Mahabharat range
  • Southern slopes are steep while northern are rugged
  • Along slopes small pastures are found called Merg

Shiwaliks

  • This is not continuous range, it also called as outer Himalayas
  • Its has hog-back appearance with steeper slopes towards south
  • In north it has valleys called Doon in west and Duar in east. They are known as Dehradun,pallidum
  • This zone consists of largely fossiliferous sedimentary rocks like sandstone,sand rocks, clay, conglomerate and limestone

On the basis of relief, alignment of ranges and other geomorphological features, the Himalayas can be divided into the following subdivisions:

  • Kashmir or Northwestern Himalayas
  • Himachal and Uttarakhand Himalayas
  • Darjeeling and Sikkim Himalayas
  • Arunachal Himalayas
  • Eastern Hills and Mountains.

Kashmir HImalayas

  • It comprises a series of ranges such as the Karakoram, Ladakh, Zaskar and Pir Panjal. The northeastern part of the Kashmir Himalayas is a cold desert, which lies between the Greater Himalayas and the Karakoram ranges.
  • Between the Great Himalayas and the Pir Panjal range, lies the world famous valley of Kashmir and the famous Dal Lake. Important glaciers of South Asia such as the Baltoro and Siachen are also found in this region
  • The Kashmir Himalayas are also famous for Karewa formations, which are useful for the cultivation of Zafran, a local variety of saffron. Some of the important passes of the region are Zoji La on the Great Himalayas, Banihal on the Pir Panjal, Photu La on the Zaskar and Khardung La on the Ladakh range.
  • Some of the important fresh lakes such as Dal and Wular and saltwater lakes such as Pangong Tso and Tso Moriri are also in this region.
  • This region is drained by the river Indus and its tributaries such as the Jhelum and the Chenab. The Kashmir and northwestern Himalayas are well-known for their scenic beauty and picturesque landscape.
  • The southernmost part of this region consists of longitudinal valleys known as ‘duns’. Jammu dun and Pathankot dun are important examples

The Himachal and Uttarakhand Himalayas

  • This part lies approximately between the Ravi in the west and the Kali (a tributary of Ghaghara) in the east
  • All the three ranges of Himalayas are prominent in this section also. These are the Great Himalayan range, the Lesser Himalayas (which is locally known as Dhaoladhar in Himachal Pradesh and Nagtibha in Uttarakhand) and the Shiwalik range from the North to the South
  • The two distinguishing features of this region from the point of view of physiography are the ‘Shiwalik’ and ‘Dun formations’. Some important duns located in this region are the Chandigarh-Kalka dun, Nalagarh dun, DehraDun, Harike dun and the Kota dun, etc
  • 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.

The Darjeeling 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.
  • It is a region of high mountain peaks like Kanchenjunga (Kanchengiri), and deep valleys. 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.
  • 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.
  • As compared to the other sections of the Himalayas, these along with the Arunachal Himalayas are conspicuous by the absence of the Shivalik formations.
  • In place of the Shiwaliks here, the ‘duar formations’ are important, which have also been used for the development of tea gardens.

The Arunachal Himalayas

  • These extend from the east of the Bhutan Himalayas up to the Diphu pass in the east
  • 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
  • These are perennial with the high rate of fall, thus, having the highest hydro-electric power potential in the country.
  • An important aspect of the Arunachal Himalayas is the numerous ethnic tribal communities inhabiting these areas.
  • Some of the prominent ones from west to east are the Monpa, Abor, Mishmi, Nyishi and the Nagas. Most of these communities practise Jhumming.
  • It is also known as shifting or slash and burn cultivation. This region is rich in biodiversity which has been preserved by the indigenous communities.

Northern 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, Naga hills, the Manipur hills and in the south as Mizo or Lushai hills.
  • These are low hills, inhabited by numerous tribal groups practising 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.
  • The physiography of Manipur is unique by the presence of a large lake known as ‘Loktak’ lake at the centre, surrounded by mountains from all sides.
  • Mizoram which is also known as the ‘Molassis basin’ which is made up of soft unconsolidated deposits