• The geological regions broadly grouped into three regions : the Himalayas and their associated group of mountains, the indo-Ganga Plain and the Peninsular Shield.
• The Himalayan mountain belt to the north and the Naga-Lushai mountain in the east, are the regions of mountain-building movement were
I Himalayan Mountain Passes
under marine conditions about 60 crore years ago. The Indo-Ganga plains are a great alluvial tract that separates die Himalayas in the Lorth from the Peninsula in the south. The Peninsula is a region of relative stability and occasional seismic disturbances.
- Highly metamorphosed rocks of the earliest periods, dating back as far as 380 crore years, occur in this peninsular area.
- River Systems
• The river systems of India can be classified into four groups viz., (i) Himalayan rivers, (ii) Deccan rivers, (iii) Coastal rivers, and (iv) Myers of the inland drainage basin.
• Himalayan rivers are formed by the melting
snow and glaciers, therefore continuously flow
throughout the year. During the monsoon
months, Himalayas receive very heavy rainfall and rivers well, causing frequent floods. Deccan rivers are rainfed and many of these are non-perennial. The Coastal streams on the west coast are short in length, have limited catchment area and most of them are non-perennial. The streams of inland drainage basin of
Rohtang Pass in Himachal Pradesh, India.
Mohan Pass is the principal pass in the Siwalik Hills, the southern most and geologically youngest foothills running parallel to the main Himalayas in Sikkim.
Kora La at 4,594 metres elevation on the Nepal-Tibet border at the upper end of Mustang. The Kali Gandaki Gorge (a graben), transects the main Himalaya and Transhimalayan ranges. Kora La is the lowest pass through both ranges between K2 and Everest, but some 300 metres (980 ft) higher than Nathula and Jelepla passes further east between Sikkim and Tibet.
Arniko Rajmarg/Friendship Highway route from Kathmandu, Nepal crossing into Tibet at Kodari/Zhangmu, to Nyalam, Lalung-La pass (5,050m), Tingri, Xegar, Lakpa La pass (5,250m), to Lhatse on the Yarlung Tsangpo/Brahmaputra River about 460 road kilometers west of Lhasa.
Gangtok in Sikkim to Lhasa in Tibet, via the Nathula Pass and Jelepla Passes
Important Tributaries Sutiej, Beas, Ravi,
Yamuna, Ramganga, Ghaghra, Gandak, Kosi, Mahananda, Sone
Chambal and Betwa (sub-tributaries)
Subansiri, Jia Bhareli, Dhansiri, Puthimari, Pagiadiya, Manas
Makku, Trang, Tuivai, Jiri, Sonai, (Barak) Rukni, Katakhal, Dhaleswari, Langachini, Maduva, Jatinga
The Western Himalayas EBA extends along the mountain chain from western Nepal (west of the Kali Gandaki valley) through Uttar Pradesh, Himachal Pradesh, Jammu and Kashmir in north-west India and northern Pakistan, and then south-west along the mountains in the border region between Pakistan and Afghanistan.
The Western region is known for blue pine, spruce, silver fir, junipers, conifers deodar, and Chirpine, which are found in abundance.
Eastern Himalaya is situated between Central Nepal in the west to Myanmar in the east, occupying southeast Tibet in China, Sikkim, North Bengal, Bhutan and North-East India. The average temperature generally recorded is 20 C.
The average rainfall in the area is about 500m m.
Eastern Himalaya can be divided into four distinguished regions : Darjeeling Himalaya, Sikkim Himalaya, Bhutan Himalaya, Arunachal Himalaya
The area has been declared a biodiversity hotspot by Conservation International.
The eastern Himalayas are famous for maples, rhododendrons, alder, and birch, oaks, laurels, and dwarf willows.