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About
Sivalik Hills |
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The
Sivalik hills is a mountain range of the outer Himalayas also
known as Manak Parbatin in ancient times. Shivalik exactly
means 'tresses of Shiva’. This range is about 2,400 km long
enclosing an area that starts almost from the Indus and ends
close to the Brahmaputra with a gap of about 90 kms between
the Teesta and Raidak rivers in Assam. The width of the
Shivalik hills varies from 10 to 50 km, their average altitude
is 1,500 to 2,000 m.
Other spelling variations used include Shivalik and Siwalik,
originating from the Hindi and Nepali word 'shiwālik parvat'.
Other names include Churia hills, Chure hills and Margalla
hills. |
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Demographics |
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Low
population densities in the Siwalik and along the steep southern
slopes of the Mahabharat Range, plus strong malaria in the damp
forests on their fringes create a cultural, linguistic and
political buffer zone between dense populations in the plains to
the south and the "hills" beyond the Mahabharat escarpment,
isolating the two populations from each other and enabling
different evolutionary paths with respect to language, race and
culture. People of the Lepcha tribe inhabit the Sikkim and
Darjeeling areas. |
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Pre-history |
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Sivapithecus (a kind of ape, formerly known as Ramapithecus) is
among many fossil finds in the Siwalik region. The Siwalik Hills
are also among the richest fossil sites for large animals
anywhere in Asia. The Hills had disclosed that all kinds of
animals lived there. They were early ancestors to the sloth
bear, Sivatherium, an ancient giraffe, Colossochelys atlas, a
giant tortoise amongst other creatures.
The remains of the Lower Paleolithic Soanian culture have been
found in the Siwalik region.Contemporary to the Acheulean, the
Soanian culture is named after the Soan Valley in the Siwalik
Hills of Pakistan. The bearers of this culture were Homo
erectus. |
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Geology |
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The Sivalik hills are the southernmost and geologically
youngest east-west mountain chain of the Himalayas. The
Siwaliks have many sub-ranges. They extend west from
Arunachal Pradesh through Bhutan to West Bengal, and
further westward through Nepal and Uttarakhand, continuing
into Kashmir and Himachal Pradesh. The hills are cut
through at wide intervals by numerous large rivers flowing
south from the Himalayas. Smaller rivers without sources
in the high Himalayas are more likely to deviate around
sub-ranges. Southern slopes have networks of channels and
small rills, giving rise to transient streams during the
monsoon and into the post-monsoon season until groundwater
supplies are exhausted.
The Sivalik hills are mainly composed of sandstone and
rock formations which are the solidified detritus of the
great range in their back but often poorly consolidated.
The remnant magnetization of siltstones and sandstones
suggests a depositional age of 16-5.2 million years with
Karnali River exposing the oldest part of the Siwalik
Group in Nepal.
They are bounded on the south by a fault system called the
Main Frontal Thrust, with steeper slopes on that side.
Below this, the coarse alluvial Bhabhar zone makes the
transition to the nearly level plains. Rainfall,
especially during the summer monsoon, penetrates into the
bhabar, then is forced to the surface by finer alluvial
layers below it in a zone of springs and marshes along the
northern edge of the Terai or plains. This wet zone was
heavily malarial crawled before DDT was used to suppress
mosquitoes. It was left forested by official decree by
Nepal's Rana rulers as a suspicious perimeter called Char
Kose Jhadi. Upslope, the permeable geology together with
temperatures usually exceeding 40° Celsius throughout
April and May only supports a low, sparse,
drought-tolerant scrub forest.
North of the Siwalik belt the 1,500-3,000 meter Lesser
Himalayas also known as the Mahabharat Range rises
suddenly along fault lines. In many places the two ranges
are adjacent but in other places structural valleys 10–20
km wide separate them. These valleys are called Duns or
Doons in India, which includes Dehradun, Patli Dun and
Kothri Dun, both in Corbett National Park in Uttarakhand,
and also Pinjore Dun in Himachal Pradesh. In Nepal, these
valleys are called Inner Terai and include Chitwan, Dang-Deukhuri
and Surkhet. |
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Birds in the Shivaliks of Himachal Pradesh |
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Chestnut-Bellied Rock Thrush pair, Chestnut-Bellied Nuthatch,
Scaly-Brested Munia (right) and Juveniles, Ashy Drongo,
Fulvous-Breasted Woodpecker, White Eye, Bush Warbler, Himalayan
Bulbul, Scarlet Minivet, Long Tailed Minivet, Minivet, Grey
Bushchat, , Bar Winged Flycatcher Shrike Black Bulbuls, Grey
Treepie, Grey-Capped Pygmy Woodpecker , White-Crested
Laughingthrush. |
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