The Sivalik Hills, also known as Churia Hills, are a mountain range of the outer Himalayas that stretches from the Indus River about eastwards close to the Brahmaputra River, spanning across the northern parts of the Indian subcontinent. It is wide with an average elevation of. Between the Teesta and Raidāk Rivers in Assam is a gap of about. In some Sanskrit texts, the region is called Manak Parbat. Sivalik literally means 'tresses of Shiva’. Sivalik region is home to the Soanian archaeological culture.
Geology
Geologically, the Sivalik Hills belong to the Tertiarydeposits of the outer Himalayas. They are chiefly composed ofsandstone and conglomeraterock formations, which are the solidified detritus of the Himalayas to their north; they are poorly consolidated. The remnant magnetisation of siltstones and sandstones indicates that they were deposited 16–5.2 million years ago. In Nepal, the Karnali River exposes the oldest part of the Shivalik Hills. They are the southernmost and geologically youngest east-west mountain chain of the Himalayas. They have many subranges and extend west from Arunachal Pradesh through Bhutan to West Bengal, and further westward through Nepal and Uttarakhand, continuing into Himachal Pradesh and Kashmir. The hills are cut through at wide intervals by numerous large rivers flowing south from the Himalayas. 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 Bhabar zone makes the transition to the nearly level plains. Rainfall, especially during the summer monsoon, percolates 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. North of the Sivalik Hills, the 1,500– to 3,000-meter Lesser Himalayas, also known as the Mahabharat Range, rise steeply along fault lines. In many places, the two ranges are adjacent, but in other places, structural valleys 10–20 km wide separate them.
Prehistory
Remains of the Lower PaleolithicSoanian culture were found in the Sivalik region. Contemporary to the Acheulean, the Soanian culture is named after the Soan Valley in the Sivalik Hills of Pakistan. The Soanian archaeological culture is found across Sivalik region in present-day India, Nepal and Pakistan. Sivapithecus is among many fossil finds in the Sivalik region. The Sivalik Hills are also among the richest fossil sites for large animals anywhere in Asia; the hills had revealed that all kinds of animals lived there. They were early ancestors to the sloth bear; Sivatherium, an ancient giraffe; and Megalochelys atlas, a giant tortoise named the Sivaliks giant tortoise; amongst other creatures. The obscure ratiteHypselornis was found here. It poses a biogeographical mystery as its closest relatives are Australian emus and cassowaries.
Demographics
Low population densities in the Sivalik Hills and along the steep southern slopes of the Lower Himalayan Range, plus virulent 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.
In culture
The Indian Navy's Shivalik-class frigate is named after these ranges.
