The Sivalik Hills of Nepal
Reaching heights of between 600 and 1,200 meters, the Sivalik Hills stretch for a distance of around 1,600 kilometers from the Teesta River in the Indian state of Sikkim, through Nepal, Uttarakhand, Kashmir and ending in Northern Pakistan. The southern slopes of Sivalik Hills consist of a series of small channels which turn into continuously flowing streams during the monsoon season, emptying into the Terai region. Large rivers flowing south from the Himalayas cut through the Sivalik Hills from time to time, while smaller rivers wind around at their base.
In a country renowned for its awe-inspiring mountains, the Sivalik Hills of Nepal may very well be overlooked. However, fossil discoveries have revealed the importance of the Sivalik Hills in the history of Nepal and surrounding countries, both geologically and from the standpoint of the evolution of animal life. Among the many fossils found in the Sivalik Hills region are the remains of an extinct type of ape known as Sivapithecus, believed to be an ancestor of today’s orangutan. Researchers have dated the Sivapithecus to the Miocene age, but more specifically as being between 8.5 million and 12.5 million years old. From the shape of the bones and teeth it has been deduced that this animal would have spent time in trees and consumed a diet of savannah grasses and seeds. Moreover, archeological discoveries in the Sivalik Hills revealed the remains of what has been categorized as the Lower Paleolithic Soanian culture belonging to Homo erectus – a species of hominid originating in Africa.
The Sivalik Hills are sparsely populated, particularly in the region within the borders of Nepal. The hills are believed to be more than sixteen million years old and are primarily made up of rock formations, sandstone and siltstone. The flowing action of the Karnali River over millions of years has exposed some of the oldest parts of the Sivalik Hills in Nepal. To the south of the hills runs a fault system causing steeper sides, blending into the lower level Terai plains – an area with a high water table that is almost constantly wet. The series of valleys between the Sivalik Hills and the Mahabharat Range, most often referred to as the Lesser Himalayas, is the Inner Terai of Nepal which incorporates Nepal’s regions of Chitwan, Dang Deukhuri and Surkhet.