The Shivaliks are the outermost and youngest range of the Himalaya, rising a few hundred metres above the plain along Punjab's northern edge in Rupnagar, Hoshiarpur and Pathankot.
They are made of the debris of the Himalaya itself, sandstone and conglomerate laid down over the last twenty million years and then folded up. They are geologically unstable, erode fast and produce the chos.
The Siwalik fossil beds are among the richest Miocene and Pliocene vertebrate fossil sites in the world. Sivapithecus, a large fossil ape, was described from them, and the beds have yielded early elephants, giraffes, hippos and hominoid material.
Kiratpur, Anandpur, Naina Devi and the whole line of Sikh hill sites sit at the point where the plain meets these hills, because that line is where defensible ground begins.
The forest on them is Punjab's only substantial natural vegetation and it has been under pressure from grazing, mining and quarrying for a century.
They are the youngest and lowest of the Himalayan ranges, made from the debris of the mountains behind them, soft rock and conglomerate that erodes fast.
That erosion is the chos. The range sheds sand and gravel onto the plain each monsoon and the check dam programme has been fighting it since the 1950s.
The wildlife sanctuaries on the Punjab side of the range are small and disconnected, and no corridor links them to the larger forests in Himachal above them.