Sivalik Hills

[5] They are chiefly composed of sandstone and conglomerate rock formations, which are the solidified detritus of the Himalayas[5] to their north; they are poorly consolidated.

[6] They are bounded on the south by a fault system called the Main Frontal Thrust, with steeper slopes on that side.

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.

[7] The Sivalik Hills are well known for fossils of vertebrates, spanning from the Early Miocene, until the Middle Pleistocene, around 18 million to 600,000 years ago.

[13] Remains of the Lower-Middle Paleolithic Soanian culture dating to around 500,000 to 125,000 years Before Present were found in the Sivalik region.