Three Cute Young Girls Shows Off On The Hill On Rocks

A hillock is a small hill. Other words include knoll and (in Scotland, Northern Ireland and northern England) its variant, knowe.
Artificial hills may be referred to by a variety of technical names, including mound and tumulus.
Hills may form through a number of geomorphic phenomena: faulting, erosion of larger landforms, such as mountains and movement and deposition of sediment by glaciers (e.g. moraines and drumlins, or by erosion exposing solid rock which then weathers down into a hill. The rounded peaks of hills results from the diffusive movement of soil and regolith covering the hill, a process known as downhill creep.
Areas that would otherwise have hills do not because of glacier cover during the Ice Age. The hills that existed before the ice age were worn down by the ice (and the rocks they carry) and/or the surrounding valleys and hollows were filled in with glacial drift, therefore leaving a level topography. The contrast between the flat plains of northern Indiana, once covered by ice, and the rugged hills of southern Indiana, where the ice never reached, is a result of this. Another example is the Driftless Zone, an island of hilly country that the ice sheets missed, surrounded by glacial plains, also in the American Midwest.