What is Peneplain? How it is formed?  

Peneplain is a region that is almost a plain. It is formed due to erosion by rivers and rain, that continues until almost all the elevated portions are worn down; the most resistant rocks generally stand above the general level of the land. When a peneplain is raised, it becomes a Plateau, that is then dissected by the river as they pass through a fresh cycle from youth to old age