The term 'flat-topped hill' is used to describe two distinct landforms: a mesa and a BUTTE. A mesa is a large, flat-topped hill with steep sides that is formed by erosion. It is usually found in dry regions such as the southwestern United States. A BUTTE is also a flat-topped hill, but it is smaller than a mesa and has more gradual slopes. It is often found in areas with more rainfall, such as the Great Plains of the United States.