This document defines and describes different types of landforms. The major landforms are mountains, hills, plateaus, and plains. Minor landforms include buttes, canyons, valleys, and basins. Specifically, it defines a valley as a low area between hills or mountains formed by erosion, a plateau as a large, relatively flat highland separated from surrounding land by steep slopes, and a mountain as a highland over 600 meters above sea level. Plains are described as low areas less than 100 meters above sea level, and hills are defined as elevated areas lower than mountains.