Ground moraine is the accumulation of glacial till which produces a topography usually independent of the underlying surface. Ground moraine occurs at or below the present surface throughout many glaciated regions. If the ground moraine is at the surface, it forms undulating plains marked by gently sloping swells, sags, and basins so that the local relief is commonly less than 6 meters; in regions where the till is very thick, the term till plain can be used.
The composition of the till can vary from 99% clay to 99% boulders. The material is usually unsorted and unstratified (see definition of till).