This unit refers to the gently undulating plains traversed by a network of former stream courses and some intermittent tributaries of the Richardson River, Wimmera River and Dunmunkle Creek. Some of these plains however, have rolling to strongly undulating topography. Also, localised areas of sand sheets and low sand rises occur in this unit. The overall area of this unit is about 63 900 hectares, occupying most of the southern plains.
The main soils included in this unit have been mapped in the Ledcourt and Wal Wal associations.