The ditch section of the Overton Down experimental earthwork provides a dated record of the degradation of two free faces with opposing aspects. The earthwork constructed in 1960 was excavated in 1968 and a record of the geomorphology of the ditch section is given. A detailed description and mechanical analysis of the ditch deposits is given as a basis for a discussion on the processes leading to asymmetrical infilling. The significance of falling turves in breaking the stratigraphy of the deposits is noted.