ABSTRACT
This chapter discusses the properties and engineering behaviour of the residual and tertiary clays of high plasticity of western Sydney. It discusses the soils maps provided by the N.S.W. Dept. of Soil Conservation, which are the most useful guide to soil profiles. The maps delineate three main profiles: Cumberland Association, Menangle Association and Mulga Association. The Cumberland Association consists of texture contrast soils developed on the lower members of the Wianamatta Group of Upper Triassic Age, comprising siltstone and shale rock types of the Ashfield Shale and lower Bringelly Shale Formations. The Menangle Association soils are located on the undulating and hilly areas to the south of the County of Cumberland. The Mulgoa Association consists of soils developed on alluvium derived from the Nepean River during Tertiary times. The Association includes the Mulgoa Series, Cranebrook Series and the poorly drained Londonderry Series.
