A summary of the geology and geomorphology of the Torrens Valley west of the Gorge, has been compiled and the engineering and environmental characteristics of the geological materials present have been assessed. The oldest rocks in the Adelaide area are the Proterozoic slates and quartzites exposed along the higher parts of the Eden and Para Fault blocks. Movement along these sub-parallel features since the Tertiary period has depressed the Proterozoic basement several hundred metres below sea level in the western suburbs, and a similar distance above sea level in the Mount Lofty Ranges. In the depressions created by this movement deposition has been successively fluviatile (Eocene sands of Highbury), Marine (Eocene-Miocene, not exposed) and fluviatile (Pleistocene to Recent alluvial deposits blanketing the present surface). During the Pleistocene successive rises and falls in sea level filled and eroded the Torrens Valley. Alluvial fans formed and coalesced at the bases of the rising Para and Eden blocks. Higher discharges eroded broad valley meanders in the upper reaches of the Torrens between Paradise and Athelstone. Recent fluctuations in sea level are recorded by two lines of sand dunes at West Beach and Fulham. The Torrens Valley has, in the past, been an important source of groundwater, brick clay, sand and gravel, but the reserves of these materials are no longer of practical significance, due to the location of alternative sources of supply and encroachment by residential and industrial land uses. Thus, no valuable construction material resouces would be sterilized by the proposed development. No foundation problems for light structures are expected, apart from the Black Earth areas where soils are expansive. Erosion of river banks does not appear to be active at the present time. The geological environment is not likely to be affected by this development, provided groundwater recharge areas adjacent to the Hills Face are protected. A number of areas of particular geological interest have been specified, but there are no unique areas requiring special protection within the study area.