Naracoorte Corporation area straddles two northwesterly trending dune ridges and their corresponding flats. Cemented limestones of the Bridgewater Formation and Gambier Limestone, occasionally mantled by windblown sands, form the two ridges; younger clays and limestones occur beneath the interdunal flats. Soil types range from heavy expansive clays (rendzina) on the flats to sandy clay (terra rossa) and deep sand (podzol) on the dune,ridges; careful footing design is required for buildings on the expansive clays. Excavation for service trenches is only likely to be difficult where hard near-surface limestone occurs on the dune ridges, and where shallow water tables are present on the flats. Groundwater and extractive mineral resources (sand and road metal) are adequate for the present demand rate; sufficient reserves occur in the area to satisfy future needs over the next 30 to 40 years. Historical evidence of seismicity and the presence of the Kannawinka Fault Zone beneath the town, which could act as a focal point for any earthquake, suggests that appropriate construction code requirements be adopted for larger buildings.