McLaren Vale, one of South Australia's major wine producing regions, is nestled in a geological province known as the Willunga Embayment, just a short drive south of Adelaide. From the sediments which were deposited in the basin-shaped embayment, soils have been derived that today nourish the McLaren Vale vineyards. The soils vary in their physical characteristics and chemical composition depending on the nature of the parent rock from which they were derived. the importance of terroir is now being recognised in McLaren Vale for producing consistent, high-quality wines. This brochure provides an overview to the geology of the region, describes the main rock types that underlie the vineyards, and introduces one of the most important issues affecting wine production — the sources and quality of water that is turned into wine