Terra rossa is a red clay soil produced by the weathering of limestone. When limestone weathers, the clay contained in the stone remains in situ, along with any other non-soluble rock material. Under oxidizing conditions, when the soils are above the water table, iron oxide forms in the clay. This gives the soil type a characteristic red to orange colour.
The Coonawarra wine region is known for world class Cabernet Sauvignon red wines produced on its famous "terra rossa" soil. The red colour of soil may improve the quality of the wine. The effects of soil on wine are a key component of the French concept of gôut de terroir. Emile Zola's (1888) novel La Terre (The Soil) discusses the subject. This effect may be a perception or it may be a truth.
Please visit the earthcache site, examine the terra rossa, and answer the following questions. After examining the soil you can visit the nearby winery and examine the excellent sample on display in the foyer.
-Grab a handful terra rossa. How does it feel? Describe the soil condition. Is it sticky when wet? Do you think it will make good wine?
Further reading
GSA http://www.geosociety.org/gsatoday/archive/26/5/article/i1052-5173-26-5-4.htm