Especially in the Mediterranean (southern Europe, North Africa, the Middle East and partly in the USA ) occurring soil type of bright red or brown-red color of clay or clay. The red color is due to the high proportion of iron compound Hematite (Glanzeisenerz) causes. Often it lies directly above a water-permeable limestone layer and is therefore also referred to as limestone red clay. It is a phenomenon in karst areas, it is believed that undisturbed rendos will develop in the long term to Terra Rossa soils. The soil formation processes took place already in the Tertiary 15 million years ago and consisted in the leaching of lime components leaving the clay minerals in the lime and other mineral impurities such as red iron compounds. However, recent research also suggests a much younger history, as it was the entry of red mineral maximum 25,000 years old dust from the Sahara and the Sahel region detected.
The Terra Rossa soils dry superficially in summer, but have an excellent due to the high clay content in the depth Water storage capacity, It is particularly suitable for agricultural use and also the viniculture, Especially at red wines this affects the im Aroma very positive. Among the most well-known wine regions with Terra Rossa soils are the related areas Carso and Teran in the border area of Slovenia and Italy, as well as the famous Australian GI area Coonawarra, Other ferrous soil types are Rotliegend, who among other things in the Rhinehessian area Rhine front occurs, as well as one in the French area Pomerol Occurring soil with a ferrous clay underclad called "Crasse de fer" (iron slag) or "Machefer". See also below soil type and geology