A mainly in the Mediterranean (Southern Europe, North Africa, Middle East and partly also in the United States ) occurring soil type of bright red or brown-red color made of clay or clay. The red color is due to the high proportion of iron compound Hematite (shiny iron ore) causes. It is often located directly above a water-permeable limestone layer and is therefore also called red limestone clay. It is a phenomenon in karst areas, it is believed that undisturbed rendzines will develop into Terra Rossa soils in the long term. The soil formation processes already took place in the Tertiary 15 million years ago and consisted in washing out the lime components while leaving the clay minerals in the lime and other mineral impurities such as red iron compounds. However, recent research also suggests a much more recent history, since the entry of red mineral dust of up to 25,000 years old from the Sahara and the Sahel region was detected.
The Terra Rossa floors dry out superficially in summer, but have an excellent depth due to the high proportion of clay in the depth Water storage capacity, It is particularly suitable for agricultural use and also viniculture, Especially with red wines does that affect Aroma very positive. The most well-known wine-growing areas with Terra Rossa soils include the connected areas Carso and Teran in the border area of Slovenia and Italy, as well as the famous Australian GI area Coonawarra, More ferrous soil types are Rotliegend, among others in the Rheinhessen area Rhine front occurs, as well as one in the French area Pomerol Occurring floor with a sub-layer made of ferrous clay, which is called "Crasse de fer" (iron slag) or "Machefer". See also under soil type and geology