Terra rossa (soil)
Encyclopedia
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
soil produced by the weathering of limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
. When limestone weathers, the clay contained in the rocks is left behind, along with any other non-soluble rock material. Under oxidizing conditions, when the soils are above the water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
, iron oxide
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...
(rust) forms in the clay. This gives it a characteristic red to orange colour.
Terra rossa is typically found in regions with a Mediterranean climate
Mediterranean climate
A Mediterranean climate is the climate typical of most of the lands in the Mediterranean Basin, and is a particular variety of subtropical climate...
.
Compared to most clay soils, terra rosa has surprisingly good drainage characteristics. This makes it a popular soil type for wine
Wine
Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...
production. Among other wine regions, it is found in La Mancha
La Mancha (DO)
La Mancha is a Spanish Denominación de Origen for wines, with over 190,000 ha planted to vines, and is the largest continuous vine-growing area in the world. It is located in the autonomous region of Castile-La Mancha in central Spain and includes 182 municipalities: 12 in the province of...
in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and Coonawarra
Coonawarra
Coonawarra is a wine region, on the Limestone Coast of South Australia, that is known for the Cabernet Sauvignon wines produced on its "terra rossa" soil. Coonawarra is an Aboriginal word meaning "Honeysuckle". It is about 380 km southeast of Adelaide, close to the border with...
in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
Red Mediterranean
In pedologyPedology (soil study)
Pedology is the study of soils in their natural environment. It is one of two main branches of soil science, the other being edaphology...
, red Mediterranean soil, also known as terra rossa (Italian
Italian language
Italian is a Romance language spoken mainly in Europe: Italy, Switzerland, San Marino, Vatican City, by minorities in Malta, Monaco, Croatia, Slovenia, France, Libya, Eritrea, and Somalia, and by immigrant communities in the Americas and Australia...
for "red soil") is a soil classification
Soil classification
Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.- Overview :...
that has been formally superseded by the formal classifications of systems such as the FAO soil classification
FAO soil classification
The Food and Agriculture Organization of the United Nations developed a supra-national classification, also called World Soil Classification, which offers useful generalizations about soils pedogenesis in relation to the interactions with the main soil-forming factors. It was first published in...
, but that is still in common use. The terra rossa classification was still, as of 1997, a part of the national soil classifications of countries such as Israel
Israel
The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...
and Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
. The UNESCO
UNESCO
The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...
/FAO
Food and Agriculture Organization
The Food and Agriculture Organization of the United Nations is a specialised agency of the United Nations that leads international efforts to defeat hunger. Serving both developed and developing countries, FAO acts as a neutral forum where all nations meet as equals to negotiate agreements and...
World map equivalents are the chromic luvisols (a sub-order of the luvisols), and the USDA soil taxonomy
USDA soil taxonomy
USDA Soil Taxonomy developed by United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series.- Example of...
equivalent is the rhodustalfs (a sub-order of the ustalfs).
The classification denotes red-coloured soils (sometimes called "red rendzina
Rendzina
Rendzina is a dark, grayish-brown, humus-rich, intrazonal soil. It is one of the soils most closely associated with the bedrock type and an example of initial stages of soil development...
s") which develop in or on the karstic landscape
Karst topography
Karst topography is a geologic formation shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite, but has also been documented for weathering resistant rocks like quartzite given the right conditions.Due to subterranean drainage, there...
of the limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
s of the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
and earlier periods, as well as calcrete
Caliche (Mineral)
Caliche is a sedimentary rock, a hardened deposit of calcium carbonate. This calcium carbonate cements together other materials, including gravel, sand, clay, and silt. It is found in aridisol and mollisol soil orders...
s in regions where the modern Mediterranean climate
Mediterranean climate
A Mediterranean climate is the climate typical of most of the lands in the Mediterranean Basin, and is a particular variety of subtropical climate...
is predominant. The most accelerated development of red Mediterranean soils occurred from the Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
to the Late Pleistocene
Late Pleistocene
The Late Pleistocene is a stage of the Pleistocene Epoch. The beginning of the stage is defined by the base of the Eemian interglacial phase before the final glacial episode of the Pleistocene 126,000 ± 5,000 years ago. The end of the stage is defined exactly at 10,000 Carbon-14 years BP...
, due to the large amount of climate fluctuation in those periods.
Terra rossa occurs in areas where heavy rainfall dissolves carbon
Carbonation
Carbonation is the process of dissolving carbon dioxide in water. The process usually involves carbon dioxide under high pressure. When the pressure is reduced, the carbon dioxide is released from the solution as small bubbles, which cause the solution to "fizz." This effect is seen in carbonated...
from the calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
parent rock and silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
s are leached out of the soil to leave residual deposits that are rich in iron hydroxides, the cause of the red colour. Such areas are usually depressions within the limestone, or areas where the vegetation is garrigue
Garrigue
Garrigue or phrygana is a type of low, soft-leaved scrubland ecoregion and plant community in the Mediterranean forests, woodlands, and scrub biome. It is found on limestone soils around the Mediterranean Basin, generally near the seacoast, where the climate is ameliorated, but where annual summer...
(low-lying scrub).