In physical
geographyGeography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...
and
geologyGeology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
, a
horst (< German
Horst 'heap') is the raised fault block bounded by normal faults or
grabenIn geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....
. A horst is formed from extension of the Earth's crust. The raised block is a portion of the
crustIn geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
that generally remains stationary or is uplifted while the land has dropped on either side.
The
Vosges MountainsFor the department of France of the same name, see Vosges.The Vosges are a range of low mountains in eastern France, near its border with Germany. They extend along the west side of the Rhine valley in a northnortheast direction, mainly from Belfort to Saverne...
in France and
Black ForestThe Black Forest is a wooded mountain range in Baden-Württemberg, southwestern Germany. It is bordered by the Rhine valley to the west and south. The highest peak is the Feldberg with an elevation of 1,493 metres ....
in Germany are examples of horsts, the Table,
JuraThe Jura Mountains are a small mountain range located north of the Alps, separating the Rhine and Rhone rivers and forming part of the watershed of each...
and the
DôleDole may refer to:*The Grain supply to the city of Rome in ancient times.* Since the early 20th Century, a colloquial term referring to government public assistance programs; see Unemployment benefits. Originally it referred to any charitable gift of food, clothing or money. The dole has taken on...
mountains are results of the latter. The word is also applied to those larger areas, such as the Russian Plain, Arabia,
IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and Central
South AfricaThe Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, where the
continentA continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...
remains stable, with horizontal table-land
stratificationStratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
, in distinction to folded regions such as the
EurasiaEurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
n chains.
Horsts and hydrocarbon exploration
In many rift basins around the world, the vast majority of discovered
hydrocarbonIn organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
s are found in conventional traps associated with horsts. For example, much of the petroleum found in the
Sirte BasinThe Sirte Basin is a late Mesozoic and Tertiary triple junction continental rift along northern Africa that was initiated during the late Jurassic Period. It borders a relatively stable Paleozoic craton and cratonic sag basins along its southern margins...
in Libya (of the order of tens of billions of barrels of reserves) are found on large horst blocks such as the Zelten Platform and the Dahra Platform and on smaller horsts such as the
Gialo HighThe Gialo High is a relatively small horst block in the eastern Sirte Basin of the Libyan oil fields. It is most important and best known for the stacked oil fields in rocks ranging from Early Cretaceous to Oligocene age...
and the Bu-Attifel Ridge.