physical geography Physical geography (also known as physiography) is one of the three main branches of geography. Physical geography is the branch of natural science which deals with the processes and patterns in the natural environment such as the atmosphere, h ...

and

geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...

, a horst is a raised

fault block Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust. Large areas of bedrock are broken up into blocks by faults. Blocks are characterized by rela ...

bounded by

normal fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

s. Horsts are typically found together with

grabens In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...

. While a horst lifted or remains stationary, the grabens on either side subside. This is often caused by extensional forces pulling apart the crust. Horsts may represent features such as plateaus, mountains, or ridges on either side of a valley. Horsts can range in size from small fault-blocks, up to large regions of stable continent that have not been not folded or warped by tectonic forces. The word ''Horst'' in

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

means "mass" or "heap," and was first used in the geological sense in 1883 by

Eduard Suess Eduard Suess (; 20 August 1831 - 26 April 1914) was an Austrian geologist and an expert on the geography of the Alps. He is responsible for hypothesising two major former geographical features, the supercontinent Gondwana (proposed in 1861) and t ...

in ''The Face of the Earth.''Originally published in 1883 in German as "Das Antlitz der Erde", translated and published in English in 1904

Geomorphology

Horsts may have either symmetrical or asymmetrical cross-sections. If the normal faults to either side have similar geometry and are moving at the same rate, the horst is likely to be symmetrical and roughly flat on top. If the faults on either side have different rates of vertical motion, the top of the horst will most likely be inclined and the entire profile will be asymmetrical. Erosion also plays a significant role in how symmetrical a horst appears in cross-section.

Horsts and hydrocarbon exploration

Horsts can form structural petroleum traps. In many

rift basin In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben wi ...

s around the world, the vast majority of discovered

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...

s are found in conventional traps associated with horsts. For example, much of the petroleum found in the

Sirte Basin The Sirte Basin is a late Mesozoic and Cenozoic triple junction continental rift (extensional basin) along northern Africa that was initiated during the late Jurassic Period. It borders a relatively stable Paleozoic craton and cratonic sag basins a ...

, 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 High The Gialo High is a relatively small horst (geology), 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. There are ...

Examples

The

Vosges Mountains The Vosges ( , ; german: Vogesen ; Franconian and gsw, Vogese) are a range of low mountains in Eastern France, near its border with Germany. Together with the Palatine Forest to the north on the German side of the border, they form a single ...

in France and

Black Forest The Black Forest (german: Schwarzwald ) is a large forested mountain range in the state of Baden-Württemberg in southwest Germany, bounded by the Rhine Valley to the west and south and close to the borders with France and Switzerland. It is t ...

in Germany are examples of horsts, as are the

Table Table may refer to: * Table (furniture), a piece of furniture with a flat surface and one or more legs * Table (landform), a flat area of land * Table (information), a data arrangement with rows and columns * Table (database), how the table data ...

, Jura, the

Dole Dole may refer to: Places * Dole, Ceredigion, Wales * Dole, Idrija, Slovenia * Dole, Jura, France ** Arrondissement of Dole * Dole (Kladanj), a village at the entity line of Federation of Bosnia and Herzegovina-Republika Srpska * Dole, Ljubušk ...

mountains and the

Rila Rila ( bg, Рила, ) is the highest mountain range of Bulgaria, the Balkans, Balkan Peninsula and Southeast Europe. It is situated in southwestern Bulgaria and forms part of the Rila–Rhodope Mountains, Rhodope Massif. The highest summit is Mus ...

Rhodope Rhodope may refer to: * Rhodope (mythology), a figure of Greek mythology * Rhodope Mountains, in Bulgaria and Greece * Rhodope (regional unit), of Greece * Rhodope (province), a Roman and Byzantine province * 166 Rhodope, an asteroid * Rhodope (genu ...

Massif In geology, a massif ( or ) is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole. The term also refers to a ...

including the well defined horsts of

Belasitsa Belasica ( Macedonian and Bulgarian: , also translit. ''Belasitsa'' or ''Belasitza'', Ottoman Turkish: بلش Turkish: ''Beleş''), Belles ( el, Μπέλλες, ''Bélles'') or Kerkini (, ''Kerkíni'';), is a mountain range in the region of M ...

(linear horst),

Rila mountain Rila ( bg, Рила, ) is the highest mountain range of Bulgaria, the Balkan Peninsula and Southeast Europe. It is situated in southwestern Bulgaria and forms part of the Rila– Rhodope Massif. The highest summit is Musala at an elevation of 2,92 ...

(vaulted domed shaped horst) and

Pirin mountain The Pirin Mountains ( bg, Пирин ) are a mountain range in southwestern Bulgaria, with Vihren at an altitude of 2,914 m being the highest peak. The range extends about 80 km from the north-west to the south-east and is about 40 ...

- a horst forming a massive

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...

situated between the complex

graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic contex ...

valleys of Struma and that of

Mesta The ''Mesta'' () was a powerful association protecting livestock owners and their animals in the Crown of Castile that was incorporated in the 13th century and was dissolved in 1836. Although best known for its organisation of the annual migrat ...

. Larger areas where the

continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...

remains stable with horizontal table-land

stratification Stratification may refer to: Mathematics * Stratification (mathematics), any consistent assignment of numbers to predicate symbols * Data stratification in statistics Earth sciences * Stable and unstable stratification * Stratification, or str ...

can be considered horsts, such as the

Russian Plain The East European Plain (also called the Russian Plain, "Extending from eastern Poland through the entire European Russia to the Ural Mountaina, the ''East European Plain'' encompasses all of the Baltic states and Belarus, nearly all of Ukraine, an ...

Arabia The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate. ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

and Central

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. This is in distinction to folded regions such as some mountain chains of

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

. The

Midcontinent Rift System The Midcontinent Rift System (MRS) or Keweenawan Rift is a long geological rift in the center of the North American continent and south-central part of the North American plate. It formed when the continent's core, the North American craton, be ...

in North America is marked by a series of horsts extending from

Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...

. The

Rwenzori Mountains The Ruwenzori, also spelled Rwenzori and Rwenjura, are a range of mountains in eastern equatorial Africa, located on the border between Uganda and the Democratic Republic of the Congo. The highest peak of the Ruwenzori reaches , and the range' ...

in the

East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. In the past it was considered to be part of a ...

are an upthrown fault block, and are the highest non-volcanic, non-orogenic mountains in the world. The

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

were formed by

isostatic uplift Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound a ...

in response to the opening of the

Rhine Graben The Upper Rhine Plain, Rhine Rift Valley or Upper Rhine Graben (German: ''Oberrheinische Tiefebene'', ''Oberrheinisches Tiefland'' or ''Oberrheingraben'', French: ''Vallée du Rhin'') is a major rift, about and on average , between Basel in the so ...

, a major extensional basin. In Palestine, the Central Highlands and Eastern Plateau surround the Jordan Valley, forming a horst and graben system

Notes

References

External links