In
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 ...
and
geology
Geology () is a branch of natural science concerned with Earth and other Astronomical object, astronomical objects, the features or rock (geology), rocks of which it is composed, and the processes by which they change over time. Modern geology ...
, a horst is a raised
fault block 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. 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
**Ge ...
means "mass" or "heap," and was first used in the geological sense in 1883 by
Eduard Suess 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 basins 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 ...
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 ...
, 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.
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 singl ...
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 ...
in Germany are examples of horsts, as are the
Table,
Jura, the
Dole mountains and the
Rila -
Rhodope Massif 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 (vaulted domed shaped horst) and
Pirin mountain - 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 t ...
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 conte ...
valleys of
Struma and that of
Mesta.
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 can be considered horsts, such as the
Russian Plain,
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 Pl ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...
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 coun ...
. 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 archipelag ...
.
The
Midcontinent Rift System 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 ...
to
Kansas
Kansas () is a U.S. state, state in the Midwestern United States, Midwestern United States. Its Capital city, capital is Topeka, Kansas, Topeka, and its largest city is Wichita, Kansas, Wichita. Kansas is a landlocked state bordered by Nebras ...
.
The
Rwenzori Mountains in the
East African Rift are an upthrown fault block, and are the highest non-volcanic, non-orogenic mountains in the world.
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 singl ...
in
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 in response to the opening of the
Rhine Graben, a major extensional basin.
In Palestine, the Central Highlands and Eastern Plateau surround the Jordan Valley, forming a horst and graben system
See also
*
Horst and graben
*
Basin and range topography
*
Fault-block mountain
*
Plateau
In geology and physical geography, a plateau (; ; ), also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. Often one or more sides ...
Notes
References
External links
*
Structural geology
Tectonic landforms
*
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