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A monocline (or, rarely, a monoform) is a step-like fold in rock
Monoclines may be formed in several different ways (see diagram)
* By differential compaction over an underlying structure, particularly a large fault at the edge of a basin due to the greater compactibility of the basin fill, the amplitude of the fold will die out gradually upwards.
* By mild reactivation of an earlier
strata
In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...
consisting of a zone of steeper dip within an otherwise horizontal or gently-dipping sequence.
Formation
Monoclines may be formed in several different ways (see diagram)
* By differential compaction over an underlying structure, particularly a large fault at the edge of a basin due to the greater compactibility of the basin fill, the amplitude of the fold will die out gradually upwards.
* By mild reactivation of an earlier extensional fault
An extensional fault is a
fault caused by stretching of the Earth's crust. Stretching reduces the thickness and horizontally extends portions of the crust and/or lithosphere. In most cases such a fault is also a normal fault, but may create a ...
during a phase of inversion
Inversion or inversions may refer to:
Arts
* , a French gay magazine (1924/1925)
* ''Inversion'' (artwork), a 2005 temporary sculpture in Houston, Texas
* Inversion (music), a term with various meanings in music theory and musical set theory
* ...
causing folding in the overlying sequence.
* As a form of fault propagation fold during upward propagation of an extensional fault in basement into an overlying cover sequence.
* As a form of fault propagation fold during upward propagation of a reverse fault in basement into an overlying cover sequence.
Examples
*Waterpocket Fold
The Waterpocket Fold is a geologic landform that extends from southern Wayne through Garfield and ending in northern Kane counties of southern Utah, United States.''Utah Atlas & Gazeteer,'' DeLorme, 9th ed., 2014, pp. 44, 52, 60-1 The geol ...
in Capitol Reef National Park
Capitol Reef National Park is an American national park in south-central Utah. The park is approximately long on its northsouth axis and just wide on average. The park was established in 1971 to preserve of desert landscape and is open all ye ...
, Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
*Comb Ridge
Comb Ridge ( nv, ) is a linear north to south-trending monocline nearly 80 miles long in Southeastern Utah and Northeastern Arizona. Its northern end merges with the Abajo Mountains some eleven miles west of Blanding. It extends essentially du ...
in southern Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
* Grandview-Phantom Monocline in Grand Canyon
The Grand Canyon (, yuf-x-yav, Wi:kaʼi:la, , Southern Paiute language: Paxa’uipi, ) is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is long, up to wide and attains a depth of over a m ...
, Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
* Grand Hogback
The Grand Hogback is a 70-mile long, curving, spine-like ridge in Western Colorado that extends from near McClure Pass in Pitkin County, Colorado, Pitkin County through Garfield County, Colorado, Garfield County and then to near Meeker, Colorado, ...
in Colorado
Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...
* Lebombo Mountains
The Lebombo Mountains, also called Lubombo Mountains ( pt, Montes Libombos), are an , narrow range of mountains in Southern Africa. They stretch from Hluhluwe in KwaZulu-Natal in the south to Punda Maria in the Limpopo Province in South Africa in ...
in Southern Africa
* Lapstone Monocline in the Blue Mountains (Australia)
The Blue Mountains are a mountainous Regions of New South Wales, region and a mountain range located in New South Wales, Australia. The region borders on Sydney's metropolitan area, its foothills starting about west of centre of City of Syd ...
* Beaumaris Monocline in Victoria (Australia)
Victoria is a state in southeastern Australia. It is the second-smallest state with a land area of , the second most populated state (after New South Wales) with a population of over 6.5 million, and the most densely populated state in ...
* Purbeck Monocline
The Purbeck Monocline is a geological fold in southern England. The term 'fold' is used in geology when one or more originally flat sedimentary strata surfaces are bent or curved as a result of plastic (i.e. permanent) deformation. A monocline is ...
on the Isle of Purbeck
The Isle of Purbeck is a peninsula in Dorset, England. It is bordered by water on three sides: the English Channel to the south and east, where steep cliffs fall to the sea; and by the marshy lands of the River Frome and Poole Harbour to the n ...
, Dorset, England
* Fore-Sudetic Monocline, Poland
* Sindh Monocline, Pakistan
Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
* Torres Flexure, southern Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
See also
*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 ...
*Homocline
In structural geology, a homocline or homoclinal structure (from old el, homo = same, cline = inclination), is a geological structure in which the layers of a sequence of rock strata, either sedimentary or igneous, dip uni ...
*Syncline
In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimpose ...
References
{{Structural geology Structural geology Deformation (mechanics)