HOME

TheInfoList



OR:

A cuesta () is a
hill A hill is a landform that extends above the surrounding terrain. It often has a distinct summit, and is usually applied to peaks which are above elevation compared to the relative landmass, though not as prominent as Mountain, mountains. Hills ...
or
ridge A ridge is a long, narrow, elevated geomorphologic landform, structural feature, or a combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, wi ...
with a gentle slope on one side, and a steep slope on the other. In geology, the term is more specifically applied to a ridge where a harder
sedimentary rock Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
overlies a softer layer, the whole being tilted somewhat from the horizontal. This results in a long and gentle backslope called a
dip slope A dip slope is a topographic or geomorphic surface which slopes in the same direction, and often by the same angle, as the true dip or apparent dip of the underlying strata.Jackson, JA, J Mehl and K Neuendorf (2005) ''Glossary of Geology.'' Ame ...
that conforms with the dip of resistant
strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...
, called
caprock Caprock or cap rock is a hard, resistant, and impermeable layer of rock that overlies and protects a reservoir of softer organic material, similar to the crust on a pie where the crust (caprock) prevents leakage of the soft filling (softer materia ...
. Where
erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
has exposed the frontslope of this, a steep slope or
escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations. Due to the similarity, the term '' scarp'' may mistakenly be incorrectly used inte ...
occurs. The resulting
terrain Terrain (), alternatively relief or topographical relief, is the dimension and shape of a given surface of land. In physical geography, terrain is the lay of the land. This is usually expressed in terms of the elevation, slope, and orientati ...
may be called scarpland.


Definition

In general usage, a cuesta is a hill or ridge with a gentle slope (backslope) on one side, and a steep slope (frontslope) on the other. The word is from
Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many countries in the Americas **Spanish cuisine **Spanish history **Spanish culture ...
: "flank or slope of a hill; hill, mount, sloping ground". In geology and geomorphology, cuesta refers specifically to an asymmetric ridge with a long and gentle backslope called a dip slope that conforms with the dip of a resistant stratum or strata, called caprock. The outcrop of the caprock forms a steeper or even cliff-like frontslope (escarpment), cutting through the dipping strata that comprise the cuesta.Cotton, CA (1952) ''Geomorphology An Introduction to the Study of Landforms.'' John Wiley and Sons, New York. 505 pp.Simonett, SD (1968) ''Cuesta.'' In RW Fairbridge, ed., pp. 233, ''The Encyclopedia of Geomorphology'' (Encyclopedia of Earth Sciences, Volume III), Reinhold, New York, 1296 pp. Jackson, JA, J Mehl and K Neuendorf (2005) ''Glossary of Geology.'' American Geological Institute, Alexandria, Virginia. 800 pp.


Formation

Cuestas are the expression of extensive outcrops of gently dipping strata, typically
sedimentary Sedimentary rocks are types of rock formed by the cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or deposited at Earth's surface. Sedime ...
strata, that consist of alternating beds of weak or loosely cemented strata, e.g.
shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...
,
mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...
, and
marl Marl is an earthy material rich in carbonate minerals, Clay minerals, clays, and silt. When Lithification, hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. M ...
and hard, well-lithified strata, e.g.
sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
and
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
. The surfaces of the hard, erosion-resistant rock strata form the caprock of the backslope (dip-slope) of the cuesta, where erosion has preferentially removed the weaker strata. The frontslope of the cuesta consists of an escarpment that cuts across the
bedding Bedding, also called bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environment ...
of the strata comprising it. Because of the gently dipping nature of the strata that forms a cuesta, a significant shift in horizontal location will take place as the landscape is lowered by
erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
. Because the slope of a cuesta dips in the same direction as the sedimentary strata, the dip angle of this bedding (θ) can be calculated by (''v'' / ''h'') = tan(θ) where ''v'' is equal to the vertical distance and ''h'' is equal to the horizontal distance perpendicular to the strike of the beds. Cuestas,
homoclinal ridge A homoclinal ridge or strike ridge is a hill or ridge with a moderate, generally between 10° and 30°, sloping backslope. Its backslope is a '' dip slope,'' that conforms with the dip of a resistant stratum or strata, called '' caprock.'' On the ...
s, and hogbacks comprise a sequence of landforms that form a gradational continuum. These landforms differ only on the steepness of their backslopes and the relative differences in the inclination of their backslopes and frontslopes. These differences depend upon whether the dip of the strata from which they have been eroded are either nearly vertical, moderately dipping, or gently dipping. Because of their gradational nature, the exact angle of the backslope that separates these landforms is arbitrary and some differences in the specific angles used to define these landforms occur in the scientific literature. It also can be difficult to sharply distinguish immediately adjacent members of this series of landforms because of their gradational nature.


Examples

In
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, two well-known cuestas in western/central
New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...
and southern
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
are the
Onondaga escarpment The Onondaga Limestone is a group of hard limestones and dolomites of Devonian age that forms geographic features in some areas in which it outcrops; in others, especially its Southern Ontario portion, the formation can be less prominent as a lo ...
and the
Niagara Escarpment The Niagara Escarpment is an approximately discontinuous, arc-shaped but generally northward-facing escarpment, or cuesta, in Canada and the United States. The escarpment begins south of Lake Ontario and circumscribes the top of the Great Lake ...
. The dip of the Onondaga is about 40 feet per mile (about 7.6 m/km) to the south. In their most populated sections both escarpments edges face north, running roughly parallel to the southern
Lake Ontario Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York (state), New York. The Canada–United Sta ...
shoreline and, for the former, the Mohawk River. The
Gulf Coastal Plain The Gulf Coastal Plain extends around the Gulf of Mexico in the Southern United States and eastern Mexico. This coastal plain reaches from the Florida Panhandle, southwest Georgia (U.S. state), Georgia, the southern two-thirds of Alabama, over m ...
in
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
is punctuated by a series of cuestas that parallel the coast, as are most coastal plains. The Reynosa Plateau is the most coast-ward cuesta, which has surface expression with the Bordes-Oakville escarpment, on the northwest side and a low ridge on the eastern boundary, called the Reynosa Cuesta, where the deposits dip below later
Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
deposits of the Willis and Lissie Formations. Cuestas have less dramatic expression in the United Kingdom, with two notable examples being the northwest-facing escarpment of the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...
White Horse Hills The Berkshire Downs are a range of chalk downland hills in southern England, part of the North Wessex Downs Area of Outstanding Natural Beauty. The Berkshire Downs are wholly within the traditional county of Berkshire, although split between ...
and the similarly aligned escarpment of the
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
limestones in the
Cotswolds The Cotswolds ( ) is a region of central South West England, along a range of rolling hills that rise from the meadows of the upper River Thames to an escarpment above the Severn Valley and the Vale of Evesham. The area is defined by the bedroc ...
, sometimes called the Cotswold Edge. Other examples include the Brecon Beacons, Wenlock Edge, the Chilterns, the North and South Downs and the Greensand Ridge of Kent and Surrey In continental Europe, the
Swabian Alb The Swabian Jura ( , more rarely ), sometimes also named Swabian Alps in English, is a mountain range in Baden-Württemberg, Germany, extending from southwest to northeast and in width. It is named after the region of Swabia. It is part of th ...
offers particularly good views of cuestas in
Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...
rock. In
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
, the term for a cuesta is the same as for a coastline: ''côte''. Notable French cuestas are the wine-growing regions of
Côte d'Or Côte Restaurants Group Limited, trading as Côte (formerly Côte Brasserie), stylised as CÔTE is a French-style British restaurant chain founded by Richard Caring, Andy Bassadone, Chris Benians and Nick Fiddler in Wimbledon, London Wimbl ...
. The Machinchang Formation outcrops in the
Langkawi Langkawi, officially known as Langkawi, the Jewel of Kedah (), is a duty-free island and an archipelago of 99 islands (plus five small islands visible only at low tide in the Strait of Malacca) located some 30 km off the coast of northwe ...
islands off the coast of northwestern
Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...
. The formation is one of the oldest exposed rock units in Southeast Asia and has an extensive eroded
anticline In structural geology, an anticline is a type of Fold (geology), fold that is an arch-like shape and has its oldest Bed (geology), beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex curve, c ...
cuesta topography—dating back to Cambrian.


See also

*


References


External links

{{Commons category, Cuestas
Escarpment geology
Geomorphology Structural geology Slope landforms Erosion landforms Ridges