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 depression is a landform sunken or depressed below the surrounding area. Depressions form by various mechanisms.

Types

Erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

-related: *

Blowout Blowout or Blow out may refer to: Film and television *''Blow Out'', a 1981 film by Brian De Palma * ''The Blow Out'', a 1936 short film * ''Blow Out'' (TV series), a TV series on Bravo * "Blow Out" (''Prison Break''), an episode of ''Prison ...

: a depression created by

wind erosion Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit mate ...

typically in either a partially vegetated

sand dune A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...

ecosystem or dry soils (such as a post-glacial

loess Loess (, ; from german: Löss ) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loess or similar deposits. Loess is a periglacial or aeoli ...

environment). *

Glacial valley U-shaped valleys, also called trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape in cross-section, with steep, straight s ...

: a depression carved by

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

by a

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such a ...

. * River valley: a depression carved by fluvial erosion by a river. * Area of subsidence caused by the collapse of an underlying structure, such as

sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

s in karst terrain. * Sink: an endorheic depression generally containing a persistent or intermittent (seasonal)

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

, a salt flat (playa) or

dry lake A dry lake bed, also known as a playa, is a basin or depression that formerly contained a standing surface water body, which disappears when evaporation processes exceeds recharge. If the floor of a dry lake is covered by deposits of alkaline c ...

, or an ephemeral lake. * Panhole: a shallow depression or basin eroded into flat or gently sloping, cohesive rock.Twidale, C.R., and Bourne, J.A., 2018
Rock basins (gnammas) revisited.
''Géomorphologie: Relief, Processus, Environnement,'' Vol. 24, No. 2. January 2018. Retrieved 9 June 2020. Collapse-related: *

Sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

: a depression formed as a result of the collapse of rocks lying above a hollow. This is common in karst regions. * Kettle: a shallow, sediment-filled body of water formed by melting glacial remnants in terminal moraines. * Thermokarst hollow: caused by volume loss of the ground as the result of

permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...

thawing. Impact-related: * Impact crater: a depression created by an impact, such as a

meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object ...

crater. Sedimentary-related: *

Sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsiden ...

: in

sedimentology Sedimentology encompasses the study of modern sediments such as sand, silt, and clay, and the processes that result in their formation (erosion and weathering), transport, deposition and diagenesis. Sedimentologists apply their understanding of m ...

, an area thickly filled with

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

in which the weight of the sediment further depresses the floor of the basin. Structural or tectonic-related: *

Structural basin A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat-lying strata. They are geological depressions, the inverse of domes. Elongated structural basins are also known as syncline ...

: a

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 ...

-like depression; a region of tectonic downwarping as a result of isostasy (the Hawaiian Trough is an example) or subduction (such as the

Chilean Central Valley The Central Valley ( es, Valle Central), Intermediate Depression, or Longitudinal Valley is the depression between the Chilean Coastal Range and the Andes Mountains. The Chilean Central Valley extends from the border with Peru to Puerto Montt in ...

). *

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 ...

or rift valley: fallen and typically linear depressions or basins created by rifting in a region under tensional tectonic forces. * Pull-apart basin caused by offset in a

strike-slip 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 ...

transform fault A transform fault or transform boundary, is a fault along a plate boundary where the motion is predominantly horizontal. It ends abruptly where it connects to another plate boundary, either another transform, a spreading ridge, or a subduct ...

(example: the

Dead Sea The Dead Sea ( he, יַם הַמֶּלַח, ''Yam hamMelaḥ''; ar, اَلْبَحْرُ الْمَيْتُ, ''Āl-Baḥrū l-Maytū''), also known by other names, is a salt lake bordered by Jordan to the east and Israel and the West Ban ...

area). * Oceanic trench: a deep linear depression on the ocean floor. Oceanic trenches are caused by

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, ...

(when one tectonic plate is pushed underneath another) of

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic ...

beneath either oceanic crust or continental crust. * A basin formed by an ice sheet: an area depressed by the weight of the ice sheet resulting in post-glacial rebound after the ice melts (the area adjacent to the ice sheet may be pulled down to create a peripheral depression.) Cites American Geological Institute's Glossary of Geology (3rd edition, revised in 1987). Volcanism-related: *

Caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

: a

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plat ...

depression resulting from collapse following a volcanic eruption. * Pit crater: a volcanic depression smaller than a caldera formed by a sinking, or caving in, of the ground surface lying over a void. * Maar: a depression resulting from phreatomagmatic eruption or diatreme explosion.

List of depressions

Aral–Caspian Depression The Aral–Caspian Depression is a lowland depression straddling Europe and Asia around the Aral Sea and Northern Caspian Sea. The most northern part is called the Caspian Depression. The desert part to the east of the Caspian Depression and ...

Baetic Depression The Baetic Depression ( es, Depresión Bética or ''Depresión del Guadalquivir'') is an alluvial plain in the lower valley of the Guadalquivir in Andalusia, Spain. It is a large triangular-shaped area in the Guadalquivir basin oriented roughly ...

* Bodélé Depression * Caspian Depression * Danakil Depression * Eider-Treene Depression *

Georgia Depression The Georgia Depression is a depression in the Pacific Northwest region of western North America. The depression includes the lowland regions of southwestern British Columbia and northwestern Washington along the shores of the Salish Sea. Format ...

* Giurgeu-Brașov Depression * Godzareh Depression * Huancabamba Depression *

Kara Depression The Kara Depression is a depression in the Extreme North of European Russia, by the mouth of Kara River, north-east of the Pay-Khoy Ridge (a continuation of the northern Ural Mountains). It is of diameter 50–60 km and filled with Quaterna ...

* Karashor Depression * Kuma–Manych Depression * Kuznetsk Depression * Mari Depression *

Mourdi Depression The Mourdi Depression is a prominent desert depression of northeastern Chad. It lies adjacent to the Ennedi Plateau. The cleft lies "between the Erdi plateau and the eastern slopes of Ennedi, and the mouth of the Wadi Guroguro." The depression i ...

Qattara Depression The Qattara Depression ( ar, منخفض القطارة, Munḫafaḍ al-Qaṭṭārah) is a depression in northwestern Egypt, specifically in the Matruh Governorate. The depression is part of the Western Desert of Egypt. The Qattara Depressi ...

Regen Depression The Regen Depression (german: Regensenke) is a wide river valley in the Bavarian Forest along the River Regen (river), Regen. As natural regions of Germany, natural region major unit no. 404 the Regen Depression belongs to the Upper Palatine-Bav ...

* Ronda Depression *

Táchira Depression The Táchira Depression ( es, Depresión de Táchira) is a saddle of land connecting the Lake Maracaibo basin to the Orinoco basin in the state of Táchira, Venezuela. It forms a break in the eastern Andes, separating the Tamá Massif to the we ...

* Tunkin Depression *

Turan Depression The Turan Depression, Turan Lowland or Turanian Basin is a low-lying desert basin region stretching from southern Turkmenistan through Uzbekistan to Kazakhstan. Geography The lowland region lies to the east of the Caspian Sea and southeast o ...

* Turpan Depression * Tuva Depression *

Upemba Depression The Upemba Depression (or Kamalondo Depression) is a large marshy bowl area ( depression) in the Democratic Republic of the Congo comprising some fifty lakes, including 22 of relatively large size including Lake Upemba (530 km) and Lake Kisal ...

Weser Depression The Weser Depression (german: Weserniederung) or Weser Lowlands is the region north of Porta Westfalica in Germany, where the River Weser no longer flows through a valley, but a broad plain consisting of meadows and river terraces. The flat pla ...

Wittlich Depression The Wittlich Depression (german: Wittlicher Senke or ''Wittlicher Rotliegend-Senke''), less commonly, the Wittlich Basin, is the continuation of the Trier Valley in a northeasterly direction. It is not only recognisable in the terrain as an elon ...

* Wümme Depression

References

{{Geology-stub

Types

List of depressions

See also

References