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

and

geomorphology Geomorphology () is the scientific study of the origin and evolution of topographic and bathymetric features generated by physical, chemical or biological processes operating at or near Earth's surface. Geomorphologists seek to understand wh ...

a planation surface is a large-scale land surface that is almost flat with the possible exception of some residual hills. The processes that form planation surfaces are labelled collectively planation and are exogenic (chiefly

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 ...

). Planation surfaces are planated regardless of

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bed ...

structures. On Earth, they constitute some of the most common landscapes. Geological maps indicate that planation surfaces may comprise 65% of the landscapes on Saturn's largest moon,

Titan Titan most often refers to: * Titan (moon), the largest moon of Saturn * Titans, a race of deities in Greek mythology Titan or Titans may also refer to: Arts and entertainment Fictional entities Fictional locations * Titan in fiction, fictiona ...

, which hosts a

hydrological cycle The water cycle (or hydrologic cycle or hydrological cycle) is a biogeochemical cycle that involves the continuous movement of water on, above and below the surface of the Earth across different reservoirs. The mass of water on Earth remains fai ...

of liquid

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

Peneplain In geomorphology and geology, a peneplain is a low-relief plain formed by protracted erosion. This is the definition in the broadest of terms, albeit with frequency the usage of peneplain is meant to imply the representation of a near-final (or ...

s and

pediplain In geology and geomorphology a pediplain (from the Latin ''pes'', genitive case ''pedis'', meaning "foot") is an extensive plain formed by the coalescence of pediment (geology), pediments. The processes through which pediplains forms is known a ...

s are types of planation surfaces planated respectively by "peneplanation" and "pediplanation". In addition to these there are planation surfaces proposed to be formed by cryoplanation, marine processes, areal glacial erosion and

salt weathering Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs ''in situ'' (on-site, with little or no movem ...

. The term ''planation surface'' is often preferred over others because some more specific planation surface types and processes remain controversial.

Etchplain An etchplain is a plain where the bedrock has been subject to considerable "etching" or subsurface weathering. Etchplanation is the process forming etchplains. Contrary to what the name might suggest, etchplains are seldom completely flat and usu ...

s are weathered planation surfaces. Large planation surfaces, like the

African Surface The African Surface or African Erosion Surface is a land surface formed by erosion covering large swathes of Africa.Burke & Gunnell 2008, pp. 6–7. The type area of the surface lies in South Africa where the surface was first identified as such ...

, are typically formed

diachronous In geology, a diachronism ( Greek ''dia'', "through" + ''chronos'', "time" + ''-ism''), or diachronous deposit, is a sedimentary rock formation in which the material, although of a similar nature, varies in age with the place where it was deposite ...

ly. Planation surfaces are often thought to form at distinct

base level In geology and geomorphology a base level is the lower limit for the vertical position of an erosion, erosion process. The modern term was introduced by John Wesley Powell in 1875. The term was subsequently appropriated by William Morris Davis wh ...

s with sequences of them representing uplift events. However the disposition of some so-called planation surfaces may at certain places reflect better the easiness of erosion into different lithologies or

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

and may therefore not fit any uplift scheme.

References

Erosion landforms + Geomorphology {{geomorphology-stub

See also

References