Erosion is the action of surface processes 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 distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.
A valley is an elongated low area often running between hills or mountains, which typically contains a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountains or polar areas.
A canyon, gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency to cut through underlying surfaces, eventually wearing away rock layers as sediments are removed downstream. A river bed will gradually reach a baseline elevation, which is the same elevation as the body of water into which the river drains. The processes of weathering and erosion will form canyons when the river's headwaters and estuary are at significantly different elevations, particularly through regions where softer rock layers are intermingled with harder layers more resistant to weathering.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
Wadi, alternatively wād, Maghrebi Arabic Oued, Hebrew: וָאדִי, romanized: wadi, lit. 'wadi') is the Arabic term traditionally referring to a river valley. In some instances, it may refer to a wet (ephemeral) riverbed that contains water only when heavy rain occurs.
A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces. Gullies resemble large ditches or small valleys, but are metres to tens of metres in depth and width, are characterized by a distinct 'headscarp' or 'headwall' and progress by headward erosion. Gullies are commonly related to intermittent or ephemeral water flow, usually associated with localised intense or protracted rainfall events or snowmelt. Gullies can be formed and accelerated by cultivation practices on hillslopes in farmland, and they can develop rapidly in rangelands from existing natural erosion forms subject to vegetative cover removal and livestock activity.
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, with the terrain dropping down on either side. The crest, if narrow, is also called a ridgeline. Limitations on the dimensions of a ridge are lacking. Its height above the surrounding terrain can vary from less than a meter to hundreds of meters. A ridge can be either depositional, erosional, tectonic, or a combination of these in origin and can consist of either bedrock, loose sediment, lava, or ice depending on its origin. A ridge can occur as either an isolated, independent feature or part of a larger geomorphological and/or structural feature. Frequently, a ridge can be further subdivided into smaller geomorphic or structural elements.
A gulch is a deep V-shaped valley formed by erosion. It may contain a small stream or dry creek bed and is usually larger in size than a gully. Sudden intense rainfall upstream may produce flash floods in the bed of the gulch.
Headward erosion is erosion at the origin of a stream channel, which causes the origin to move back away from the direction of the stream flow, lengthening the stream channel. It can also refer to the widening of a canyon by erosion along its very top edge, when sheets of water first enter the canyon from a more roughly planar surface above it, such as at Canyonlands National Park in Utah. When sheets of water on a roughly planar surface first enter a depression in it, this erodes the top edge of the depression. The stream is forced to grow longer at the very top of the stream, which moves its origin back, or causes the canyon formed by the stream to grow wider as the process repeats. Widening of the canyon by erosion inside the canyon, below the canyon side top edge, or origin or the stream, such as erosion caused by the streamflow inside it, is not called headward erosion.
Tempe Terra is a heavily cratered highland region in the northern hemisphere of the planet Mars. Located at the northeastern edge of the Tharsis volcanic province, Tempe Terra is notable for its high degree of crustal fracturing and deformation. The region also contains many small shield volcanoes, lava flows, and other volcanic structures.
The Lerderderg Gorge is in Victoria, Australia and largely within the Lerderderg State Park. The Lerderderg River which emerges from the Great Dividing Range has cut a deep gorge as it winds toward the southern plains. It is suggested that the name Lerderderg is perhaps a corruption of the Wurundjeri word "Larderdark," from 'larh' -stone house and 'dark' -peppermint gum.
The Geology of Pennsylvania consists of six distinct physiographic provinces, three of which are subdivided into different sections. Each province has its own economic advantages and geologic hazards and plays an important role in shaping everyday life in the state. From the southeast corner to the northwest corner of the state, they include: the Atlantic Plain Province, the Piedmont Province, the New England Province, the Ridge and Valley Province, the Appalachain Province, and the Central Lowlands Province.
Nesquehoning Creek is an east flowing 14.9-mile-long (24.0 km) tributary of the Lehigh River in northeastern Pennsylvania in the United States.
In geography, a defile is a narrow pass or gorge between mountains or hills. The term originates from a military description of a route through which troops can march only in a narrow column or with a narrow front. On emerging from a defile into open country, soldiers are said to "debouch".
The Kreyenhagen Hills are a range of foothills of the Diablo Range in western Fresno County and Kings County, California. The Kreyenhagen Hills form a long foothill belt in the soft formations between Reef Ridge and Kettleman Plain. They are divided into several groups, each a few miles wide, by streams crossing them at right angles. They meet with the steep face of Reef Ridge, and are distinct from the mountains which begin there. To the northeast the strata form ridge after ridge, parallel to each other, and extend the length of the separate divisions between the main stream valleys. These ridges, appear like a series of waves advancing, toward Reef Ridge, and elsewhere to broken waves, as in a choppy sea. The ridges are slightly asymmetric, the northeast flank being a dip slope and fairly smooth, while the southwest flank is a steeper, strike face that is in many places eroded so as to leave sharp gullies and conical intermediate ridges extending outward. The groups of hillocks so produced bear some resemblance to an encampment of tents or huts, and the name Jacalitos,, may have been applied to Jacalitos Creek owing to this feature of the hills through which it flows. The greatest symmetry of the parallel ridges appear's in the portion of the Kreyenhagen Hills between Jacalitos Creek and Big Tar Canyon, and there the long, straight, smooth troughs between the ridges doubtless gave rise to the name Canoas, meaning trough, applied to Canoas Creek which passes across the central portion of the hills. Kreyenhagen was the name of the family who originally owned the land in the area.
This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic data. It is split across two articles:
The common surface features of Mars include dark slope streaks, dust devil tracks, sand dunes, Medusae Fossae Formation, fretted terrain, layers, gullies, glaciers, scalloped topography, chaos terrain, possible ancient rivers, pedestal craters, brain terrain, and ring mold craters.
Nesquehoning Mountain or Nesquehoning Ridge is a 15–17-mile-long (24–27 km) coal bearing ridge dividing the waters of Lehigh Valley to the north from the Schuylkill River valley and the several near parallel ridgelines of the Ridge-and-valley Appalachians barrier range all local members of which run generally WSW-ENE in the greater overall area.
This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic data. It is split across two articles:
