|
Sag (geology)
In geology a sag, or trough, is a depressed, persistent, low area; the opposite of an arch, or ridge, a raised, persistent, high area. The terms sag and arch were used historically to describe very large features, for example, characterizing North America as two arches with a sag between them. Also, a sag is a former river bed which has been partially filled with debris from glaciation or other natural processes but which is still visible in the surface terrain. Sags formed by the former river beds of large rivers often become the valleys of smaller streams after a change of course by the main river. Examples of sags include the former continuations of the Grand, Moreau, and White rivers in South Dakota in the United States. Before the last ice age, these rivers continued eastward past their current confluences with the present course of Missouri River. The sags are prominently visible on the plateau of the Missouri Coteau The Missouri Coteau, or Missouri Plateau, (french: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Earth sciences, including hydrology, and so is treated as one major aspect of integrated Earth system science and planetary science. Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks. By combining these tools, geologists are able to chronicle the geological history of the Earth as a whole, and also to demonstrate the age of the Earth. Geology provides the primary evidence for plate tectonics, the evolutionary history of life, and the Earth's past climates. Geologists broadly study the properties and processes of E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trough (geology)
In geology, a trough is a linear structural depression that extends laterally over a distance. Although it is less steep than a trench, a trough can be a narrow basin or a geologic rift. These features often form at the rim of tectonic plates. There are various oceanic troughs on the ocean floors. Examples of oceanic troughs * Benue Trough * Cayman Trough * Kings Trough * Hesperides Trough * Nankai Trough * Northumberland Trough * Okinawa Trough in the East China Sea * Rockall Trough and others along the rift of the mid-oceanic ridge * Salton Trough * South Shetland Trough * Suakin TroughDinwiddie, Robert et al. (2008) ''Ocean: The World's Last Wilderness Revealed'', London, Dorling Kindersley, page 452. in the Red Sea * Timor Trough See also * Walker Lane * Oceanic basin In hydrology, an oceanic basin (or ocean basin) is anywhere on Earth that is covered by seawater. Geologically, ocean basins are large geologic basins that are below sea level. Most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ridge
A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The lines along the crest formed by the highest points, with the terrain dropping down on either side, are called the ridgelines. Ridges are usually termed hills or mountains as well, depending on size. Smaller ridges, especially those leaving a larger ridge, are often referred to as spurs. Types There are several main types of ridges: ;Dendritic ridge: In typical dissected plateau terrain, the stream drainage valleys will leave intervening ridges. These are by far the most common ridges. These ridges usually represent slightly more erosion resistant rock, but not always – they often remain because there were more joints where the valleys formed or other chance occurrences. This type of ridge is generally somewhat random in orientation, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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#Glaciology, ablation over many years, often Century, centuries. It acquires distinguishing features, such as Crevasse, crevasses and Serac, seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions, but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand. Between lati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grand River (South Dakota)
The Grand River ( lkt, Čhaŋšúška Wakpá) is a tributary of the Missouri River in South Dakota in the United States. The length of the combined branch is 110 mi (177 km). With its longest fork, its length is approximately 200 mi (320 km). Course It is formed by the confluence of the North Fork (which rises in North Dakota) and the longer South Fork (which rises in South Dakota and passes through the town of Buffalo) in northwestern South Dakota near Shadehill in Perkins County, near several parcels of the Grand River National Grassland. Shadehill Reservoir is located at this confluence. It flows east, through the Standing Rock Indian Reservation and joins the Missouri in Lake Oahe, approximately northwest of Mobridge. The lower of the river form an arm of the Lake Oahe reservoir. It is the northernmost of South Dakota's major West River streams: the Grand, Moreau, Cheyenne, Bad, and White. Draining about of the northern plateaus of the sta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moreau River (South Dakota)
The Moreau River is a tributary of the Missouri River, approximately 200 miles (320 km) long, in South Dakota in the United States. Moreau River has the name of a pioneer trader. It rises in two forks in northwestern South Dakota, in the Badlands of Butte and Harding Counties. The North Fork rises approximately 10 miles (16 km) northeast of Crow Buttes. The South Fork rises approximately 20 miles (32 km) west of the headwaters of the North Fork. The two forks flow ESE and unite near Zeona in southern Perkins County. The combined stream flows east, past Usta, and across the Cheyenne River Indian Reservation, past Iron Lightning, Thunder Butte, Green Grass and Whitehorse. It joins the Missouri in Lake Oahe, with the lower 25 miles (40 km) of the river forming an arm of the reservoir. The river generally parallels its neighbor to the north, the Grand River, running from west to east to join the Missouri. Draining the Pierre Hills and Northern Plateaus, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White River (Missouri River)
The White River is a Missouri River tributary that flows through the U.S. states of Nebraska and South Dakota. The name stems from the water's white-gray color, a function of eroded sand, clay, and volcanic ash carried by the river from its source near the Badlands. Draining a basin of about , about of which is in South Dakota, the stream flows through a region of sparsely populated hills, plateaus, and badlands. The White River rises in northwestern Nebraska, in the Pine Ridge escarpment north of Harrison, at an elevation of above sea level. It flows southeast then northeast past Fort Robinson and north of Crawford. It crosses into southwestern South Dakota and flows north across the Pine Ridge Indian Reservation, then northeast, receiving Wounded Knee Creek and flowing between units of Badlands National Park. It flows east-northeast and southeast at the northern edge of the reservation, forming the northern boundary of the reservation and the southern boundary of Buffalo Ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Dakota
South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota people, Dakota Sioux Native Americans in the United States, Native American tribes, who comprise a large portion of the population with nine Indian reservation, reservations currently in the state and have historically dominated the territory. South Dakota is the List of U.S. states and territories by area, seventeenth largest by area, but the List of U.S. states and territories by population, 5th least populous, and the List of U.S. states and territories by population density, 5th least densely populated of the List of U.S. states, 50 United States. As the southern part of the former Dakota Territory, South Dakota became a state on November 2, 1889, simultaneously with North Dakota. They are the 39th and 40th states admitted to the union; Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plateau
In geology and physical geography, a plateau (; ; ), also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. Often one or more sides have deep hills or escarpments. Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Plateaus are classified according to their surrounding environment as intermontane, piedmont, or continental. A few plateaus may have a small flat top while others have wide ones. Formation Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, Plate tectonics movements and erosion by water and glaciers. Volcanic Volcanic plateaus are produced by volcanic activity. The Columbia Plateau in the north-western United States is an example. They may be formed by upwelling of volcanic magma or extrusion of lava. The un ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Missouri Coteau
The Missouri Coteau, or Missouri Plateau, (french: Coteau du Missouri) is a large plateau that stretches along the eastern side of the valley of the Missouri River in central North Dakota and north-central South Dakota in the United States. In the Canadian provinces of Saskatchewan and Alberta this physiographic region is classified as the Uplands Missouri Coteau, which is a part of the Great Plains Province or Alberta Plateau Region, which extends across the southwest corner of the province of Saskatchewan as well as the southeast corner of the province of Alberta. Historically, in Canada the area was known as the Palliser's Triangle and regarded as an extension of the Great American Desert and unsuitable for agriculture and thus designated by Canadian geographer and explorer John Palliser. The terrain of the Missouri Coteau features low hummocky, undulating, rolling hills, potholes, and grasslands. Apart from being a geographical area, the Missouri Coteau also has a cultural co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
