Topography is the study of the forms and features of land surfaces . The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps.
76-585: Western Cordilleras can refer to The North American Cordillera , along the western side of North America Mountain ranges in the Andes of South America: Cordillera Occidental (Central Andes) , in Bolivia and Chile Cordillera Occidental (Colombia) Cordillera Occidental (Ecuador) Cordillera Occidental (Peru) Part of the Cordillera Central (Luzon) in
152-413: A broader sense is used, particularly in medical fields such as neurology . An objective of topography is to determine the position of any feature or more generally any point in terms of both a horizontal coordinate system such as latitude, longitude, and altitude . Identifying (naming) features, and recognizing typical landform patterns are also part of the field. A topographic study may be made for
228-589: A narrow sense involves the recording of relief or terrain , the three-dimensional quality of the surface, and the identification of specific landforms ; this is also known as geomorphometry . In modern usage, this involves generation of elevation data in digital form ( DEM ). It is often considered to include the graphic representation of the landform on a map by a variety of cartographic relief depiction techniques, including contour lines , hypsometric tints , and relief shading . The term topography originated in ancient Greece and continued in ancient Rome , as
304-486: A remote sensing technique that uses a laser instead of radio waves, has increasingly been employed for complex mapping needs such as charting canopies and monitoring glaciers. Terrain is commonly modelled either using vector ( triangulated irregular network or TIN) or gridded ( raster image ) mathematical models. In the most applications in environmental sciences , land surface is represented and modelled using gridded models. In civil engineering and entertainment businesses,
380-420: A surface or extract land surface objects. The contour data or any other sampled elevation datasets are not a DLSM. A DLSM implies that elevation is available continuously at each location in the study area, i.e. that the map represents a complete surface. Digital Land Surface Models should not be confused with Digital Surface Models, which can be surfaces of the canopy, buildings and similar objects. For example, in
456-405: A variety of reasons: military planning and geological exploration have been primary motivators to start survey programs, but detailed information about terrain and surface features is essential for the planning and construction of any major civil engineering , public works , or reclamation projects. There are a variety of approaches to studying topography. Which method(s) to use depends on
532-823: Is 40 to 60 miles (60 to 100 km) wide, with the Sierra Nevada to the east and the Coast Ranges to the west. In northwestern Oregon, the fertile Willamette Valley lies between the Oregon Coast Range and the Cascades ; this depression continues north into Washington as the Puget Trough . The Gulf of California is a body of water that separates the Peninsular Ranges from the Sierra Madre Occidental on
608-703: Is a mountain range on the Olympic Peninsula of western Washington in the United States . The mountains , part of the Pacific Coast Ranges , are not especially high – Mount Olympus is the highest at 7,962 ft (2,427 m) – but the western slopes of the Olympics rise directly out of the Pacific Ocean and are the wettest place in the 48 contiguous states. Most of the mountains are protected within
684-571: Is a field of geoscience and planetary science and is concerned with local detail in general, including not only relief , but also natural , artificial, and cultural features such as roads, land boundaries, and buildings. In the United States, topography often means specifically relief , even though the USGS topographic maps record not just elevation contours, but also roads, populated places, structures, land boundaries, and so on. Topography in
760-413: Is a general term for geodata collection at a distance from the subject area. Besides their role in photogrammetry, aerial and satellite imagery can be used to identify and delineate terrain features and more general land-cover features. Certainly they have become more and more a part of geovisualization , whether maps or GIS systems. False-color and non-visible spectra imaging can also help determine
836-763: Is an extremely arid region characterized by basin and range topography. The Colorado Plateau is an area of high desert located in Arizona , New Mexico , Colorado , and Utah , bisected by the Colorado River which flows westward through the southern part, and the Green River which flows south from the northernmost part of the plateau. The Green is a tributary of the Colorado, the confluence being west of Moab, Utah in Canyonlands National Park. The Mexican Plateau
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#1732836900587912-456: Is concerned with underlying structures and processes to the surface, rather than with identifiable surface features. The digital elevation model (DEM) is a raster -based digital dataset of the topography ( hypsometry and/or bathymetry ) of all or part of the Earth (or a telluric planet ). The pixels of the dataset are each assigned an elevation value, and a header portion of the dataset defines
988-694: Is different from Wikidata All article disambiguation pages All disambiguation pages North American Cordillera The North American Cordillera , sometimes also called the Western Cordillera of North America , the Western Cordillera , or the Pacific Cordillera , is the North American portion of the American Cordillera , the mountain chain system along the Pacific coast of
1064-561: Is located in southern British Columbia and northern Washington . The Interior Plateau also includes the Quesnel Highland , Fraser Plateau , Nechako Plateau , and McGregor Plateau . California's Central Valley is a large, flat valley that dominates the central portion of California , stretching inland and parallel to the Pacific Ocean coast. Its northern half is referred to as the Sacramento Valley , and its southern half as
1140-582: Is one of six distinct physiographic sections of the Basin and Range Province , which in turn is part of the Intermontane Plateaus physiographic division. It is a large arid-to-semiarid plateau that occupies much of northern and central Mexico . Averaging 1,825 m (5,988 ft) above sea level, it extends from the United States border in the north to the Trans-Mexican Volcanic Belt in
1216-525: Is raw and uninterpreted. It may contain holes (due to cloud cover for example) or inconsistencies (due to the timing of specific image captures). Most modern topographic mapping includes a large component of remotely sensed data in its compilation process. In its contemporary definition, topographic mapping shows relief. In the United States, USGS topographic maps show relief using contour lines . The USGS calls maps based on topographic surveys, but without contours, "planimetric maps." These maps show not only
1292-422: Is to something else). Topography has been applied to different science fields. In neuroscience , the neuroimaging discipline uses techniques such as EEG topography for brain mapping . In ophthalmology , corneal topography is used as a technique for mapping the surface curvature of the cornea . In tissue engineering , atomic force microscopy is used to map nanotopography . In human anatomy , topography
1368-558: The Americas . The North American Cordillera covers an extensive area of mountain ranges , intermontane basins , and plateaus in Western and Northwestern Canada , Western United States , and Mexico , including much of the territory west of the Great Plains . The precise boundaries of this cordillera and its subregions, as well as the names of its various features, may differ depending on
1444-655: The Cascade Range and the Rocky Mountains , cut through by the Columbia River . In one of various usages, the term " Columbia Basin " refers to more or less the same area as the Columbia Plateau. The Basin and Range province covers most of the state of Nevada and parts of the states of Arizona , California , Idaho , New Mexico , Oregon , Texas , Utah , and Wyoming , as well as much of northern Mexico . It
1520-675: The Coast Range Arc whereas the metamorphic formed when intruding magma heated the surrounding rock to produce schist . The Insular Mountains extend from Vancouver Island in the south to Haida Gwaii in the north on the British Columbia Coast . It contains two main mountain ranges, the Vancouver Island Ranges on Vancouver Island and the Queen Charlotte Mountains on Haida Gwaii. The Olympic Mountains
1596-688: The Hazelton Mountains and Coast Range to the west and northwest. Within the Interior plateau, the Shuswap Highland consists of a portion of the foothills between the Thompson Plateau and Bonaparte Plateau on the west, and the Monashee Mountains and Cariboo Mountains on the east and northeast. Also within the Interior plateau, the Thompson Plateau forms the southern portion of
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#17328369005871672-909: The Interior Plains to the east, and over the Great Basin to the west, and extend south to the Rio Grande in New Mexico. The United States definition of the Rockies includes the Cabinet and Salish Mountains of Idaho and Montana, whereas their counterparts north of the Kootenai River , the Columbia Mountains , are sometimes considered a separate system lying to the west of the huge Rocky Mountain Trench which runs
1748-692: The Interior Plateau . The southernmost extends into the Washington, where it is named by the American spelling Okanogan Highland (and was the first-named of these groupings). The Cascade Range (called the Cascade Mountains in Canada) extends from northern California in the United States to British Columbia , Canada. It consists of non-volcanic and volcanic mountains: all of the known historic eruptions in
1824-551: The Liard River , just south of the British Columbia – Yukon border near Watson Lake, Yukon . The trench bottom is 3 to 16 km (2 to 10 miles) wide and ranges from 600 to 900 m (2,000 to 3,000 ft) above sea level. The general orientation of the Trench is almost uniformly pointing north. Some of its topography has been carved into glacial valleys , but it is primarily a byproduct of faulting . The Trench separates
1900-483: The Mexican mainland. The Gulf of California is 1,126 km (700 miles) long and 48 to 241 km (30 to 150 miles) wide, with an area of 177,000 km (68,000 sq mi), a mean depth of 818.08 m (2,684.0 ft), and a volume of 145,000 km (35,000 cu mi). The Rocky Mountain Trench is a large valley that extends approximately 1,600 km (990 mi) from Flathead Lake , Montana , to
1976-721: The Okanagan Range , which lies along the Cascades' northeastern margin, separated by the Similkameen River . The Sierra Nevada forms an inland mountain spine of northern California, extending from the terminus of the Cascade Range south of Lassen Peak southwards along the east flank of the Central Valley of California to the Transverse Ranges , forming a mountain region of complex terrain and varied geology which separates
2052-565: The Pacific Coast Ranges in the west, the Nevadan belt in the middle (including the Sierra Nevada ), and the Laramide belt in the east (including the Rocky Mountains ). These three orogenic belts (also called "orogens") arose due to the engagement of tectonic plates which deformed the Earth's lithosphere (crust and uppermost mantle). For example, the Laramide orogeny changed the topography of
2128-657: The Rocky Mountains on its east from the Columbia Mountains and the Cassiar Mountains on its west. It is up to 25 km (16 miles) wide, if measured peak-to-peak. For convenience the Rocky Mountain Trench may be divided into northern and southern sections. The dividing point reflects the separation of north and easterly flows to the Arctic Ocean versus south and westerly flows to the Pacific Ocean. A break in
2204-670: The San Joaquin Valley . The two-halves meet at the huge Sacramento-San Joaquin River Delta of the Sacramento and San Joaquin Rivers, which along with their tributaries drain the majority of the valley and flow into San Francisco Bay . The Central Valley covers an area of approximately 22,500 square miles (58,000 km ), making it slightly smaller than the state of West Virginia and about 13.7% of California's total area. The Central Valley
2280-846: The Sierra Madre Occidental , and the Sierra Madre Oriental further east, surround the Mexican Plateau . To the west of the Sierra Madre Occidental, the Peninsular Ranges border the Pacific Ocean, and the Sierra Madre del Sur is the southern extension of the Peninsular Ranges. Sierra Madre means "Mother Range" in Spanish. The Nevadan belt runs up and down the middle of the North American Cordillera. Therefore,
2356-461: The Thompson Plateau in a less rugged fashion than in most other parts of the range. The North Cascades are very different in character from the series of high volcanic stratovolcanoes from Rainier southwards to Mount Shasta and Lassen Peak , and are more severely alpine and steeply rugged, particularly the Skagit Range . Inland portions of the range are dryland and plateau-like in character, e.g.
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2432-740: The Yukon Territory at Champagne Pass and Chilkat Pass northwest of Haines, Alaska . The Saint Elias Mountains lie to their west and northwest, while the Yukon Ranges and Yukon Basin lie to their north. On the inland side of the Boundary Ranges are the Tahltan and Tagish Highlands and also the Skeena Mountains , part of the Interior Mountains system, which also extend southwards on
2508-568: The Yukon , Canada. This range has an area of 364,710 km (140,820 sq mi). The Coast Mountains run from the lower Fraser River and the Fraser Canyon northwestward, separating the Interior Plateau from the Pacific Ocean. Their coastal flank is characterized by an intense network of fjords and associated islands, very similar to the Norwegian coastline , while their inland side against
2584-640: The "Topographical Bureau of the Army", formed during the War of 1812 , which became the Corps of Topographical Engineers in 1838. After the work of national mapping was assumed by the U.S. Geological Survey in 1878, the term topographical remained as a general term for detailed surveys and mapping programs, and has been adopted by most other nations as standard. In the 20th century, the term topography started to be used to describe surface description in other fields where mapping in
2660-401: The California coast (the Transverse Ranges, Peninsular Ranges and the Klamath Mountains are not included). The Sierra Madre del Sur mountains in southwestern Mexico form a southern extension of the Peninsular Ranges of Baja California . The Peninsular Ranges are separated from the Sierra Madre del Sur by an expanse of ocean. The Nevadan belt is located between the Pacific coast belt and
2736-414: The Central Valley from the Great Basin to the east. The mean height of the mountain summits in the Sierra Nevada gradually increases from north to south, culminating at Mount Whitney (14,505 feet (4,421 m)), the highest point in the contiguous United States . From east to west, the Sierra is wedge-shaped: the west slope gradually rises and the east slope forms a steep escarpment , particularly so in
2812-489: The Continental U.S., for example), the compiled data forms the basis of basic digital elevation datasets such as USGS DEM data. This data must often be "cleaned" to eliminate discrepancies between surveys, but it still forms a valuable set of information for large-scale analysis. The original American topographic surveys (or the British "Ordnance" surveys) involved not only recording of relief, but identification of landmark features and vegetative land cover. Remote sensing
2888-430: The Interior Plains area, is the Rocky Mountain System, then the Intermontane Basins and Ranges, and in the southern part of the state are the Pacific Mountains and Valleys. In the Alaska panhandle , the mainland mountain ranges and offshore islands (the Alexander Archipelago ) are extensions of respective ranges further south. In Canada, the North American Cordillera is usually divided into three physiographic regions:
2964-408: The Interior Plateau. It is bordered on the south by the Canadian Cascades and on the north by the Thompson River . The Okanagan Highland is the part of the Interior Plateau to the east of the Thompson Plateau, and is bounded by the Okanagan River on the west, the Shuswap River on the north, and the Kettle River on the east side. The Okanagan Highland is described as being a hilly plateau, and
3040-405: The Laramide belt. Nevada means "snow-covered" in Spanish. In Canada, the Northern Interior Mountains are a northern extension of the Columbia Mountains. They include the Hazelton Mountains , Cassiar Mountains , Omineca Mountains , and Skeena Mountains . The Columbia Mountains are a designation in British Columbia for a group of four ranges lying between the Rocky Mountain Trench (to
3116-428: The Pacific Coast Ranges, the Central Valley , the Sierra Nevada, the Basin and Range Province (forming many narrow ranges and valleys), the Colorado Plateau , and the Rocky Mountains. In the United States, another major feature of the Cordillera is the Columbia Plateau , located north of California between the Cascade Range – which is a northern extension of the Sierra Nevada – and the Rocky Mountains. In Mexico,
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3192-524: The Philippines A mountain range in Borneo [REDACTED] Topics referred to by the same term This disambiguation page lists articles about distinct geographical locations with the same name. If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Western_Cordillera&oldid=1126918874 " Category : Place name disambiguation pages Hidden categories: Short description
3268-477: The Rocky Mountains in the United States. To the west of the Monashees and Cariboos, there are three intermediary upland areas which are transitional between the mountain ranges and the plateaus flanking the Fraser and Thompson Rivers . These – the Quesnel , Shuswap and Okanagan Highlands , are sometimes considered as being part of the neighbouring ranges rather than the plateaus and are often spoken of that way locally but are formally designated as being part of
3344-449: The Selkirks and Monashees. The southward extension of the Selkirks, Purcells and Monashees into the United States are reckoned to be part of the Rocky Mountains and the designation Columbia Mountains is not used there (the Purcells, also, go by the name "Percell Mountains" in the United States). The Salish and Cabinet Mountains south of the Kootenai River are essentially part of the same landform, but are officially designated part of
3420-439: The Southern California coast the Channel Islands archipelago of the Santa Monica Mountains extends for 160 miles (260 km). In southern Alaska, the primary mountain ranges are the Alaska Range , Wrangell Mountains , Saint Elias Mountains , Kenai Mountains , Chugach Mountains , and Talkeetna Mountains . The Yukon Ranges comprise the mountains in the southeastern part of the U.S. state of Alaska and most of
3496-477: The United States that are considered part of the Rocky Mountains, and therefore the Columbia Mountains are often treated as being part of the Rockies. The Selkirks and Purcells lie entirely within the basin of the Columbia River, while the Monashees lie to the river's west on its southward course from its Big Bend and are flanked on the west by the basin of the Thompson and Okanagan Rivers . There are many named subranges of all four subgroupings, particularly in
3572-669: The area of coverage, the units each pixel covers, and the units of elevation (and the zero-point). DEMs may be derived from existing paper maps and survey data, or they may be generated from new satellite or other remotely sensed radar or sonar data. A geographic information system (GIS) can recognize and analyze the spatial relationships that exist within digitally stored spatial data. These topological relationships allow complex spatial modelling and analysis to be performed. Topological relationships between geometric entities traditionally include adjacency (what adjoins what), containment (what encloses what), and proximity (how close something
3648-455: The basis for much derived topographic work. Digital Elevation Models, for example, have often been created not from new remote sensing data but from existing paper topographic maps. Many government and private publishers use the artwork (especially the contour lines) from existing topographic map sheets as the basis for their own specialized or updated topographic maps. Topographic mapping should not be confused with geologic mapping . The latter
3724-486: The bounds of the Olympic National Park . The Oregon Coast Range is the part of the Coast Range system that is denoted as between the mouth of the Columbia River and the Middle Fork Coquille River . It is about 200 miles (320 km) long. The highest peak is Marys Peak , at 4,101 ft (1,250 m). The California Coast Ranges are one of the eleven traditional geomorphic provinces of California. This province includes several – but not all – mountain ranges along
3800-747: The case of surface models produces using the lidar technology, one can have several surfaces – starting from the top of the canopy to the actual solid earth. The difference between the two surface models can then be used to derive volumetric measures (height of trees etc.). Topographic survey information is historically based upon the notes of surveyors. They may derive naming and cultural information from other local sources (for example, boundary delineation may be derived from local cadastral mapping). While of historical interest, these field notes inherently include errors and contradictions that later stages in map production resolve. As with field notes, remote sensing data (aerial and satellite photography, for example),
3876-576: The central Rocky Mountains and adjoining Laramide regions (from central Montana to central New Mexico) during the Late Cretaceous 80 million years ago. Prior to this time the Rocky Mountain region was occupied by a broad basin. Further topographical evolution occurred during the Eocene (55–50 million years ago) and Oligocene (34–23 million years ago), but since that time the region has been relatively stable. Generally speaking, it will be convenient here to consider these three belts going west to east, and north to south. In Alaska , south of
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#17328369005873952-414: The common points are identified on each image . A line of sight (or ray ) can be built from the camera location to the point on the object. It is the intersection of its rays ( triangulation ) which determines the relative three-dimensional position of the point. Known control points can be used to give these relative positions absolute values. More sophisticated algorithms can exploit other information on
4028-466: The contiguous United States have been from the volcanoes of the Cascade Volcanic Arc . The highest peak in the Cascade Range is Mount Rainier (14,409 feet (4,392 m)), a stratovolcano . The small portion of the Cascade Range in Canada is called the Cascade Mountains or Canadian Cascades, and in its southwestern area is similar in terrain to the area north of Glacier Peak , known as the North Cascades , and its northern and eastern extremities verge on
4104-454: The contours, but also any significant streams or other bodies of water, forest cover , built-up areas or individual buildings (depending on scale), and other features and points of interest. While not officially "topographic" maps, the national surveys of other nations share many of the same features, and so they are often called "topographic maps." Existing topographic survey maps, because of their comprehensive and encyclopedic coverage, form
4180-436: The definitions in each country or jurisdiction, and also depending on the scientific field; this cordillera is a particularly prominent subject in the scientific field of physical geography . The North American Cordillera extends from the U.S. state of Alaska to the southern border of Mexico , and includes some of the highest peaks on the continent. Its mountain ranges generally run north to south along three main belts:
4256-415: The detailed description of a place. The word comes from the Greek τόπος ( topos , "place") and -γραφία ( -graphia , "writing"). In classical literature this refers to writing about a place or places, what is now largely called ' local history '. In Britain and in Europe in general, the word topography is still sometimes used in its original sense. Detailed military surveys in Britain (beginning in
4332-438: The east) and the Interior Plateau (to the west). These ranges are the Cariboo Mountains , which are the northernmost and sometimes considered to be part of the Interior Plateau, the Selkirk Mountains , the Purcell Mountains , and the Monashee Mountains . The Columbia Mountains are classified as being in Canada's interior system, rather than its eastern system. However, the Columbia Mountains are an extension of mountains in
4408-485: The first topographic maps was begun in France by Giovanni Domenico Cassini , the great Italian astronomer. Even though remote sensing has greatly sped up the process of gathering information, and has allowed greater accuracy control over long distances, the direct survey still provides the basic control points and framework for all topographic work, whether manual or GIS -based. In areas where there has been an extensive direct survey and mapping program (most of Europe and
4484-460: The inland side of the Kitimat Ranges . The terrain of the main spine of the Coast Mountains is typified by heavy glaciation, including several very large icefields of varying elevation. Of the three subdivisions, the Pacific Ranges are the highest and are crowned by Mount Waddington , while the Boundary Ranges contain the largest icefields, the Juneau Icefield being the largest. The Kitimat Ranges are lower and less glacier-covered than either of
4560-426: The intermontane areas of the cordillera can be divided up into the areas east of the Nevadan belt, and those west of the Nevadan belt. The Pacific Coast Ranges, comprising the Pacific Coast Belt, parallel the North American Pacific Coast, and comprise several mountain systems. Along the British Columbia and Alaska coast, the mountains intermix with the sea in a complex maze of fjords , with thousands of islands. Off
4636-405: The late eighteenth century) were called Ordnance Surveys , and this term was used into the 20th century as generic for topographic surveys and maps. The earliest scientific surveys in France were the Cassini maps after the family who produced them over four generations. The term "topographic surveys" appears to be American in origin. The earliest detailed surveys in the United States were made by
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#17328369005874712-400: The length of British Columbia. The Sierra Madre Oriental mountains in eastern Mexico are a southern extension of the Rocky Mountains . The Sierra Madre Oriental spans about 1,000 km (600 miles). Mexico's Gulf Coastal Plain lies to the east of the range, between the mountains and the Gulf of Mexico coast. The Mexican Plateau lies to the west of the range. The Nevadan belt runs down
4788-456: The lie of the land by delineating vegetation and other land-use information more clearly. Images can be in visible colours and in other spectrum. Photogrammetry is a measurement technique for which the co-ordinates of the points in 3D of an object are determined by the measurements made in two photographic images (or more) taken starting from different positions, usually from different passes of an aerial photography flight. In this technique,
4864-417: The middle of the North American Cordillera. Therefore, the intermontane areas can be divided up into the areas east of the Nevadan belt, and those west of the Nevadan belt. The Interior Plateau is the northern continuation of the Columbia Plateau , and covers much of inland British Columbia . The Cariboo Mountains and Monashee Mountains lie to the east, the Canadian Cascades are to the southwest, and
4940-479: The most representations of land surface employ some variant of TIN models. In geostatistics , land surface is commonly modelled as a combination of the two signals – the smooth (spatially correlated) and the rough (noise) signal. In practice, surveyors first sample heights in an area, then use these to produce a Digital Land Surface Model in the form of a TIN . The DLSM can then be used to visualize terrain, drape remote sensing images, quantify ecological properties of
5016-456: The northern flank of the lower Yukon River basin, separating it from Alaska's North Slope region, facing the Beaufort Sea . The Brooks Range is considered part of (or an extension of) the Rockies . South of the Brooks Range are the Mackenzie Mountains , and the Canadian Rockies . In the Rocky Mountains , the highest peak is Mount Elbert in Colorado at 14,439 feet (4,401 m) above sea level. The American Rockies rise steeply over
5092-433: The northernmost of the major mountain systems of the North American Cordillera, and extends along an east–west axis across northern Alaska from near the northern opening of the Bering Strait to the northern Yukon Territory. Major subranges include the British Mountains and Richardson Mountains , towards their eastern end, and at their farthest west is the small subrange that De Long Mountains . The Brooks Range forms
5168-403: The other two groupings, but are extremely rugged and dense. The Coast Mountains are made of igneous and metamorphic rock from an episode of arc volcanism related to subduction of the Kula and Farallon Plates during the Laramide orogeny about 100 million years ago. The widespread granite forming the Coast Mountains formed when magma intruded and cooled at depth beneath volcanoes of
5244-433: The plateau they transition to the high plateau in dryland valleys notable for a series of large lakes similar to the alpine lakes of southern Switzerland, beginning in deep mountains and ending in flatland. They are subdivided in three main groupings, the Pacific Ranges between the Fraser and Bella Coola , the Kitimat Ranges from there northwards to the Nass River and the Boundary Ranges from there to their terminus in
5320-425: The scale and size of the area under study, its accessibility, and the quality of existing surveys. Surveying helps determine accurately the terrestrial or three-dimensional space position of points and the distances and angles between them using leveling instruments such as theodolites , dumpy levels and clinometers . GPS and other global navigation satellite systems (GNSS) are also used. Work on one of
5396-462: The scene known a priori (for example, symmetries in certain cases allowing the rebuilding of three-dimensional co-ordinates starting from one only position of the camera). Satellite RADAR mapping is one of the major techniques of generating Digital Elevation Models (see below). Similar techniques are applied in bathymetric surveys using sonar to determine the terrain of the ocean floor. In recent years, LIDAR ( LI ght D etection A nd R anging),
5472-524: The south and is bounded by the Sierra Madre Occidental and Sierra Madre Oriental to the west and east, respectively. A low east–west mountain range in the state of Zacatecas divides the plateau into northern and southern sections. These two sections, called the Northern Plateau (Spanish: Mesa del Norte ) and Central Plateau (Spanish: Mesa Central ), are now generally regarded by geographers as sections of one plateau. Topography Topography
5548-571: The southern portion. The northern Sierra surface rocks are predominantly volcanic, while the southern Sierra granitic batholith has been sculpted by glaciers into dramatic U-shaped valleys and thin ridges called arêtes . The Sierra Madre Occidental mountain range is a southern extension of the Sierra Nevada. The range extends from near the Arizona border down to the Sierra Madre del Sur, along
5624-659: The valley system at around 54°N near Prince George , British Columbia may be used for this purpose. There are three main mountain ranges in the Canadian area named the Rocky Mountains, the Columbia Mountains, and the Coast Mountains. The Columbia Plateau is a geologic and geographic region that lies across parts of the U.S. states of Washington , Oregon , and Idaho . It is a wide flood basalt plateau between
5700-626: The western mainland of Mexico. The high plateau that is formed by the range is cut by deep river valleys. The Laramide belt is on the side of the North American Cordillera most distant from the Pacific Coast Ranges. It is named for the Laramie Mountains of eastern Wyoming (in turn named for Jacques La Ramee , a trapper who disappeared in the Laramie Mountains in 1820 and was never heard from again). The Brooks Range includes
5776-590: The western system, the interior system, and the eastern system. The western system includes the Coast Mountains , the interior system includes the Columbia Mountains , and the eastern system includes the Canadian Rockies . At its midsection between San Francisco , California and Denver , Colorado , the North American Cordillera is about 1,000 miles (1,600 km) wide, and its physiographic provinces at this midpoint are as follows, going from west to east:
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