Misplaced Pages

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82-795: Although some of its topography has been carved into U-shaped glacial valleys , it is primarily a byproduct of geologic faulting . The Trench separates the Rocky Mountains on its east from the Columbia Mountains and the Cassiar Mountains on its west. It also skirts part of the McGregor Plateau area of the Nechako Plateau sub-area of the Interior Plateau of British Columbia . It

164-407: A terrane was accreted to the edge of the continent. Any of this material may be folded, refolded and metamorphosed. New igneous rock may freshly intrude into the crust from underneath, or may form underplating , where the new igneous rock forms a layer on the underside of the crust. The majority of continental crust on the planet is around 1 to 3 billion years old, and it is theorised that there

246-459: A weak zone on which the harder (stronger) limestone cover was able to move over the hard basement, making the distinction between basement and cover even more pronounced. In Andean geology the basement refers to the Proterozoic , Paleozoic and early Mesozoic ( Triassic to Jurassic ) rock units as the basement to the late Mesozoic and Cenozoic Andean sequences developed following

328-631: A 'federal' national park in the Northern Trench. 1998 - After several years of round table discussions The British Columbia Government takes first legislative steps to establish a 'provincial' Muskwa-Kechika Management Area [3] It covers an area considerably larger than the floor of the Trench and its immediate tributaries. 1999 - Karsten Heuer completes the final section of the Y2Y hike (Yellowstone to Yukon) at Lower Post [4] 2000 - Extension of

410-400: 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 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

492-492: 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 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

574-469: A few cat trails for fire, outfitters, or logging. It is due to several turns of fate, and strategic administrative decisions since 1824, that the most natural land transportation corridor in northern British Columbia has been left in a wild state. On many government maps produced since 1897, indications of a passable trail have been published. However, with changes in the terrain caused by beaver dams or forest fires, and despite maintenance by guide-outfitters,

656-510: A few communities. From north to south they are: Topography 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. Topography 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

738-579: A growing weekend and permanent recreational population. Hunting, fishing, off-roading, and camping will continue to be attractive pastimes. These include guided activities and individual pursuit of the area. The generous mix of low elevation, good climate, fine scenery, diverse recreation and resort accommodation has fostered a vacation-based real estate industry for communities and rural areas surrounding Cranbrook , Windermere , Invermere , Radium , and Golden . There are many other local unincorporated communities and post offices. The Trench has hosted only

820-862: A marker left by Black and report it to historic Fort Halkett on the Liard River. [1] 1831 - John Macleod of the HBC records the mouth of the Kechika River emptying out of the northern end of the Trench into the Liard near the BC-Yukon border. 1872 - Capt. William F. Butler ascends part of the Finlay River and records both the Fox River and Fox Lake to the north (Ft. Ware / Kwadacha was not yet established.) 1897 to 1898 – The Canadian government sends

902-405: A part of geovisualization , whether maps or GIS systems. False-color and non-visible spectra imaging can also help determine 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

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984-583: 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 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

1066-473: A plate of oceanic crust is subducted beneath an overriding plate of oceanic crust, as the underthrusting crust melts, it causes an upwelling of magma that can cause volcanism along the subduction front on the overriding plate. This produces an oceanic volcanic arc , like Japan . This volcanism causes metamorphism , introduces igneous intrusions , and thickens the crust by depositing additional layers of extrusive igneous rock from volcanoes. This tends to make

1148-552: A police patrol under Inspector Moodie to map a possible supply route from the Peace River to the Yukon - specifically Dawson City. The patrol, assumed to have perished, eventually arrived at Fort Selkirk . They proved the viability of the route and produced a surviving map of it. (Yukon Archives) 1898 – McGregor's book The Klondike Rush Though Edmonton summarizes various sources (papers) saying up to 45 parties were reported along

1230-622: A road route over Sifton Pass. 1934 - Charles Bedaux , a noted international workplace management consultant (time and motion studies) leads and finances the Bedaux Expedition - formally known as the Bedaux Canadian Subarctic Expedition. While his advance scouts arrive at McDame Post near Good Hope Lake, the leader and entourage abandon their mission at Driftpile Creek due to fatigue, lack of horse feed, and impending winter. The controversial adventure

1312-572: A spur line which extends northward up the southern Trench between Cranbrook and Golden. This serves to interconnect the southerly rail route of the Crowsnest Pass to the CPR mainline through Rogers Pass . Today it carries Crowsnest coal to Tsawwassen for export. A southerly rail-link through Yahk enables freight shipments into Idaho and the Western US. Tourism has become an active force in

1394-598: 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 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

1476-477: Is superficial human anatomy . In mathematics the concept of topography is used to indicate the patterns or general organization of features on a map or as a term referring to the pattern in which variables (or their values) are distributed in a space. Topographers are experts in topography. They study and describe the surface features of a place or region. Basement rock In geology , basement and crystalline basement are crystalline rocks lying above

1558-588: Is closely aligned with the Tintina Trench near the British Columbia-Yukon border at 60 degrees north latitude, and the two trenches could arguably be classified as one and the same - or 'extensions' of each other. The Tintina Trench extends further north-westward through the Yukon into Alaska . The visible expression of the two trenches is lost where they plunge under the boreal forests of

1640-460: 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

1722-428: 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 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

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1804-502: Is found in the southern trench is not considered significant. The extensional faulting was nonetheless substantial, having extended as deep as 13.5 km (8.4 mi). The southern trench also differs from the northern trench in that it is more sinuous and is asymmetrical in cross-section (perpendicular to its length). The western side of the Southern Rocky Mountain Trench is more subdued and irregular than

1886-438: 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),

1968-547: 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 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

2050-588: 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

2132-541: Is the subject of a 1995 Bedaux film biography titled Champagne Safari . 1942 - February a final decision was reached regarding the A, B, and C routes for a northern Highway. It will connect the North West Staging Route airfields and bypass the Northern Trench for the joint Canada-Alaska Highway Alcan Highway , alternately Alaska Highway . The three routes had been the subject of considerable economic competition between governments and communities since

2214-422: 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

2296-676: Is up to 25 km (16 mi) wide, if measured peak-to-peak, and varies in valley relief, but is clearly visible by air and satellite/ remote sensing and is easily discernible to those ascending any of the mountains or ridges lining it. The Trench is drained by four major river basins : the Columbia , Fraser , Peace and Liard . Two reservoirs of the Columbia River Treaty fill much of its length today - Lake Koocanusa and Lake Kinbasket . A further British Columbia power initiative created Lake Williston . Rivers that follow

2378-634: 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 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,

2460-884: The Hart Ranges . The Copley Range of the Arctic Pacific Lakes Provincial Park forms the drainage divide between the northerly Parsnip - Finlay - Peace system into the Arctic Ocean (via the Mackenzie River ) and the southwesterly McGregor - Fraser system into the Pacific Ocean . The northern end of the Columbia Mountains at ~54°N near Prince George , British Columbia , where the Fraser River leaves

2542-697: The Muskwa-Kechika Management Area into the Northern Trench. Much of the Northern Rocky Mountain Trench's furthest reach is within this British Columbia Protected Area. Significant exposure is given to the M-KMA in the November 2008 National Geographic Magazine as a follow-up to their partial funding of a recent expedition to Gataga Pass. [5] In 2009 context the Northern Trench could have, and might yet, become

Rocky Mountain Trench - Misplaced Pages Continue

2624-573: The NAWAPA proposal by Parsons Engineering Group - would see flooding of the portions of the Trench as part of a continental-scale water diversion. 1971 - Sir Ranulph Fiennes descends the Trench from Kechika mouth - mostly on foot, partly solo as part of his circum-polar expedition [2] . For this and other feats he is later recorded by Guinness Book of Records as the World's 'Greatest Living Explorer.' 1981 - 'Skook' Davidson; long time outfitter proposes

2706-562: The 300 km (190 mi) natural route as The Trail of The Ancient Ones . They also call it the Davie Trail honoring David Braconnier, the founding chief of the community at Ware (Fort Ware - originally called Kwadacha which the HBC named Whitewater Post) 1797 - John Finlay records the forks of the Finlay and Parsnip Rivers and ventures part way up each river. The Finlay River later comes to bear his name. 1823 to 1825 - Samuel Black

2788-875: The Columbia at Castlegar, BC after a meander through the United States as the Kootenai River (US spelling). For convenience the Rocky Mountain Trench may be divided into two sections, the Northern Trench (between the Muskwa Ranges and Interior Mountains ) and the Southern Trench (between the Continental Ranges and Columbia Mountains ), separated by the northeastern portion of the Interior Plateau west of

2870-495: The Earth's continents being accreted into one giant supercontinent . Most continents, such as Asia, Africa and Europe, include several continental cratons, as they were formed by the accretion of many smaller continents. In European geology , the basement generally refers to rocks older than the Variscan orogeny . On top of this older basement Permian evaporites and Mesozoic limestones were deposited. The evaporites formed

2952-587: The Fox, Parsnip and Finlay Rivers are part of the Peace River system. The Canoe River is a short tributary of the Columbia system, draining into Kinbasket Lake , a reservoir on the Columbia River. The Kootenai River, however, does not fully follow the Trench but exits Canada southwest via Lake Koocanusa reservoir to the Libby Dam . The Kootenay River (Canadian spelling) is a tributary of the Columbia , joining

3034-477: The HBC closes. Today the Kaska Dena Community of Fort Ware (Ware) remains as a full-time settlement. 1957 - Swedish industrial savant Axel Wenner-Gren advocates resource mega-developments for the Peace River area. Among his proposals he envisions a monorail up the Northern Trench. Some area proposals came to partial fruition but the monorail did not. 1960 to 1967 - The Government of BC declines

3116-602: The Klondike Gold Rush. The A route was a Stikine option similar to Highway 37 of today. The B route favors the Trench option. The C route following the airfields east of the Rocky Mountains and then crossing to the west near the Liard River is the chosen route. 1942 - March 28 the American government initiates a highly secret survey. It was undertaken for the purpose of assessing a military railway link up

3198-672: The Liard Plain proximate to the small communities of Watson Lake, Yukon and Lower Post, BC. The highest point in the northern Trench is Sifton Pass at an elevation of about 1,010 m (3,310 ft) near the bend of Scarcity Creek. Right-lateral strike-slip movement of the Tintina Fault on the Tintina-Northern Rocky Mountain Trench may have begun during the middle Jurassic . The fastest rates of slip probably occurred during two pulses in

3280-512: The Northern Rocky Mountain Trench or the Tintina Trench. 1949 - US Congress Public Law 391 authorises a location survey for a railway from Prince George to Fairbanks. Prince George Board of Trade advocates the Trench route - the B route. 1950 - October, Canadian Transport Minister Lionel Chevrier advocates the 1942 route in a secret document to Federal Cabinet. A budget of $ 750,000,000 is presented. 1953 - Whitewater Post or Kwadacha of

3362-432: The Northern Rocky Mountain Trench. It was completed on Sept 28. Nov 15 US General Somervell declines to proceed with a military railway. Canada's Major Charles presents drawings for the Northern Trench portion of a railway from Ware to Lower Post of 351.6 km (218.5 mi), $ 112,000,000 cost, with 17,000 personnel over 400 days. Of the 1217 total miles of proposed railway to Alaska, 530 are on Canadian soil and lie within

Rocky Mountain Trench - Misplaced Pages Continue

3444-649: The Northern Trench as their strategic railway choice, favoring instead a route to the west similar to the telegraph route. Part of the reason is that the Lower Finlay and Parsnip River portions of the Northern Trench would be flooded by the damming of the Peace River. Reservoir land acquisition commences. Their selected westerly rail route - the Dease Lake Extension along the A Route - has been, in part, abandoned, and in lesser part been reopened to Takla Siding for logging use. 1964 - US Congress tables

3526-512: The Southern Rocky Mountain Trench consist mainly of Precambrian and Paleozoic metasedimentary and sedimentary rocks. Within the trench are unconsolidated Cenozoic sandstones and conglomerates . The aforementioned basement ramp along which orogeny -related thrust faulting and subsequent strike-slip and normal faulting occurred is probably associated with the ancient continental shelf of Paleozoic and Mesozoic time. The southern Rocky Mountain Trench comprises approximately one half of

3608-614: The Southern Rocky Mountain Trench: The southward transborder extension of the Trench into Montana is the primary containment for Lake Koocanusa , a Kootenay River reservoir created by the Libby Dam near Libby, Montana . The large valley and tributaries have always offered an economy based on ranching and logging. This has been supplemented by fortuitous locations of several mines - often in side valleys and producing lead , zinc , coal and gypsum . The Canadian Pacific Railway (CPR) also constructed

3690-545: The Trench in British Columbia and includes three regions, the Robson Valley , Columbia Valley and East Kootenay (from north to south). It hosts dozens of communities and two major reservoirs - Kinbasket Lake , and Lake Koocanusa (an acronym of Kootenay/Canada/USA.) There are intersections with two other trench features. At the approximate midpoint of Kinbasket Lake, the now submerged Columbia River exits

3772-629: The Trench in an almost southerly direction toward Revelstoke and flows beyond to its point of exit from Canada south of Trail BC. West of Donald BC, the Beaver river flows in from the south - but it represents the intersection of the lesser but impressive feature called the Purcell Trench. The Purcell Trench as it proceeds southward becomes the valley of the Duncan River and Duncan and Kootenay Lakes . There are four geographic segments of

3854-597: The Trench to enter the Interior Plateau, may be used for this purpose. The northern portion of the Trench is dominated by strike-slip faulting , while the southern part of the Trench was created by normal faults . Despite differences in timing and faulting styles of the northern and southern portions, they were aligned with each other because faulting for both was controlled by a pre-existing, west-facing, deep basement ramp with over 10 km (33,000 ft) of vertical offset. The Northern Rocky Mountain Trench

3936-1036: The Trench, at least in part, are the Kootenay River , the Columbia River , the Canoe River , the Flathead River , the Fraser River , the Parsnip River , the Finlay River , the Fox River , and the Kechika River . The North Fork of the Flathead River, flowing into Flathead Lake with the other branches of the Flathead River, is part of the Columbia River system. The Kechika is part of the Liard River system, and

4018-569: 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 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

4100-745: The ages is visible as well. The basement rocks of the continental crust tend to be much older than the oceanic crust. The oceanic crust can be from 0–340 million years in age, with an average age of 64 million years. Continental crust is older because continental crust is light and thick enough so it is not subducted, while oceanic crust is periodically subducted and replaced at subduction and oceanic rifting areas. The basement rocks are often highly metamorphosed and complex, and are usually crystalline . They may consist of many different types of rock – volcanic, intrusive igneous and metamorphic. They may also contain ophiolites , which are fragments of oceanic crust that became wedged between plates when

4182-669: 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

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4264-442: The basement can be called a "cover" or "sedimentary cover". Crustal rocks are modified several times before they become basement, and these transitions alter their composition. Basement rock is the thick foundation of ancient, and oldest, metamorphic and igneous rock that forms the crust of continents , often in the form of granite . Basement rock is contrasted to overlying sedimentary rocks which are laid down on top of

4346-417: The basement rocks after the continent was formed, such as sandstone and limestone . The sedimentary rocks which may be deposited on top of the basement usually form a relatively thin veneer, but can be more than 5 kilometres (3 mi) thick. The basement rock of the crust can be 32–48 kilometres (20–30 mi) thick or more. The basement rock can be located under layers of sedimentary rock, or be visible at

4428-455: 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

4510-708: The context of plate tectonics , strike-slip movement of the Tintina Fault on the Tintina-Northern Rocky Mountain Trench is also related to strike-slip movement along the San Andreas Fault , the extension of the Basin and Range Province , and other extensional or strike-slip fault systems in western North America. The Tintina Fault is one of the two major fault zones paralleling the Northern Cordilleran Volcanic Province ,

4592-454: 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

4674-416: The crust thicker and less dense, making it immune to subduction. Oceanic crust can be subducted, while continental crust cannot. Eventually, the subduction of the underthrusting oceanic crust can bring the volcanic arc close to a continent, with which it may collide. When this happens, instead of being subducted, it is accreted to the edge of the continent and becomes part of it. Thin strips or fragments of

4756-455: 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 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

4838-476: 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 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,

4920-422: The east side. During late Paleozoic to Mesozoic time, rapid sediment deposition and subsidence to the west transitioned in the area of the modern Rocky Mountain Trench into a stable continental shelf in the east. The Nevadan Orogeny destroyed the western wedge of sedimentary rocks during Jurassic to middle Cretaceous time, thrusting them up into metamorphic fold belts. Currently, strata on either side of

5002-399: The economy. The Southern Trench is also known for a number of ski resorts in the trench or in the nearby tributary valleys. These destinations include Fairmont, Panorama, Kimberley, Purden, Kicking Horse and the original Bugaboo heli-ski lodge. Numerous other ski touring and back country lodges are also found here. The summer sports of golf, boating, fishing, and hiking round out the appeal to

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5084-511: The edge of the continent. There are exceptions, however, such as exotic terranes . Exotic terranes are pieces of other continents that have broken off from their original parent continent and have become accreted to a different continent. Continents can consist of several continental cratons – blocks of crust built around an initial original core of continents – that gradually grew and expanded as additional newly created terranes were added to their edges. For instance, Pangea consisted of most of

5166-420: The gravel road up the west side of the Reservoir to Ware. Beyond that point the northbound traveller will only find a narrow cat guard (a cat guard is a primitive road constructed as a fire guard by heavy equipment-usually a bulldozer-to prevent the spread of a forest fire by creating a fuel free perimeter) for a few kilometres. The Kaska Dena culture of Fort Ware and Lower Post refer to their ancestral use of

5248-411: The mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The basement rocks lie below a sedimentary platform or cover, or more generally any rock below sedimentary rocks or sedimentary basins that are metamorphic or igneous in origin. In the same way, the sediments or sedimentary rocks on top of

5330-439: 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, 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

5412-409: The middle Cretaceous and early Cenozoic , respectively, with the latter probably occurring during the Eocene . Between 750 km (470 mi)to over 900 km (560 mi) of total right-lateral movement has occurred, of which 450 km (280 mi) of offset has occurred since the mid- Cretaceous . The result is that terrains to the west of the fault system have moved toward the north. In

5494-480: The most applications in environmental sciences , land surface is represented and modelled using gridded models. In civil engineering and entertainment businesses, 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

5576-425: The most eventual and most practicable for a railway form the Fraser River to the Yukon. 1914 - Premier McBride advocates a railway on Insp. Moodie's route according to B. Kenelly in a pamphlet 'The British Columbia Peace. Fort St John' 1936. 1926 - Whitewater Post is established by HBC. Whitewater is the translation of Kwadacha, a nearby river. 1930 to 1931 - British Columbia Department of Public Works investigates

5658-420: The onset of subduction along the western margin of the South American Plate . When discussing the Trans-Mexican Volcanic Belt of Mexico the basement include Proterozoic, Paleozoic and Mesozoic age rocks for the Oaxaquia, the Mixteco and the Guerrero terranes respectively. The term basement is used mostly in disciplines of geology like basin geology , sedimentology and petroleum geology in which

5740-412: The other being the Denali Fault in the Yukon , the U.S. state of Alaska and along the British Columbia Coast . First Nations have traditionally always travelled the northern Trench. There are several post-European contact travels up the northern Trench - often of large proportion. The Trench here remains mostly wild, and the northern 300 km (190 mi) is essentially without roads, excepting

5822-525: The point. Known control points can be used to give these relative positions absolute values. More sophisticated algorithms can exploit other information on 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

5904-596: The police resources to connect with the more westerly Telegraph Trail route. Under protest, the NWMP field team did so. That trail was soon abandoned due to its non-viable character. The political route departure from Fort Graham westward added 400 rugged snowy kilometres to the total distance without going any favorable ground or measurable distance closer to the north. The Davie Trail is noted to be excellent for wintering horse due to low snow accumulations. 1912 - British Columbia Magazine - prospector Bower reports Sifton Pass as

5986-475: 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 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

6068-405: The preferred route for the 120-year-old concept of a Canada Alaska Railway [6] concept. Discussions among feasibility experts still do not seem to favor the B Route despite it being lower, more direct, fewer major river crossings and considerably less snow. The Southern Rocky Mountain Trench was created mainly by Cenozoic-aged extension ( normal faulting ). What little strike-slip movement that

6150-646: The route from Fox River to Sylvestre's Landing. There was also a reported drive of cattle on this route (echoed in Moodie's reports and in Kaska oral history.) 1906 – A North West Mounted Police patrol under field supervision of Inspector Constantine began the construction of the Police Trail westward from Hudson Hope and then northward up the Northern Trench from HBC's post at Fort Graham. 1907 - British Columbia Premier R. McBride intervened and asked Canada to direct

6232-618: The surface. Basement rock is visible, for example, at the bottom of the Grand Canyon , consisting of 1.7- to 2-billion-year-old granite ( Zoroaster Granite ) and schist ( Vishnu Schist ). The Vishnu Schist is believed to be highly metamorphosed igneous rocks and shale , from basalt , mud and clay laid from volcanic eruptions, and the granite is the result of magma intrusions into the Vishnu Schist. An extensive cross section of sedimentary rocks laid down on top of it through

6314-399: 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 a broader sense is used, particularly in medical fields such as neurology . An objective of topography is to determine

6396-417: The terrain of the ocean floor. In recent years, LIDAR ( LI ght D etection A nd R anging), 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

6478-602: The trail from Fox Lake north is often hard to find, or obliterated to all but indigenous and experienced Kaska natives. It may be more commonly used as an aviation route today. The northern trench from the Highway 97 bridge on the Parsnip River has routes on both sides of Williston Lake to Fort Ware . The route up the east side cannot be followed due to the Peace Reach of the reservoir. The road traveler will use

6560-414: The underthrusting oceanic plate may also remain attached to the edge of the continent so that they are wedged and tilted between the converging plates, creating ophiolites . In this manner, continents can grow over time as new terranes are accreted to their edges, and so continents can be composed of a complex quilt of terranes of varying ages. As such, the basement rock can become younger going closer to

6642-572: Was at least one period of rapid expansion and accretion to the continents during the Precambrian. Much of the basement rock may have originally been oceanic crust, but it was highly metamorphosed and converted into continental crust . It is possible for oceanic crust to be subducted down into the Earth's mantle , at subduction fronts, where oceanic crust is being pushed down into the mantle by an overriding plate of oceanic or continental crust. When

6724-500: Was sent by the HBC north through Finlay Forks to The Fox River (Kwadacha) and returned later that season. He narrowly missed being the first white person to go all the way up the Northern Trench to the Liard River but chose not to listen to his guide - heading north westward seeking the source of the Finlay River instead. He travels far enough NW to discover the headwaters of another Trench tributary - The Turnagain River. Natives there find

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