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59-791: The Canadian Shield is a physiographic division comprising four smaller physiographic provinces: the Laurentian Upland , Kazan Region , Davis and James. The shield extends into the United States as the Adirondack Mountains (connected by the Frontenac Axis ) and the Superior Upland . The Canadian Shield is a U-shaped subsection of the Laurentia craton signifying the area of greatest glacial impact (scraping down to bare rock) creating

118-446: A basin they form centripetal or inland drainage pattern. A deranged drainage system is a drainage system in drainage basins where there is no coherent pattern to the rivers and lakes. These can form in areas with extensive limestone deposits, where surface streams can disappear into the groundwater via caves and subterranean drainage routes. They can also form in areas where there has been much geological disruption. A classic example

177-603: A central playa . An axial river existed in the Espanola Basin as early as 13 million years ago, reaching the Santo Domingo Basin by 6.9 million years ago. However, at this time, the river drained into a playa in the southern Albuquerque Basin where it deposited the Popotosa Formation . The upper reach of this river corresponded to the modern Rio Chama , but by 5 million years ago, an ancestral Rio Grande draining

236-504: A central high point. Volcanos usually have archetypal features on which this commonly develops are modest or hard domes pattern develops when streams flow in many general directions (meaning quite long-term) In India, the Amarkantak range and Ramgarh crater are most archetypal; and Dogu'a Tembien in Ethiopia . When the streams converge at a point, which is generally a depression or

295-408: A mineral. The kimberlite eruptions then bring the diamonds from over 150 kilometres (93 mi) depth to the surface. The Ekati and Diavik mines are actively mining kimberlite diamonds. Physiographic region Physiographic regions are a means of defining Earth 's landforms into independently distinct, mutually exclusive areas, independent of political boundaries. It is based upon

354-405: A myriad population of other birds, including ravens and crows , predatory birds and many songbirds . The Canadian Shield is one of the world's richest areas in terms of mineral ores . It is filled with substantial deposits of nickel , gold , silver , and copper . There are many mining towns extracting these minerals. The largest, and one of the best known, is Sudbury , Ontario. Sudbury

413-573: A preference by many Earth scientists for the term "geomorphology" in order to suggest an analytical approach to landscapes rather than a descriptive one. In current usage, physiography still lends itself to confusion as to which meaning is meant, the more specialized "geomorphological" definition or the more encompassing "physical geography" definition. For the purposes of physiographic mapping, landforms are classified according to both their geologic structures and histories. Distinctions based on geologic age also correspond to physiographic distinctions where

472-573: A single lower base level. An example of an integrated drainage is the area drained by the Rio Grande River . The sedimentary basins forming the modern Rio Grande Valley were not integrated into a single river system draining into the Gulf of Mexico until relatively recent geologic time. Instead, the basins formed by the opening of the Rio Grande rift were initially bolsons , with no external drainage and

531-822: A tangential or greater concentric path along a belt of weak rock so, with others, a roughly traced out ring can be seen. It is best displayed by streams draining a maturely dissected structural dome or basin where erosion has exposed rimming sedimentary strata of greatly varying degrees of hardness, as in the Red Valley , which nearly encircles the domal structure of the Black Hills of South Dakota . Astroblemes and mud diapirs are also thought to be able to cause this kind of drainage pattern. Angular drainage patterns form where bedrock joints and faults intersect at angles other than rectangular drainage patterns. Angles can be more or less than 90 degrees. An integrated drainage

590-429: Is a mature drainage system characteristic of arid climates. It is formed by coalescing of individual basins formerly separated by high ground, such as mountains or ridges. Headward erosion from a lower basin may breach the barrier, as may spilling over from a higher basin due to aggradation (accumulation of sediments in the basin). The effect of integration of a drainage system is to replace local higher base levels with

649-622: Is an exception to the normal process of forming minerals in the shield since the Sudbury Basin is an ancient meteorite impact crater . Ejecta from the meteorite impact was found in the Rove Formation in May 2007. The nearby but less-known Temagami Magnetic Anomaly has striking similarities to the Sudbury Basin. This suggests it could be a second metal-rich impact crater. In northeastern Quebec,

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708-472: Is available. Per the lie of channels , drainage systems can fall into one of several categories, known as drainage patterns. These depend on the topography and geology of the land. All forms of transitions can occur between parallel, dendritic, and trellis patterns. A drainage system is described as accordant if its pattern correlates to the structure and relief of the landscape over which it flows. A discordant system or pattern does not correlate to

767-469: Is intimately associated with certain branches of geology, as sedimentation , while geomorphology connects physiography with geography. The dynamic interlude representing the active phase of physiography weaves the basic threads of geologic history." The U.S. Geological Survey defines physiography as a study of "Features and attributes of earth's land surface", while geomorphology is defined separately as "Branch of geology dealing with surface land features and

826-566: Is one of the world's best preserved mineralized Neoarchean caldera complexes, which is 2.7 Ga. The Canadian Shield also contains the Mackenzie dike swarm , which is the largest dike swarm known on Earth. The North American craton is the bedrock forming the heart of the North American continent, and the Canadian Shield is the largest exposed part of the craton's bedrock. The Canadian Shield

885-712: Is part of an ancient continent called Arctica , which was formed about 2.5 Ga during the Neoarchean era. Mountains have deep roots and float on the denser mantle much like an iceberg at sea . As mountains erode, their roots rise and are eroded in turn. The rocks that now form the surface of the shield were once far below the Earth's surface. The high pressures and temperatures at those depths provided ideal conditions for mineralization. Although these mountains are now heavily eroded, many large mountains still exist in Canada's far north called

944-405: Is removed and the river continues to flow over a seemingly new surface, but one in fact made up of rocks of old geological formation. Dendritic drainage systems (from Greek δενδρίτης , dendrites , "of or like a tree") are not straight and are the most common form of the drainage system. In this, there are many sub-tributaries (analogous to the twigs of a tree), which merge into tributaries of

1003-464: Is sometimes as the science which describes and explains the physical features of the earth's surface". By 1911, the definition of physiography in Encyclopædia Britannica had evolved to be "In popular usage the words 'physical geography' have come to mean geography viewed from a particular standpoint rather than any special department of the subject. The popular meaning is better conveyed by

1062-491: Is the Canadian Shield . During the last ice age , the topsoil was scraped off, leaving mostly bare rock. The melting of the glaciers left land with many irregularities of elevation and a great deal of water to collect in the low points, resulting in the region's many lakes. The drainage basins are young and are still sorting themselves out; eventually the system will stabilize. In an annular drainage pattern, streams trace

1121-463: The Arctic Cordillera . This is a vast, deeply dissected mountain range, stretching from northernmost Ellesmere Island to the northernmost tip of Labrador. The range's highest peak is Nunavut's Barbeau Peak at 2,616 metres (8,583 ft) above sea level. Precambrian rock is the major component of the bedrock. The current surface expression of the shield is one of very thin soil lying on top of

1180-400: The 21st century, some confusion remains as to exactly what "physiography" is. One source states "Geomorphology includes quaternary geology, physiography and most of physical geography", treating physiography as a separate field, but subservient to geomorphology. Another source states "Geomorphology (or physiography) refers to the study of the surface features of the earth. It involves looking at

1239-635: The Canadian Shield is approximately circular, bounded on the northeast by the northeast edge of Greenland, with Hudson Bay in the middle. It covers much of Greenland, all of Labrador and the Great Northern Peninsula of Newfoundland , most of Quebec north of the St. Lawrence River , much of Ontario including northern sections of the Ontario Peninsula , the Adirondack Mountains of New York ,

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1298-632: The Precambrian (between 4.5 Ga and 540 Ma) and have been repeatedly uplifted and eroded. Today it consists largely of an area of low relief 300–610 m (980–2,000 ft) above sea level with a few monadnocks and low mountain ranges (including the Laurentian Mountains ) probably eroded from the plateau during the Cenozoic Era. During the Pleistocene Epoch, continental ice sheets depressed

1357-426: The bedrock, with many bare outcrops . This arrangement was caused by severe glaciation during the ice ages that covered the shield and scraped the rock clean. The lowlands of the Canadian Shield have a very dense soil that is not suitable for forestation; it also contains many marshes and bogs ( muskegs ). The rest of the region has coarse soil that does not retain moisture well and is frozen with permafrost throughout

1416-501: The bulk rock so erosion tends to preferentially open the joints and streams eventually develop along the joints. The result is a stream system in which streams consist mainly of straight line segments with right-angle bends and tributaries join larger streams at right angles. This pattern can be found with the Arun River in Nepal. In a radial drainage system, the streams radiate outwards from

1475-580: The case of polar bears ( Ursus maritimus ), the shield area contains many of their denning locations, such as the Wapusk National Park . The many lakes and rivers on the shield contain a plentiful quantity of different sports fish species, including walleye , northern pike , lake trout , yellow perch , whitefish , brook trout , arctic grayling , and many types of baitfish. The water surfaces are also home to many waterfowl , most notably Canada geese , loons and gulls . The vast forests contain

1534-403: The case. A maturely dissected plateau may grade without a break from rugged mountains on the one hand to mildly rolling farm lands on the other. So also, forms which are not classified together may be superficially similar; for example, a young coastal plain and a peneplain . In a large number of cases, the boundary lines are also geologic lines, due to differences in the nature or structure of

1593-469: The classic three-tiered approach by Nevin M. Fenneman in 1916, that separates landforms into physiographic divisions, physiographic provinces , and physiographic sections. The classification mechanism has become a popular geographical tool in the United States, indicated by the publication of a USGS shapefile that maps the regions of the original work and the National Park Services's use of

1652-457: The concept became embroiled in controversy surrounding the appropriate concerns of that discipline. Some geomorphologists held to a geological basis for physiography and emphasized a concept of physiographic regions while a conflicting trend among geographers was to equate physiography with "pure morphology," separated from its geological heritage. In the period following World War II, the emergence of process, climatic, and quantitative studies led to

1711-422: The definition of the term physiography. "In England, physiography is regarded as the introduction to physical science in general. It is made to include the elements of physics , chemistry , astronomy , physical geography, and geology , and sometimes even certain phases of botany and zoology . In America, the term has a somewhat different meaning. It is sometimes used as a synonym for physical geography, and

1770-401: The distribution of land, water, soil and rock material that forms the land surface. Land is closely linked to the geomorphology of a particular landscape", regarding physiography as synonymous with geomorphology. Yet another source states "Physiography may be viewed from two distinct angles, the one dynamic, the other passive". The same source continues by stating "In a large fashion geodynamics

1829-615: The eastern San Juan Mountains had joined the ancestral Rio Chama. The ancestral Rio Grande progressively integrated basins to the south, reaching the Palomas basin by 4.5 million years ago, the Mesilla basin by 3.1 million years, to Texas by 2.06 million years, and finally joining the Pecos River at 800,000 years to drain into the Gulf of Mexico. Volcanism in the Taos Plateau reduced drainage from

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1888-601: The exposed area of the shield covers approximately 8,000,000 km (3,100,000 sq mi). The true extent of the shield is greater still and stretches from the Western Cordillera in the west to the Appalachians in the east and as far south as Texas , but these regions are overlaid with much younger rocks and sediment. The Canadian Shield is among the oldest geologic areas on Earth, with regions dating from 2.5 to 4.2 billion years. The multitude of rivers and lakes in

1947-418: The facts of mathematical geography, and the three are so closely inter-related that they cannot be rigidly separated in any discussion". The 1919 edition of The Encyclopedia Americana: A Library of Universal Knowledge further adjusted the definition to be "Physiography (geomorphology), now generally recognized as a science distinct from geology, deals with the origins and development of land forms, traces out

2006-484: The field. In Germany, Oscar Peschel in 1870, proposed that geographers should study the morphology of the Earth's surface, having an interest in the study of landforms for the development of human beings. As the chair of geography (and a geologist by training) in Bonn, Germany, Ferdinand von Richthofen made the study of landforms the main research field for himself and his students. Elsewhere, Thomas Henry Huxley 's Physiography

2065-400: The forms are so recent as to be in their first erosion cycle , as is generally the case with sheets of glacial drift . Generally, forms which result from similar histories are characterized by certain similar features, and differences in history result in corresponding differences of form, usually resulting in distinctive features which are obvious to the casual observer, but this is not always

2124-502: The giant Manicouagan Reservoir is the site of an extensive hydroelectric project (Manic-cinq, or Manic-5). This is one of the largest-known meteorite impact craters on Earth , though not as large as the Sudbury crater. The Flin Flon greenstone belt in central Manitoba and east-central Saskatchewan "is one of the largest Paleoproterozoic volcanic-hosted massive sulfide ( VMS ) districts in

2183-401: The gradient of the land. Geomorphologists and hydrologists often view streams as part of drainage basins (and sub-basins ). This is the topographic region from which a stream receives runoff , throughflow , and its saturated equivalent, groundwater flow . The number, size, and shape of the drainage basins varies and the larger and more detailed the topographic map , the more information

2242-413: The history of geologic changes" to descriptions that also include vegetation and/or land use. Deranged drainage system In geomorphology , drainage systems , also known as river systems , are the patterns formed by the streams , rivers , and lakes in a particular drainage basin . They are governed by the topography of land, whether a particular region is dominated by hard or soft rocks, and

2301-489: The interval 2.45–1.24 Ga, with the most substantial growth period occurring during the Trans-Hudson orogeny , between c. 1.90–1.80 Ga. The Canadian Shield was the first part of North America to be permanently elevated above sea level and has remained almost wholly untouched by successive encroachments of the sea upon the continent. It is the Earth's greatest area of exposed Archean rock. The metamorphic base rocks are mostly from

2360-551: The land surface (creating Hudson Bay ) but also tilted up its northeastern "rim" (the Torngat ), scooped out thousands of lake basins, and carried away much of the region's soil. The northeastern portion, however, became tilted up so that, in northern Labrador and Baffin Island , the land rises to more than 1,500 metres (5,000 feet) above sea level. When the Greenland section is included,

2419-618: The main river (the branches and the trunk of the tree, respectively). They are seen to feed a river channel that matches and is strongly accordant to the overriding gradient of the land. Truly dendritic systems form in V-shaped valleys ; as a result, the rock types must be impervious and non-porous . A parallel drainage system occurs on elongate landforms like outcropping resistant rock bands), typically following natural faults or erosion (such as prevailing wind scars). The watercourses run swift and straight, with very few tributaries, and all flow in

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2478-412: The most northerly parts of Manitoba and Saskatchewan. Hydrologic drainage is generally poor, the soil compacting effects of glaciation being one of the many causes. Tundra typically prevails in the northern regions. Many mammals such as beaver , caribou , white-tailed deer , moose , wolves , wolverines , weasels , mink , otters , grizzly bear , polar bears and black bears are present. In

2537-583: The northernmost part of Lower Michigan and all of Upper Michigan , northern Wisconsin , northeastern Minnesota , the central and northern portions of Manitoba , northern Saskatchewan , a small portion of northeastern Alberta , mainland Northwest Territories to the east of a line extended north from the Saskatchewan-Alberta border, most of Nunavut's mainland and, of its Arctic Archipelago , Baffin Island and significant bands through Somerset , Southampton , Devon and Ellesmere islands. In total,

2596-447: The processes of contemporary change in the crust and the circulation of the fluid envelopes. It thus draws upon physics for the explanation of the phenomena with the space-relations of which it is specially concerned. Physical geography naturally falls into three divisions, dealing respectively with the surface of the lithosphere – geomorphology; the hydrosphere – oceanography ; and the atmosphere – climatology . All these rest upon

2655-489: The processes that create and change them". Partly due to this confusion over what "physiography" actually means, some scientists have refrained from using the term physiography (and instead use the similar term geomorphology) because the definitions vary from the American Geological Institute's "the study and classification of the surface features of Earth on the basis of similarities in geologic structure and

2714-442: The region is classical example of a deranged drainage system , caused by the watersheds of the area being disturbed by glaciation and the effect of post-glacial rebound . The shield was originally an area of very large, very tall mountains (about 12,000 m or 39,000 ft) with much volcanic activity, but the area was eroded to nearly its current topographic appearance of relatively low relief over 500 Ma. Erosion has exposed

2773-576: The roots of the mountains, which take the form of greenstone belts in which belts of volcanic rock that have been altered by metamorphism are surrounded by granitic rock. These belts range in age from 3.6 to 2.7 Ga. Much of the granitic rock belongs to the distinctive tonalite–trondhjemite–granodiorite family of rocks, which are characteristic of Archean continental crust . Many of Canada's major ore deposits are associated with greenstone belts. The Sturgeon Lake Caldera in Kenora District , Ontario,

2832-527: The same direction. This system forms on very long, uniform slopes, for instance, high rivers flowing southeast from the Aberdare Mountains in Kenya and many rivers of Myanmar . This sometimes indicates a major fault that cuts across an area of steeply folded bedrock. The geometry of a trellis drainage system is similar to that of a common garden trellis . Along a strike valley, smaller tributaries feed into

2891-786: The steep slopes of mountainsides. These tributaries enter the main river about perpendicular, causing a trellis-like appearance of the system. They form where hard and soft formations exist on both banks of the main river, and are reflective of height, accentuated by erosion. Trellis drainage is characteristic of folded mountains, such as the Appalachian Mountains in North America and in the north part of Trinidad . Rectangular drainage develops on rocks that are of approximately uniform resistance to erosion , but which have two directions of jointing at approximately right angles or 90 degrees. The joints are usually less resistant to erosion than

2950-493: The terminology to describe the regions in which its parks are located. Originally used in North America , the model became the basis for similar classifications of other continents. During the early 1900s, the study of regional-scale geomorphology was termed "physiography". Physiography later was considered to be a portmanteau of " physi cal" and "ge ography ", and therefore synonymous with physical geography , and

3009-479: The thin soils. The age of the Canadian Shield is estimated to be 4.28 Ga . The Canadian Shield once had jagged peaks, higher than any of today's mountains, but millions of years of erosion have changed these mountains to rolling hills. The Canadian Shield is a collage of Archean plates and accreted juvenile arc terranes and sedimentary basins of the Proterozoic Eon that were progressively amalgamated during

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3068-434: The topographic expression of structure, and embodies a logical history of oceanic basins, and continental elevations; of mountains , plateaus and plains ; of hills and valleys. Physical geography is used loosely as a synonym, but the term is more properly applied to the borderland between geography and physiography; dealing, as it does, largely with the human element as influenced by its physiographic surroundings". Even in

3127-500: The topography and geology of the area. Discordant drainage patterns are classified into two main types: antecedent and superimposed , while ante position drainage patterns combine the two. In antecedent drainage, a river's vertical incision ability matches that of land uplift due to tectonic forces. Superimposed drainage develops differently: initially, a drainage system develops on a surface composed of 'younger' rocks, but due to denudation activities this surface of younger rocks

3186-484: The underlying rocks. The history of "physiography" itself is at best a complicated effort. Much of the complications arise from how the term has evolved over time, both as its own 'science' and as a synonym for other branches of science. In 1848, Mary Somerville published her book Physical Geography which gave detailed descriptions of the topography of each continent, along with the distribution of plant, animals and humans. This work gave impetus to further works along

3245-470: The word physiography, a term which appears to have been introduced by Linnaeus , and was reinvented as a substitute for the cosmography of the Middle Ages by Professor Huxley. Although the term has since been limited by some writers to one particular part of the subject, it seems best to maintain the original and literal meaning. In the stricter sense, physical geography is that part of geography which involves

3304-471: The world, containing 27 copper - zinc -( gold ) deposits from which more than 183 million tonnes of sulfide have been mined." The portion in the Northwest Territories has recently been the site of several major diamond discoveries. The kimberlite pipes in which the diamonds are found are closely associated with cratons, which provide the deep lithospheric mantle required to stabilize diamond as

3363-513: The year. Forests are not as dense in the north. The shield is covered in parts by vast boreal forests in the south that support natural ecosystems as well as a major logging industry. The boreal forest area gives way to the Eastern Canadian Shield taiga that covers northern Quebec and most of Labrador. The Midwestern Canadian Shield forests that run westwards from Northwestern Ontario have boreal forests that give way to taiga in

3422-594: Was published in 1877 in Britain . Shortly after, the field of "physical geography" itself was renamed as "physiography". Afterwards, physiography became a very popular school subject in Britain, accounting for roughly 10% of all examination papers in both English and Welsh schools, and physiography was now regarded as an integral, if not the most important aspect of geography. In conjunction with these 'advances' in physiography, physically and visually mapping these descriptive areas

3481-641: Was underway as well. The early photographers and balloonists, Nadar and Triboulet, experimented with aerial photography and the view it provided of the landscape. In 1899, Albert Heim published his photographs and observations made during a balloon flight over the Alps; he is probably the first person to use aerial photography in geomorphological or physiographical research. The block diagrams of Fenneman, Raisz, Lobeck and many others were based in part upon both aerial photography and topographic maps, giving an oblique "birds-eye" view. By 1901, there were clear differences in

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