The relief, minerals of North America - all this is studied today at school at geography lessons. Knowledge of these topics is necessary not only for passing the exam, but also for general development. After all, each of us must understand what constitutes the surface of the planet on which we live.
North America, the relief of which we will consider in this article, resembles South America in the type of vertical partition. The powerful belt of the Cordillera Mountains stretches along the west coast for 7,000 km. Mostly flat is the eastern half of this continent. All this allows us to say that the relief of North and South America has significant similarities. However, there are significant differences between these continents. In particular, the Cordillera as a mountain system is much wider and more complex than the Andes (also called the Andean Cordillera). They consist of a whole system of ridges that differ in tectonic and geological structure, which are isolated.
Eastern belt
5 orotectonic longitudinal zones are distinctly distinguished practically throughout the entire Cordillera. The first of them, the eastern one, is the ridge of the Lamian folding: the Mackenzie Mountains, the Brooks Range, the Eastern Sierra Madre Range, the Rocky Mountains. The latter can be divided according to the features of orography into two parts: southern and northern. Between them, the Yellowstone Plateau acts as the border. The clear straightforwardness of the forms is a vivid orographic feature.
Rocky Mountains Front Range
The forward range of the Rocky Mountains (North America) has the following relief: it stretches for almost 2000 km in a straight line, striking with the continuity, integrity and uniformity of its geological structure. The mountain range, distinctly expressed, is crowned by steep high peaks, the height of which reaches 4000 m. It gradually descends in the east to the Great Plains. The forward ridge in the west is bounded by a tectonic fault in the northern part. In the middle of the mountain are lowered. They are crossed by the river Pease, which is one of the sources of the Mackenzie River. The forward ridge in the southern part is expanding. It is divided into individual ranges, the height of which is significant: Lewis, Caribou, Selkirk. In this part, the largest peaks of the Forefront are located. This is Mount Robson (height 3954 m) and Mount Columbia (3747 m). Alpine landforms of North America are typical of the Forward Range. It is also characterized by impassability and significant glaciation.
Rocky mountains in the south
The Rocky Mountains do not form a single mountain range in the southern part. Here they consist of separate massifs, sometimes isolated and separated by "parks" - wide basins, which are plateau-shaped sections that connect the Great Plains with the Great Basin. Part of the ranges (Sangre de Cristo, Wasatch) is stretched almost from north to south. Others (for example, Uinta) - in the west-east direction, perpendicular to them. The considerable height and width of this mountain belt compensates for the lack of continuity. The border between the Great Plains and the Rocky Mountains is very clearly expressed: a steep wall - the slope of the mountains. The southern segment is a typical epiplatform mountains that were formed after the activation of the edge of one of the ancient platforms.
Belt of inner plateaus and plateaus
The next is a belt of internal plateaus and plateaus formed in the Nevadian folding on the mainland North America. The relief is characterized by folded nevadic structures represented by penilen. Within this belt, there are also plateaus that are confined to the "fragments" of the North American ancient platforms and are held by the Cordillera ridges (North Mass, Colorado Plateau). The largest intermountain plains: Fraser, Yukon, Great Basin, Colombia, North and Central Mass, Colorado.
Large Pool
The Big Basin is the largest denudation plateau in area. This territory, the width of which reaches 800 km, as a whole is an alternation of plain and mountain surfaces with the predominance of the former. On average, the surface of the plateau is elevated by 1,500 m. However, fluctuations in heights are great. Parallel ridges cross the plateau with heights of about 3 km (peak Wheeler - 3982 m). Deep depressions, called bolsons, lie between them. These are semi-closed and closed basins, which are areas of internal flow. Death Valley is one of them (-85 m).
Remaining peaks are often found here (including the cones of volcanoes).
Colorado Plateau and Grand Canyon
The Colorado Plateau is one of the unique corners of our planet that North America is famous for. Its relief is very beautiful. In its geological structure (undisturbed horizontal plates of sedimentary rocks of different ages - from the Upper Paleozian to the oldest, lying on the crystalline basement), this plateau is similar to the North American platform. Its surface is a hilly plain, whose heights reach 3860 m.
The attraction of the plateau is the Grand Canyon (North America). The relief and climate attract many tourists to this place. The Grand Canyon (pictured below) was formed near the Colorado River, in its middle course. Its depth reaches 1800 m, with a width of 8 to 25 km at the plateau level and up to 1 km at the bottom level. The steep slopes of an interesting, bizarre shape are characteristic of the Grand Canyon. They arose as a result of erosion destruction and weathering processes. A sinuous narrow channel is embedded in the crystalline base.
Inner mountain belt
The third belt, the inner mountain, is the belt of the Nevada ranges: the Coastal Range, the Alaskan Range, the Cascade Mountains, the Sierra Nevada, the Transverse Volcanic and Western Sierra Madre. These mountain ranges are straightforward. Igneous rocks prevail in their structure. Cascade Mountains - batholith with volcanic cones planted on it. The Sierra Nevada Range is an asymmetric giant crystalline batholith with gentle western and steep eastern slopes.
Synclinorium Belt
The fourth belt is the synclinorium belt. This is the zone of subsidence, which took shape in the Neogene. Part of it is currently represented by various sea bays and straits. On land, this is Death Valley, the Great California Valley, the lower reaches of the Colorado River.
Extreme western belt
The fifth belt is the extreme western. This is the coastal belt of folded alpine ranges such as Aleutian (there are 25 active volcanoes here), the Kenai Peninsula, the Island Range with the Victoria Peak (height - 2200 m), the Chugach Range, the Victoria Peninsula, the Coastal Ranges, the South Sierra Madre Ridge. All of them are mid-altitude, only the most prominent peaks above 2 km.
Depending on the degree of glaciation, the severity of the orographic longitudinal zones, and tectonic and erosive dismemberment, the Cordilleras are divided into 4 morphostructural areas: the Cordillera of Mexico, the Cordillera of the USA, the Cordillera of Canada and the Cordillera of Alaska.
Eastern mainland
What is the relief in North America in the east? Let's figure it out. As we have already noted, the relief forms of North America are mostly flat in the eastern part of the continent. These are mainly elevated (Central, Lavrentian) and high plains. Lowlands are located along the coastline: the Pre-Mexican, Atlantic, Prigudzonskaya, and also Mississippi in the lower reaches of the river of the same name.
Appalachian Mountain Belt
In North America, in contrast to South, another mountain belt stretches along the east coast - the Appalachian. This is a system of mountain ranges located from St. Lawrence Bay to about 33-32 0 s. sh., that is, almost 2300 km. Newfoundland Island is the northern link. The Appalachians are epiplatform mid-high mountains. A significant difference between the southern and northern parts of this mountain system caused the peculiarities of the tectonic and geological structure. Graben Hudson is the border between the South and North Appalachians. The Northern Appalachians as a whole is a wavy plateau. Above it towers individual mountains, ranges or mountain ranges. The Northern Appalachians were blocked by Quaternary glaciation. Therefore, the forms of the mountains are now gentle, only circuses with steep walls remained on the highest peaks.
Southern Appalachians
Alternating long parallel valleys and ridges are the southern Appalachians. From east and west, plateaus extend along the foot of the mountains. This is Piedmont in the west - a denudation flat plain formed by Early Cambrian crystalline rocks. A chain of mountain ranges, almost uninterrupted (Kohuta, Unaka, Cherny, Smoky, Bolshoi, Goluboy, etc.), rises 1-1.5 km in height in the west from it. These are "ancient mountains" - dense caledonide nuclei prepared by denudation.
Belt of ridges and valleys
One of the most remarkable areas of the Appalachians is located west of them. These are the so-called Young Mountains, or the Belt of ranges and valleys. Here are some interesting features of the relief of North America. The entire territory is composed of sedimentary rocks from the Paleozoic era: ridges - shales and sandstones, valleys - dolomites and limestones. Elongated hundreds of kilometers from the south-west to north-east along the line of the mountains, wide valleys alternate with flat-topped or with narrow crest-like ridges. At an altitude of 500-600 m lies the bottom of the valleys. The peaks of the ranges reach 1-1.2 km. The tectonic valleys are anticlinoria, and the ridges are synclinoria. That is, in this place there is a clear discrepancy with the type of tectonic structure of the modern form, which the relief of North America has here. A photo of the Appalachians is presented below.
This is an example of a reversed, or inverse, type of terrain. It is quite rare in the mountains and is most pronounced in the Appalachians. This type of relief, by analogy, became known as the "Appalachian relief." The belt of "young mountains" from the west interrupts the Appalachian Plateau (Cumberland, Allegansky). It is a ledge, the height of which is 300-400 m. This plateau is significantly higher than Piedmont. Its surface near the eastern edge lies at an altitude of about 1.2 km, and at the western - 500 m. In some places, the plateau is deeply divided by valleys of various rivers (gorges with narrow bottoms and steep slopes).
Well, now that the relief of North America was briefly considered in this article, we hope it will be easier for you to make an idea about it.