The height of the mountains of the Cordillera. Cordillera on the map. Geography of the Cordillero mountain system

CORDILLERA OF NORTH AMERICA, part of the Cordillera mountain system, occupying the western margin of North America (including Central America) and extending for more than 9 thousand km from the Beaufort Sea (69 ° north latitude) to the Isthmus of Panama (9 ° north latitude). The width of the mountain belt in Alaska reaches 1200 km, in Canada - 1000 km, in the United States - about 1600 km, in Mexico - 1000 km, in Central America - 300 km.

Relief. The Cordilleras of North America are the largest mountainous region of the mainland and are represented by a system of high-altitude linearly arranged ridges, mountain ranges and extensive denudation surfaces. The characteristic features of the relief are great fragmentation, mosaic morphostructures, the presence of chains of volcanoes and other forms of active relief formation. In the Cordillera of North America, 3 longitudinal belts are clearly expressed: eastern, inland and western.

The eastern belt, or the belt of the Rocky Mountains, is represented by a chain of high massive mountain ranges, for the most part serving as a watershed between the river basins of the Pacific, Atlantic and Arctic oceans. In the east, the belt abruptly breaks off to the foothill plateaus (Arctic, Great Plains), in the west it is limited in some places by deep tectonic depressions (the "Moat of the Rocky Mountains") or the valleys of large rivers (Rio Grande), and in some places it gradually turns into mountain ranges and plateaus. In Alaska, the Brooks Range belongs to the Rocky Mountain belt, in the northwestern part of Canada, the Richardson Range (height up to 1753 m) and the Mackenzie Mountains, bounded from the north and south by the through valleys of the Peel and Liard rivers. In the northern part of the belt, peaked blocky-folded massifs with alpine landforms, large ice fields, cirques, cirques, and trough valleys predominate. In the Rocky Mountains of Canada, narrow straight ridges and longitudinal valleys are common. They are joined to the west by the Columbian Mountains. Between 45° and 32° north latitude, the eastern belt reaches its greatest width and is represented by the Rocky Mountains in the United States (altitude up to 4399 m, Mount Elbert). They are characterized by the predominance of large nodes of short arched-folded-block ridges separated by vast plateaus (the so-called basins, parks). The highest are the ridges of Peredovaya (height up to 4345 m), Wind River (up to 4207 m), Uinta Mountains (up to 4123 m), Absaroka (up to 4009 m). Alpine massifs in the area of ​​batholith development in the state of Idaho are distinguished by sharp forms (for example, the Lost River Range, height up to 3859 m). The southern part of the eastern belt is represented by the Eastern Sierra Madre Ridge (altitude up to 4054 m).

The inner belt, or belt of internal plateaus and plateaus, is located between the eastern belt and the belt of the Pacific ridges in the west. It is characterized by denudation plateaus and plateaus (Yukon, Inner, Nechako) 750-1800 m high, deeply dissected by river valleys. In the inner part of Alaska, vast tectonic depressions occupied by river valleys alternate with flat-topped mountain ranges 1500-1700 m high (mountains Kilbak, Cuscoquim, Ray). In Canada, this belt is narrow, in many places it is interrupted by the mountain ranges of Skin, Cassiar, Omineka (height up to 2469 m). Volcanic plateaus are common (eg Fraser, Columbia Plateau, Yellowstone). On the territory of the USA and Mexico, this belt is also represented by the Great Basin Highlands, the Colorado Plateau, and the Mexican Highlands. The southern part is characterized by vast areas of deserts (Mojave, Sonora, etc.).

The western belt consists of two parallel chains of ridges separated by longitudinal tectonic depressions. The highest chain of the Pacific ridges borders the inner plateaus of the Cordilleras of North America from the west and includes the Alaska Range (height up to 6194 m, Mount McKinley - the highest point of the mainland North America), the Wrangel Mountains (up to 5005 m, Mount Bona) and the mountains of St. Elijah ( up to 5951 m, Mount Logan). The line of the Pacific ridges is continued by the Alsek Mountains (height up to 2265 m), the Boundary Range (up to 3136 m), the Coast Range, the Cascade Mountains, complicated by a series of volcanoes (Rainier, 4392 m; Lassen Peak, Shasta, etc.). To the south, the Sierra Nevada, Western Sierra Madre, Transverse Volcanic Sierra ridges stretch with the volcanoes Orizaba (height 5610 m), Popocatepetl (5465 m), Istaxiuatl (5230 m) and others. To the south of the tectonic basin of the Balsas River, the Sierra Madre South mountain ranges are , Sierra Madre (height up to 4220 m, Tahumulco volcano - the highest point in Central America), Central volcanic Cordillera with volcanoes Poas (2704 m), Irazu (3432 m) and others; in the southern narrowed part of the mainland there are two arcs of uplifts of the Isthmus of Panama - the folded ridges of San Blas and Serrania del Darei (height up to 1875 m). The extreme western chain of the Pacific ridges includes the Aleutian Islands, the Aleutian Range, the Chugach Mountains (height up to 4016 m, Mount Marcus-Baker), a series of coastal mountainous islands (Kodiak Island, the Alexander Archipelago, Queen Charlotte Islands, Vancouver), Coast Ranges, mountains on the peninsula California (up to 3100 m, Mount Diablo).

In the northern part of the Cordilleras of North America (to the north of 40-49 ° north latitude), ancient glacial (troughs, kars, terminal moraine ridges, loess, outwash and lacustrine plains) and modern nival landforms (kurums, upland terraces, etc.) are widespread. confined to the highest levels of mountains (Alaska Range, Rocky Mountains). In areas not subjected to glaciation (the interior of Alaska), and in the Arctic Lowland, thermokarst and polygonal forms are widely represented. In the rest of the Cordillera of North America, water-erosion forms predominate: valley dismemberment - in the most humid areas (Cordillera Canada), table forms and canyons - in arid areas (Colorado Plateau, Columbia). Desert areas (Great Basin, Mexican Highlands) are characterized by denudation and eolian landforms.

Geological structure and minerals. In tectonic terms, the Cordillera of North America is a grandiose fold-cover mountain structure in the northern part of the East Pacific mobile belt. They experienced several phases of folding: Antlerian (Late Devonian; 370-330 million years ago), Sonomian (end of Permian - Middle Triassic; 250-235 million years ago), Nevada (Late Jurassic; 150-140 million years ago), Sevierian ( the end of the Early Cretaceous; 110-100 million years ago) and Laramian (the boundary of the Cretaceous and Paleogene; 65 million years ago). The extreme western Pacific part of the Cordillera of North America belongs to the area of ​​incomplete Alpine tectogenesis. There are 2 longitudinal tectonic mega-zones: outer (eastern) and inner (western). The Outer Megazone includes: the Brooks Range in the north, the Rocky Mountains in the central part, and the Eastern Sierra Madre Range in the south. In its main part (Rocky Mountains), the mega-zone is underlain by the Early Precambrian crystalline basement located to the east of the North American Platform (the boundary of the platform basement extends farthest to the west into the region of the top of the Gulf of California and into the Yukon River basin); the mega-zone developed during the Paleozoic and Mesozoic and experienced final deformations in the Laramian phase of folding. Within the Brooks and Eastern Sierra Madre ranges, the mega-zone is superimposed on the Paleozoic fold structures of the Innuit and Washita-Marathon systems, respectively; its development here is limited to the Mesozoic. The outer mega-zone is formed mainly by shelf carbonate and terrigenous deposits of the former passive margin of the North American continent, which compose a system of tectonic covers torn from the basement and displaced to the northeast and east (in the Brooks Ridge - to the north). In the western part of the Rocky Mountains, Upper Proterozoic predominantly detrital rocks with covers of basalts and horizons of glacial deposits (tillites) accumulated during the rifting stage, which preceded the formation of the passive margin of the ancient North American continent, are widespread. The outer megazone reaches its greatest width in the USA, which is due to the involvement of a large section of the North American Platform in the Laramian deformations. In the north of the deformed section of the platform, a series of differently oriented basement uplifts arose, which were pushed over the deep depressions separating them, filled with Cretaceous and Paleocene deposits. In the southern half of the site (Colorado Plateau), a large block of basement was uplifted, bounded on the east by linear uplifts of the Southern Rocky Mountains and a young Rio Grande rift. On the territory of Mexico, the extreme eastern part of the outer megazone was subjected to fold deformations in the Miocene. A chain of foredeeps (filled with Cretaceous-Cenozoic molasses) stretches in front of the thrust front of the Cordillera of North America, which include basins: Colville in Alaska (the largest and deepest), Mackenzie and Alberta in Canada, Powder, Denver and Rayton in the USA, Chicontepec in Mexico .

The inner mega-zone of the Cordillera of North America has been developing since the Late Jurassic (there are relics of the oceanic crust - ophiolites of this age), since the passive margin of North America was transformed into an active one. The mega-zone is characterized by an exceptionally complex internal structure with numerous melange zones, overthrusts and strike-slips, formed as a result of deformations that began in the Permian and culminated in the Cretaceous. The mega-zone is a so-called collage (mosaic) of terranes, which arose as a result of the attachment (tectonic accretion) of many dozens of large and small blocks of the earth's crust of different nature and age: fragments of intra-oceanic uplifts, the crust of marginal seas, volcanic island arcs, micro-continents, sharply differing in the structure and composition of their sections and not revealing mutual transitions. Some of the terranes experienced northward movement along the edge of the continent for many hundreds (perhaps more than a thousand) kilometers.

After the end of the main deformations, intermountain troughs filled with Cretaceous and/or Cenozoic molasses were superimposed in places on the fold-and-thrust structure of the Cordilleras of North America, for example, the Central Valley trough in California, Bowser in Canada, and a number of troughs in western Alaska. The underthrust (subduction) of the lithosphere of the Pacific Ocean under the continent of North America was associated with the formation of Jurassic-Cretaceous granite batholiths of the Alaska Range, the Coast Range, the Sierra Nevada Range and the California Peninsula, the manifestation of Oligocene-Miocene volcanism in the Western Sierra Madre Range, the formation of still active volcanoes Aleutian Island Arc, Aleutian and Alaska Ranges, Cascade Mountains, Trans-Mexican Volcanic Belt. To the east, the intrusion of small granite intrusions occurred at the end of the Cretaceous - the beginning of the Paleogene only in the southern part of the Rocky Mountains and on the Colorado Plateau. In the Miocene, in the rear of the Cascades, basalt volcanism intensively manifested itself, creating the Columbia Plateau. The Cenozoic became the era of rifting, when an extensive polyrift system (basins and ridges zone) arose in the central part of the orogen with a reduced thickness of the earth's crust and lithosphere to 30 km or less, the Rio Grande rift, the Gulf of California rift, was formed, continuing on the continent.

The southern part of the Cordilleras of North America (to the south of the valleys of the Polochik and Matagua rivers, marking a large shear-fault zone) belongs to the tectonic Antilles-Caribbean region.

The Cordillera of North America, especially their Pacific part, retain high mobility with the manifestation of intense seismicity, which is associated with the processes occurring at the border of the North American continent - Pacific Ocean transition: subduction (subduction) of the Pacific lithospheric plate under the North American in the Aleutian deep-water trench and along the coast of Washington and Oregon (USA); horizontal slippage of the Pacific Plate along the North American plate along the Queen Charlotte and San Andreas shear zones; the subsidence of the East Pacific Rise (spreading ridge) under the North American continent at the top of the Gulf of California; subduction of the Cocos Plate (south of the Gulf of California) under the North American Plate in the Central American Trench. To the east, in the Cordillera of North America, seismic activity weakens, but does not completely die out: the western, southern, and eastern peripheries of the Great Basin and the Rio Grande rift are seismic.

The bowels of the Cordillera of North America are rich in minerals. Typical are copper-molybdenum-porphyry deposits. There are a number of ore zones and blocks: the gold-mercury zone of the Coast Range, the gold-copper and tungsten zones of the Sierra Nevada ridge, the gold-silver zone of the Great Basin, the uranium-bearing block of the Colorado Plateau, the zone of the Front Range with deposits of molybdenum and gold-silver ores, etc. There are known deposits of ores of iron, lead, zinc, nickel, as well as bauxites, phosphorites, barite, fluorite, etc. Deposits of oil and natural combustible gas, coal, rock and potassium salts, natural borates .

Climate. The northern regions of the Cordilleras of North America are located in the arctic (Brooks Ridge) and subarctic (most of Alaska, northern Canada) zones, the territory up to 42 ° north latitude on the coast (in the inner belt up to 37 ° north latitude) - in the temperate zone, to the south - in the subtropical, the Mexican Highlands and the California Peninsula - in the tropical, south of 12 ° north latitude - in the subequatorial zone. On the slopes facing the Pacific Ocean, almost all types of climate are characterized by relatively mild oceanic features, while for the interior regions they are sharper, continental. Altitudinal climate zonality is observed everywhere. In the northern part of the Cordillera of North America on the coast, winters are rainy, mild, summers are cool and damp, with frequent fogs. Average January temperatures, ranging from 0 to -5°C south of the Alaska Range, vary to -30°C (absolute minimum -62°C) in the Yukon Plateau; the average July temperatures are approximately the same - about 15°C. The annual amount of precipitation in the south of Alaska (mountains Chugach, St. Ilya, Wrangel) is 3000-4000 mm (the thickness of the snow cover is up to 150 cm or more), in the area of ​​the Yukon plateau - about 300 mm. In the temperate zone, cyclonic activity is observed throughout the year. In the coastal region of Canada, the average January temperatures are about 0 ° C, July 15.5 ° C. The annual amount of precipitation on the western slopes of the Coastal Range is 6000 mm, on the inner plateaus it decreases to 200-400 mm. In the Rocky Mountains, frosts down to -30°C are not uncommon in winter (the absolute minimum is -54°C), summers are sunny and dry, the average temperature in July is 19-20°C. 600-1200 mm of precipitation falls annually.

In the subtropical zone in the southern part of the US Cordillera and the northern part of the Mexican Highlands on the slopes facing the Pacific Ocean, the climate is oceanic (at the latitude of San Francisco - Mediterranean), in the interior - dry continental. Average temperatures increase as you move deeper into the mainland in January from 0 to 5°C (minimum to -17°C, Great Basin), in July from 14-17°C to 20-28°C (absolute maximum 56.7°C). C, Death Valley). On the coast, winters are rainy, with a decrease in annual precipitation from north to south from 2000 to 350 mm. The inner zone has dry, hot summers and relatively cold, moderately humid winters. Precipitation from 100 to 400 mm per year. In the tropical zone, the southeastern part is best moistened. The climate of the northwestern part of Mexico and the California Peninsula due to the influence of the Hawaiian anticyclone is trade wind, dry all year round, on the coast - with high relative humidity and fogs. In the northern part of the belt, the average temperatures of the coldest month (January) are 13-14°С, the warmest (May) 20°С, in the southern part - 21-23°С and 26-27°С, respectively. In the western and central regions of the northern part, the annual precipitation is 100-200 mm and increases to 500 mm in the south. The dry winter season with temperatures from 21° to 24°C lasts up to 6-8 months. In the southern part of the belt, 1500-2000 mm of precipitation falls annually. In the subequatorial belt, the average annual temperatures are 26-27°C. In the mountains at an altitude of 3800 m, they drop to 6 ° C, on the constantly wet Atlantic slopes, 2000-4000 mm of precipitation falls per year. Tropical hurricanes are not uncommon in the eastern part, bringing heavy rainfall and destructive power.

Glaciation. The area of ​​modern glaciation of the Cordilleras of North America is 67 thousand km2. Large differences in the latitudinal and altitudinal position of the Cordilleras of North America, as well as a sharp difference in the moistening of the territory, led to the uneven development of glaciation. The lowest (300-450 m) snow line is located on the Pacific slope of the mountains of South Alaska, in some places descending to the ocean level. On the northern slopes of the Chugach and St. Elias mountains, the snow limit is at an altitude of 1800-1900 m, on the Alaska Range - from 1350-1500 m (southern slope) to 2250-2400 m (northern slope). The area of ​​glaciation in the northwestern part of the Pacific ridges is 52 thousand km2. In the Brooks Range and the Mackenzie Mountains, glaciation is developed only on the highest peaks. To the south, the snow limit passes at an altitude of 1500-1800 m in the Coast Range and up to 2250 m in the Columbian Mountains. The total area of ​​glaciation in the interior of Alaska and the Cordillera of Canada is only 15,000 km2. In the United States, the snow limit to the south rises to 2500-3000 m in the Cascade and Rocky Mountains, up to 4000 m or more in the Sierra Nevada, up to 4500 m or more in Mexico. The area of ​​modern glaciation in the USA is 0.5-0.6 thousand km 2, in Mexico - 0.01 thousand km 2. All major types of glaciers are represented in the Cordillera of North America: extensive ice fields and caps, foothill or foot glaciers (for example, Malaspina), valley glaciers (for example, Hubbard in the Coast Range), cirque and short hanging glaciers, mostly disappearing (Sierra -Nevada). Star-shaped glaciers with numerous glacial flows form on volcanic peaks (for example, on Mount Rainier).

surface waters. Within the Cordillera of North America, the sources of many river systems of the mainland are located: Yukon, Peace - Mackenzie, Saskatchewan - Nelson, Missouri - Mississippi, Columbia, Fraser, Colorado, Rio Grande. The main watershed between the Pacific and Atlantic oceans is the eastern belt of mountains, so the rivers of the Pacific basin are the most full-flowing. To the north of 45-50 ° north latitude, the rivers are fed by glacier and snow with a clearly pronounced spring flood. In the south, rain feeding prevails with a winter maximum on the Pacific coast and spring-summer in the interior. In the southern part of the Cordilleras of North America, significant territories do not have a runoff into the ocean and are irrigated mainly by watercourses ending in drainless salt lakes (the largest of them is the Great Salt Lake). In the north, there are numerous fresh lakes of glacial-tectonic origin (Atlin, Kooteney, Okanagan, etc.), in the south - tectonic (Chapala, Nicaragua). The rivers of the Cordillera of North America have a huge hydroelectric potential and are widely used for electricity and irrigation. Large reservoirs have been built on the Yukon, Columbia, Colorado, and other rivers.

Landscape types. Due to the significant height throughout the Cordillera of North America, the altitudinal zonality of natural landscapes is clearly expressed. At the same time, the stretching of mountain ranges in the direction perpendicular to the main flow of moisture causes significant differences between the landscapes of the coastal (Pacific) and inland parts of the territory. The biggest changes in landscapes are associated with the latitudinal position of the mountain system, with its transition from the subarctic zone to the temperate, subtropical, tropical and subequatorial. In the northern part of the Cordillera, the Cordillera of Alaska and Canada are distinguished, in the southern part, the Cordillera of the USA, Mexico and Central America.

Cordillera of Alaska. With the exception of the coast of the Gulf of Alaska, permafrost rocks are widespread throughout the Cordillera of Alaska. The spectrum of altitudinal zones is represented by foothill woodlands (forest tundra) in river valleys and mountain tundra on high plateaus and slopes of ridges in northern Alaska. On the southwestern coast, subarctic oceanic meadows (reed grass, pike, sedge, forbs) are developed on gley soils and cryozems, on the slopes of the Aleutian Range from a height of 200-300 m - shrub tundra. On the southern slopes of the Alaska Range, forests rise almost to the snow line. Dense coniferous forests of Sitka spruce are common, to which, on the slopes of the Kenai, Chugach, Wrangel mountains, western hemlock, Nutkan cypress (red cedar) are mixed. In the river valleys flowing into Cook Inlet (for example, Matanuska), the land is partly used for agriculture.

Cordillera of Canada. Pacific slopes up to a height of 1200-1500 m are covered with productive tall forests dominated by conifers: giant and folded arborvitae (red cedar), western hemlock, Sitka spruce, Douglas fir, or pseudo-hemlock yew. Engelman spruce and alpine fir grow higher, subalpine coniferous light forests are widespread. Soils vary from mountain brown-taiga to mountain-podzolic. In inland areas north of 53° north latitude, taiga forests of white, black spruce and fir (balsamic, great, etc.) are widespread on podzolic soils, to the south (as evaporation increases) forests of pine (yellow, twisted) on gray forest soils are replaced by forest-steppe, in which islands of pine forests are combined with vast areas of dry meadows of fescue and feather grass, and in the southern part of the Fraser Plateau they turn into steppes. The altitudinal range of landscapes of the Columbian Mountains includes steppes, mountain coniferous forests of giant fir, Weymouth pine, Douglas, white and red firs, red cedar, balsam pine on podzolic-brown mountain forest soils and subalpine meadows. The ridges of the Rocky Mountains up to a height of 1800-2400 m are covered with dense mountain taiga forests of white spruce, balsam fir, banks pine and white birch, the bald tundra, snowfields, glaciers are developed higher, subalpine meadows appear in the northern part.

In forest areas, a significant proportion is made up of forest landscapes. In the southern parts of the wide intermountain basins there are arable and pasture landscapes. Secondary pine forests after fires and logging are widespread.

The Cordilleras of the United States have a unique variety of natural landscapes. The western slopes of the Pacific Ranges and the Rocky Mountains are characterized by the most complex structure of altitudinal zonality. On the slopes of high ridges (Vedovaya, Sierra Nevada), belts of mountain pine forests (yellow, lodgepole, sugar, and edible pines), mountain spruce and fir forests, subalpine coniferous light forests, and alpine meadows are developed. In the more arid southern regions of the Rocky Mountains, a steppe-forest-meadow type of altitudinal zonality is developed. On the slopes descending to the Great Plains, the mountain steppes are replaced by pine forests, and at an altitude of 1800-2200 m - by spruce-fir (Douglas fir, Engelman spruce) forests. The lower parts of the mountain ranges, facing the deserts of the interior plateaus, are occupied by patches of steppes of grama, selina, mesquite grass, scrub oaks, juniper, mesquite shrubs and succulents. The gentle western slope of the Sierra Nevada up to a height of 2800 m is covered with mixed forests dominated by yellow pine, Douglas, oaks (giant sequoia, or “mammoth tree” is found as an admixture), higher - fir and subalpine shrubs and meadows. On the dry eastern slopes, only pine-juniper woodlands grow. On the slopes of the northern part of the Coastal Ranges, mixed forests with douglas, arborvitae, western hemlock, and cypress on acidic mountain brown soils are common. The southern part of the ranges is characterized by summer-dry mixed hard-leaved forests of pines, Douglas, evergreen oaks, and strawberry trees on mountain brown soils. Evergreen sequoia groves have been preserved in northwestern California near the Pacific coast. On the slopes of the southernmost ranges, receiving 250-350 mm of precipitation per year, chaparral is common - a formation of dry-loving shrubby evergreen oaks with an admixture of acacia, sumac on gray-brown soils. The inner plateaus are occupied by sagebrush semi-deserts and deserts, in the eastern, more humid part, dry steppes of gram and bison grass are developed on chestnut soils. On the Columbian Plateau there are typical cereal steppes on ordinary chernozems. In the Great Basin, mid-mountain ranges covered with pine woodlands and hollows occupied by sagebrush semi-deserts with the participation of quinoa and garden trees alternate in a mosaic pattern. In subtropical regions, the vegetation cover is dominated by creosote bush, acacia, mesquite tree, cacti (opuntia, echinocactus, columnar cacti, saguaro, agave, yucca). The soils are predominantly brown desert-steppe, gray soils, solonchaks and solonetzes (in basins), mountain brown. On the Colorado Plateau, forest-steppe subtropical vegetation is common - pines and acacias, junipers and creosote bushes, Mexican succulents, and cereals. In the southern part of the interior highlands exotic features of desert landscapes are given by the picturesque forms of weathering of sandstones in the form of arches and pedestals.

Most of the forests in the Coast Ranges have been cut down, and agricultural and residential landscapes predominate. Irrigated plantations (vineyards, citrus fruits) and pastures are concentrated in the intermountain valleys. The Great California Valley is the largest area of ​​irrigated agriculture.

Cordillera of Mexico. The low ridges of the northern part of the Mexican Highlands and the short slopes of the Western and Eastern Sierra Madre facing its interior are covered with mountain coniferous-hard-leaved forests. Moist forest landscapes predominate in the southeastern and southern regions. The rest of the territory is dominated by succulent and shrubby (with a creosote bush) deserts and semi-deserts. The Mexican Highlands is the richest genetic center of the endemic Mexican flora, there are about 500 species of cacti, 140 species of agave, several species of yucca. The windward slopes of the peripheral ridges at the foot are occupied by low-growing spiny forests and light forests of caesalpinia (including quebracho), acacia, mimosa and mesquite on brown-red soils. To the south of 22° north latitude, on the southeast windward slopes of the Eastern Sierra Madre and on the southern slopes of the Transverse Volcanic Sierra, up to a height of 600-1000 m, constantly wet evergreen tropical forests grow with an abundance of ficuses, palms, and tree ferns on yellow ferrallitic soils. The forests are distinguished by an exceptionally rich species composition of woody plants: mahogany (mahogani, or caoba), paleto, allspice, breadfruit, cordia, andir, chlorophore. On the slopes facing the moisture-saturated trade winds, at an altitude of 1000-2500 m, broad-leaved forests of oaks, liquidambar, maples, willows, sambucus, spikes with tree-like ferns and podocarpus in the lower tier dominate. The trees are entwined with vines and epiphytes from begonias, bromeliads and orchids. The upper parts of the slopes are occupied by coniferous-deciduous and coniferous forests of Weymouth and Mexican pines and sacred fir. The Pacific slopes of the ridges and the lee slopes of volcanoes are covered with seasonally wet winter-dry deciduous-evergreen forests of various species composition. In the forests there are up to 100 species of tree species, including cordia, carapace, cedrela, mahogany, enterolobium, chimenea, andir, chlorophore, Brazilian calophyllum. Dry low-growing deciduous and semi-deciduous tropical forests grow in arid interior basins in the south of the Mexican Highlands. Breeds such as cedrela, bursera, morning glory, ceiba cotton tree, pseudobombax, cordia are widespread. In the northwest of the Mexican Highlands and on the California Peninsula, tropical coastal deserts dominate with peculiar tree and shrub formations with the participation of succulents, mesquite, yucca, and ironwood.

The Cordillera of Mexico is an area of ​​extensive grazing and irrigated agriculture. On the plains and in the foothills, large areas of forests have been cleared for plantations of sugar cane, bananas, cocoa, coffee and tropical fruits, in arid regions - cotton and agave.

In the Cordillera of Central America, the forest-meadow type of altitudinal zonality is clearly expressed. Oceanic tropical and subequatorial humid and moderately humid forests predominate on the abundantly moistened northeastern slopes and seasonally humid forests on the leeward southwestern slopes. In the mid-mountain belt on the slopes there are mixed evergreen-deciduous and coniferous forests on siallite yellow-brown soils. Savannahs and light forests are widespread in the basins and along coastal areas. The eastern part of Central America is dominated by evergreen and semi-evergreen (rain) forests of complex composition - selvas with an abundance of lianas and epiphytes, palms, ficuses, bamboo, trees with valuable wood, rubber plants on ferrsiallite and allite red-yellow soils. The biological diversity of forest formations is enormous, there are about 5,000 species of vascular plants. The most common tree species are mahogany, akhras, brasimum, paleto, allspice, breadfruit, ampelosera, mazakilla, cordia, Brazilian calophyllum, castilla, Amazonian terminalia. At an altitude of about 2000 m, “forests of fog” appear from beeches, lindens with thickets of tree-like ferns and bamboos. Alpine meadows are developed on high ridges and volcanoes. The monsoon-prone Pacific plains and low mountains of the extreme south of Central America are covered with deciduous evergreen forests (Tambelnia, Ipomoea, Bombax). Plantations of coffee, bananas, sugar cane, etc. predominate on the lowlands and gentle slopes of the mountains.

Environmental problems and protected natural areas. The adverse effects of human economic activity are manifested in a large area of ​​the Cordilleras of North America and are associated with the intensive use of natural resources, primarily forest, mineral, soil, and water. In the southern part of the Cordillera of Canada and in the western United States, forests have been intensively cut down since the 2nd half of the 20th century. Plantations of Sitka spruce, Douglas, and redwoods were especially affected. In the south of the Coast Range and the Columbia Mountains, in the Cascade Mountains, clearings occupy not only gentle, but also steep areas. Deforestation, fires, shooting of animals and loss of their habitats, high recreational loads create an unfavorable ecological situation in a number of regions of the Cordilleras of North America. In large areas, accelerated erosion is manifested. Pollution of water sources with pesticides and nitrates is noted. Mexico has a deforestation rate of 0.8% per year, with the highest erosive loss in the Cordillera of North America. Valuable species of trees are cut down: cedrela, caoba, or mahogany, quebracho, ceiba, camphe tree, Brazilian calophyllum, pines, sacred fir. A serious problem associated with deforestation and oil pollution of coastal waters of the Gulf of Mexico is the conservation of mangrove ecosystems. In the state of Arizona (USA), as well as in the basin of the city of Mexico City (Mexico), groundwater depletion is observed.

The largest and most famous protected natural areas in the Cordillera of North America are Denali National Parks, the Gates of the Arctic, Katmai, Lake Clark (USA); Montes Azules Biosphere Reserve, National Parks Nevado de Toluca, Tepozteco, Popocatepetl Istaxiuatl, Pico de Orizaba (Mexico). The World Heritage List includes the parks and reserves of Mount Wrangel and Mount St. Elijah, Kluane, Glacier Bay, Waterton-Glacier International Peace Park (all in the USA and Canada), parks of the Canadian Rockies (Canada), national parks Yellowstone, Olympic, Grand Canyon, Redwood, Yosemite (USA), Mariposa Monarca Biosphere Reserve (Mexico), Rio Platano National Parks (Honduras), Darien, Coiba (Panama), Talamanca - La Amistad (World Biosphere Project, Costa Rica and Panama), protected area of ​​Guanacaste (Costa Rica).

Lit .: Vitvitsky G.N. Climates of North America. M., 1953; King F. B. Geological development of North America. M., 1961; Tamayo J. L. Geografia general de Mexico. 2nd ed. Mekh., 1962. Vol. 1-4; Antipova A. V. Canada. M., 1965; Ignatiev G. M. North America. M., 1965; Thornbury W. D. Regional geomorphology of the United States. N.Y., 1965; Relief of the Earth. M., 1967; Sanderson A. North America. M., 1979; Kraulis J. A., Gault J. The Rocky Mountains. N.Y., 1986; Wilson K. M., Hay W. W., Wold C. M. Mesozoic evolution of exotic terranes and marginal seas, Western North America // Marine Geology. 1991 Vol. 102; Golubchikov Yu. N. Geography of mountainous and polar countries. M., 1996; Gebel P. Natural Heritage of Humanity. M., 1999; Khain V. E. Tectonics of continents and oceans (year 2000). M., 2001.

T. I. Kondratieva; V. E. Khain (geological structure and minerals).

McKinley (Nic McPhee) McKinley (Cecil Sanders) Airplane view of the Cordillera (Vivis Carvalho) Denali National Park and Preserve Cordillera (Ross Fowler) Ross Fowler Helicopter in the background of the Cordillera (The U.S. Army) Pablo Trincado Denali National Park (Harvey Barrison) View of the Cordillera (Maykol Saavedra) View of the Cordillera (Miguel Vera León) Beautiful view of McKinley (Christoph Strässler) Mount McKinley, Denali National Park (Christoph Strässler) The highest point of the Cordillera (Denali) National Park and Preserve Denali National Park and Preserve Denali National Park and Preserve Carlos Felipe Pardo Cordillera, Andes (Ross Fowler) View of the Cordillera, Chile (Daniel Peppes Gauer) Cordillera (Nacho) Cordillera -Blanca, Peru (Mel Patterson) Cordillera Blanca, Peru (Mel Patterson) Cordillera Blanca, Peru (Mel Patterson)

What continent are they located on? The Cordilleras are unusual in that they are located on two continents at once. If you look at the map, you can see that these mountains stretch almost 18,000 kilometers from north to south, along the Pacific coast of North and South America - from Alaska to the island of Tierra del Fuego.

The Cordilleras are subdivided into two major systems, the Cordillera of North America and the Cordillera of South America, also commonly known as the Andes. Within the framework of this article, only the Cordillera of North America, stretching from Alaska to southern Mexico, will be described.

The height of the Cordillera is the highest point

The highest peak of the Cordilleras of North America is Mount Denali, until recently known as McKinley, whose height is 6190 m. Its coordinates are 63 ° 04′10 ″ north latitude 151 ° 00′26 ″ west longitude.

Mount McKinley, Denali National Park (Christoph Strässler)

Geographical characteristic

The length of the mountain system is almost 9000 km with a width of 800 to 1600 km. At the same time, the Canadian Cordilleras have the smallest width, and the mountains reach the maximum width in the USA. Almost along their entire length, these mountains form 3 belts - eastern, western and internal.

View of the Cordillera (Miguel Vera León)

The Eastern Belt, also known as the Rocky Mountain Belt, forms a series of high mountain ranges that form a watershed that separates the Pacific Ocean to the west and the Atlantic and Arctic Oceans to the east. In addition to the Rocky Mountains themselves, it includes the Brooks Range in Alaska, the Richardson Range and the Mackenzie Mountains in Canada, and the Eastern Sierra Madre mountain range in Mexico. The highest point of the belt is Mount Elbert, which is located within the state of Colorado. Its peak has an absolute mark of 4399 meters.

The western belt is represented by folded and volcanic ridges that run parallel to the Pacific coast. It includes the Aleutian, Alaska and Coast Ranges, the Cascade Mountains, the Sierra Nevada mountain system, the Western and Southern Sierra Madre, and the Transverse Volcanic Sierra. Within the Alaska Range is the highest mountain not only of this belt, but of all of North America - Mount Denali (McKinley), whose height is 6190 m.

The inner belt includes a number of plateaus and plateaus located between two other belts. It includes the Fraser Plateau, the Columbia Mountains, the Great Basin Highlands, the Colorado Plateau, and the Mexican Highlands.

The three main mountain arcs of the Cordillera

In Central America and the islands of the Caribbean, the Cordilleras fall into three main mountain arcs, which are separated by depressions.

Cordillera (Ross Fowler)

Thus, the arc, which is a structural continuation of the Rocky Mountains and the Eastern Sierra Madre, forms the mountains of the islands of Cuba, northern Haiti and Puerto Rico.

The southern Sierra Madre is geologically continued by the mountains of Jamaica, the south of Haiti, and in Puerto Rico they merge with the mountains of the first arc.

The third arc runs from the southern borders of Mexico through all the countries of Central America to the west of Panama. Its continuation is the Andes.

The Cordilleras cross all the geographical zones of the continent, from the arctic in the north to the subequatorial in the south. During their course, the climate of the area, flora and fauna change very much.

Natural conditions change no less strongly when moving from west to east of the mountain system; often the climate and vegetation change in this direction much faster than when moving from north to south. In addition, as in all high mountains, altitudinal zonation is of great importance here.

Geology

The Cordilleras of North America are composed of various geological structures of different ages. The mountains began to form in the Jurassic, a little earlier than the Andes, whose formation began only at the end of the Cretaceous.

Mountain building has not ended to this day, as evidenced by the fairly frequent earthquakes and the presence of active volcanoes. Approximately north of the parallel of 45 degrees north latitude, Quaternary glaciation had a significant impact on the formation of the relief.

In the Cordillera, gold, mercury, tungsten, copper, molybdenum and other ores are mined. Of the non-metallic minerals, there are deposits of oil, coal, etc.

Hydrography

In the Cordillera there are sources of such large rivers as the Yukon, Mackenzie, Missouri, Columbia, Colorado, Rio Grande and many others.

Denali National Park and Preserve

To the north of the 50th latitude, the snow supply of watercourses predominates, and to the south - rain. Many mountain rivers have great energy potential. Especially many hydroelectric power plants have been built in the Columbia River basin.

In the interior regions of the mountain system there are large drainless areas. The discharge of a few streams, which are mostly temporary, is carried out here into salty drainless lakes, the largest of which is the Great Salt Lake.

Freshwater lakes are also quite numerous: Atlin, Okanagan, Kootenay (Canadian Cordilleras); Utah, Tahoe, Upper Klamath (USA).

Climate

Due to the very long extent in the meridional direction, the climate in the Cordillera varies greatly. In Alaska, Canada and the northwestern United States, on the Pacific slopes, the climate is characterized as rather mild and humid.

Denali National Park (Harvey Barrison)

The total precipitation on the islands off the coast of Canada and Alaska, as well as on the western slope of the Coast Ranges, exceeds 2000 mm, and in some areas can reach 6000 mm.

The maximum precipitation here occurs in winter, and therefore, most of it falls in the form of snow. Winters are relatively warm and humid, while summers are cool and dry.

Average temperatures in July usually vary from 13 to 15 degrees, and average temperatures in January - from 0 to 4 degrees.

Away from the coast, the climate is very different; it is characterized as continental. On some plateaus, the amount of precipitation does not exceed 400-500 mm. Winters here become more frosty, and summers, on the contrary, are warmer.

View of the Cordillera (Maykol Saavedra)

In the southwestern United States, the climate is characterized as subtropical. Precipitation here also falls mainly in winter. Their number can reach up to 2000 mm on the western slopes of the Coast Ranges, and up to 1000 mm in the west of the Sierra Nevada.

In the Rocky Mountains, by contrast, eastern elephants receive more rainfall (700-800 mm) than western elephants (300-400 mm). This is due to the fact that air masses from the Atlantic Ocean reach the eastern slopes. Some deep interior basins receive less than 200 mm of precipitation per year.

The most arid deserts are the Mojave and Sonoran deserts, as well as the western part of the Great Basin. In some areas of these deserts, only about 50 mm of precipitation falls.

The climate of the intermountain basins is characterized as sharply continental with very large daily and annual temperature fluctuations. In the intermountain depression "Death Valley" the highest temperature in the world was recorded, which amounted to 56.7 degrees, while in winter the temperatures here often drop below zero.

The total area of ​​glaciers is more than 60,000 square kilometers. The height of the snow line varies from 300-450 meters on the coastal slopes of the mountains of the south and southeast of Alaska to 4500 meters or more in Mexico.

In the Rocky and Cascade Mountains in the United States, the snow line is at an altitude of 2500-3000 meters, and in the Sierra Nevada mountains - up to 4000 meters.

Flora and fauna

The flora of the Cordillera varies greatly not only depending on the height above sea level, as in all other mountains; it also strongly depends on the latitude of a particular area and on its distance from the ocean.

Denali National Park and Preserve

In the north of the mountain system, the slopes of the ridges are covered mainly with coniferous forests.

The interior plateaus, plateaus and depressions of the United States and northern Mexico are occupied mainly by arid steppes and deserts, which is explained by the rain shadow effect, due to which moist air masses are trapped by high mountains and almost never reach these areas.

Part of the coast of California and northwestern Mexico is characterized by hard-leaved shrub vegetation known as chaparral.

On the western slopes in southern Mexico and Central America, both evergreen and deciduous tropical forests are common. On the eastern slopes and in the intermountain basins, the vegetation is much more sparse and is represented by various shrubs, cacti and savannahs. The variety of cacti and agaves is especially great, of which hundreds of species are found here.

The fauna of mountain forests is quite similar to the fauna of the lowland North American taiga. Grizzly bears, foxes, wolves, beavers, wolverines, lynxes, cougars, etc. are found here. Of the species characteristic only of the mountains, mountain sheep are found. Pumas, coyotes, steppe wolves, hares, and various rodents live in the steppes and deserts. The fauna of the tropical forests is represented by various monkeys; of predators here you can meet the jaguar.

Beautiful view of McKinley (Christoph Strässler)

National parks in the Cordillera

On the territory of the Cordillera there are numerous national parks that attract millions of tourists from all over the world. Photos of the local extraordinary landscapes amaze even people who have traveled a lot around the world.

On the western part of the Sierra Nevada mountains is one of the most famous national parks in the United States - Yosemite, which is famous for its high granite cliffs, waterfalls and simply untouched nature.

A little to the south of it is Sequoia Park, famous, as the name implies, thanks to its giant sequoias. Mount Rainier National Park is located in the Cascade Mountains, on the territory of which the volcano of the same name is located. On the Colorado Plateau is the oldest park in the United States - the Grand Canyon, which is a canyon of the Colorado River.

Photo gallery not open? Go to site version.

Description and characteristics

The total length of the mountain range is more than 18 thousand km, the maximum width in North America is 1600 km, in South America - 900 km. Almost throughout its entire length, it plays the role of a watershed between the basins of two outstanding oceans - the Atlantic and the Pacific, as well as a pronounced climatic natural boundary. In terms of height, the Cordillera is second only to the Himalayas (the highest mountains in the world, located between the Tibetan Plateau and the Gangetic Plain) and the mountain ranges of Central Asia. The highest peaks of the Cordillera are McKinley Peak (English Mount McKinley; Alaska, North America, 6193 m) and (Spanish Aconcagua; Argentina, South America, 6962 m).

The Cordilleras cross almost all geographical zones (except for the Antarctic and Subantarctic). The mountain system is characterized by a wide variety of landscapes and a clearly defined altitudinal zonality. The snow limit lies at altitudes: in Alaska - 600 m, in Tierra del Fuego - from 600 to 700 m, in Bolivia and Peru it rises to 6500 m. If in the northwest of North America and in the southeast of the Andes glaciers descend almost to ocean level , then in the tropical zone they crown only the highest peaks.

The mountain system is divided into 2 parts, consisting of many parallel ranges: the Cordillera of North America and the Cordillera of South America, called. One mountain branch passes through the Antilles, the other passes into the territory of the South American mainland.

The main processes of mountain building, as a result of which the Cordillera were formed, took place in North America from the end of the Jurassic period to the beginning of the Paleogene, in South America - from the middle of the Cretaceous period, actively continuing in the Cenozoic era. To date, the formation of the mountain system has not been completed, which is confirmed by frequent earthquakes and high-intensity volcanic processes. There are more than 80 active volcanoes here, of which the following are the most active: Katmai (eng. Katmai; south p / o Alaska), Lassen Peak (eng. Lassen Peak; North America), Colima (Spanish Volcan de Colima; western regton Mexico), (Spanish Volcan de Antisana; 50 km southeast of Quito, Ecuador), (Spanish Sangay; Ecuador), (Spanish Volcan San Pedro; northern Chile), Orizaba (Spanish Pico de Orizaba ) and Popocatepetl (Spanish: Popocatepetl) in Mexico, etc.

Relief structure

The relief of the Cordillera is quite complex, the system is subdivided into folded-blocky ridges, volcanic mountains and developing young platform depressions (accumulative plains). Mountain folds were formed at the junction of 2 lithospheric plates, in the area of ​​compression of the earth's crust, which is crossed by many faults starting at the bottom of the ocean.

The largest relief structures of the Cordillera include: Alaska Range (eng. Alaska Range; Alaska), Coast Ranges (eng. Coast Ranges), Rocky Mountains (eng. Rocky Mountains; western USA and Canada), Colorado Plateau (eng. Colorado Plateau; west USA), Cascade Mountains (Eng. Cascade Range; West of North America), Sierra Nevada (Spanish: Sierra Nevada; North America). The ranges are cut by deep river valleys called canyons.

Cordillera

Andean Cordillera, or (Spanish Cordillera de los Andes) - the southern part of the Cordillera with a length of about 9 thousand km, they border the entire South American continent from the northwest. The average width of the Andes is 500 km (maximum width: 750 km), the average height is about 4 thousand meters.

The Andean ranges are a giant inter-oceanic divide. In the mountains, the rivers of the Atlantic Ocean basin originate and flow to the east (and many of its tributaries, tributaries of Paraguay, the Patagonian rivers), to the west - small rivers of the Pacific Ocean basin.

The Andean ranges serve as the most important climatic barrier, protecting the territories lying to the west of the Main Cordillera chain from the influence of the Atlantic Ocean, and the eastern territories from the influence of the Pacific Ocean. The mountains stretch across 5 climatic zones: equatorial, subequatorial, tropical, subtropical and temperate.

Due to the impressive length, the individual landscape parts of the Andes are strikingly different from each other. According to the nature of the relief and climatic differences, 3 main regions are distinguished: Northern, Central and Southern Andes.

The Andes stretch from north to south through the territories of 7 South American states: Colombia, Venezuela, Ecuador, Peru, Bolivia, Argentina and Chile. Behind (Spanish Drake) is the Antarctic Peninsula, which is a continuation of the South American Andes.

Minerals

The Cordilleras are characterized by a variety of minerals, in particular, huge reserves of ferrous and non-ferrous ores. The Andes are predominantly rich in non-ferrous metal ores, there are significant deposits of tungsten, vanadium, bismuth, tin, molybdenum, lead, arsenic, zinc, antimony, etc.

The territory of Chile has large deposits of copper. In the foothills of Argentina, Bolivia, Peru, and Venezuela there are oil and gas deposits, as well as brown coal deposits. In the Bolivian Andes there are iron deposits, in the Chilean Andes - sodium nitrate, in the Colombian - underground pantries of platinum, gold, silver and emeralds.

Cordillera: Climate

Northern Andes. The northern part of the Andes belongs to the subequatorial zone of the northern hemisphere with alternating dry and wet seasons. The rainy season is from May to November. The Caribbean Andes are located at the junction of the tropical and subequatorial belts; a tropical climate with low rainfall dominates here all year round.

The equatorial belt is characterized by an abundance of precipitation and an almost complete absence of seasonal temperature fluctuations, for example, in (Spanish Quito - the capital of Ecuador) fluctuations in average monthly temperatures per year is about 0.4 ° C. The altitudinal zonality is clearly expressed here: in the lower part of the mountains the climate is hot and humid with almost daily precipitation, in the lowlands there are many swamps. As the altitude increases, the amount of precipitation decreases, but the massiveness of the snow cover increases. From a height of 2.5 - 3 thousand meters, daily temperature fluctuations increase (up to 20 ° C). At altitudes of 3.5 - 3.8 thousand meters, the average daily temperatures are about + 10 °C. Even higher - the climate is dry, harsh, with frequent snowfalls; at positive daytime temperatures, severe frosts occur at night. Above 4.5 thousand meters - the zone of eternal snow.

Central Andes. One can note an obvious asymmetry in the distribution of precipitation: the eastern Andean slopes are moistened much more intensively than the western ones. To the west of the Cordillera Main chain, the climate is desert, with very few rivers, in this part of the Andes extends (Spanish: Desierto de Atacama), the driest place on the planet. In some places the desert rises up to 3 thousand meters above sea level. Few oases are mainly located in the valleys of small rivers, fed by water from the melting of mountain glaciers. The average January temperature of the coastal zones ranges from +24°C (in the north) to +19°C (in the south); mid-July - from +19°C (in the north) to +13°C (in the south). Above 3 thousand meters there is also little precipitation, there are invasions of cold winds, then the temperature sometimes drops to -20 ° C. The average July temperature is not higher than +15°C.

Fog is frequent at low altitudes. The climate is very severe, the average annual temperatures do not rise above +10°C. It has a great softening effect on the climate of the surrounding area.

Southern Andes. The Chilean-Argentinean Andes are characterized by a subtropical climate, with dry summers and wet winters. As the distance from the ocean increases, the continentality of the climate increases, and seasonal temperature fluctuations increase.

As you move south, the subtropical climate of the western slopes gradually turns into a temperate oceanic climate. Powerful western cyclones bring a huge amount of precipitation to the coast - more than two hundred days a year there are heavy rains, thick fogs are frequent here, the sea is constantly stormy. The eastern slopes are drier than the western ones, the average summer temperature on the western slopes of the mountains ranges from +10°C to +15°C.

At the southernmost tip of the Andes (Tierra del Fuego), the climate is very humid, shaped by powerful southwesterly winds. Precipitation falls for most of the year, often in the form of drizzle; low temperatures prevail throughout the year with very little seasonal variation.

Vegetation

Impressive heights, a pronounced difference in moistening of the western and eastern slopes of the mountains - all this determines the great diversity of the vegetation cover of the Andes, 3 altitudinal belts are usually distinguished here:

• Tierra caliente (Spanish Tierra caliente - "Hot Land"), the lower forest belt in the mountains of Central (up to 800 m) and South America (up to 1500 m);
• Tierra fria (Spanish Tierra fria - "Cold Earth"), the upper forest belt in Central and South America, from 1700-2000 m (in low latitudes) to 3500 m (under the equator);
• Tierra Ellado (Spanish: Tierra helado - "Frosty Land"), a high mountain belt (between 3500-3800 and 4500-4800 m) with a harsh climate.

AT Venezuelan Andes shrubs and deciduous forests grow. The lower slopes ("tierra caliente") from the Northwestern to the Central Andes are covered with humid tropical (equatorial) and mixed forests, which are characterized by various palm trees, banana and cocoa trees, ficuses, etc.

In the tierra fria zone, the nature of the vegetation changes noticeably: tree-like ferns, bamboos, cinchona, and coca bushes are typical for this zone. Between 3000 and 3800 m shrubs and stunted trees grow: creepers and epiphytes, tree ferns, myrtle, heather and evergreen oaks are common. Even higher, predominantly xerophytic vegetation grows, moss swamps and lifeless rocky cliffs are located. Above 4500 m there is a belt of ice and eternal snow.

South, in the subtropics Chilean Andes evergreen shrubs predominate. High mountain plateaus in the north are covered with wet equatorial meadows - (Spanish: Paramo), in Peruvian Andes and in the east of Tierra helado - dry mountain-tropical cereal steppes of Khalka (Spanish: Hulka), on the Pacific west coast - desert vegetation, in the Atacama Desert - numerous succulent epiphytes and cacti. Between 3000 m and 4500 m semi-desert vegetation (dry puna) prevails: dwarf shrubs, lichens, cereals and cacti. To the east of the Main Cordillera, a large amount of precipitation falls, here there is steppe vegetation with cushion-shaped shrubs and various grasses: feather grass, fescue, reed grass.

Tropical forests (cinchona, palm trees) rise along the wet slopes of the Eastern Cordillera up to 1500 m, turning into undersized evergreen forests (bamboos, ferns, lianas); and above 3000 m - in the high-mountain steppes. A typical representative of the flora of the Andean highlands (found up to 4500 m) is polylepis (Polylepis, Rosaceae family) - this plant is common in Bolivia, Peru, Colombia, Chile and Ecuador.

In the middle part of the Chilean Andes, today the mountain slopes are practically bare, there are only separate groves consisting of pines, araucaria, beeches, eucalyptus and plane trees.

The slopes of the Patagonian Andes are covered with subarctic multi-tiered forests of tall trees and evergreen shrubs; there are many lianas, mosses and lichens in the forests. To the south there are mixed forests in which magnolias, beeches, tree ferns, conifers and bamboos grow. Oriental Patagonian Andes overgrown mainly with beech forests. The extreme south of the Patagonian slopes is characterized by tundra vegetation.

Mixed forests of tall deciduous and evergreen trees (canelo and southern beeches) occupy a narrow coastal strip in the west of the Andean ranges of Tierra del Fuego; almost immediately above the border of the forest, a snow belt extends. Subantarctic alpine meadows and peatlands are widespread in the east.

Animal world

The Andean fauna is characterized by a large number of endemic species. Alpacas and llamas live in the mountains (the local population uses representatives of these species to obtain meat and wool, as well as pack animals), various types of monkeys, pudu deer, relic spectacled bear and gaemal (endemic) guanaco, vicuña, sloth, Azar fox, marsupial opossum, chinchilla, anteater and degu rodents. In the south live: Magellanic dog, blue fox, tuko-tuko (endemic rodent), etc.

A variety of birds live in abundance in the "foggy forests" (tropical rainforests of Colombia, Ecuador, Bolivia, Peru and northwestern Argentina), among them are hummingbirds, which can be found even at altitudes of more than 4 thousand meters. The endemic condor lives at altitudes up to 7 thousand m. Some species of animals, such as chinchillas (which were uncontrollably exterminated in the 19th and early 20th centuries for valuable skins), as well as the Titicaca whistler and wingless grebes, living only in the vicinity of Lake Titicaca (Spanish: Titicaca), today are on the verge of extinction.

A feature of the animal world of the Andes is a wide species diversity of amphibians (about 1000 species). Also, about 600 species of mammals (13% of which are endemic), more than 1.7 thousand species of birds (33.6% are endemic) and up to 500 species of freshwater fish (of which 34.5% are endemic) live in the Andean mountains. .

Despite the fact that few people live in large areas, the vulnerable nature of the region has been damaged, which is difficult to restore.

In Alaska, 13 national parks have been created, where typical natural complexes are protected, as well as local animal species - mountain sheep, caribou, black bear (baribal) and grizzly.

Cordillera of Canada and Northwestern United States

This part of the Cordillera system is characterized by a relatively low mountain height and relative narrowness. It includes the Canadian Coast Range, the inland Fraser Plateau, the Columbian Plateau, and the Rocky Mountains up to about 48°N. sh. The westernmost orotectonic zone passes into the islands here. It is only in the south that the region expands, as this zone "returns" to the mainland. Its southern border runs along the northern outskirts of the Great Basin and the Sierra Nevada mountains.

Young folded ridges of the coastal zone are fragmented and lowered. The intermountain valleys are flooded with the sea and are straits and narrow long bays, deeply protruding into the land. The coast ridge continues the Nevadian zone, but its height is less than that of Alaska (2000-3000 meters, in the south - up to 4000 meters). It is dissected and processed by glaciers. The coast here is fjord-like.

Some general lowering of the mountains of the region in comparison with other parts of the Cordillera is presumably explained by the large area of ​​glaciation, both ancient and modern. It is possible that the earth's crust here, as it were, sags under the weight of ice. The inner plateaus are composed of lava covers reaching a thickness of up to 1200 meters. They are high (800-1500 meters), but narrow, expanding only to the south (Columbia Plateau - up to several hundred kilometers). Rivers, cutting through the plateau, form canyons. The Rocky Mountains consist of a series of longitudinal ridges up to 4000 meters high, separated by valleys and abruptly dropping to the east. A graben filled with glacial deposits stretches along the western slopes - the "Moat of the Rocky Mountains". It is believed that this is a continuation of the mid-ocean rift.

The amount of precipitation decreases from west to east (a common pattern for the Cordillera). The ocean coast receives 2000-3000 mm per year. Maximum - winter, snow cover in the mountains reaches an average thickness of up to 6-9 m. Summer is cool, cloudy. The climate is the same as on the coast of Alaska, only a little warmer.

Here, as well as on the coast of Alaska, "rain" coniferous forests of Sitka spruce, Douglas, western hemlock, etc. grow with dense undergrowth, epiphytic mosses, and ferns.

On the inner plateaus, features of continentality appear: there is little precipitation (300-400 mm), temperature amplitudes increase. In the north there are areas of taiga on podzolic soils, which are replaced by forest-steppe and steppe to the south. Wormwoods appear in the extreme south. The slopes of the Rocky Mountains are covered with pine forests and shrubs, while the valleys are treeless.

The Cordillera of Canada has a large number of mountain glaciers of various types.

The region is rich in minerals, both ore (copper, iron, lead, zinc, silver, gold) and non-metallic, such as coal. Forest resources and the hydro potential of rivers are used. Tourism is developed, especially in the mountains of British Columbia. A number of national parks have been created for nature protection - Jasper, Banff, Glacier, etc.

Cordillera of the Southwestern United States

The physiographic country is located approximately between 48 ° and 32 ° N. sh. in the widest and most diverse part of the Cordillera mountain system. The region experienced a general uplift in the Paleogene-Neogene, which was accompanied by faults, denudation, and large erosional dissection.

Here, the manifestations of faults are most clearly visible at the junction of the continental (North American) and oceanic (Pacific) crust. Quite clearly visible are the zones of deep subsidence of the oceanic crust under the continental crust in the California region, where there is a huge gap in the coastal areas. The San Andreas Fault extends in a northwesterly direction for almost 900 km. It has existed since the pre-Mello time, and is still very active today.

Three structural and morphological zones are clearly traced: axial, the most ancient - Nevadian, in the east - Laramian, in the west - young Cenozoic Coast Ranges, the development of which continues to the present.

Modern climatic conditions are characterized by high contrast, which is associated with the position in two climatic zones (temperate and subtropical), significant altitude amplitudes, and the presence of mountain barriers in the path of sea air masses.

Areas with annual precipitation up to 100 mm and maximum temperatures up to +57 ° C (Death Valley) are adjacent to mountains where annual precipitation is up to 2000 mm and negative temperatures prevail even in summer (upper parts of the Sierra Nevada). In the west it has a Mediterranean type climate. In other parts of the region, features of continentality appear in climatic conditions.

Different parts of the region differ significantly in all components of nature.

The eastern (Laramian) structures of the Rocky Mountains are often referred to as the continental divide, with elevations of 1,800 m and above.

The ridges are anticlinal folds that have Precambrian cores. Some of them are elongated in the general direction of the entire mountain system from northwest to southeast (the Front Range, Sangre de Cristo, etc.), but there are ranges of a different orientation, sometimes even sublatitudinal. Between them formed vast plateau-like areas connecting the Great Plains with the Great Basin - the so-called "parks". They are composed of sedimentary strata of Paleozoic-Mesozoic age. The summit areas were covered by the Wisconsin glaciation, preserved troughs and kars. Spruce-fir and pine forests are widespread on the slopes of the mountains, the bottoms of the "parks" are usually treeless. In the south and along the slopes of the mountains, steppes and semi-deserts rise.

In the northeast is the Yellowstone Plateau (“yellowstone” in English means “yellow stone”) with a Paleogene cover and young lava covers, having a thickness of more than 1000 meters.

It is known as one of the largest areas of the Earth with geysers and thermal springs. Under powerful lava covers (300-600 meters) forests of ancient sequoias are buried. Their petrified trunks are often found (there is a section with 12 layers of petrified forest covered with volcanic ash). In 1872, the Yellowstone National Park was founded here (an area of ​​about 900 thousand hectares, located at an altitude of 2100 m to 3400 m). There are 200 water thermal and mud springs, about 300 geysers on the territory of the park. The greatest geyser Exilor with a griffon diameter of 8-10 meters "works" here, which throws water up to 100 meters up. The mineral sediment forms geyserite of various shades - blue, purple, pink, etc. The wildlife of the park is rich - bison (their number has increased 20 times since the beginning of the century and amounts to several hundred heads), a variety of brown bear - grizzly, coyote, fox, skunk, badger, puma and 150 species of permanent birds. Access to the park is regulated. The park is divided into zones, each of which solves certain problems: there is a strict protection zone where no human influence is allowed, a “managed” protection zone (to preserve natural landscapes), an organized tourism zone and a tourist-administrative zone (camping sites, parking lots, cafes , administrative buildings).

In the inner part of the physiographic country, west of the Rocky Mountains, there is the largest inland highland - the Great Basin and the Colorado Plateau.

The Great Basin has undergone a complex history of formation: Paleozoic and Mesozoic folding, Mesozoic sedimentation, and intense deformation of structures.

The modern relief was formed in the Cenozoic under the influence of submeridional faults along the rift between the Rocky Mountains and the Sierra Nevada mountain range. Clastic material filled intermountain depressions. Active volcanism appeared in the northwest. At present, the rejuvenated relief with numerous internal drainless depressions has a wide variation in absolute heights - from 1500-2000 meters to -85 meters (Death Valley). This is the result of powerful vertical movements.

Due to the barrier role of the Cascade Mountains and the Sierra Nevada, which prevent the transfer of Pacific air masses, a climate with well-defined features of continentality has developed.

The annual amount of precipitation here does not exceed 90-100 mm. The result of the dry climate is the weak development of the river network, which has no flow into the ocean. There is no removal of destruction products outside the basin, so the clastic material buries and levels the mountainous terrain.

Within the highlands, there are a hundred relict lakes - the Great Salt Lake (the remnant of Bonneville Lake, most of which was drained by the Snake River).

The soil and vegetation cover and fauna are typical for deserts and semi-deserts of the temperate and subtropical zones. The Americas have a different appearance than the deserts of Eurasia.

Along with saline and rocky deserts, there are areas with a pronounced seasonality, when ephemera bloom brightly in spring. In the southern part of the basin, a “woodland” of cacti (up to 10 meters high) and yucca has formed. Pine and juniper with steppe grasses grow on the slopes of the ridges. Picturesque Sonoran Desert in Arizona. The hilly plain is composed of sedimentary rocks and has insular volcanic mountains. The desert is inhabited by many species of cactus, including the giant tree squaw. Volcanic mountains overgrown with this plant seem from afar to be covered with a sparse forest, devoid of small branches and leaves. The age of cacti is tens and hundreds of years, height 10-12 meters, trunk thickness up to 70 cm, coyotes and many poisonous snakes live under them. In addition to cacti, other xerophytic plants grow in Sonora, which can tolerate not only drought, but also extremely high air and soil temperatures. The fauna of the desert is diverse and interesting.

The Colorado Plateau is an area of ​​horizontal occurrence of Phanerozoic rocks of different lithological composition. A highly elevated structural plain (more than 3,500 meters in places) is framed by cuestas.

The deeply incised river network has created steep-sided canyons that expose all the different colored rocks that make up the plateau. On the outskirts of the plateau, volcanic rocks are widely represented in the form of intrusions and laccoliths. The main watercourse - r. Colorado, which cut through the plateau, creating the Grand Canyon. The main canyon has a winding shape, its depth is 1800 m, the maximum width is up to 25 km, and the length is more than 300 km.

To the west of the internal plateaus are Nevadian structures - the Sierra Nevada mountains. This is a large block structure (horst boulder with comb-like peaks), the blocks are inclined to the west, there are batholiths at the base. The Cascade Mountains are a prime example of a volcanic range with a number of active volcanoes. The folded structures within them are covered by Cenozoic lavas, and high (some higher than 4000 m) volcanic cones are planted on them. Among them there are also very active: in the 80s. 20th century Mount St. Helens erupted two years in a row, there were many deaths. There are also extinct, but showing post-volcanic activity.

The vegetation of the mountains is typically American.

Here in the valley Merset (Yosemite Valley) preserved forest (park) of the giant sequoiadendron. For their large size (the height of many trees reaches 80-100 meters) and for bending, like mammoth tusks, their branches were called mammoth trees. In the lower tier of the mountains - chaparral (American variety of maquis).

Coastal ridges - low (up to 2400 meters) Pacific structures are separated from the Nevadian structures by the Willamette and California valleys. This is the result of subduction with the latest formation of slips and faults, such as, for example, San Andreas.

This fault is especially active. The blocks of the earth's crust move horizontally relative to each other at high speed. The process is accompanied by strong earthquakes. So, for example, in 1992, an earthquake occurred 150 km from Los Angeles in the Mojave Desert, during which more than 5,000 shocks of various strengths were recorded in 10 days. Large cities suffer from tremors - San Francisco was badly destroyed in 1906, in Los Angeles there were tremors of 7-8 points in 1971.

The climate here is subtropical with humid warm winters (up to 10°C) and dry summers. On the coast, summers are cool (average July temperatures are about 15°C), due to the influence of air masses with a northern component and cold currents. When moving inland, summer becomes much warmer (20-22°C). The annual amount of precipitation is 500-600 mm with a winter maximum. The lower tier of mountains is occupied by an analogue of the Mediterranean maquis - chaparral (thickets of shrubby oak, deciduous and evergreen, 1.5-2 meters high, less often - 3 meters, on brown, above 600 meters - stony soils). In the south - thickets of acacia, cacti, yucca. The upper tiers are dominated by coniferous forests of Sitka spruce, Douglasia, pines, sequoias.

On the northern parts of the western slopes there are national parks, where evergreen sequoia forests (mahogany) are taken under protection. Redwood National Park is located north of San Francisco, in the valley of the river. Redwood Creek. Sequoias are the tallest and oldest trees, along with mammoth trees from the same family. Sequoia grows up to 2000 years. The phytomass of the thousand-year-old sequoia is more than 4,000 thousand c/ha (1% is needles, the rest is the trunk and branches), the yield of commercial wood is 10 thousand m 3 /ha. Trees are not afraid of fires.

Of all the regions of North America, the Cordillera of the southwestern United States stands out for its variety of natural attractions that attract tourists from all over the world.

In addition to recreational, this region has good agro-climatic and land resources. In the Great California Valley, the natural vegetation of dry wormwood steppes and semi-deserts has been completely replaced by cultivated vegetation. On lands irrigated by the waters of rivers flowing down from the mountains, a variety of subtropical crops are grown. On the Pacific coast, giant urban agglomerations have formed, connected by high-speed highways. From Richmond, Oakland, San Francisco to Los Angeles, including the famous Hollywood, continuous urban development stretches.

The most acute problem is pollution: all harmful emissions remain near the surface of the earth, since the anticyclonic regime and downward air currents prevail for a significant part of the year. Frequent fogs.