Geographical position and peculiarities of the country
The United States of America, often briefly referred to as the United States of America, the United States, or simply America, is a state in North America. The area is 9.5 million km² (4th place in the world). The population is 325 million people (2016, estimate, 3rd place in the world). The United States has a federal form of organization, administratively divided into 50 states and the federal district of Colombia; in their subordination there is also a number of island territories (Puerto Rico, the Virgin Islands, Guam and others).
The capital is the city of Washington. The United States borders the north with Canada, in the south — with Mexico, also have a maritime border with Russia. They are washed by the Pacific Ocean from the west, the Atlantic Ocean — from the east and the Arctic Ocean — from the north.
The United States of America was formed in 1776 with the unification of thirteen British colonies that declared their independence. The War of Independence lasted until 1783 and ended in the victory of the colonists. In 1787, the US Constitution was adopted, and in 1791 — the Bill of Rights, which significantly limited the powers of the government towards citizens. In the 1860s, the contradictions between the slave-owning southern and industrial northern states led to the beginning of the four-year Civil War. The consequence of the victory of the northern states was the widespread prohibition of slavery, as well as the restoration of the country after the split that arose when the southern states merged into the Confederation and declared their independence.
The main US territory (called continental states) is located on the North American continent and extends from the Atlantic Ocean in the east to the Pacific Ocean in the west. In the south, the United States borders Mexico, in the north — with Canada. In addition, the US includes 2 more states. The extreme north-west of the American continent is Alaska, also bordering Canada. In the Pacific Ocean is the state of Hawaii. The border with Russia passes through the Bering Strait. The United States also owns a number of islands in the Caribbean (for example, Puerto Rico) and the Pacific (American Samoa, Midway, Guam and others).
Under a particular US administration, there are (but are not included in) a number of island territories with different status. The Constitution of the United States fully operates on the territory of the uninhabited atoll of Palmyra. The remaining territories have their own basic legislation. The largest of these territories is Puerto Rico.
In the mainland, west of the Atlantic lowlands are the Appalachian mountains, behind which are the Central Plains (200—500 m above sea level), the Great Plains (600—1500 m) plateau. Almost the whole west is occupied by the Cordillera mountain system.
Most of the territory of the United States belongs to the North American platform. In the east it is framed by the Paleozoic Appalachian folded system, in the west by the Mesozoic-Cenozoic folded Cordillera system, in the south by the young plateau on the coast of the Gulf of Mexico, which passes northeast into the Atlantic flank of the same age. The foundation of the North American platform is exposed in the US territory in several small areas: Adirondack of the Canadian Shield (Middle Riphean rocks) in the states of Minnesota, Wisconsin and Michigan (rocks: granite gneisses over 3.5 billion years old, Archaean formation of greenstone belts and granites, Lower Proterozoic shelf deposits, quartzites, overlapping rocks of the Archean, Upper Proterozoic continental red clastic sediments, basalts and gabbros), in the Eastern Scalists mountains, in the states of Montana, Wyoming, Colorado, New Mexico, Arizona (north — Archean education, and to the south of Wyoming — Lower Proterozoic). The rest of the area is represented by acidic ground volcanics and granites. The platform cover within the continental United States has a Paleozoic age — from the very tops of the Cambrian or more often Ordovician to the lower Permian in the Peredapalach trough. Deposits of the Lower and Middle Paleozoic are predominantly shelf carbonates with subordinate packets of quartz sandstones and black mudstones («shales»). In the Michigan (Silurian) and Willstonian (Devonian) basins there are known evaporites (salts) and in the first of them — reefogenic limestones. Depositions of the Middle-Upper Carboniferous (Pennsylvanian system of American geologists) represent a paralyzed, cyclically constructed coal-bearing formation. It forms the central part of the Peredapalachsky trough, the basins (syneclise) of Michigan and Illinois (the Inner East coal-and-coal basin), Forest City and Celain (Inner Western Coal Basin), the intermediate elevation — the anteclise of Cincinnati and Ozark, and Bend in the south — the east — are composed from the surface of the Lower Paleozoic, and the wings are Silurian and Devonian. In the deep East Texas syneclise in the southwestern corner of the platform is a complete section of Permian sediments. The rocks of the Triassic and Jurassic (coastal-marine and continental) are known only in the west of the Great Plains, as well as in the large Willston syneclise. More often there are carbonate-terrigenous deposits of chalk — in a wide band from the Canadian border to the Gulf of Mexico. The Cenozoic deposits are of low power, the continental ones are limited, closer to the Rocky Mountains, along the foot of which the deflections of the Powder River, Denver and Reton are located. The southwestern corner of the platform is separated from its main part by the complex Wichita avlacogen, which extends to the west, in the northern part of the Colorado plateau.
The Rocky Mountains
The Rocky Mountains are the main mountain range in the Cordillera system of North America, in the west of the USA and Canada, between 60 and 32° N. w.
Rocky Mountains stretch for 4830 kilometers from north to south from the northern point in the province of British Columbia (Canada) to the state of New Mexico in the southwest of the United States. The width of the mountains reaches 700 kilometers. The Rocky Mountains are a natural watershed between the basins of the Pacific and Atlantic Oceans. In the Rocky Mountains, the rivers of Missouri, Colorado, Rio Grande, Snake, Arkansas and many others originate. Rocky Mountains were formed from 80 to 55 million years ago in the era of Laramie’s orogeny. Since then, under the influence of water and glaciers in the mountain range spectacular valleys and peaks were formed. At the end of the last ice age, people began to colonize the Rocky Mountains. After several expeditions, such as the journey of Alexander McKenzie or the expedition of Lewis and Clark, the Rockies began to settle; minerals and furs gave rise to the initial economic development of the mountains, despite the fact that the Rocky Mountains remained a sparsely populated area. Currently, most of the territory of the Rocky Mountains is protected by national parks and forest lands. Rocky Mountains — a popular place for tourists, especially for hiking, mountaineering, fishing, hunting, skiing, snowboarding and others.
The name «Rocky Mountains» was given by the Canadian pioneer of French origin Pierre Gauthier Varenne de la Verandry after he crossed the river Pierre Jaune (today it is Yellowstone — the river of yellow stone) on January 1, 1743. Alexander Mackenzie crossed the mountains in 1793 and named them «Stony Mountains». In the second half of the XIX century, the mountains were returned to the previous name.
The Northern Rocky Mountains (north of 45° N) are mainly composed of granites up to 3954 m in height (Robson Mountain); The southern Rocky Mountains, or the Rocky Mountains of the United States, consist of short ridges composed of sandstones, shales, limestones, up to 4,401 m (Albert Mountain — the highest point of the Rocky Mountains). There are extensive deposits of molybdenum, copper, gold, silver, polymetals, oil, and coal. Volcanic phenomena are observed: geysers, thermal springs, and earthquakes.
In the Rockies is a typical mountain climate. The average annual temperature in the valleys is within 6° C. In July, the warmest month, the average temperature reaches 28° C. In January, the average temperature is about -14° C, and this is the coldest month of the year. The average annual precipitation is about 360 mm.
In the Rocky Mountains in the summer it is usually warm and dry, as rain clouds from the west linger on the mountain ridge on its western side. The average temperature in summer is 15° C, and the average amount of precipitation is about 150 mm. Winters are very long and cold, with an average temperature of -2° C, and an average thickness of snow cover of 29 cm. In the spring, the average temperature is 4° C, and the precipitation is 107 mm. In autumn, the average rainfall is 66 mm and the temperature is about 7° C.
Vegetation — mainly forests, mountain-taiga in the north and pine in the south. The height of the forest boundary is from 1500 m (in the north) to 3600 m (in the south), higher — alpine meadows and eternal snow.
In the forests grow spruce, pine and fir, on the lower tiers, they mix with birches and white maple. Most of the mountains of the Arctic latitudes are covered with dwarf birches. On taiga soil not only coniferous, but also deciduous trees grow: birch, poplar and aspen.
In the valleys there are steppes and semi-deserts.
High-altitude animals here are snow goats, thick-nosed, elks and foxes. In the areas below, there is a marmot, a hare-hare, a black-tailed meadow dog and a coyote.
Most of the birds living in the Rocky Mountains are flying. In the summer months they feed the chicks here. Constantly in the mountains there live a three-toed woodpecker, a white partridge, some species of finches and owls.
In the Rockies are national parks Jasper (Canada), Banff (Canada), Yoho (Canada), Kootenay (Canada), Waterton Lakes (Canada), Glacier (USA), Yellowstone (USA), Rocky Mountain (USA).
Great Plains — a piedmont plateau in the US and Canada, east of the Rocky Mountains. The height is about 700—1800 m above sea level. The length is about 3600 km, the width is from 500 to 800 km.
On the Great Plains are the territories of the Canadian provinces of Alberta, Manitoba and Saskatchewan and the American states of New Mexico, Texas, Oklahoma, Colorado, Kansas, Nebraska, Wyoming, Montana, North Dakota and South Dakota.
Great plains from north to south are divided into such major zones as the Missouri Plateau, the central High Plains, the Llano Estacado Plateau and Edwards. In some areas erosion of rocks is observed (these are the so-called bad lands, «badlands»). In the south they pass to the Mexican Highlands.
The climate within the plains is continental. Vegetation is mostly steppe.
On the plateau territory, wheat production is developed (the Great Plains are often called the «World Bread-Bread»), pasture cattle breeding. The US began to develop this area after the Louisiana purchase (1803). As early as 1820, researchers recognized these lands as unsuitable for life.
The Great Lakes
The Great Lakes (Grands Lacs, sometimes also the Great Laurentian lakes) are a system of freshwater lakes in North America, in the United States and Canada (Lake Michigan is entirely in the USA, the rest of the lakes and the short rivers that connect them cross the border between the USA (⅔ the water area) and Canada (⅓ the water area of lakes)). Includes a number of large and medium-sized reservoirs, connected by rivers and straits. The five largest ones are the Great Lakes themselves: Upper, Huron, Michigan, Erie and Ontario, although they sometimes include the St. Claire Lake, they form the largest group of freshwater lakes on Earth (a total area of 244,106 km², a total of 22,671 km³)), containing 21% of the surface in the world of fresh water (and 84% of freshwater in North America). Several middle lakes are associated with them, the most important of which are: St. Marys, Manitou, Nipigon, Nipissing. Lakes belong to the basin of the Atlantic Ocean, drain on the St. Lawrence River.
The formation of lake basins is most affected by tectonic processes; Great lakes began to form at the end of the last glacial period, about 10,000 years ago, when the mass of the glacier crushed the earth’s crust, and after the glacier melt, a slow reverse process began, glacioisostasis, which is also very noticeable in the Gulf of Bothnia and Finland. The water mass of the lakes was formed during the melting of the glacier. The northern coast of the Great Lakes rises faster than the southern one, which leads to the effect of «transfusion» of water and the slow flooding of lands in the south. Earlier, the Great Lakes had an additional runoff through the current rivers Illinois and Ottawa, but due to all the same geological processes, they, even today, near the shores of the lakes, changed their course somewhat and radically changed the source. As a result, today the natural runoff exists only along the St. Lawrence River.
With the help of canals, a waterway has been formed for sea ships with a length of about 3,000 km. Great lakes are connected by canals with the Hudson River and the Mississippi River basin.
Great lakes are among the largest on Earth accumulations of fresh water. Only Baikal and the glaciers of Greenland and Antarctica can compete with them. They are interconnected by rivers and canals, and therefore water flows from one to the other. The upper lake is the largest freshwater lake in the world, and Ontario alone is larger than the largest lake in Europe, Ladoga. Their average depth, not being very large, exceeds the average depth of the Baltic and North Seas.
The length of the coastline (with islands) is about 18 thousand km. The total area is 244,106 km², the basin area is 768,000 km² (including the area of the lakes themselves), the total volume of 22,671 km³, the four lakes of depth exceed 200 m and only Erie Lake has the greatest depth of 64 m, and St. Clare only 8. The largest and deepest of the Great Lakes is Lake Superior, the smallest — Lake St. Clair.
Several hundred small rivers flow into the Great Lakes, the flow from the lakes occurs along the St. Lawrence River, flowing from Lake Ontario and flowing into the Atlantic Ocean; the average water discharge at its source is 6637 m³ / s.
Previously, sewage, paper and other factories were discharged into these lakes. At first, the Erie Lake was significantly polluted, it was silt, many kinds of commercial fish disappeared from it. The government allocated significant funds for cleaning the lakes. Now the lakes are relatively clean. Great lakes are very important objects of rest and navigation.
The climate of the Great Lakes is humid, temperate, similar to the climate of the Middle Baltic. The area of the Great Lakes is characterized by sharp changes in weather conditions. This is due to the proximity of such different regions as the cold Hudson Bay in the north and the very warm Mexican Gulf in the south. The most variable season is winter, it is snowy, active cyclones are observed. Cyclones are also associated with frequent intrusions of Arctic air at this time, leading to a sharp cooling, and sometimes in a matter of hours frozen important areas for navigation. In winter, ice first covers Lake Superior, then — Huron and Michigan, lastly — Erie. The lakes are not frozen completely, but navigation stops, becoming impossible from December to April. Spring lasts a long time, often freezing. The summer is cool, it is, like winter, changeable, with frequent rains and a strong wind. Autumn includes a period of up to two weeks, called «Indian summer» with clear and dry weather. Autumn is considered the best season in the Great Lakes region.
Because of the direction of the wind in the cold seasons on the southern and eastern shores of lakes, the snowy effect of the lake appears.
Rivers of the USA.
Snake is the largest tributary of the Columbia River. Its length is about 1735 kilometers, and the basin area is 278,450 square kilometers. The beginning of Snake takes in the west, in the district of Wyoming. Runs on the territory of 6 states in the region of mountain plains. Has a huge number of tributaries, the largest — Palus with a length of 270 km. Snake is a navigable river. Its main food is due to snow and rainwater.
Colombia is located in North America. Presumably its name was in honor of the ship of the same name, on which Captain Robert Gray traveled — he was one of the first who discovered and passed the whole river. Its length is 2000 kilometers, and the area of the basin is 668,217 square kilometers. km. It has more than 60 tributaries, the largest of which are: Snake, Willamette, Kuteni and others. It flows into the Pacific Ocean. Colombia feeds on glaciers, due to which it has a large volume of water and a fairly fast current. More than a dozen hydroelectric power stations have been built on its territory. Like Snake, Colombia is navigable.
Ohio — one of the largest rivers in the United States, is the most full-fledged tributary of the Mississippi. Its length is 2102 kilometers, and the pool area is 528,100 square kilometers. The pool is formed by the confluence of two rivers — Allegheny and Monongahil, originating in the Appalachian mountains. Its main tributaries are Maiami, Maskingham, Tennessee, Kentucky and others. On Ohio, there are strong floods, which are catastrophic. The food of the river is due to groundwater, rainwater, as well as from the rivers flowing into it. One of the largest hydroelectric power stations in the country is built in the Ohio basin.
Southern Red River (Red River) — one of the longest American rivers, is one of the largest tributaries of the Mississippi. Its name was due to clay lands in the watershed of the river. The length of the Red River is about 2190 kilometers. It was formed from the confluence of two small Texan rivers. The South Red River was blocked in the 1940s by a dam to prevent devastating floods. The Red River was surrounded by Tehomo lakes, formed as a result of the installation of the dam, and Fr. Caddo, next to which is located the largest cypress forest on earth. The food of the river is rain and soil.
Colorado is located in the south-west of the United States and is one of the largest and most beautiful rivers of not only the country but also the world. Its total length is 2334 kilometers, and the area of the basin is 637,137 square kilometers. km. Colorado starts from the Rocky Mountains, and connects to the Pacific Ocean in the Gulf of California. Colorado has more than 25 tributaries, the largest are Eagle River, Green River, Hila, Little Colorado and others. It is one of the most controlled rivers in the world: it has 30 large dams. The first of them was built in 1907 and formed the reservoir Powell. In the waters of Colorado, there are about 50 species of fish.
Arkansas is one of the longest rivers and the largest tributaries of the Mississippi. It begins in the Rocky Mountains, Colorado. Its length is 2348 kilometers, and the pool area is 505,000 square kilometers. km. It crosses four states: Arkansas, Kansas, Colorado, Oklahoma. The largest tributaries of Arkansas are Simarrok and Salt Fork-Arkansas. Arkansas is a navigable river and is a source of water for local residents. Because of the rapid current in the mountainous areas, the river has become popular among tourists who want to go in for extreme swimming.
Rio Grande (Great River) — the largest and longest river in North America. It is on the border of two states of the USA and Mexico. The Mexican name is Rio Bravo. The Rio Grande takes its start in the state of Colorado, the mountains of San Juan and flows into the Gulf of Mexico. The most important and large tributaries are the Rio Conchos, Pecos, Devils River. Despite its size, the Rio Grande is not navigable, as it has considerably become shallow. Due to shallowing under threat of extinction are some species of fish and animals. Rio Grande in some areas can dry up and form small ponds, such as lakes. The main food is rain and snow water, as well as mountain keys. The length of the Rio Grande is 3,057 kilometers, and the area of the basin is 607,965 square kilometers.
Yukon (Big River) opens the three longest rivers in the United States. The Yukon flows around the state of Alaska (USA) and in the northwest of Canada. It is a tributary of the Bering Sea. Its length is 3184 kilometers, and the pool area is 832,000 square meters. It begins in Lake Marsh and then moves to the border with Alaska, dividing the state into two equal parts. Its main tributaries are Tanana, Pelly, Koyukuk. Yukon is navigable for three months, as the rest of the year it is covered with ice. The big river is in a mountainous area, so it is full of rapids. In its waters there are valuable species of fish such as salmon, pike, nelma, grayling. The main food of the Yukon is snow water.
Missouri (Big and muddy river) is the longest river in North America, and also the largest tributary of the Mississippi. Its origin Missouri takes in the Rocky Mountains. It flows on the territory of 10 US states and captures 2 Canadian provinces. The river stretched for 3,767 kilometers and formed a basin with an area of 1,371,010 square meters. km., which is one-sixth of the entire territory of the United States. It was formed by the confluence of the rivers Jefferson, Gallatin and Madison. Missouri takes about a hundred major tributaries, the main are Yellowstone, Platt, Kansas and Osage. The turbidity of the Missouri water is explained by the washing out of the mountain stream by a powerful stream of the river. The river feeds on rain and snow waters, as well as the waters of tributaries. Currently it is navigable.
Mississippi is the most important river in the United States, and also ranks third in the world (in the confluence with the tributaries of Missouri and Jefferson) along the lengths after the Amazon and the Nile. It was formed from the confluence of the rivers Jefferson, Madison and Gallatin. Its source is the lake of Aitask. It occupies a part of 10 US states. Uniting with its main tributary of Missouri, it forms an extension of more than 6,000 kilometers. The river’s own length is 3,734 kilometers, and the area of the basin is 2,981,000 square kilometers. The food of the Mississippi is mixed.
Due to the large size of the country, its length and wide variety of geographical features in the US, it is possible to find areas with almost any climatic characteristics. Most of the USA (states south of 40 degrees north) is located in the subtropical climate zone, temperate climate prevails to the north, Hawaii and southern Florida lie in the tropics, and the north of Alaska belongs to the polar regions. The great plains to the west of the 100th meridian are classified as semi-deserts, the Great Basin and the areas around it are arid, and the coastal regions of California are a Mediterranean climate. The type of climate within the boundaries of one belt can vary significantly depending on the terrain, the proximity of the ocean and other factors. The favorable climate had a considerable influence on the settlement of the continent by Europeans and in many ways contributed to the US occupying the leading positions in the world.
The overall temperature background is fairly uniform. In summer, the temperature in most areas ranges from +22° C to +28° C, with the difference between the northern and southern states is relatively small. Winter in most of the country is quite mild — the average January temperature ranges from -2° C in the north to +8° C in the south. However, considerable temperature fluctuations are not uncommon due to free penetration of air masses both from the Arctic region and from tropical latitudes (the mountain systems of the USA located in the meridional direction act as a kind of «pipe» through which cyclones and anticyclones move from north to south or vice versa, practically without encountering obstacles). In the mountainous regions it is always cooler than in the adjoining territories of the plains — in the summer by 4—8 degrees, in winter — by 7—12. At the same time, in the pre-oceanic regions in winter it is always warmer, and in the summer it is cooler than in the center of the country (the eastern coast of the country, heated by the warm Gulf Stream, has a temperature 5—7 degrees above all central and western regions).
Depending on the nature of the mountain systems, weather stability also changes markedly: in low Appalachians the climate differs little from the flat areas of the east of the country and is quite constant, while the extensive and high ridges of the Cordillera system are widely known for their cooler, dry and unstable weather.
The nature of the distribution of precipitation is also very uneven. In the southeastern states and on the Pacific coast, it drops to 2000 mm of rain per year, in the Hawaiian Islands — up to 4000 mm and more, while in the central regions of California or Nevada — no more than 200 mm. And the nature of the distribution of precipitation depends entirely on the terrain — the western slopes of the mountains and the Atlantic regions receive significantly more rain than the eastern ones, while in the entire Great Plains, from the coastal lowlands of the south to the wooded areas of the north, there is almost the same amount of precipitation 300—500 mm).
At any time of the year, you can find the US region, where rest would be comfortable in its weather conditions. The swimming season in the north and in the center of the Atlantic coast lasts from June to August-September, although to quite acceptable values the water warms up in May and in October. On the coast of Florida you can swim practically all year round (the average temperature of the water even rarely falls below +22° С even in winter months), however in the period from July to September it is quite hot (+36—39° С) and very high air humidity (up to 100%), and from June to November, tropical hurricanes are not uncommon.
The Pacific coast has a noticeably larger difference in water and air temperatures between the northern and southern regions. In the southern part of the coast, you can swim practically all year round, although in the period from November to March even in California, the temperature of the water rarely rises above +14° C (many seas with well-heated water are used for sea recreation). At the same time in the north, in Oregon and Washington, even in the summer months, there are often noticeable cold snaps of both water and air, in winter the temperature regime is quite common for regions with a temperate marine climate (air from -6 to +4° C, water — about +4° C). Contrary to popular belief, Oregon’s climate is dry enough (rain falls less than in Atlanta or Houston) and warm enough (summer highs rarely exceed +30° C, and in winter the thermometer remains at +2° C). Therefore, you can find excellent opportunities for recreation almost all the year round.
To the north, in the state of Washington, two distinct climatic zones, west of the Cascade Mountains, on the Pacific coast and in Seattle, quite clearly distinguish themselves, in the summer, it is rarely hotter than +26° C, and in the winter — colder +8° C, while the eastern part of the staff has a noticeably warmer summer and a cool winter. Traditionally, the summer tourist season here begins with Memorial Day and continues until Labor Day, and even some of the sights are open to visitors only during this period.
The central mountain areas can be visited all year round, in the southern part of the Rocky Mountains in the summer it is too hot (+26—34° C), therefore it is recommended to plan your trip for the spring or autumn. To avoid the influx of tourists, it is recommended to plan visits to national parks, for example, in late autumn or early spring, when the weather conditions are quite comfortable. The western slopes of the Rocky Mountains and the eastern part of California during the summer are also not very pleasant to visit — too hot, however, the seaside part of the same California at this time has quite pleasant weather conditions.
There are no seasonal restrictions for visiting Los Angeles. Despite its dry and hot semi-desert climate, the city is protected from the burning heat by mountain chains in the north and east, as well as by the Pacific Ocean itself. August and September are the hottest months (+24—30° C), January and February are the coolest (around +12° C) and the wettest, but at any time of the year ocean breezes soften the weather in the direction of greater comfort. However, the city smog combined with the summer heat makes the end of the summer not the best time to visit the metropolis, while the resort areas adjacent to it from the north and south have excellent weather conditions during this period.
The climate of Alaska is quite severe, since 30% of its territory is beyond the Arctic Circle. In northern and central regions with their subarctic climate, the thermometer’s column often drops to -45-50° C in winter, while in summer the air warms up to +16—20° C (in northern regions — +2—6° C) with very low precipitation (about 250 mm per year). In the southern and central regions the climate is temperate marine, the average temperature here in the summer is about +18° C, but often the air warms up to +30° C), in winter — from -6° C to +4° C, precipitation falls from 400 to 600 mm per year.
The vegetation of the USA
Through the territory of the United States there are various climatic zones, and in some parts of this vast country there is a truly unique microclimate in which an amazing plant world has formed.