por The reliefs of america They include large mountain ranges, extensive plains furrowed by wide and long rivers and imposing massifs of great antiquity. If you look at the map of the relief of America, you will notice that along the entire western edge (to the left of the map) there is a long mountain range that runs from the north (top of the map) to the south (bottom).
While on the opposite side, to the east (right), a relief made up of discontinuous massifs can be seen. They are observed in eastern North America and also in northeastern and eastern South America. In the middle of that long mountain range to the west and these massifs to the east, there are great plains.
This is because the American continent is a land mass formed by two fundamental tectonic plates. These are the North American Plate and the South American Plate, and among them the Caribbean Plate and other minor ones forming Central America and the islands of the Caribbean Sea.
On the other hand, America extends in a north-south direction from the Arctic Circle to the Antarctic Circle. The plates that make up the American continent rise at the bottom of the mid-Atlantic ocean to the east and then develop to the west.
These plates then collide with the Pacific Plate, which sinks beneath the Americas, producing uplifts that make up part of its mountain system.
With all these tectonic movements that cause earthquakes and volcanic eruptions, the ancient massifs of the east arose first. Subsequently, the long mountain range to the west and in the middle the plains and plateaus.
Characteristics of the relief of America
America is a large continent, oriented from north to south, with a mostly high relief, made up of 4 main parts. These are North America or North America, Central America or Central America, the Antilles or Caribbean islands, and South America or South America.
A large continent oriented north to south
America is the second largest continent after Asia, reaching 42,111,231 km2, being the longest in a north-south direction. It has a length of about 15,500 km from the extreme north to the extreme south.
A largely elevated continent
The highest altitude of the continent is the Aconcagua peak in the Andes of Argentina, which reaches 6960.8 meters above sea level. While the lowest part corresponds to the Gran Bajo de San Julián in Argentina, with the Laguna del Carbón at 105 meters below sea level. However, on average a large part of America is above 1,500 meters above sea level.
A structure in 4 fundamental parts
The American continent is subdivided into 4 subcontinents: South America, Central America, the Antilles and North America. This corresponds to the tectonic plates that form America, the two main ones being the North American Plate and the South American Plate.
Then there is the Caribbean Plate, covered by the sea and on whose eastern edge are the islands of the Antilles. Finally, joining the North and South plates, are a series of small plates that form Central America.
An orogeny from east to west
The orogeny refers to the origin of the relief, more specifically of the mountains, and on this continent the oldest are to the east. The plates that make up the Americas originate from the ocean floor in the mid-Atlantic, where new soil is generated by volcanic activity.
From there, the plates spread westward (to the left of the map) and collide with the Pacific Ocean plates coming from the east. At this shock line, the Pacific Plate and other minor plates sink under the American plates.
This sinking mass of ocean floor pushes up and the edge of the American plates rises. That’s why you see that long range of mountains across the west of the American continent that runs from Chile and Argentina in the south to Alaska in the north.
But before that ridge, other land masses rose up further east, many millions of years ago in the Paleozoic. They are the massifs that you see on the right of the map.
These massifs are so old that erosion has flattened them somewhat, turning them into plateaus and mountains with less abrupt and even concave tops. While the western range, being younger, from the Cenozoic, still retains its abrupt relief, with steep peaks and higher altitudes.
The action of great rivers
If you now detail the entire area located between the long mountain range to the west and the massifs to the east, you see plains. This is because when the great mountain ranges emerge in the west, great rains occur.
This occurs because the winds, when colliding with the high mountains, ascend and discharge their humidity. Therefore, in these mountain ranges many rivers are born, which as they join together form other larger ones.
These rivers run downhill to the east, to empty into the Atlantic Ocean and erode the mountains, carrying large amounts of sediment. Upon reaching the bottom, they lose strength and deposit sediments, filling the terrain between the western mountain ranges and the eastern massifs, forming the plains.
The longest rivers in America are the Amazon, Paraná, Mississippi, Yukon, Yuruá, Bravo, Purús, San Francisco and Paraguay.
Main reliefs of America
The main reliefs of America are:
The eastern plateaus and massifs.
The ranges with mountains of the west
The plains.
There are also many other local or regional reliefs, with valleys, depressions, minor mountain ranges and hills.
The eastern plateaus and massifs
In North America, these older massifs lie to the east, forming the Canadian Shield. The Appalachian Mountains are located here, which stretch from the island of Newfoundland (Canada) to Alabama (USA).
While in South America there is the Guiana-Brazilian Shield, which includes the Guiana shield, the Brazilian massif and the Patagonian Plateau.
In the Guyanese massif in northern South America, the tepuis are formed, which we find from Colombia to Venezuela and northern Brazil. These are huge tabular sandstone mountains with concave tops that reach over 2,000 meters above sea level.
While in the central east of South America is the Brazilian Massif, which is a series of plateaus that cover a large part of Brazil. In addition to the Argentine northeast, the Gran Chaco and the Pampa. This massif limits to the south with the Patagonian Plateau in Argentina, with the mountains called Patagonides that do not reach 2,000 meters above sea level.
The western cordilleras (west)
The youngest and highest and steepest mountain ranges that form to the west from south to north are also the longest. The longest is the Andes mountain range that runs from the southern tip of Chile and Argentina to the north of South America in Colombia and Venezuela. This is the longest mountain range in the world, reaching 8,500 km in length.
Then, in Central America, the folding continues with small elevations in the El Darién zone, no higher than 1,875 meters above sea level, which are continuous with the Sierra Madre. The latter covers all of Central America to northern Mexico in North America, with the highest Central American elevation being the Tajumulco volcano at 4,222 meters above sea level.
While in the Mexican section the highest elevation is Pico Orizaba with 5,610 meters above sea level. Subsequently, in western North America the mountain range continues, with the Rocky Mountains in the US and Canada. The highest point here being Mount Elbert in Colorado (USA), with 4401 meters above sea level.
great central plains
In North America are the North American Great Plains, in English the Great Plains. These form on a plateau that covers southern Canada, the entire central United States, and northern Mexico.
These plains are crossed by large rivers such as the Missouri and the Mississippi, and have an average altitude of 116 meters above sea level and a maximum of 1,680 meters above sea level. On the other hand, in the rest of Mexico there is the central plateau and in Central America the coastal and intermediate plains.
While in South America there are large flat areas, such as the Colombian-Venezuelan plains to the north with altitudes that do not exceed 200 meters above sea level. Then in the center you can see the great undulating plain of the Amazon river basin, with altitudes between 100 and 500 meters above sea level and to the south are the Chaco and the pampas.
Hills, valleys, mountain ranges and minor ridges
In all the mountain ranges canyons, plateaus and valleys are formed, while in the plains hills and hills arise. In the north of South America and in the Caribbean islands there are also smaller mountain ranges.
Such is the case of the Venezuelan Caribbean Coast Range, whose highest altitude is the Naiguatá peak at 2,765 meters above sea level. As well as the Sierra Maestra on the island of Cuba, with Turquino Peak (1,974 masl) and the John Crow and Montes Azules in Jamaica, with the Blue Mountain at 2,256 masl.
References
Allen, JL (2005): Atlas of World Events. New York, McGraw-Hill.
Guimaraens, M. (2014). Children’s Atlas of South America. Publisher Weeble Books. Available at: weeblebooks.com
Kapeluz. Geography of America. Rule. Secondary Education. with digital texts. Taken from: editorialkapelusz.com
Bruno (1990). New Universal Geographic Atlas. Editorial. Editorial Bruno.