To understand the relief of America, it is convenient to visualize this extensive continent from east to west and briefly describe its orogeny: to the east are the oldest geological formations , today already worn by erosive factors.
Throughout the entire American West we find a less ancient orogenic zone, which arose as a result of the collision of the continental plates with the oceanic one, while the central zone has a mainly sedimentary origin .
Next we will analyze the different landforms in America, and their characteristics.
It can serve you: Relief of Europe .
Characteristics of the relief of America :
- Almost all of the American territory is above sea level, with a considerable proportion of it even above 1500 meters (with its corresponding cold climates by altitude). The most marked depression is located in Argentine Patagonia, it is the Laguna del Carbón, which is 105 meters below sea level.
- In both North America and South America, the northeast corresponds to shields that originated a long time ago, in the Paleozoic or Primary era. These are the Canadian Shield and the Guiana-Brazilian Shield, respectively.
- These systems originated the present formations of the continental east: the Appalachian Mountains (North America), the Brazilian massif; the Guyanas massif and the Patagonian plateau (South America). These are today moderate or low discontinuous elevations, the result of thousands of years of erosion.
- Parallel to the extensive coastline of the Pacific Ocean, the western region is dominated by a mountainous relief of large young ridges that corresponds to the Alpine folding produced in the Cenozoic (or Tertiary) era as a result of the collision between the tectonic plates that today form the continent. The folded massif of the west corresponds to this orogeny, which includes the Rocky Mountains of North America, the Sierra Madre (Mexico and Central America) and the great region of the Andes, in South America.
- This forms a large expanse of abrupt shapes with numerous sharp peaks, including the highest peaks on the continent (Aconcagua, 6960 meters; Tupungato, 6800 meters; Mc Kinley, 6200 meters). Only in Central America and for a few hundred kilometers the continuity of the complex is lost, which exhibits great seismic and volcanic activity in some sections and is crossed by narrow valleys.
- Within these large groups, others of smaller extension are differentiated locally. For example, the plateaus of Columbia and Colorado, in the United States, or the Altiplano or Puna, in South America.
- Between the great mountains of the west and the ancient and eroded reliefs of the east, in the Quaternary period of the Cenozoic era, some rivers were forming large basins and, together with the action of the winds, they filled low areas, thus giving rise to the current plains such as the Orinoco River, the Amazon or the Chaco-Pampean plain in South America; or that of the Mississippi River or the great Central Plain in North America.
- The action of various agents, such as glaciers or volcanoes, for example, has very slowly modified the relief of the continent.
- Among the old eroded mountain ranges of the east, today we find important massifs and mountain groups. It is worth mentioning among them the Laurentian plateau and the Appalachian mountains, the Ozark plateau, the Guiana massif, the Borborena mountain range, the Brazilian plateau, the Mato Grosso and the Ventania and Tandilia system.
- In short, the most representative reliefs of the American continent are three; from highest to lowest seniority:
- Plateaus or massifs derived from the old eastern shields (Brazilian plateau, Matto Grosso plateau, Guyanas massif, Laurentine plateau);
- Great western cordon (Rocky Mountains, Sierra Madre and Cordillera de los Andes);
- Great Central Plains (Chaco-Pampeana Plain, Amazonian Plain, Great Central Plain of North America).
- Valleys, mountains and hills are presented as more local phenomena. Such is the case, for example, of the Sierra Nevada of the United States, in the states of California and Nevada.