What is the Amazon Basin
Amazon and Amazonia
The term "Amazonia" is ambiguous and is used somewhat vaguely. For example, the Amazonia denotes the tropical rainforest as a habitat on the Amazon.
But the entire Amazon basin is also often called the Amazon: a huge plain in which the actual rainforest on the Amazon grows.
Sometimes the term is also used for the entire catchment area of the Amazon. In other words, for the area from which precipitation sooner or later flows into the Amazon.
The catchment area of the Amazon covers an area of more than seven million square kilometers, making it roughly the size of Australia.
It extends over nine South American states, with the largest area belonging to Brazil. But French Guiana, Suriname, Guyana, Venezuela, Colombia, Ecuador, Peru and Bolivia are also involved in the catchment area.
The Amazon rainforest is an ancient habitat that has been thriving and developing here for millions of years. The tropical rainforest has repeatedly been subject to major climatic fluctuations due to the alternation of warm and ice ages.
In the cool phases of the Ice Age, the rainforest shrank to small, climatically favored areas that were distributed like a mosaic across the Amazon basin.
From these retreat areas, the so-called refuges, the forest then expanded again at the beginning of the warm periods. The Amazon forest is actually in such a phase of expansion (the last ice age ended 21,000 years ago) - if it weren't for humans.
Until the beginning of the 20th century, the rainforest extended over the unimaginable area of around six million square kilometers. However, estimates assume that around 40 percent of the forest has been destroyed in the past 50 years. Until today the destruction of the rainforest could not be stopped.
The Amazon is the main stream of the largest flowing water system on earth. Few people know another superlative: the Amazon is the longest river on earth. In a measurement from the 1980s, it came to a length of 6,788 kilometers.
That makes it 117 kilometers longer than the Nile. More than 10,000 tributaries feed it in total, of which around 1,000 are quite significant tributaries (17 of its tributaries are themselves over 1,600 kilometers long).
The Amazon river bed is so deep that overseas ships can sail 3700 kilometers upstream to Iquitos in Peru. And even in the dry season, the Amazon reaches a width of ten to 20 kilometers in places. For comparison: Lake Constance is 14 kilometers wide at its widest point.
In the rainy season, the swelling river can penetrate many kilometers further into the rainforest on both sides of the banks. At its mouth, it is more than 250 kilometers wide, with up to 160,000 cubic meters of fresh water flowing into the Atlantic every second. 40 kilometers from the estuary you can swim in fresh water in the middle of the ocean.
But the sea and with it the tides also have a noticeable effect on the Amazon. The influence of the tides is noticeable up to the town of Obitos, which is 700 kilometers inland.
And when the water is high, twice a month, namely at full and new moon, a water wave up to five meters high rolls up the river at considerable speed.
It is created by the flood penetrating the estuary, which damms the flowing river water here. The wave is associated with a thundering noise, which the forest Indians call "Pororocá", which means something like "thundering water".
Geology of Amazonia
The Amazonia lies in a huge plain that borders the Guyana countries in the north, the Cordilleras in the west and the Brazilian mountains in the south.
Most of the Amazon is covered with geologically relatively young sedimentary rocks, but it is only a thin blanket.
When drilling, one quickly encounters igneous rock that is more than 500 million years old. So it's no wonder that erosion eroded all of the elevations during this period.
More than 150 million years ago, the Amazon and its tributaries were part of an even larger river system that belongs to the Gondwana supercontinent. When it breaks up into the continents known to us today, South America and Africa, the Uramazonas, as it is called today, is also cut in half.
With the formation of the Andes, the original confluence with the Pacific is blocked and a gigantic lake builds up in the lowlands for a long time, until finally the water masses in the east find a new drain. The Amazon as we know it was created.
During the Ice Ages, the sea level sinks so much that the Amazon flows over a gigantic waterfall into the Atlantic at its mouth. As a result, the water flows at high speed and digs deep canyons into the rock.
The Amazon owes its deep river bed to this fact, so that today it can even be navigated far inland by ocean-going ships.
With the end of the Ice Age, the sea level rises tremendously, so that today the Amazon flows extremely comfortably into the Atlantic with a gradient of only 38 meters over 1000 kilometers.
Today it is assumed that the American continent was settled by humans from the Asian mainland.
During the Ice Ages, land bridges formed twice between the two continents in the past 100,000 years. From the north, these people finally settled the entire American continent in the course of only a few millennia.
There is evidence that Europeans did not enter America until the end of the 15th century. With the conquerors (conquistadors) from Spain and Portugal, a period of colonization and exploitation of South America begins, from which the natives have not yet recovered.
The first Europeans report in their records of great cultures and numerous cities on the banks of the Amazon. Cities of sometimes impressive dimensions and with a large population.
But these disappear so quickly that the reports are soon mistaken for exaggerations and fantasies. How many Indians fall victim to the conquistadors is difficult to estimate, but in total it must have been several million.
Scientists are now discovering more and more traces of these great past civilizations that once lived on the Amazon.
And part of their heritage, namely the fertile Indian black earths (Terra Preta), which can be found in small areas all over the jungle, have been preserved to this day and testify to the amazing abilities of these people.
The problems and threats to the Amazon are many and varied. The most far-reaching consequences, however, are undoubtedly the destruction of the rainforest.
The purely profit-oriented international timber corporations are involved, which cause severe damage to huge areas of the rainforest for the relatively small amount of timber that is felled in the forest. In addition, they open up the forest for large-scale settlement by building logging roads.
The Brazilian government even lured settlers into the jungle with the construction of a road, the Transamazonica. She wanted to open up new agricultural areas for the rapidly growing population.
But only four percent of the soils in the Amazon are suitable for agriculture. The remaining soils are so depleted within a few years that despite fertilization hardly any yields can be generated.
The result: The settlers move on after a short time and clear a new piece of land - or, frustrated, migrate to the slums of the big cities, such as Manaus.
In addition to the mostly completely destitute settlers, there are also large landowners who, with the help of state subsidies, build huge cattle pastures or soy plantations in the rainforest. A large part of the food they produce is ultimately exported and ends up in Germany as animal feed, for example.
Large projects also lead to the destruction of large rainforest areas, for example the construction of hydropower plants and the extraction of existing mineral resources such as gold or bauxite.
Another threat arises from the genetic diversity in the rainforest, which has enormous potential for new drugs or crops.
International seed and pharmaceutical companies are currently practicing an unprecedented appropriation of nature, supported by questionable patent procedures. The fact that they mostly owe their knowledge to the indigenous population is not even rudimentarily taken into account.
The most important challenge for the future of the Amazon will be to be able to feed the growing population through sustainable agriculture. Among other things, the secret of Terra Preta - unusual areas of humus-rich soil in the otherwise barren jungle soil - could be of great importance.
This has been studied intensively by scientists for several years. And soon this knowledge could help to transform the nutrient-poor soils of the Amazon into dark, humus-rich and fertile soils.
It will also be of crucial importance to achieve a rethink in the minds of the local people. Because the rainforest is not a jungle that needs to be civilized, but a treasure trove of earthly biodiversity, which we should protect and preserve as such.
This also includes the extensive knowledge of the indigenous people who have lived in and with the rainforest for thousands of years.
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