More than two-thirds of the basin is covered by an immense rainforest, which grades into dry forest and savanna on the higher northern and southern margins and into montane forest in the Andes to the west. Deforestation has accelerated, especially south of the Amazon River and on the piedmont outwash of the Andes, as new highways and air transport facilities have opened the basin to a tidal wave of settlers, corporations, and researchers. Significant mineral discoveries have brought further influxes of population. The ecological consequences of such developments, potentially reaching well beyond the basin and even gaining worldwide importance, have attracted considerable scientific attention see Sidebar:
The women of the tribe fought alongside the men, as was their custom. It appeared following a global reduction of tropical temperatures when the Atlantic Ocean had widened sufficiently to provide a warm, moist climate to the Amazon basin. The rainforest has been in existence for at least 55 million years, and most of the region remained free of savanna -type biomes at least until the current ice agewhen the climate was drier and savanna more widespread.
Climate fluctuations during the last 34 million years have allowed savanna regions to expand into the tropics. During the Oligocenefor example, the rainforest spanned a relatively narrow band.
It expanded again during the Middle Miocenethen retracted to a mostly inland formation at the last glacial maximum.
During the mid-Eoceneit is believed that the drainage basin of the Amazon was split along the middle of the continent by the Purus Arch. Water on the eastern side flowed toward the Atlantic, while to the west water flowed toward the Pacific across the Amazonas Basin.
Analyses of sediment deposits from Amazon basin paleolakes and from the Amazon Fan indicate that rainfall in the basin during the LGM was lower than for the present, and this was almost certainly associated with reduced moist tropical vegetation cover in the basin.
Some scientists argue that the rainforest was reduced to small, isolated refugia separated by open forest and grassland;  other scientists argue that the rainforest remained largely intact but extended less far to the north, south, and east than is seen today. The dust contains phosphorusimportant for plant growth.
The yearly Sahara dust replaces the equivalent amount of phosphorus washed away yearly in Amazon soil from rains and floods. CALIPSO has measured variations in the dust amounts transported— an 86 percent drop between the highest amount of dust transported in and the lowest in A possibility causing the variation is the Sahela strip of semi-arid land on the southern border of the Sahara.
When rain amounts in the Sahel are higher, the volume of dust is lower. The higher rainfall could make more vegetation grow in the Sahel, leaving less sand exposed to winds to blow away. Based on archaeological evidence from an excavation at Caverna da Pedra Pintadahuman inhabitants first settled in the Amazon region at least 11, years ago.
For a long time, it was thought that the Amazon rainforest was only ever sparsely populated, as it was impossible to sustain a large population through agriculture given the poor soil.
Archeologist Betty Meggers was a prominent proponent of this idea, as described in her book Amazonia: Man and Culture in a Counterfeit Paradise. She claimed that a population density of 0.
It is believed that the civilization was later devastated by the spread of diseases from Europe, such as smallpox.
The development of this fertile soil allowed agriculture and silviculture in the previously hostile environment; meaning that large portions of the Amazon rainforest are probably the result of centuries of human management, rather than naturally occurring as has previously been supposed.
Among those were evidence of roads, bridges and large plazas. Wet tropical forests are the most species-rich biomeand tropical forests in the Americas are consistently more species rich than the wet forests in Africa and Asia.
One in ten known species in the world lives in the Amazon rainforest. The region is home to about 2. To date, at least 40, plant species, 2, fishes 1, birds, mammals, amphibians, and reptiles have been scientifically classified in the region. Scientists have described between 96, andinvertebrate species in Brazil alone.
Leaves expand during the dry season when sunlight is at a maximum, then undergo abscission in the cloudy wet season. These changes provide a balance of carbon between photosynthesis and respiration. Among the largest predatory creatures are the black caimanjaguarcougarand anaconda.
In the river, electric eels can produce an electric shock that can stun or kill, while piranha are known to bite and injure humans. There are also numerous parasites and disease vectors.
Vampire bats dwell in the rainforest and can spread the rabies virus.Mar 23, · The Amazon rainforest covers over million square miles of tropical terrain in South America. Most of the Amazon lies in Brazil, though several other countries, including Peru and Ecuador, also.
The Amazon Rainforest is located in 9 different countries but the majority of it (around 60%) is located in Brazil. The rest of it can be found in Peru, Colombia, Ecuador, Bolivia, Venezuela, Guyana, Suriname and French Guiana (which .
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The Amazon Rainforest is home to over 2, species of animals. Some are found in the trees like the Gold Lion Tamarin, while others are found in the amazon rainforest river like the dolphin. A golden lion tamarin in the Amazon Rainforest in Brazil.
rainforest waters By Rhett Butler | Last updated July 31, Tropical rainforests have some of the largest rivers in the world, like the Amazon, Madeira, Mekong, Negro, Orinoco, and Congo (Zaire), because of the tremendous amount of precipitation their watersheds receive.
In fact, the Amazon River is responsible for about one-fifth (twenty percent) of the fresh water that flows into the world's oceans.
2. The Amazon River is the second longest river in the world (the Nile River in Africa is the longest) and is about 4, miles ( km) long.