At one time Amazon River flowed westward, perhaps as part of a proto-Congo (Zaire) river system from the interior of present day Africa when the continents were joined as part of Gondwana. Fifteen million years ago, the Andes were formed by the collision of the South American plate with the Nazca plate. The rise of the Andes and the linkage of the Brazilian and Guyana bedrock shields, blocked the river and caused the Amazon to become a vast inland sea. Gradually this inland sea became a massive swampy, freshwater lake and the marine inhabitants adapted to life in freshwater. For example, over 20 species of stingray, most closely related to those found in the Pacific Ocean, can be found today in the freshwaters of the Amazon. About ten million years ago, waters worked through the sandstone to the west and the Amazon began to flow eastward. At this time the Amazon rainforest was born. During the Ice Age, sea levels dropped and the great Amazon lake rapidly drained and became a river. Three million years later, the ocean level receded enough to expose the Central American isthmus and allow mass migration of mammal species between the Americas. The Ice Ages caused tropical rainforest around the world to retreat. Although debated, it is believed that much of the Amazon reverted to savanna and montane forest (see chapter 3-Ice Ages and Glaciation). Savanna divided patches of rainforest into "islands" and separated existing species for periods long enough to allow genetic differentiation (a similar rainforest retreat took place in Africa. Delta core samples suggest that even the mighty Congo watershed was void of rainforest at this time). When the ice ages ended, the forest was again joined and the species that were once one had diverged significantly enough to be constitute designation as separate species, adding to the tremendous diversity of the region. About 6000 years ago, sea levels rose about 130 meters, once again causing the river to be inundated like a long, giant freshwater lake.
If a group of Brazilian scientists get their way, the answer to “What is the longest river in the world” may no longer be the Nile. An expedition by scientists are said to have discovered that the source of the Amazon is really in the South of Peru which, if true, gives the Amazon a calculated length of 6,800km (4,250 miles). The Nile, by comparison is 6,695km in length. Sometimes called The River Sea.The Amazon River or River Amazon (Portuguese: Rio Amazonas; Spanish: Río Amazonas) of South America is the largest river in the world by volume, with greater total river flow than the next eight largest rivers combined, & the largest drainage basin in the world. Because of its vast dimensions it is sometimes called The River Sea. Most sources regard the Amazon as the second longest river; however, some sources disagree. The Amazon has been measured by different geographers as being anywhere between 6,259 kilometres (3,889 mi) & 6,712 kilometres (4,171 mi) long. The Nile River in Africa is reported to be anywhere from at 5,499 kilometres (3,417 mi) to 6,690 kilometres (4,157 mi).The area covered by the water of the River & its tributaries more than triples over the course of a year. In an average dry season 110,000 square kilometres (42,000 mi²) of land are water-covered, while in the wet season the flooded area of the Amazon Basin rises to 350,000 square kilometres (135,000 mi²). At its widest point the Amazon River can be 11 kilometres (7 mi) wide during the dry season, but during the rainy season when the Amazon floods the surrounding plains it can be up to 40 kilometres (25 mi) wide.The quantity of fresh water released by the Amazon to the Atlantic Ocean is enormous: up to 300,000 m³ per second in the rainy season. The Amazon is responsible for a fifth of the total volume of fresh water entering the oceans worldwide. Offshore of the mouth of the Amazon, potable water can be drawn from the ocean while still out of sight of the coastline, & the salinity of the ocean is notably lower a hundred miles out to sea.The Amazon estuary is over 325 kilometres (202 mi) wide. The main river (which is between approximately one & six miles wide) is navigable for large ocean steamers to Manaus, 1,500 kilometres (930 mi) upriver from the mouth. Smaller ocean vessels of 3,000 tons & 5.5 metres (18 ft) draft can reach as far as Iquitos, Peru, 3,600 kilometres (2,240 mi) from the sea. Smaller riverboats can reach 780 kilometres (485 mi) higher as far as Achual Point. Beyond that, small boats frequently ascend to the Pongo de Manseriche, just above Achual Point.The Amazon drains an area of some 6,915,000 square kilometres (2,670,000 mi²), or some 40 percent of South America. It gathers its waters from 5 degrees north latitude to 20 degrees south latitude. Its most remote sources are found on the inter-Andean plateau, just a short distance from the Pacific Ocean.The Amazon has changed its course several times. In early Cenozoic times, before the uplifting of the Andes, it flowed westward.
Source & Upper AmazonThe Amazon originates from a cliff at the Nevado Mismi, with a sole sign of a wooden cross.The Upper Amazon comprises a series of major river systems in Peru (many of which originate in Ecuador) that flow north & south into the Marañón & Amazon. Among others, these include the following rivers: Morona; Pastaza; Nucuray; Urituyacu; Chambira; Tigre; Nanay; Napo; Huallaga; & Ucayali. Originating in the snow-crested Andes high above Lake Lauricocha in central Peru, the headstream of the Marañón River rises in the glaciers in what is known as the Nevado de Yarupa. Rushing through waterfalls & gorges in an area of the high jungle called the pongos, the Marañón River flows about 1,000 miles (1,600 km) from west-central to northeast Peru before it combines with the Ucayali River, just below the provincial town of Nauta, to form the mighty Amazon River. The primary tributaries of the Marañón River are--from south to north--the Crisnejas, Chamayo, Urtcubamba, Cenepa, Santiago, Moroña, Pastaza, Huallaga, & Tiger Rivers (Cavero-Egusquiza 1941:49-51).The most distant source of the Amazon has only recently been firmly established as a glacial stream on a snowcapped 5,597 m (18,363 ft) peak called Nevado Mismi in the Peruvian Andes, roughly 160 km (100 mi) west of Lake Titicaca & 700 km (430 mi) southeast of Lima. The mountain was first suggested as the source in 1971 but this was not confirmed until 2001. The waters from Nevado Mismi flow into the Quebradas Carhuasanta & Apacheta, which flow into the Río Apurímac which is a tributary of the Ucayali which later joins the Marañón to form the Amazon proper. Formally, though, the union of the Ucayali & the Marañón form the Río Amazonas, which changes its name to Solimões on the triple frontier between Peru, Colombia & Brazil, & later changes its name back to the Amazon only after it meets the Rio Negro near Manaus.After the confluence of Río Apurímac & Ucayali, the river leaves Andean terrain & is instead surrounded by flood plain. From this point to the Marañón, some 1,600 km (990 mi), the forested banks are just out of water, & are inundated long before the river attains its maximum flood-line. The low river banks are interrupted by only a few hills, & the river enters the enormous Amazon Rainforest.The river systems & flood plains in Brazil, Peru, Ecuador, Colombia & Venezuela whose waters drain into the Solimões & its tributaries are called the "Upper Amazon".Amazonian Rainforest
Effect on Species Diversity </li></ul>http://homepages.see.leeds.ac.uk/~eargah/TerraMobilis/TM1an_loop.gif<br />http://rainforests.mongabay.com/amazon/<br />http://i.telegraph.co.uk/telegraph/multimedia/archive/01185/arts-graphics-2008_1185233a.jpg<br />
Amazon River: The Numbers<br />Page 3<br /><ul><li> Length: 6,800km or 4,250 miles
13-20 ft. wave back up river</li></ul>Amazon River. Courtesy of NASA<br />http://geolounge.com/amazon-trumps-the-nile/<br />http://www.mbarron.net/Amazon/factfile.htm<br />http://www.extremescience.com/zoom/index.php/earth-records/3-greatest-river<br />http://www.lonympics.co.uk/amazonriver.htm<br />http://blogs.nationalgeographic.com/blogs/news/chiefeditor/amazon-river-mouth-picture.jpg<br />
Amazon River: Source<br />Page 4<br /><ul><li> Thousands of tributaries