Pliocene

The Pliocene (/ˈplaɪəˌsiːn/; also Pleiocene) Epoch (symbol P_O) is the epoch in the geologic timescale that extends from 5.333 million to 2.58 million years BP. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations entirely within the Pleistocene, the Pliocene also included the Gelasian stage, which lasted from 2.588 to 1.806 million years ago, and is now included in the Pleistocene.

As with other older geologic periods, the geological strata that define the start and end are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The boundaries defining the Pliocene are not set at an easily identified worldwide event but rather at regional boundaries between the warmer Miocene and the relatively cooler Pliocene. The upper boundary was set at the start of the Pleistocene glaciations.

South America

South America is a continent located in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. It is also considered as a subcontinent of the Americas, which is the model used in Spanish-speaking nations and most of South America.

It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest. It includes twelve sovereign states – Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Uruguay, and Venezuela – and two non-sovereign areas – French Guiana, an overseas department of France, and the Falkland Islands, a British Overseas Territory (though disputed by Argentina). In addition to this, the ABC islands of the Netherlands and Trinidad and Tobago may also be considered part of South America.

South America has an area of 17,840,000 square kilometers (6,890,000 sq mi). Its population as of 2005 has been estimated at more than 371,090,000. South America ranks fourth in area (after Asia, Africa, and North America) and fifth in population (after Asia, Africa, Europe, and North America). The most populous countries are Brazil, Colombia, Argentina, Venezuela and Peru.