<P> As a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments . In this way, Iceland is considered part of Europe and Madagascar part of Africa . Extrapolating the concept to its extreme, some geographers group the Australian continental plate with other islands in the Pacific into one continent called Oceania . This divides the entire land surface of Earth into continents or quasi-continents . </P> <P> The ideal criterion that each continent is a discrete landmass is commonly relaxed due to historical conventions . Of the seven most globally recognized continents, only Antarctica and Australia are completely separated from other continents by the ocean . Several continents are defined not as absolutely distinct bodies but as "more or less discrete masses of land". Asia and Africa are joined by the Isthmus of Suez, and North and South America by the Isthmus of Panama . In both cases, there is no complete separation of these landmasses by water (disregarding the Suez Canal and Panama Canal, which are both narrow and shallow, as well as being artificial). Both these isthmuses are very narrow compared to the bulk of the landmasses they unite . </P> <P> North America and South America are treated as separate continents in the seven - continent model . However, they may also be viewed as a single continent known as America or the Americas . This viewpoint was common in the United States until World War II, and remains prevalent in some Asian six - continent models . This remains the more common vision in Latin American countries, Spain, Portugal, France, Italy and Greece, where they are taught as a single continent . </P> <P> The criterion of a discrete landmass is completely disregarded if the continuous landmass of Eurasia is classified as two separate continents: Europe and Asia . Physiographically, Europe and South Asia are peninsulas of the Eurasian landmass . However, Europe is widely considered a continent with its comparatively large land area of 10,180,000 square kilometres (3,930,000 sq mi), while South Asia, with less than half that area, is considered a subcontinent . The alternative view--in geology and geography--that Eurasia is a single continent results in a six - continent view of the world . Some view separation of Eurasia into Asia and Europe as a residue of Eurocentrism: "In physical, cultural and historical diversity, China and India are comparable to the entire European landmass, not to a single European country . (...)." However, for historical and cultural reasons, the view of Europe as a separate continent continues in several categorizations . </P>

Why are north and south america different continents
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