What is Island?
[[File:MODIS - Great Britain and Ireland - 2012-06-04 during heat wave.jpg|thumb|180px|[[Ireland]] (left) and [[Great Britain]] (right), are islands of north-west Europe]] [[Image:Bangchuidao Island.JPG|thumb|180px|Bangchuidao Island is an [[islet]] composed mostly of rock, in [[Dalian]], [[Liaoning|Liaoning Province]], China.]] [[Image:Fernando noronha.jpg|thumb|180px|The islands of [[Fernando de Noronha]], [[Brazil]], are the visible parts of submerged mountains.]] An '''island''' is a piece of [[land]] that is surrounded by a [[body of water]] such as a [[lake]], [[river]], [[sea]] or [[ocean]].<ref>{{Cite web|last=Society|first=National Geographic|date=2012-08-27|title=island|url=http://www.nationalgeographic.org/encyclopedia/island/|access-date=2020-12-07|website=National Geographic Society|language=en|archive-date=2021-06-17|archive-url=https://web.archive.org/web/20210617165729/https://www.nationalgeographic.org/encyclopedia/island/|url-status=dead}}</ref> Islands are smaller than [[continent]]s. Although there are many Islands that surround fresh water, the vast majority of them surround oceans. [[Greenland]] and [[Australia]] are huge islands, but they are built of continental rock, and the latter is generally considered a continent. The most ancient part of continental rock is far older and chemically more complex than the rock of the [[sea floor]]. The heart of continents is their [[craton]]s, which are the most ancient and stable parts of the [[Earth's crust]]. In the cratons are all the rare elements needed for electronic equipment. They were swept up as the [[Sun]] moved through areas where [[supernovae]] had exploded. The rare elements we need were all got indirectly from supernovae explosions. The Sun's energy comes from turning hydrogen into helium. There are some islands which do have rare elements, and that is a sign that they were once part of a large [[supercontinent]]. So [[Great Britain]] was once part of a supercontinent. The oldest rocks are 2,700 million years old, and include many