A chain of islands formed when a tectonic plate moves over a stationary plume of lava arising from the earth's deep mantle. For example, the Hawaiian archipelago was formed as the Pacific tectonic plate moved northwestward (at a rate estimated to be about 9 cm per year) over just such a hot spot. This erupted periodically, perforating the plate with volcanoes that grew until some of them rose above sea level to form an island chain. Kauai was the first of the large islands to be formed, 5 million years ago. Hawaii, the youngest island, was formed about 500,000 years ago, and its three active volcanoes sit above the hot spot. An undersea volcano, Loihi, is also erupting 30 km off shore on the southeast flank of Mauna Loa. The hot spot hypothesis, put forth in 1963 by J. Tuzo Wilson, is now the main unifying theory that explains the origin of many groups of oceanic islands worldwide. The Galapagos islands (q.v.) are also a hot spot archipelago. They began as a group of submarine volcanoes that grew progressively from the ocean floor until about 4.5 million years ago, when they emerged above sea level. The northwest islands of Fernandina and Isabela, which currently lie above the hot spot, have active volcanoes. See plate tectonics.
Subjects: Genetics and Genomics.