Mondo Knows Facts
Subduction recycles old ocean floor
Dense seafloor sinks into the mantle and its water triggers volcanic arcs Oceanic crust cools, thickens and becomes denser than the mantle beneath it, so it bends and descends at a trench. As it sinks, water trapped in the rock lowers the melting point of the overlying mantle. The resulting magma rises to build chains of volcanoes behind the trench. It sits in Mondo's science collection, one of 200 facts that each trace back to the reference below.
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More facts like this
Iceland is a landmass where tectonic plates drift apart above sea levelIceland sits directly atop the Mid-Atlantic Ridge where the North American and Eurasian plates diverge.Seafloor spreading builds new ocean crustMagma rises at mid ocean ridges and pushes the older plates outwardWegener proposed that continents driftMatching fossils and coastlines convinced him, but he lacked a mechanismIndia colliding with Asia raised the HimalayaThe impact crumpled crust upward and the mountains are still risingHawaii sits over a fixed mantle hotspotThe Pacific plate slides across a plume, leaving a trail of volcanic islandsThe Great Rift Valley is a continuous trench splitting East AfricaExtending over 6,000 kilometres from the Middle East to Mozambique, the rift is slowly splitting Africa.
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Tags: geology, tectonics, volcanoes
Subduction recycles old ocean floor: the short answers
- Where does this come from, and can I check it?
- Dense seafloor sinks into the mantle and its water triggers volcanic arcs. The figure is taken from British Geological Survey, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a science fact?
- Yes. It sits on the Science shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.