A volcano is an opening, or rupture, in a planet’s surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time.
Volcanoes are generally found where tectonic plates are diverging [...]
Joseph Wright of Derby (British 1734-1797).
Vesuvius from Portici c.1774-76. Credit J Brew
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