Icelandic lava

Lava is molten rock expelled by a volcano during eruption. This molten rock is formed in the interior of the earth. When first erupted from a volcanic vent, lava is a liquid at temperatures from 700 °C to 1,200 °C (1,300 °F to 2,200 °F). Although lava is quite viscous, with about 100,000 times the viscosity of water, it can flow great distances before cooling.