It is created when magma travels through a conduit and rises above the surface of the earth.
When this material surrounds an elevated area of land, kipukas are formed. Coulées are domes of this material. Argon can escape from this material, making potassium-argon dating possible. Dikes are formed when this material fills a crack and hardens. It is classified based on viscosity and darkness, both related to silica content, as felsic or mafic, which form rhyolite and (*) basalt. Temperature determines whether this substance takes a ropey form called pahoehoe ["pa-ho-ay-ho-ay"] or a stony and sharp form called aa ["ah-ah"]. It is created when magma travels through a conduit and rises above the surface of the earth. For 10 points, name this molten rock expelled during a volcanic eruption.
When this material surrounds an elevated area of land, kipukas are formed.
lava [accept magma until "pahoehoe"]