igneous rock produced by eruption and solidified on or near the earth's surface; rhyolite or andesite or basalt; "volcanic rock includes the volcanic glass obsidian"
explosively unstable; "a volcanic temper"
relating to or produced by or consisting of volcanoes; "volcanic steam"; "volcanic islands such as Iceland"; "a volcanic cone is a conical mountain or hill built up of material from volcanic eruptions"
upright in position or posture; "an erect stature"; "erect flower stalks"; "for a dog, an erect tail indicates aggression"; "a column still vertical amid the ruins"; "he sat bolt upright"