Igneous rock the partial melting of rocks within the mantle and crust. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks. They are formed by the cooling of molten magma on the earth's surface. The magma, which is brought to the surface through fissures or volcanic eruptions, solidifies at a faster rate. Hence such rocks are smooth, crystalline and fine-grained. Basalt is a common extrusive igneous rock and forms lava flows, lava sheets and lava plateaus. Some kinds of basalt solidify to form long polygonal columns. The Giant's Causeway in Antrim, Northern Ireland is an example. The molten rock, with
Nisga'a Memorial Lava Bed Provincial Park legend that accounts for the lava as well as geological causes. The park has waterfalls, pools, cinder cones, tree moulds, lava tubes, spatter cones, a lava-dammed lake, caves and other features created by lava flows. The park aims to protect moose, goats, marmots, bears and many other species of wildlife. The park covers 178.93 square kilometres in area. It is believed to be the site of Canada's most recent volcanic eruption and lava flow, a geological disaster that killed an estimated 2,000 people. The source of the eruption was the Tseax Cone. Large lava flows dammed the Nass River and