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
Cave-in-Rock State Park Cave-in-Rock State Park Cave-In-Rock State Park is an Illinois state park, on 240 acres, in the town of Cave-in-Rock, Hardin County, Illinois in the United States. The state park contains the historic Cave-In-Rock, a landmark of the Ohio River. It is maintained by the Illinois Department of Natural Resources (IDNR). Cave-in-Rock's primary feature is a striking -wide riverside cave formed by wind and water erosion and cataclysmic effects of the 1811–12 New Madrid earthquakes at Cave-in-Rock State Park , just upriver from the village. The Cave-in-Rock was worn into the limestone bluffs of the Ohio River by floods, especially during