Giant's Causeway cases the horizontal fracture has resulted in a bottom face that is convex while the upper face of the lower segment is concave, producing what are called "ball and socket" joints. The size of the columns is primarily determined by the speed at which lava from a volcanic eruption cools. The extensive fracture network produced the distinctive columns seen today. The basalts were originally part of a great volcanic plateau called the Thulean Plateau which formed during the Paleocene. According to legend, the columns are the remains of a causeway built by a giant. The story goes that the Irish
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