Geology of Ireland longest known free-hanging stalactites. Geology of Ireland The geology of Ireland consists of the study of the rock formations in Ireland. The island contains rocks from every age from Proterozoic to Holocene and a large variety of different rock types is represented. The basalt columns of the Giant's Causeway together with geologically significant sections of the adjacent coast have been declared a World Heritage Site. The geological detail follows the major events in Ireland's past based on the geological timescale. The oldest known Irish rock is about 1.7 billion years old and is found on Inishtrahull Island off the north
Cave-In-Rock, Illinois 43.8% of those under age 18 and 24.1% of those age 65 or over. Cave-in-Rock's primary feature is a striking riverside cave formed by wind and water erosion and by cataclysmic effects of the 1811–12 New Madrid earthquakes. The cave is located at , just upriver (east) from the village. The first European to come across it was M. de Lery of France, who found it in 1739 and called it ""caverne dans Le Roc"". Other names for the cave include Rock-In-Cave, Rocking Cave, Rock-and-Cave, House of Nature, The Cave, Big Cave, and Murrell's Cave. The cave is the main