Geology of Ireland 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 coast of Ulster. Outcrops
Cave-in-Rock State Park the meltoff following the Wisconsin ice age. It was not formed by typical karst processes like Mammoth Cave in nearby Kentucky; it is a tunnel eroded into the bluff. Cave-in-Rock was known and used for thousands of years by the Native Americans. The first European to discover the Cave was M. de Lery of France, who in 1729 mapped and named it ""caverne dans Le Roc"" (cf. supra). This name, translated directly into English, is the name the cave bears to this day. Other names for the cave included Rock-In-Cave, Rocking Cave, Rock-and-Cave, House of Nature, The Cave, Big Cave,