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 S sea level and below the Great Gibraltar Sand Dune that was once used to capture rainwater which served as Gibraltar's main water supply. The cave is about from the north end of the Rock and opens on the east face of the Rock just above Holy Boy's Cave. The cave provides evidence of marine life indicating that despite its current altitude it was once a sea cave. This is not the only evidence of rising and falling sea levels in Gibraltar which have historically varied greatly. Wynfrid Duckworth described the cave's floor as falling in height towards the entrance and