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
The Holy Cave, Hunterston 19th century. The visible remains suggested a souterrain, but the near absence of records of these in south-west Scotland make this unlikely. The passage is lined with corbelled drystone walling, roofed with capstones, and leads into a natural cave section which may have been formed by wave action as it shows a water-scour likely to have been created by wave action. Some areas of undisturbed stratified deposits have been found, together with evidence of occupation, such as a hearth, bones, and a fragment of glass. A similar cave or rock shelter survives on Holy Isle (off the east coast of