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
Geological Exploration of the Fortieth Parallel Geological Exploration of the Fortieth Parallel The Geological Exploration of the Fortieth Parallel was a geological survey made by order of the Secretary of War according to acts of Congress of March 2, 1867, and March 3, 1869, under the direction of Brig. and Bvt. Major General A. A. Humphreys, Chief of Engineers, by Clarence King, U. S. geologist. More commonly known as the Fortieth Parallel Survey, the survey conducted field work from 1867 to 1872, exploring the area along the fortieth parallel north from northeastern California, through Nevada, to eastern Wyoming. The results of the survey were published in