Giant's Causeway cases the horizontal fracture has resulted in a bottom face that is convex while the upper face of the lower segment is concave, producing what are called "ball and socket" joints. The size of the columns is primarily determined by the speed at which lava from a volcanic eruption cools. The extensive fracture network produced the distinctive columns seen today. The basalts were originally part of a great volcanic plateau called the Thulean Plateau which formed during the Paleocene. According to legend, the columns are the remains of a causeway built by a giant. The story goes that the Irish
Geological Survey of Newfoundland and Labrador Geological Survey of Newfoundland and Labrador The Geological Survey of Newfoundland and Labrador is a scientific research agency that is part of the Department of Natural Resources of the Government of Newfoundland and Labrador. It is the agency responsible for performing geological mapping and surveying which provides geological maps, reports, and mineral analysis, and for developing Newfoundland and Labrador's natural resources and protecting the environment. The Geological Survey is a division of the Mines Branch. The Survey currently has 5 sections (Regional Geology; Mineral Deposits; Geochemistry, Geophysics and Terrain Sciences; Geoscience Data Management and Geoscience Publications and Information) and a