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
Cave of the Crystals only endure approximately ten minutes of exposure at a time. The cave was discovered by the brothers Eloy and Javier Delgado. It has since been allowed to re-flood, with the cavern now filled once more with the water rich in minerals required for the crystals to grow. A group of scientists known as the "Naica Project" have been heavily involved in researching these caverns. Naica lies on an ancient fault above an underground magma chamber which is approximately below the cave. The magma heated the ground water which was saturated with sulfide ions (S). Cool oxygenated surface water contacted the