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 history of the Chiricahua Mountains hundreds of thousands of years of weathering and erosion. The hoodoos originated from a thick deposit of tuff laid down by the Turkey Creek Caldera. As the tuff cooled, it contracted and formed joints. Differential chemical and physical weathering concentrated along these joints, initiating the formation of thousands of rock columns. Balanced rocks that perch, sometimes precariously, on top of many of the hoodoos are a distinctive feature of the monument. Geological history of the Chiricahua Mountains The Geologic history of the Chiricahua Mountains concerns the Chiricahua Mountains, an inactive volcanic range located in Coronado National Forest of southeastern Arizona,