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
Callao Cave and a height of . The cathedral-like room has been turned into a chapel by the local people. A rock formation serves as the altar of the chapel lit by a stream of light coming from a rooftop opening. The conditions inside the caves have caused the formation of stalactites and stalagmites, more so in the deeper chambers. Several spectacular speleothems or formations are found inside the cave like flowstones, glittering dripstones, cave curtains, crystal helictites, columns, etc. Callao Cave is classified by the Department of Environment and Natural Resources as a Class II cave. This describes caves with areas