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
Ogdens Cave Natural Area Preserve Ogdens Cave Natural Area Preserve Ogdens Cave Natural Area Preserve is a Natural Area Preserve located in Frederick County, Virginia. The preserve protects a cave that carries a below-ground branch of Buffalo Marsh Run, which also flows overland through the preserve. With nearly of the cave mapped, Ogdens Cave is the longest known cave in Frederick County. Several rare invertebrate species are found within the cave, including the thin-neck cave beetle ("Pseudanophthalmus parvicollis"), two amphipods, an isopod, and the Appalachian springsnail ("Fontigens bottimeri"). These species are sustained by nutrients delivered by the cave's stream and by various animals, such as