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
S bridge part of the original National Road, which was built circa 1825. The S Bridge in Berks County, Pennsylvania, and the Claysville S Bridge in Washington County, Pennsylvania, are listed on the National Register of Historic Places. Another S bridge, in Anderson County, Kentucky, is located on U.S. Route 62 east of Lawrenceburg. It has undergone major roadway replacement and has been widened. Another S bridge of note is located in Hertford, North Carolina. It connects a causeway from Winfall to the Town of Hertford, over the Perquimans River. S bridge An S bridge is a bridge whose alignment follows a