Giant’s Causeway, Ireland

The Giant's Causeway (known as Clochán an Aifir or Clochán na bhFomhórach in Irish and tha Giant's Causey inUlster-Scots) is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic eruption.

It is located in County Antrim on the northeast coast of Northern Ireland, about three miles (4.8 km) northeast of the town of Bushmills.

Around 50 to 60 million years ago, during the Paleogene Period, Antrim was subject to intense volcanic activity, when highly fluid molten basalt intruded throughchalk beds to form an extensive lava plateau. As the lava cooled, contraction occurred. Horizontal contraction fractured in a similar way to drying mud, with the cracks propagating down as the mass cooled, leaving pillarlike structures, which are also fractured horizontally into "biscuits". In many 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 Paleogene.

Some of the structures in the area, having been subject to several million years of weathering, resemble objects, such as the Organ and Giant's Boot structures. Other features include many reddish, weathered low columns known as Giants Eyes, created by the displacement of basalt boulders; the Shepherd's Steps; theHoneycomb; the Giant's Harp; the Chimney Stacks; the Giant's Gate and the Camel's Hump.