Giant's Causeway
The towering cliffs of northern Antrim overlook an extraordinary promontory. Some 40,000 dark column head out into the sea, each formed with such geometrical precision that it seems as though some supernatural hand has been at work. This is the Giant's Causeway. Altogether, it is an astounding sight, set against a 4 mile stretch of cliffs that soar some 400ft into the air.
The Causeway juts out from the base of the cliffs and has been eroded into three parts - known as the Grand, Middle and Little Causeway. About half of the columns are hexagonal; others have four, five, seven or eight sides. Many of them have horizontal cracks that divide them in lengths of 12-14in.
THE LEGEND Although the more prosaically minded will tell you the Causeway is the result of ancient volcanic activity, the legend is almost more convincing. It is said that the Causeway was built by the Ulster hero Finn MacCool as he hurried to Scotland, perhaps to fight a rival, or maybe to visit his lady love. Certainly, the flat tops of the column form excellent stepping stones, and a similar rock formation re-emerges on the Scottish island of Staffa.
THE GEOLOGISTS' VIEW According to geologists, the Causeway was formed some 60 million years ago as a result of repeated outpourings of volcanic basalt, during the Tertiary period of the earth's evolution. The columns were formed by the slow and even cooling and contraction of molten lava. The fine- grained basalt columns stand on a thick base of medium-grained basalt, in places over 300ft deep. Between these two dark layers is a striking strip of reddish, soft rock, formed during a long break in volcanic activity when the climate was subtropical.
Elsewhere along the Causeway cliffs, the basalt has been thrown up into a number of bizarre structures which have been colourfully named by generations of local guides - the Wishing Chair, the Keystone, the Honeycomb and the Giant's Loom, the Giant's Organ, the King and his Nobles, the Hoarse Back, the Harp, and others.
The scientific 'discovery' of the Causeway in the 17th century helped British and European scientists to understand the nature of volcanic rocks such as basalt. Today, it is Northern Ireland's most popular tourist attraction and is protected by the National Trust. It was declared a World Heritage Site in April 1987.