Giant's Causeway

Giant's Causeway, is an extraordinary grouping of steplike basalt columns some 75 miles across the sea coast on the edge of the Antrim plateau in Northern Ireland. The tops of the columns form stepping stones that lead from the cliff foot and disappear under the sea. Altogether there are 40,000 of these stone columns; some of them have four, five, eight, or even ten sides, but the majority are perfect hexagons ranging from 15 to 20 inches in diameter. Viewed from above, the columns look exactly like paving stones, all neatly fitted into place.
This striking landscape was caused by intense volcanic activity, which brought large amounts of molten basaltic lava to the surface. The molten lava cooled at a slow, very even rate. And as it cooled, the lava gradually contracted, forming prismatic patterns in the cooling rock. As cooling and shrinkage continued, the cracks on the surface extended through the entire lava mass to form a network of vertical joints seperating the flat-sided basaltic columns. Giant's Causeway is a National Natural Reserve, declared a World Heritage site by UNESCO, and is the most popular tourist destination in Northern Ireland. Similar assemblages of basaltic columns are found in many other places, but few can rival the precise geometry of those making up the Giant's Causeway.