The Giants Causeway

In northern Ireland, at the heart of one of Europe’s most magnificent coastlines, the Giants Causeway with its rugged symmetry is visited by half a million tourists each year. The Causeway consists of an amazing array of massive black basalt columns.
This article appeared in Vol. 4, No. 3 - 2007


The Causeway consists of an amazing array of massive black basalt columns. It is estimated that there are around 40,000 in total. The tops of the columns form stepping stones that lead from the cliff foot and disappear under the sea. As a visitor, you are free to wander over the stones.
The Giants Causeway was discovered in 1693, but it was formed during the early Tertiary some 62-65 million years ago. Highly fluid molten rock was forced up through fissures in the chalk bed to form an extensive lava plateau.
The larger fissures, through which the lava flowed, can be clearly seen as bands of dark rock.
There were three periods of volcanic activity in the early Tertiary, known as the Lower, Middle and Upper Basalts. The hexagonal columns of the causeway occur in the middle basalt layer.
The world famous columnar structure formed as a result of crystallization under conditions of accelerated cooling. This usually occurs when molten lava comes into immediate contact with water, as happens today in Hawaii, the resulting fast accelerated cooling process causes cracking and results in what we see today at the causeway.
The Giants Causeway was inscribed as a world heritage site in 1986.


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