The Giant's Causeway, the 173 acres of hexagonal basalt columns that hug the Antrim coast of Northern Ireland, has long been a source of wonder and mystery. How could nature have formed such perfect geometry? Scientists finally have the answer.
For centuries, the prevailing legend surrounding the Giant's Causeway in Northern Ireland was that Fionn Mac Cumhaill (Finn McCool), the mythical hunter-warrior of Irish mythology associated with the Fenian cycle, was behind the causeway's existence, constructing it to reach his arch-rival, a giant named Benandonner, also known as the Red Man, who was believed to roam Scotland.
In the modern age, scientists have been able to attribute the formation of the 40,000 interlocking columns - a UNESCO World Heritage Site since 1986 - to volcanic eruptions some 50 or 60 million years ago. However, the mystery behind their nearly perfect hexagonal shape has persisted.
Until now, that is. In a new article in the journal Nature Communications, a team led by Yan Lavallée, professor of volcanology at the University of Liverpool, have published findings that shed light on the wondrous geometry of the Giant's Causeway and other such formations around the world - and even as far a the planet Mars.
Using basalt cores drilled from the Eyjafjallajökull volcano in Iceland, the team recreated the conditions of formation in a laboratory setting, heating them to 1,832°F (1000°C) until they began to melt back into lava. With the lava held in place by mechanical grips, the team watched for the point and temperature at which the columnar jointing would take place.
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“[This] is a question that has fascinated the world of geology for a very long time," Dr. Lavallée told The Guardian. "We have been wanting to know whether the temperature of the lava that causes the fractures was hot, warm or cold.”
They discovered that the geometric fracturing happens when the cooling basalt reaches between 1544-1634°F (840-890°C) - a state much more solid than previously thought.
Those are the settings and temperature at which the Giant's Causeway formed.
“I have spent over a decade pondering how to address this question and construct the right experiment to find the answer to this question,” Dr. Lavallée told The Guardian. “Now, with this study, we have found that the answer is hot, but after it solidified.”