Giant's Causeway 'created in days' not thousands of years, study suggests

Northern Ireland's fascinating landmark is the country's only World Heritage Site

The Giant's Causeway in Northern Ireland. Getty
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Those who believe the story of Finn McCool may feel a sense of vindication after a geologist in Northern Ireland suggested a new theory on the origins of the Giant's Causeway, one of the country's most popular tourist attractions and a Unesco World Heritage Site.

Legend has it that the giant laid the stones to create a walkway to Scotland after being challenged to a fight by a rival. Others prefer to rely on more scientific theories.

The origin of the striking stones, which have attracted visitors from around the world, has fascinated people for centuries.

Dr Mike Simms, senior curator of natural sciences at National Museums NI, has now put forward the first new interpretation since 1940.

He suggests the formation event may have taken only a few days rather than thousands of years. So a perfectly ordinary task for a giant.

Dr Simms considered why the extraordinary geological features are only found at sea level.

To mark Unesco’s International Geodiversity Day on October 6, he has explained why he believes they were formed in a matter of days.

The scientific explanation, widely accepted for decades, is that a river valley was filled with lava that ponded to a greater depth than normal.

As the thick layer of lava cooled and solidified it formed regular columns.

But Dr Simms said that, if this lava-filled hollow was a valley, it would have cut through old layers of lava beneath.

He has identified layers of old lava on the shore either side of the Giant’s Causeway sloping inward, where older layers have not eroded away.

Dr Mike Simms of National Museums NI at the Giant's Causeway. PA

“An analogy I find helpful when explaining this involves cake. Eroding a river valley is rather like cutting through a layer of cake to reveal layers beneath the surface," Dr Simms said.

“In my interpretation, what we actually see are layers of older rock sloping towards the Causeway – more like a badly baked cake that has sunk in the middle.

“I believe the ground subsided as lava moved up and erupted at the surface.

“The lava filled the depression creating the conditions for the columns to form. This event likely took just a few days rather than the many thousands of years that would be needed for erosion to create a river valley.”

He said he first began thinking about the theory when he led a trip to the site in 2012.

“I owe a particular debt of gratitude to another geologist, a young Brazilian man who was on a field trip I was leading in 2012,” he said.

“He questioned how long it would take to erode the supposed river valley, and it was this that opened my eyes to the evidence before me.

“I had visited the Giant’s Causeway many times before, and until that moment I had just accepted the previous theory.

“It goes to show that even at world famous landmarks such as this, new discoveries can be made from a simple observation.”

The Giant’s Causeway is Northern Ireland’s only Unesco World Heritage Site and is operated by the National Trust, which has acknowledged Dr Simms’s theory.

Legend has it that Finn McCool laid the stones as a walkway to Scotland after being challenged to a fight by a rival. Wikimedia Commons

Max Bryant, general manager at Giant’s Causeway and Carrick-a-Rede, said there could always be new possibilities and perspectives on how the site was formed.

“It highlights just how marvellous, magnificent and mysterious a geological formation we have here in Northern Ireland to share with the world,” he said.

Kathryn Thomson, chief executive of National Museums NI, said she was proud to support Dr Simms’s theory.

“I think it’s wonderful he has showcased the expertise of our team and how important museums are,” she said.

“Yes, we provide spaces for people to explore and learn, but our teams also make meaningful contributions elsewhere.

“As a knowledge-based organisation, our staff are uniquely placed to present research and ideas.

“By using our vast natural science collections, for instance, we can support new discoveries and promote responsible and ethical action when it comes to our natural world.”

Updated: October 06, 2022, 8:23 AM
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