History of Giant's Causeway

Basalt columns at Giant's Causeway, Co Antrim, Northern Ireland | © National Trust Images / John Millar

The Giant’s Causeway is almost 60 million years in the making and counting. Find out how the world-famous hexagonal basalt stones were formed, and discover the legend of the giant who made the causeway – but was it for love or battle?

The making of the Giant’s Causeway

The Giant’s Causeway formed just under 60 million years ago, and at that time Ireland was still attached to North America. Europe was starting to rip away from North America, and as it did so it created huge rifts in the earth’s surface. Those rifts produced cracks, and up through those cracks came lots of molten rock and lava.

Much later, erosion then caused rivers to form in the basalt. Then more lava came, which flowed through the river valleys. In this river valley, the Giant’s Causeway we think of today was formed.

Key stages in the formation of the Giant’s Causeway

Volcanic eruptions caused layers of basalt to form on the chalk landscape
Erosion caused rivers to form
More lava filled the river valley
As the bottom cooled slowly it crack in even patterns
Glaciers then scraped away the top layers of rock
As things warmed up and the sea level rose, waves began to wear away and further expose the rock.

View of Giant's Organ, long trunk-shaped rocks in Giant's Causeway, County Antrim, Northern Ireland | © National Trust Images / Joe Cornish

Why is it called the Giant’s Causeway?

A giant legend

Legend has it that an Irish giant named Finn McCool created a causeway to get across the Irish Sea to face his rival, the Scottish giant Benandonner.

Following their fearsome meeting, Benandonner ripped up the causeway as he fled back to Scotland, leaving what you see here today.

Finn McCool's giant boot also lies fossilised at the Giant's Causeway in the bay locals refer to as 'Port Noffer' or 'bay of the giant.'

Built for love

However, a little-known fable provides an alternative version of the story. This lesser-known story was told by Causeway guides in the 1700s and early 1800s – of Finn building the Causeway for love rather than battle.

A poem found in a library in Norway by Eva Hov recounted the tale they told. Written in 1830 by Mary Anne, the poem gives the version of events told by the Causeway guides.

'Finn had fallen in love with a Scottish maiden. Sad that he couldn’t reach her, he walked along the shore, skimming stones out across the sea. Seeing the splash they made, Finn suddenly hit upon a plan – he would build a Causeway in order to see his love.

Finn laboured all day, and made good progress in his task, extending the Causeway nearly halfway across the sea. Tired, he went home to rest, confident he would finish the job the next day. But sadly his grandmother had other ideas.
Afraid of losing him forever to Scotland, she used her magic to call up an enormous storm. The waves and wind lashed the partly-built Causeway and the rocks were torn apart. Finn awoke the next day to see his handiwork had disappeared.

Undaunted, he began to build a new Causeway. Once more the stones stretched out into the ocean, but that very night his work was destroyed. Finn tried again and again: the harder he laboured, the more violent the storms. Worn out, he made one last attempt, building on through the night.

The storms rose up around Finn, tearing at him with thunder and lightning, while wild waves beat at every rock he tried to lift. At last he reached the other side, but the trial was too much, even for a giant. Exhausted, he fell down and died in the arms of his beloved.

Behind him the Causeway he had built slipped below the waves for a final time. A mighty thunderclap sounded and Finn’s Granny climbed to the top of a hill to see what had happened. Horrified by what her magic had done, she turned to stone. She stands there to this day.'

– Mary Anne, 1830

Frozen in stone

If you visit the Giant's Causeway, look to the West of Port Ganny (the bay before the Little Causeway) and you can see the stooped figure of Granny heading up the Stookans headland frozen in stone.

At Port Noffer the Giant's Boot reputedly lost by Finn McCool can be seen.

The Giants Boot left behind at the Giant's Causeway in County Antrim, Northern Ireland — Giant's Causeway, County Antrim, Northern Ireland | © National Trust Images / Peter Greenway

Becoming a World Heritage Site

Designated in 1986

The Giant’s Causeway was designated as a World Heritage Site in 1986. In order to be listed, a site must meet at least one of the organisation’s strict criteria - the Giant’s Causeway meets two, confirming that this special place is of outstanding universal value.

The first criteria (No.7) means the site has superlative natural phenomena or areas of exceptional national beauty and aesthetic importance
The second criteria (No.8) means the site is an outstanding example which represents major stages in the earth’s history, including the record of life, significant ongoing geological processes in the development of landforms or significant geomorphic or physiographic features.

An international treasure

This makes the Giant’s Causeway an international treasure, which requires protection for future generations. Since acquiring the site in 1961, the National Trust has been the proud guardian of the Giant’s Causeway.

Over the past 50 years or so the site has been opened up to visitors with miles of footpaths opened so that visitors can explore this dramatic part of the coastline.

With your support, we have been able to look after this place so that present and future generations can enjoy and learn from this internationally important site – thank you