Name: Giant's Causeway
Address: 44 Causeway Rd, Bushmills BT57 8SU, UK
Telephone: 028 2073 1855
Rating: 4.7

Basalt columns jut upwards out of the sea at this iconic landform with a modern visitor's centre.

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The Giant's Causeway is made up of around 40,000 interlocking basalt columns, a truly impressive natural structure.

Column Count

Legend says the causeway was built by the Irish giant Fionn mac Cumhaill (Finn McCool) as a path to Scotland to fight a rival giant.

Giant's Origin

The Causeway was formed by intense volcanic activity around 50 to 60 million years ago during the Paleocene Epoch.

Geological Formation

While some columns have four, five, seven, or even eight sides, most of the columns are hexagonal (six-sided) in shape.

Column Shape

The Giant's Causeway was designated a UNESCO World Heritage Site in 1986, recognizing its outstanding universal value.

World Heritage Site

Similar basalt columns can be found on the Scottish island of Staffa, particularly at Fingal's Cave, supporting the geological connection and the legend.

Counterpart in Scotland

Giant's Causeway

The Giant's Causeway, a UNESCO World Heritage site, is distinguished by its estimated 40,000 interlocking basalt columns, a geological marvel resulting from intense volcanic activity during the Tertiary period. These predominantly hexagonal columns, though some possess four, five, seven, or even eight sides, create a pavement-like landscape that descends into the sea. The tallest columns reach approximately 12 meters in height, while the solidified lava in the cliffs is nearly 28 meters thick in places. Legend attributes the formation to the Irish giant Fionn mac Cumhaill, who supposedly built the causeway to reach Scotland. Intriguingly, similar basalt formations exist on the Scottish island of Staffa, specifically at Fingal's Cave, lending credence to the geological connection and fueling the mythical narrative. The Causeway's unique polygonal jointing patterns, a result of contraction during cooling, are rarely found on such a grand scale elsewhere, making it a globally significant geological site.

Introduction

The Giant's Causeway is renowned for its approximately 40,000 interlocking basalt columns, a direct result of Paleogene volcanic activity around 50 to 60 million years ago. These columns, predominantly hexagonal but also exhibiting four, five, seven, or eight sides, form a unique stepping stone landscape leading from the cliffs into the sea. The tallest columns reach about 12 meters in height, while the solidified lava cliffs measure up to 28 meters thick.

The columns' formation is attributed to the cooling and contraction of highly fluid molten basalt that intruded through chalk beds, creating an extensive volcanic plateau. Horizontal contraction during cooling led to fracturing, similar to drying mud, resulting in the pillarlike structures. The size of the columns was determined by the rate at which the lava cooled. The extensive fracture network produced the columns and in many cases, horizontal fractures resulted in ball and socket joints.

These basalts were originally part of the Thulean Plateau. Similar basalt formations from the same volcanic episodes can be found at Fingal's Cave on the Isle of Staffa in Scotland. The unique geological heritage of the Giant's Causeway, particularly the origin of its basalt columns, led to its inclusion as one of the International Union of Geological Sciences' 100 "geological heritage sites" worldwide.

Basalt Columns

The Giant's Causeway, a key feature of the Causeway Coast in Northern Ireland, presents a dramatic landscape of approximately 40,000 interlocking basalt columns. These columns, predominantly hexagonal, form a pavement-like structure extending from the foot of the cliffs into the sea, the result of volcanic activity during the Paleogene period. As part of the Causeway Coast, a designated World Heritage Site, the Giant's Causeway plays a crucial role in understanding basaltic volcanism. The strata exposed in the cliff faces have been instrumental in shaping the understanding of Earth's geological history.

The site's significance extends beyond geology, intertwining with local legends of giants striding across the sea to Scotland. This blend of natural wonder and mythology has made it a celebrated attraction for centuries, drawing nearly one million visitors in 2019. The Causeway Coast area is also a haven for seabirds and unique plant life, adding to its ecological value.

Access to the Giant's Causeway is free, with a visitor center providing additional information and context. However, the center's exhibits have faced scrutiny, particularly regarding the presentation of scientific and creationist viewpoints. Despite this, the National Trust emphasizes the scientific explanation for the causeway's formation, while acknowledging traditional beliefs. The site is connected to nearby towns via the Belfast-Derry railway line and Ulsterbus, with a scenic walk from Portrush offering an alternative route alongside other landmarks of the Causeway Coast.

Causeway Coast

The Giant's Causeway and Causeway Coast, Northern Ireland's sole UNESCO World Heritage Site recognized for geological heritage, showcases volcanic activity from the Palaeogene period, approximately 60 million years ago. The fragmentation of Laurasia and the opening of the North Atlantic Ocean triggered cataclysmic volcanic events, forming the site's rocks and similar formations in western Scotland. Initial eruptions, at least six in number, were followed by a dormant period that led to the creation of the Interbasaltic Formation, a red layer rich in iron and aluminum, as lava weathered. This dormant phase saw the lava fields transform into forested landscapes.

Resumed volcanic activity filled valleys with lava, accumulating a 90m-deep lava lake at the Causeway. The slow, even cooling of this lava resulted in regular stress patterns, causing contraction cracks and forming thousands of distinctive columns. Subsequent eruptions created the Causeway Tholeiite Member, with the initial eruption producing the thickest flow. Another extended dormancy preceded the final series of eruptions, known as the Upper Basalt Formation. The columnar jointing observed is a direct result of the gradual cooling process. The Palaeocene rocks of the Giant's Causeway and Causeway Coast were included by the International Union of Geological Sciences (IUGS) in its assemblage of 100 "geological heritage sites" around the world.

Geological Heritage

In Irish mythology, the Giant's Causeway is linked to the legend of Fionn mac Cumhaill (Finn MacCool), an Irish giant from the Fenian Cycle. According to the tale, Fionn was challenged to a fight by the Scottish giant Benandonner. To accept the challenge, Fionn built the causeway across the North Channel, creating a path for the two to meet. One version recounts Fionn defeating Benandonner, while another tells of Fionn realizing Benandonner's superior size and hiding. In this version, Fionn's wife, Sadhbh (or Oonagh), disguises him as a baby in a cradle. When Benandonner sees the enormous "baby," he assumes the father, Fionn, must be a giant of immense proportions and flees back to Scotland in terror, destroying the causeway to prevent pursuit.

The Irish name for the Giant's Causeway, Clochán na bhFomhóraigh or Clochán na bhFomhórach, translates to "stepping stones of the Fomhóraigh." The Fomhóraigh are a race of mythological beings in Irish mythology, sometimes described as giants and possibly pre-Christian deities. While no pre-Christian stories about the Giant's Causeway survive, it may have originally been associated with these Fomorians. Over time, pagan gods in Irish folklore diminished into fairies, while heroes grew into giants in the popular imagination. Despite the legend, Fionn mac Cumhaill is typically portrayed as a hero with supernatural abilities rather than a giant within Irish mythology.

Irish Mythology

The Giant's Causeway in Northern Ireland is a prime example of Paleogene volcanic activity, showcasing around 40,000 interlocking basalt columns that extend into the Atlantic Ocean. These columns are the result of an ancient volcanic fissure eruption, part of the North Atlantic Igneous Province, dating back approximately 50 to 60 million years. The area's geological significance lies in its contribution to understanding basalt origins, a debate that began in the late 18th century between Neptunists and Vulcanists. The Causeway's columnar basalts provided key evidence supporting the Vulcanist theory, which posits that basalt is volcanic in origin.

The formation began with multiple lava eruptions, followed by a period of volcanic inactivity that led to the creation of the Interbasaltic Formation, a layer rich in iron and aluminum. Subsequent volcanic activity caused lava to accumulate, forming a large lava lake around 90 meters deep. As this lava cooled slowly and evenly, it created regular stress patterns, resulting in contraction cracks that formed the distinctive columns. The size of these columns was determined by the rate at which the lava cooled. Three distinct lava flows are present: the Lower Basalt, the Causeway lava, and the Upper Basalt, interspersed with interbasaltic horizons. The Antrim basalts, which include the Giant's Causeway, are part of a larger igneous province formed during the opening of the North Atlantic Ocean.

Giant's Causeway

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Column Count

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Geological Formation

Column Shape

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