On the north coast of County Antrim is the 4m long promontory of around 40,000 basalt columns of the Giants Causeway. Each stone column, with 5 to 7 irregular sides, juts out of the cliff face in a staggered fashion forming irregular steps. They are amassed along basaltic cliffs with some of them reaching 83ft.
These geological formations were produced by volcanic activity around fifty to sixty million years ago during the Tertiary Period. When the lava met the sea, layers of basalt formed these column shapes and the pressure between them forced them into polygonal shapes.
The Causeway is preserved because of its outstanding importance of basaltic joining in the world, natural beauty, geological interest and haven for a diverse variety of different wildlife. The surrounding landscape of grasslands, marshes and seashores support more than 200 species of plants and 50 different types of birds.