Geology of Antrim Coast & Glens

To read today's landscape requires a journey back in geological time. In the past the land surfaces consisted of sedimentary rocks: sandstones, limestones, shales and clays.

On the surface some 55-60 million years ago poured lavas which formed a massive basalt plateau, capping and preserving the softer rocks below. To the north-west all these rocks have been stripped away to reveal silvery schists - the oldest rocks of the area some 300 million years old.

This geological variation produces many contrasts - red sandstones, grey clays, black basalts and white limestones, creating an ever-changing display reflected in local place names - Red Bay, Blackcave, Whitebay, while the 'dhu' in many names is Irish for black.

The present shape and form of the glens and coast is the result of intense glacial erosion during the last glaciation which was drawing to a close only 17,000 years ago. Ice has sculpted the landscape deepening pre-glacial valleys as at Glenariff and Glenballyemon.

At Fair Head and Rathlin rock surfaces bear the scars of passing ice, and ice-scoured hollows are filled with small loughs and bogs.