Grid Reference: C 856412
Portrush is not only famous for its sticks of peppermint rock, but also for a small area of seashore rock which has helped us understand the way in which the earth was formed. Two hundred years ago, the origin of basalt was a mystery. Was this hard rock produced by sediments settling in layers on the bed of ancient seas? Or was it the result of lava spilling out of volcanoes?
Rocks which have formed on the beds of seas are called sedimentary rocks and often contain fossils. The rock exposed on the seashore at Portush looks like basalt but it contains fossils! Because of this, scientists thought that basalt must be a sedimentary rock. Later it was shown that Portrush rock was not basalt at all but was instead a sedimentary shale which had been baked hard by molten lava.
Today, scientists accept that basalt is formed from volcanic lava which has cooled and turned solid. Some of the fossils which were discovered in Portrush are on display in the Portrush Coastal Zone. In order to safeguard this nature reserve, visitors are asked not to remove specimens.
The site manager is located at County Hall, Castlerock Road, Coleraine: Tel: 028 7035 9977
Search discovernorthernireland.com for further information and places of interest near Portrush.