Cliffs form much of the coastline of Northern Ireland, and are composed of several different kinds of rock. In Cos Londonderry and Antrim, the cliffs are predominantly of basaltic rock or chalk, and can produce magnificent coastal scenery such as at the Giant's Causeway or Fair Head. In Co Down the geology is quite different, with rather low cliffs produced from soft fluvio-glacial deposits such as those at Ballyhornan Bay or at Ballymartin, or low cliffs of Silurian shales along the coast south from Newcastle. Raised beaches frequently separate an old sea cliff from the modern shoreline. Caves are not infrequent, especially in basalt and chalk cliffs. There are particularly fine caves at Red Bay where the cliffs are composed of conglomerate or sandstone.
The flora of sea cliffs is interesting and one of the few habitats largely undamaged by human activity. Typical species include: