Ballycastle Coalfield ASSI

Ballycastle Coalfield is the best exposure of a coalfield sequence in Ireland.

It contains a series of Carboniferous sedimentary rocks (335-330 million years old) with contemporary lavas and younger Tertiary igneous rocks (60 M.y.).

The sedimentary rocks were deposited in a shallow marine bay which gradually developed into a vegetated coastal swamp subject to periodic flooding by the sea. The vegetation was preserved as seams of coal. Fossils that have been found include goniatites (shellfish), fish remains, giant clubmosses and arthropod insects. The Tertiary dykes have metamorphosed the carboniferous shales to produce porcellanite and a range of minerals.

The site also contains evidence of early industrial activity: the coals and iron ores were mined between the 16th and 19th centuries.The underlying geology and the spoil heaps give rise to both base rich and acidic habitats, including wet grassland, base-rich flushes and maritime heath. Limited saltmarsh occurs on some of the beaches.