The geology of Northern Ireland records a fascinating history of events extending over more than 800 million years. The varied geology gives rise to often striking scenery and some of the most spectacular geological sites anywhere in Britain or Ireland. Indeed, the Giant's Causeway represents the only geological World Heritage Site anywhere in Britain or Ireland. However, this wealth of geological features in the province is not reflected in a similar richness of palaeontologically important sites. Although many of the marine sequences in Northern Ireland do contain fossils which are important for any palaeoenvironmental or biostratigraphic interpretation, the contained biota often is unremarkable by comparison with many palaeontologically important sites elsewhere in the UK. Nonetheless, some important sites do exist in areas that have not otherwise been designated as Areas of Special Scientific Interest (ASSIs).
The geological succession in Northern Ireland spans more than 800 million years yet is far from complete. Even those parts of the succession that are present are not always fossil bearing. Significant parts of the geological column are represented by metamorphic rocks too old and deformed to yield any recognisable fossils, by extrusive or intrusive igneous rocks, or by non-marine sediments in which fossils are rare or absent. In fact richly fossiliferous rocks form only a very small proportion of the total in Northern Ireland. The palaeontological significance of the various parts of the geological succession in Northern Ireland is summarised below.
