Local Carboniferous Sandstone
Carboniferous sandstone outcrops throughout Northern Ireland particularly in Counties Fermanagh, Tyrone and Derry. Much of the Carboniferous Period (354-290 million years ago) Ireland was dominated by coastal alluvial plains and shallow tropical waters where the sedimentary rocks sandstones, limestones and mudstones were formed in marine and delta environments. The sandstones are often interbedded with limestone units and the two building stone types are seen built together with limestone as rubble stone and sandstone as quoins, dressings and carved details.
A small pocket of Carboniferous sandstone outcrops near Ballycastle in County Antrim and this was used for construction of local churches and buildings in that area and transported further afield once the railways became established. In County Londonderry, Dungiven Sandstone was popular building material as well as Carboniferous sandstone brought over the border from County Donegal. In County Tyrone Dungannon Sandstone (Millstone Grit) was used locally and exported to Belfast.
Local Carboniferous sandstone varies widely in terms of colours, textures and sedimentary structures and often it can be difficult to distinguish varieties.