Summary of site:
Directly east of Clabby are two abandoned quarries exposing the Ballyshannon Limestone Formation of the Carboniferous period. The larger, now flooded, is 1.3 km to the east of the village and exposes dark grey, sandy limestones consisting of grains, mostly crinoid fragments, in contact with each other, with a little fine lime mud between. The limestones are separated by thin shale partings which yielded a plentiful fauna, particularly of corals and brachiopods, as well as a rich microfauna of foraminifera. The larger fossils, particularly the corals, match a classic Cumbrian fauna from the north west of England which belongs to the middle Arundian stage giving a time around 344 million years ago. The foraminifera, however, suggest a slightly earlier time in the preceding Chadian stage, roughly 2 million years earlier.
The second, neighbouring, quarry is about 1.1 km east of the village and here the limestone is coarse-grained with virtually no matrix, the intergranular spaces filled with calcite (calcium carbonate). The fauna here is less plentiful with less variety, mostly brachiopods with long age ranges.
The different lithologies of the two quarries are typical of the Ballyshannon Limestone Formation, a deposit that formed on the bed of an equatorial ocean. These are the best exposures of the formation in the area.
The wealth of the fauna in the flooded quarry would justify a measure of protection from the most obvious threats which are dumping and landfill.