Summary of site:
In the middle beach at Greencastle, between Greencastle Point and Soldiers Point, there are two exposures, both of lime-rich sandstones, sandy limestones and oolitic limestones (limestones with almost spherical grains of concentric layers of calcium carbonate). Sedimentary structures include eroded bed bases, cross bedding, rippled surfaces and fine, parallel laminations. Lenses of grit and fine pebbles contain fragmentary fossils including carbonized plant debris. The pebbles originate from a wide variety of local sources and include reworked limestone, Silurian greywacke and coarse-grained igneous rocks.
The rocks belong to the Arundian stage of the Carboniferous period, making them about 345 million years old.