Southerndown Coast is a Site of Special Scientific Interest (SSSI) in St Brides Major community, in the Vale of Glamorgan, South Wales. It forms part of the Glamorgan Heritage Coast, bordered by the Monknash Coast to the southeast. The nearby villages are Southerndown and Ogmore-by-Sea. The SSSI extends over 5 kilometres (3 miles) of south-west facing coastline, with rocky limestone cliffs, broad beaches and deeply fissured wave-cut platforms.[1]
The 153ha stretch of shore, cliff, cliff-top, and several short, steep valleys, are designated an SSSI for their geological and botanical value.[2] The cliffs expose the Jurassic geological strata and some of the underlying Carboniferous Limestone, the latter dating from between 359 to c. 330 million years ago. By the Triassic period, 200 million years ago, the Carboniferous rocks had already been tilted and eroded.[2] A new deposition phase created more sedimentary rocks, including a red Triassic conglomerate, and a creamy white Jurassic limestone known as Sutton Stone, a freestone much sought-after for carved stonework, and so widely quarried where it occurs.[1] The SSSI is in two parts. The northern section is the wave-cut platform alongside Ogmore-by-Sea. The southern section, with a short gap, covers both the intertidal areas and the cliffs and grassy cliff-tops of Dunraven Bay, Trwyn y Witch headland and the valleys and shoreline of Cwm Mawr and Cwm Bach.[2] The whole length of the SSSI is traversed by the South Wales section of the Wales Coast Path.[3]
Geological SSSIs are selected to protect sites that display one or more geological features. Three geological features are noted for this site as being of particular significance:–
Places to look for these geological features include:-
The cliff-top grassland is species-rich, with a range of plant communities. Where the limestone is at the surface, calcareous wildflowers are abundant, notably quaking grass, rock-rose and wild thyme. Other localities have neutral, deeper soil and cowslips, dog-violets and bird's foot trefoil are common. Nearer the sea, salt spray gives a maritime grassland community, including red fescue, sea carrot and buck's-horn plantain.[4]