CYNGOR CEFN GWLAD CYMRU

COUNTRYSIDE COUNCIL FOR WALES

SITE OF SPECIAL SCIENTIFIC INTEREST CITATION

VALE OF GLAMORGAN BARRY ISLAND

Date of Notification: 1958, 1990

National Grid reference: ST 110662 and ST 120661

O.S. Maps: 1:50,000 Sheet number: 171

1:25,000 Sheet number: ST 16

Site Area: 16ha

Description:

The marginal facies of the Mercia Mudstone Group is seen in a unique unconformable relationship with the Carboniferous Limestone at Barry Island. Several horizontal to sub-horizontal terraces up to 15m wide are cut into the Carboniferous Limestone. These terraces are joined by vertical cliffs up to 5 m high and covered by marginal lacustrine facies of the Mercia Mudstone Group. The terraces are covered by poorly sorted angular breccias, interpreted as fossil screes, and better sorted gravels associated with wave-rippled and desiccated finer sediments which are interpreted as lacustrine short zone (beach) sediments. The locality is unique in showing such a spectacular exposure of marginal Triassic facies.