Most of the island is covered with a coarse grass. A damp central depression on the island supports a reed bed about in extent. Geology The sea cliff exposures of Sully Island provide an excellent insight into the environment of the area in Triassic times, approximately 200 million years ago. Red mudstones, sandstones and breccias (rocks made from angular pebbles) indicate that this area was a beach situated on the margin between steep semi-desert land and a large shallow lake or marine lagoon. These Triassic rocks were deposited on top of much older Carboniferous limestone which can be seen at the base of the cliffs. Recent history In 1985 the Vale of Glamorgan Council refused an application for outline planning permission for a Health and Holiday Hydro facility on Sully Island. In July 2011, the island was marketed for sale by a firm of local chartered surveyors, Cooke & Arkwright. The island was advertised as comprising . An initial guide price of £1.25 million was reduced to just £95,000, due to lack of interest. Grassroots campaign "Save Sully Island" attempted to raise the purchase price, but failed. However, a mystery buyer stepped in at the last minute with a bid well in excess of the guide price. The buyer, a sailor, had contributed to the grassroots campaign, and promised to keep the island open to the public. References External links 1985 Planning Application for Health & Hydro Celtic Ocean history of the area Swanbridge photos from the 1950s BJ Ford page on Sully Island with links to maps and photographs BBC page on Bendricks Rock History of British Wine Making Tidal islands of Wales Islands of the Vale of Glamorgan Sites of Special Scientific Interest in the Vale of Glamorgan Islands of the Bristol Channel Ports and harbours of Wales Populated coastal places in Wales Articles containing video clips