Geography of Dorset is the Blackmore Vale, a relatively low-lying area of clays and limestones of Jurassic age. The south-east of the county forms part of the Hampshire Basin, an asymmetric syncline covered in sands and gravels of Paleogene age. The main rivers in the county are the Stour, Frome and Piddle. The Stour is the county's largest river, although its source is in the neighbouring county of Wiltshire. The Frome and Piddle both lie wholly within the county. The whole of Dorset's coastline is designated part of the Jurassic Coast World Heritage Site, and contains examples of many different coastal landforms, reflecting
UNESCO Convention on the Protection of the Underwater Cultural Heritage sites have now disappeared without any trace. Due to the sheer mass of the world's oceans and the inability to monitor all activity that takes place therein, pirates and underwater thieves continue to pose a significant threat to the preservation of cultural heritage and cultural property. In 2006, the UNESCO convention was ratified by an additional state, Portugal, needing international protection for the looting of its underwater cultural heritage sites. At least six international treasure hunting organizations had established themselves off the coasts of Portugal to reap the benefits of the nation's coastline after new legislation had allowed for the