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
World Heritage Site in visitor numbers. A sizable lobbying industry has grown around the awards because World Heritage listing has the potential to significantly increase tourism revenue from sites selected. Site listing bids are often lengthy and costly, putting poorer countries at a disadvantage. Eritrea's efforts to promote Asmara are one example. In 2016, the Australian government was reported to have successfully lobbied for Great Barrier Reef conservation efforts to be removed from a UNESCO report titled 'World Heritage and Tourism in a Changing Climate'. The Australian government's actions were in response to their concern about the negative impact that an 'at risk'