There are 167 Sites of Special Scientific Interest (SSSIs) in Cornwall (including the Isles of Scilly). Cornwall, in the south-west of England, UK, has a population of 545,335 (mid-2014 est.) across an area of 3,546 km2 (876,235.7 acres), making it one of the least densely populated counties within England. The north coast of Cornwall falls on the Celtic Sea in the Atlantic Ocean, which also surrounds the Isles of Scilly, the south coast falls on the English Channel and the county is bounded by the River Tamar, forming the border with Devon, to the east. Cornish geology consists mainly of rocks from the Devonian and Carboniferous geological periods. Granite forms a large part of these, with mineralisations of tin, copper, lead and arsenic having been mined in the area. This gives rise to m