Castletown, Isle of Man House of Keys moved from Castletown to Douglas. The Isle of Man Census 2011 lists the town's population as 3,097 (2006: 3,109) It is the fourth largest town on the island, after Douglas, Ramsey and Peel, but is also smaller than Onchan and Port Erin, which have the status of villages. The town lies on the northwest side of Castletown Bay. The opposite shore of the bay is the west coast of the distinctively-shaped Langness Peninsula. To the north-east are Ronaldsway Airport and industrial zone, and the village of Ballasalla; to the north-west the villages of Ballabeg and Colby; and
Geography of the Isle of Man the Ordovician period. There is a belt of younger Silurian rocks along the west coast between Niarbyl and Peel, and a small area of Devonian sandstones around Peel. A band of Carboniferous period rocks underlies part of the northern plain, but is nowhere seen at the surface; however similar age rocks do outcrop in the south between Castletown, Silverdale and Port St Mary. Permo-Triassic age rocks are known to lie beneath the Point of Ayre but, as with the rest of the northern plain, these rocks are concealed by substantial thicknesses of superficial deposits. The island has significant deposits of