Black Nore Lighthouse

About

Black Nore Lighthouse is a grade II listed building in Portishead, Somerset, England. The cast iron white-painted lighthouse was built in 1894 by Trinity House to guide shipping in the Severn Estuary as it made its way in and out of Bristol Harbour. It sits on a small outcrop where the estuary opens out into the Bristol Channel. Before its light was decommissioned, the lens array (a rotating fourth-order 250 mm biform optic) flashed twice every ten seconds. The waters off Black Nore have one of the largest tidal ranges in the world, reaching about 14.8 metres (49 ft) at nearby Avonmouth. This produces fast tidal streams and short windows for safe navigation. Approaches are marked by shifting sandbanks, such as the Welsh Hook and the English and Welsh Grounds, where depths and channels change continuously as the seabed moves.

Adapted from Wikipedia (CC BY-SA). Photography via Wikimedia Commons.