The island was originally called Bearn Back, derived from the Old English words burn and bæc which means The spring brook island.[3] It was pronounced by locals as Be-arn Back which has since become corrupted into the current name Birnbeck.[4] The rock is limestone, giving rise to the geological term "Birnbeck Limestone Formation".[5] Prior to the construction of the pier, Birnbeck Island could be accessed by a natural causeway at low tide.[6] A proposal was made in 1845 to connect Birnbeck Island to the mainland at the western end of Worlebury Hill.