Wharves for the shipping of slate from the Dinorwic slate quarries were established along the narrow estuary of the Afon Heilyn from the late 18th century. In 1900-1902 a floating dock system, with an entrance lock 55 metres x 9.75 metres, was engineered by Philip Ayres. The 350 metre-long dock was crossed by a single-leaf bascule bridge, at the site where there had been a swing bridge across the estuary. At the end of the dock were ship-repair facilities with a graving-dock, with stepped sides and a polygonal inner end and formerly closed by an iron caisson. Some of the quayside bollards and lock sluice operating gear are marked 'Cleghorn & Wilkinson, Engineers, Northwich'. The dock is now a marina, with new housing on the south side of the upper basin.
W J Crompton, RCAHMW, 28 October 2009.