Probably natural indent in the hillside but used for turning at adjacent Plas-isaf Limestone wharf. This an example of how topography affects width of the canal and how this was used by canal trade. Built in 1804-08 as part of the navigable feeder canal from Horseshoe Falls to Trevor Basin by the engineers Thomas Telford & Thomas Denson. Visited on 14.07.2006 when the basin was in water, the edges have been relined with concrete and water-escape stairs built into the side.

Stephen R. Hughes, 11.09.2007.