All Wales LiDAR suggests enhancement of what was perhaps originally a natural gravel bank. The eastern side is particulary well defined and may have been used as wharf or a jetty for the Benlass/Pennar ferry (see NPRN 506740)

Sources include:
All Wales LiDAR (2m resolution), Environment Agency 2012
NAW Aerial photography 2006-9
OS 1st edition 25in mapping

Maritime Officer, RCAHMW, November 2012.