The Ploumanac'h rests at a depth of ten meters, five miles offshore, facing Perros-Guirec (Côte d'Armor). Swell and current in this zone made research difficult.
The shipwreck was surveyed by the Department for Underwater and Undersea Archeological Research (DRASSM). It is of explicit archeological importance, chiefly because of its cargo of lead ingots which are tangible evidence of the trade in raw materials in the English Channel in Antiquity.

Inscription on one of the lead ingots.
These roughly shaped ingots do not belong to a specific type, but carry various imprints falling into three categories: names, numbers, and symbols. Epigraphic studies of the inscriptions found similarities with the names of Celtic tribes of Great Britain and made it possible to date the wreck to the Roman High or Low Empire (between the second and the fourth centuries AD).

Electrolysis treatment tank for the lead ingots.
Before being examined, the ingots had to undergo a cleaning and stabilization treatment using electrolysis in a tank that was installed close to the site. Following this, the ore was subjected to an elaborate metallographic study; an isotopic analysis may lead to the discovery of the mine that supplied the lead.

Excavation : Michel L'Hour, DRASSM.

Photos : Yves Gladu, Michel L'Hour and Gérard Réveillac.