Site archéologique d’Iliz-Coz

The parish enclosure swallowed up by the sand
Just a stone's throw from the sea, at a place called Saint-Michel in the commune of Plouguerneau, lies one of the most moving archaeological sites in the Pays des Abers. Iliz Koz - "the old church" in Breton - is the former parish church of Tréménac'h, the monks' village, sunk for centuries under the sands of the Leonard coastline and brought back to light through patient excavations.

Tréménac'h, a forgotten parish
Tréménac'h is a word composed of the Old Breton treb, "village", and the Breton menec'h, "monks". For centuries, this ancient parish on the north coast of Léon was home to a very real religious and community life, with its church dedicated to the Holy Trinity, its presbytery, its manor houses, its mills and its chapels.
The parish church, which had no transept, was surrounded by its own enclosure: cemetery to the south, ossuary, Parscau seigniorial chapel. Nearby, Michel Le Nobletz, the father of the Breton Missions, spent a year as a hermit between 1607 and 1608. Abers heritage

Silting up, a natural tragedy
The silting up of this shoreline seems to be due to marine regression: climatic cooling is thought to have led to a drop in sea level, with the winds drying out the shores and creating dunes that move inland during storms.
As early as 1550, the Menan manor archives record "land sold because of silting". The critical threshold was reached around 1700, and the following three decades saw a veritable deluge of sand fall on the enclosure, reaching several metres in height in places. In the end, the parishioners trapped in the church had to escape via the roofs. In 1729, the church was abandoned and worship was transferred to the Martyre chapel.

Rediscovery: a collective project
In 1969, earth-moving machinery on a building site came up against tombstones and walls. Dr Gérard Philipps, a researcher from Brest, undertook the first excavations, soon followed by volunteers. The commune of Plouguerneau acquired the land in 1977 and, from the 1980s onwards, gradual desilting campaigns restored the site to its former glory. An association of enthusiastic volunteers has been running guided tours ever since.

What can be discovered on site
The site reveals a medieval parish enclosure that has been remarkably well preserved under its sandy covering. The cemetery has yielded nearly a hundred tombstones, nineteen of which bear engravings: knights' swords and shields, priests' chalices, trade emblems - including a weaver - and, exceptionally, a slab decorated with a caravel at anchor, rare evidence of Breton maritime trade at the end of the Middle Ages.
Inside the church, the walls have revealed five layers of superimposed wall paintings, ranging from a series of 13th-century Gothic roses to early 17th-century geometric decorations, including a 15th-century representation of a knight or archangel, framed by coats of arms. These carefully restored paintings are now on display in the site's reception area.

In the presbytery, during desilting operations in 1992, three keys were found, carefully placed in one of the windows - the final gesture of the last inhabitant before leaving the site forever. They are preserved in the site museum.