A lost world...
Under the lake, another world
The building of the hydro-electric dam at Guerlédan in the 1920s inevitably led to the valley being flooded. The valley was inhabited at the time and the Nantes-Brest and boats and barges still navigated this stretch of the canal, with lock-keepers managing the passing traffic.
Many quarry workers who were employed to extract the stone from the schist quarries, relaxed in the evening in the small cafés and people could be heard getting on with their lives in the valley.
All that came to an end when the lake was created and the valley submerged forever in 1930, the Nantes-Brest canal was permanently cut in two which interrupted navigation on the waterway.
As time has gone by, the lake has become a place where families spend their leisure time or do sporting activities.
Draining the lake in 2015
Essential repair work needed to be carried out on the EDF dam meant that the lake was drained in 2015 for several months.
The largest lake in Brittany was slowly drained of its water, thirty years after the last time it was emptied in 1975. For 6 months, the valley landscape dried out, evolved and changed in colour and look. Nature soon took over the banks of the Nantes-Brest canal which reappeared at the bottom of the dry lake.
From the initial moonscapes, the valley became a crisp lush green, seeds sprouted and flowers grew on the valley floor. The fossilised trees reappeared near the lock-keepers’ cottages, if you let your imagination take over, you could imagine the last inhabitants of this landscape frozen in time.
Seeing the slate mines again was impressive and many a tale was told of the men who worked the mines, some of whom came from afar to extract the valuable rock.
A unique landscape
During the dry period there were a million visitors, curious to see the valley and these places which were a testimony to the past.
There were organised visits, former inhabitants came to tell their stories of life in the valley, geologists came looking for answers to questions on the ground formations, photographers strolled up and down cameras at the ready, a video was filmed as well as a short film.
Traces of extremely ancient marine life, trilobites, were found – the sea came up this far – over 480 million years ago. Everyone was looking for something in the lost world of Guerlédan.
