Dating of marine fossil levels on the Brittany Coast begins, as part of the "cron-BRET" Project linked to the MSCA-Bienvenüe-Bretagne Programme 2023. We will join Geology, Sedimentology, Geomorphology, Palaeo-Climaotology, Luminescence and Cosmogenic Nuclide Dating, among others disciplines. The Team Work will include Prof. David Menier (Univ. Bretagne Sud), Dr. Guillaume Guérin (Geosciences- Univ. Rennes1), Prof. Tibor Dunai (Univ. of Cologne, Germany), Prof. Pierre Stephan (Univ. Bretagne Occidentale), DR. Benjamin Sautter (UBS), Dr. Marine Laforge (Rennes-1) and Project leader: Dr. Carlos Arce-Chamorro from Geology Institute of the University of Coruña. The aim of the Project is to study the sea-level variations in the past regarding to glacial/interglacial cycles at Late Pleistocene (last 500,000 years). This helps to understand the present coastline and its evolution, as well as future projections within a Climate Change Framework and pre-Holocene sea-level rise. Science at the service of Society, just developing useful tools for a improved management of Human Activities and Environmental knowledge at Brittany (West France).