Description
The authors examined very high resolution seismic profiles from three estuary locations on the Atlantic coast of France (~ 48.95°N, 1.23°W; 45.2°N, 1.43°W; 46.25°N, 1.43°W). Common to all three locations was a "very sharp" sedimentary transition from basal sand to muddier sediments, from which two shells were recovered and radiocarbon dated to AD 720 and 1100. Speaking of this transition, they say "it could correspond to the transition between the cold period of the Dark Age (AD 400-900) and the Medieval warm period (AD 900-1400)," as warmer temperatures brought about higher rainfall and more frequent floods that resulted in an increase of estuarine mud supply to the region.