"Délits d'eau" et "volements de sables", les "offensives éoliennes" sur les côtes bretonnes au XVIIIème siècle

Abstract

The historians of climate have long neglected the "wind caprices", to the extent that some of the destructive storms that have affected northern France over the past two decades have been qualified as unprecedented. However, the eighteenth century is characterized by an atmospheric turbulence that hardly spared the coasts of Brittany. Alongside the parish registers the military archives, and more particularly the abundant correspondence exchanged between intendants of the port of Brest and Navy secretaries of State, provided a source so far neglected. No less than 60 tempestuous events of force equal to or greater than 10 on the Beaufort scale have been identified, with the reservations that such a codification may generate. They manifest themselves suddenly by surges and floading of low coasts, and, often more insidiously, by sandy advances in several coastal sections, notably in Leon: in this case, the reactivation of dune fields appears to have been enhanced by a reduction of the vegetation cover during periods of drought that have multiplied over the course of the century, as suggested by an increased frequency of propitiatory ceremonies.

Keywords

• storms
• coasts
• coastal floading
• droughts
• sand dunes
• 18th century