In cold climates, vegetation becomes sparse and no longer protects the ground from the harmful effect of the wind. The dust blown from exposed areas settles in the sheltered areas where it piles up to create very thin alluvia also called loess.
Loess is in fact a light, fertile soil much valued by the earliest farmers. But being very fragile, it rapidly deteriorated through agricultural use.
In western France, the best preserved loess deposits are located in Normandy, in the north of Brittany, and in the Val-de-la-Loire area. Some traces of loess were also found in the Morbihan area, and especially in Locmariaquer. The agricultural quality of the loess was certainly a factor in the development of Neolithic settlements in this part of Brittany.
Dust storms during the glacial periods also wore away and eroded the stones on the ground. The hardest stones became shiny and acquired typical shapes, with a number of edges due to to the changes in wind direction and to the random movements of the stones. These "multi-faceted pebbles" (called dreikanters by German geographers) were much valued by Neolithic settlers who used them as strikers to sharpen flint stones and also as pecking tools used to decorate megalithic monuments (especially at Gavrinis).
Loess deposit eroded cliff (tip of Guilben Paimpol, Côtes-d'Armor).
Faceted pebble used as a firing pin (Gavrinis excavations).