FLAKING BY INSOLATION DRYING AND SALT WEATHERING ON THE SWEDISH WEST-COAST

A conceptual model of flaking close to the sea is proposed. It is base d on the flaking distribution in three areas on the Swedish west coast . Solar drying of saline water and thermal expansion of salt crystals in microcracks-especially on southlooking rock surfaces-are the main p rocesses. Drying is most effective in the bare zone between the black littoral belt with algae and marine lichens at the water edge and the terrestrial lichens at higher elevation. The lower limit of flaking (0 .5-4 metres above sea level) depends on high water and exposure to wav es, since too much wetting prevents the drying process. At higher leve l, where wetting by salt water is less and chemical weathering promote s mineral weathering, flaking fades out. The present land upheavel (0. 25 m/100 years) suggests that flaking starts 200 years or less after l ifting of the rock surface above the mean sea level. However, due to w aves and atidal sea level fluctuations the drying process seems to sta rt only some decades before flaking appears on the rock surface. In ex posed sites the vertical distribution indicates a lifetime of an indiv idual flaking of at most 2000 years.