Dune palaeosurface sequences on the Eastern Canary Islands were investigated for stable isotope records in gastropod shells of the genus Theba . Due to the ecology of the taxon and the special oceanic insularity of the study site, we assume that δ 18 O shell signals in our case mainly reflect shifts in δ 18 O signals of sea surface water. We found that a rapid decrease in δ 18 O shell signals is associated with significant cha...