Variations in the number of dinoflagellate cysts species recovered from the Rhodano-Swabian sedimentary basin in northern Switzerland have been correlated with sequence and sedimentary cycles established for this basin. The variation in dinoflagellate cyst abundance corroborates the sequence boundaries erected by Gygi et al. (1988) using other parameters such as lithology and macrofossil content of the sediments. Highstands of sea level are marked by a sharp increase in species diversity (sometimes up to 50). In contrast, lowstands are indicated by a sharp decline in the abundance of species: in a case only 3 species.
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