DO "RED BEDS" INDICATE DESERTS OR MONSOONS?

Terrestrial “red beds” have long been interpreted as desert deposits, by comparison with modern red deserts. However, both presently active deserts and the geologic record have preserved many examples of non-red deserts. More recently “red beds” have been interpreted as evidence of seasonally dry conditions and a Permo-Triassic Pangean monsoon. While this interpretation may be correct in some instances, many “red bed” sequences lack evidence analogous to Miocene-modern monsoonal conditions. “Red beds” of Cala Viola, Sardinia are identified as paleosols and used to reconstruct late Permian paleoclimatic conditions. The lack of free soil carbonate and the degree of chemical weathering are consistent with a humid, temperate climatic regime. There is no evidence of severe dryness as in a desert or of extreme seasonality as in monsoon-dominated climate. Instead, it is suggested that the red color of the paleosols is a result of former good drainage, and that a priori, red color does not indicate specific paleoclimatic conditions.