Robert Gastaldo, the Whipple-Coddington Professor of Geology, and Kaci Kus ’18 have coauthored a paper just published in the Journal of Sedimentary Research that’s based on Kus’s honors thesis. The paper, “Calcic Vertisols in the upper Daptocephalus Assemblage Zone, Balfour Formation, Karoo Basin, South Africa: Implications for Late Permian Climate,” stems from research Kus conducted for a project in South Africa where she detailed the ancient (Permian age) soil profile in one of the classic latest Permian localities in the Eastern Cape Province. With her data, the authors reconstructed the mean annual temperature and mean annual precipitation estimates for an interval prior to the end-Permian crisis on land.

According to Gastaldo, “previous interpretations of soils with calcium-carbonate soil nodules have been that these features formed under dry and arid conditions. Our geochemical data from stable carbon isotopes shows that these soils developed under regionally cool conditions, with a mean annual temperature of 10 C (68 F), and an estimate of 1100 mm/year (+/- 180 mm). Hence, these soils, often thought to represent dry conditions, formed under a cool and humid climate. These results change our understanding of the paleoclimate of the latest Permian in the Karoo Basin of South Africa.”