9304815 Grossman PIs will conduct a stable isotope study to investigate the paleoceaonographic, paleoclimatic and geochemical changes associated with Carboniferous glaciation and the formation of Pangaea. They will continue to develop isotope stratigraphy for the Carboniferous to P-Tr boundary based on brachiopods, sampling more locations in North America, as well as in Russia. A Carboniferous geographic divergence will be further studied, with consideration of diagenesis, calibration of species effects, and evaluation of preservation of original shell chemistry. The cause of this excursion/divergence will be investigated; oxygen isotope data will be used to test for glaciation and climate change on the North American and Russian platforms. ***