Figure 4. Illustration of the central problem to be tested in our NSF study on coordinated stasis: what is the relationship between the processes controlling redox history and the formation of organic carbon-rich facies, and the degree of stasis/turnover in the Devonian Appalachian basin? Dashed lines represent species range data; zones F1-F3 represent distinct faunal assemblages that experience little evolution or immigration/emigration between turnovers; faunal turnover events are marked at right; Redox Proxy is represented by solid line, % faunal turnover by dashed line. We are collecting a multi-proxy geochemical and paleobiologic data set and will be analyzing it with such techniques as Q-mode factor analysis.