My research has focused on the determination of changes in the isotopic composition of the oceans through time, by the analysis of stragraphic suites of little-altered carbonate rocks. Thus far, most of these studies have centered around Neoproterozoic (ca. 1000-544 million-year-old) sedimentary successions in Svalbard/East Greenland, Namibia, arctic Canada and Alaska, India, and the western USA. Temporal variations in C and Sr isotopes can be used as stratigraphic tools within and between basins, and through detailed correlations allow us to order key tectonic, biogeochemical, and paleoenvironmental events in Earth history.