基金We would like to thank all the people, including members of the ISCS, involved in the process of defining the base of the Drumian for stimulating discussion and scientific support. J.G. 0gg thoroughly reviewed the final GSSP proposal. A.M. English and L.A. Ford assisted with assembly of the final illustrations. This work was supported in part by a grant from the U.S. National Science Foundation (EAR-0106883) to Babcock.