Sincere thanks are extended to Kevin Cannariato for assistance with the figures, Karen Thompson for much careful technical assistance, and JoAnne Sharpe and Diana Kennett for secretarial help. David Pierce took considerable care in producing the scanning electron microscope photographs. We appreciate the useful discussions with Michal Kucera. Thanks are also extended to T. Saito and B.A. Christensen for their useful reviews of this paper and to J. Ingle and G. Keller for their valued comments. This research was supported by JOI/USSAC postcruise funding (ODP Leg 167) and the U.S. National Science Foundation (Earth System History 9904024).