I thank Mitch Lyle, Itaru Koizumi, and the Leg 167 shipboard scientists for their ready exchange of data and ideas. Scott Starratt of the U.S. Geological Survey processed the samples. This paper was reviewed by R.Z. Poore, D. Bukry, and S.W. Starratt of the U.S. Geological Survey and Carina Lange of the Scripps Institution of Oceanography. I also thank Constance Sancetta and Eileen Hemphill-Haley for related discussions.