J.I. Soto would like to thank ODP for inviting him to participate in Leg 161. We would also like to thank the Shipboard Scientific Party, the ODP technicians, and the SEDCO drilling crew of Leg 161 for their help, and Menchu Comas, one of the Co-Chief Scientists, for her support. This paper has benefited from the thorough revisions done by Ian Fitzsimons and Virginia Sisson. J.I. Soto acknowledges financial support provided by Project AMB95-1557-CICYT. J.P. Platt acknowledges grant number GR3/10828 from the Natural Environmental Research Council of Great Britain.