J.I. Soto acknowledges 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. We are indebted to Rainer Abart and Bernardo Cesare for their constructive reviews and suggestions. We also thank Christine Laurin for her revision of the English text and Phyllis M. Garman for editorial comments. Financial support was provided by Projects AMB95-1775-CICYT, and AMB95-0535.