This research used samples and data provided by the Ocean Drilling Program (ODP). ODP is sponsored by the U.S. National Science Foundation (NSF) and participating countries under the management of Joint Oceanographic Institutions (JOI), Inc. This work was funded by National Science Foundation grants OCE-9819053, OCE-0241940, and OCE-0326714 and by U.S. Scientific Support Program postcruise funding. We thank the officers, crew, scientists, and technicians who collected the physical property data set during Leg 210 aboard the JOIDES Resolution in the summer of 2003 and the SCREECH seismic reflection data set aboard the Maurice Ewing and the Oceanus in the summer of 2000. We gratefully acknowledge Dennis Harry and Andrew Goodliffe, who provided thoughtful and constructive reviews of this manuscript. We also thank Christian Berndt, who assisted with the software package Nucleus. This is Lamont-Doherty contribution number 6980.