The ODP leg 172 on the northwest Atlantic continental margin: preliminary results

Leg 172 achieved or exceeded most of its initial objectives. At all sites, high sedimentation rates throughout the Pleistocene allowed the precise tra cking of ocean and climate changes such as the evolution to the 100 ka worl d from the 40 ka world. Sequences which extended to the Middle Pliocene wer e recovered at several sites and will permit the study of the origin of the Northern Hemisphere glaciations. Millenial and perhaps centennial-scale cl imatic changes should be resolvable at some sites. Records of the Earth's m agnetic field provide some high resolution signals with previously unseen v ariability. Preliminary shipboard results have also brought new insights ab out the geographic extent of gas hydrates, and new definitions of first and last occurrences of foraminiferal datum. ((C) Academie des sciences / Else vier, Paris.).