99, 78 (1987). Our results specifically apply only to in obtaining sediment samples. This research was boundary spherules (Table 1) cannot be a spinel-bearing spherules in the K-T boundary, but supported by NSF grant EAR-8904833 and a grant coincidence. Although these impact events the impact association is clear. from the Institute of Geophysics and Planetary differ greatly in magnitude, both have pro- 16. Curation of Eltanin cores is supported by the NaPhysics-Lawrence Livermore National Laboratory. tional Science Foundation (NSF). We are indebited duced remarkably similar deposits with high to A. Kaharoeddin and D. S. Cassidy for assistance 30 October 1990; accepted 31 January 1991 concentrations of Ir (3) and trace amounts of spherules. As in the late Pliocene deposits, K-T boundary spherules typically constitute