Measurements on cores from the Ontong Java Plateau demonstrate that on-equator sediment accumulates more 230Th than is produced in the overlying water column. In contrast, cores from 3.8 ¿N accumulate an amount of excess 230Th more nearly equal to that produced in the overlying water column. Taken together with the observation that both the CaCO3 and non-CaCO3 components of the sediment accumulate at approximately twice the rate in on-equator than in off-equator cores [Broecker et al., 1999>, this requires either that the rain of the larger amount of organic matter generated above the equatorial upwelling plume entrains excess clay and 230Th during its fall to the sea floor or that physical transport processes, either in the upper ocean or near the sea bed, redistribute sediments in such a way that they preferentially accumulate-in a narrow (¿1¿ latitude) equatorial-centered belt. ¿ 1999 American Geophysical Union