Figure F1 illustrates the pattern of changes in gamma-ray attenuation (GRA) bulk density downcore through Core 172-1063D-4H. Qualitative estimates of diatom abundances for the abundant and common categories are also illustrated in this figure; the dark gray bars represent periods with abundant diatoms, and the light gray bars show common occurrences. The interval between 1.75 and 9 mbsf stands apart from the rest of the record illustrated in that the density is slowly increasing over this interval. This is quite different from the large changes observed on either side of this period. In this interval, there are three periods with common or abundant diatoms in the sediment; all three occur in the upper portion of this depth interval between 1.75 and 3.6 mbsf. The decrease in density at 9 mbsf is again accompanied by a period of abundant diatoms.