The total IRD MARs are listed in Table 1 and are plotted as a function of age in Figure 1. The lithologic composition of the coarse sand-sized IRD and the resultant MARs for each grain type are also listed in Table 1 and are plotted as a function of age in Figure 2, Figure 3, Figure 4, Figure 5, and Figure 6.

The total MARs of coarse-sand IRD (Fig. 1) range from 0 to ~0.50 g/cm²/k.y., with large amplitude fluctuations primarily older than 250 ka. The distribution of peaks in the IRD MAR profile suggests cyclic variations in IRD supply, with periodicity on the order of 40-100 k.y. The details of this cyclicity will be investigated further by future correlation with an isotopically based time scale.

Quartz, basalt, and granite/coarse-grained acidic are the most abundant IRD grain types at Site 919; MARs of quartz IRD range from 0 to 0.25 g/cm²/k.y. (Fig. 2), MARs of basalt IRD range from 0 to 0.19 g/cm²/k.y. (Fig. 3), and MARs of granite/coarse-grained acidic IRD range from 0 to 0.10 g/cm²/k.y. (Fig. 4). With the exceptions of a few single-point peaks, the MARs of coarse-grained basic IRD and sedimentary rock fragment IRD are low throughout Site 919 (Fig. 5, Fig. 6).

Peaks in the profile of total IRD MARs (Fig. 1) generally result from increases in the MARs of both quartz and basalt IRD (Fig. 2, Fig. 3), suggesting that IRD supply from at least two geographically and geologically distinct source regions varied synchronously through the Pleistocene. Future work will compare these compositional characteristics with those from nearby Site 918 in order to determine the relative effects of regional glacial histories and iceberg dispersal patterns on the histories of IRD MARs.