EPMA data for 36 individual tephras (layers and pods) were analyzed from Site 1151 (Tables T2, AT2), spanning an age interval, suggested by original shipboard age estimations, of ~130 ka to 4.8 Ma. Data for tephras younger than ~2.25 Ma are presented in Figure F6. Tephrogeochemical populations are generally well clustered in terms of individual element oxides, which is encouraging in terms of their tephrochronological utility; tephras from Samples 186-1151C-2H-6, 42-44 cm, through 9H-1, 14-16 cm, for example, all plot discretely in terms of TiO2 and K2O. However, as the data set expands, geochemical equifinality becomes apparent, with shared geochemical fingerprints arising between tephra Samples 186-1151C-9H-1, 14-16 cm, and 186-1151A-7R-1, 35-37 cm, 186-1151C-2H-6, 42-44 cm, and 186-1151A-6R-4, 26-28 cm; and 186-1151C-5H-4, 145-146 cm, and 9H-5, 143-145 cm (Fig. F6). This is likely to be a greater problem than we have currently identified because of our partial sampling of the Neogene tephra record. Where major element geochemistry is insufficient to characterize a tephra uniquely, additional geochemical data may prove helpful (e.g., trace element characterization by laser ablation-inductively coupled plasma mass spectrometry [ICP-MS], e.g., Bryant et al. [1999], Pearce et al. [1999]). Failing this, additional stratigraphic or geochronological evidence such as marine isotope stage (MIS) characterization is required. Currently available age models lack the robustness to facilitate correlation with MIS stratigraphy determined in the Japan region. Despite the large, albeit incomplete, number of tephras analyzed from Site 1151, we are unable to propose a single specific correlation, either with the tephra record of Site 1150 or with the onland or regional marine tephrostratigraphy. The lack of correlation between sites is particularly surprising, given their relative proximity. Potential explanatory factors that require further exploration include (1) localized variation in bottom-current activity and zones of sediment movement and deposition and (2) possible hiatuses in the upper parts of the Site 1151 record.