Pyroclastic and other sediments derived from volcanic terranes are prominent constituents of the sediment column in the central and eastern parts of the Philippine Sea. On the Palau-Kyushu Ridge (Site 448), basement is overlain by over 100 meters of vitric-tuff deposits, which are overlain in turn by about 170 meters of nannofossil chalk and ooze. In contrast, thick accumulations of vitric tuff are overlain by minor accumulations of pelagic clay in the east-central Parece Vela Basin (Sites 53, 54, and 450), (Fischer, Heezen, et al., 1971), and almost 900 meters of vitric tuff, ash, and breccia overlie igneous basement at Site 451 on the adjacent West Mariana Ridge. The seismic velocities of these vitric tuffs at in situ pressures can be usefully applied in the interpretation of seismic-reflection data collected in this region.

Supplement to: Carlson, Richard L; Christensen, Nikolas I; Wilkens, Roy H (1981): Acoustic properties of volcaniclastic sediments recovered from the floor of the Philippine Sea, Deep Sea Drilling Project Leg 59. In: Kroenke, L; Scott, R; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 59, 519-522