The pumice clasts are typically aphyric, and the bulk composition of a pumice-rich sample is trachytic. The volcaniclastic sequence also includes pumice beds, reworked volcaniclastic sediments, and highly altered ash deposits that contain accretionary lapilli. Several boundaries are oxidized, suggesting subaerial weathering between eruptions. The relatively thin flows at Site 1138 resemble Hawaiian lavas, and contrast with the generally thicker flows drilled at Sites 1136 and 1137. Most flows have unique flow top breccias that are not easily classified.
All basalts show normal magnetic inclinations.
We calculated a mean inclination of -60.8x, which corresponds to a paleolatitude of 46.4x S assuming a geocentric dipole field. The paleolatitude is thus 7x north of Site 1138. This southward shift in latitude since Late Cretaceous time is consistent with the 8.5x difference we found at Site 1137 on Elan Bank. The massive parts of flow Units 3 to 22 are slightly to locally highly altered, whereas alteration ranges from high to complete in the brecciated zones. Rubbly flow tops are partly to completely altered to clay minerals and abundant euhedral zeolites form the matrix, fill veins, and partly fill vesicles and large voids.