Samples from eight dredge hauls collected during BMR cruise 107 from several seamounts in the Vening Meinesz chain, south of Christmas Island, yielded calcareous nannofossils, foraminiferids, and fragmentary macrofossils with ages ranging from Late Cretaceous to Holocene. Many samples are mixtures, suggestive of debris flows, and some contain lithologies of various ages. The Late Cretaceous assemblages suggest shallow-water to upper bathyal depths. The seamounts were built up rapidly by volcanism, probably commencing during the Albian or Santonian, continuing through the Campanian, by which time they had shoaled, and ceasing during the Maastrichtian. Atolls comprising mounds of shelly algal biostromes dominated by rudists and Inoceramus had formed by the Maastrichtian. The sea was warm at this time, when the area was at latitudes far south of those of today. The Palaeogene assemblages suggest increasingly deeper depositional environments. The Paleocene is indirectly indicated by the presence of nannofloras of this age reworked into younger assemblages, but Eocene calcareous microfossils are well represented. Shallow-water assemblages (including large neritic benthic foraminifetids) are wide-spread in the late Early to early Middle Eocene samples, suggesting subtropical or tropical water temperatures. The fresh volcanic content in some samples hints at the possibility of renewed volcanism during the Eocene. The Oligocene is marked by pelagites containing nannofossils. Most of the Neogene assemblages are Late Miocene or younger, although some Middle Miocene nannofloras were recovered. Depositional depths appear to have been bathyal during this time, an accompaniment to seamount sinking and crustal and subcrustal cooling. Volcanism had ceased. Debris flows, however, continued to transport shallow-water sediments downslope. Holocene and present-day oozes mantle all previous deposits.
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