Abstract: The uppermost Middle to lowermost Upper Ordovician succession of interbedded radiolarian chert and shales exposed at Seal Creek in southeastern Australia contains a diverse, abundant, and well-preserved trace-fossil assemblage that inhabited pelagic, deep-oceanic sediments on an abandoned section of a submarine fan complex. Trace fossils occur throughout the measured section, but the types and abundance of the trace fossils vary from horizon to horizon. Planolites and Palaeophycus are common in all chert beds, while Zoophycos, Alcyonidiopsis, Compaginatichnus-like, and Teichichnus-like trace fossils are limited to the upper part of the succession. Shales interbedded with the cherts have a much less diverse and abundant ichnofauna than the siliceous layers. The appearance of Zoophycos on the deep-ocean floor in the earliest Late Ordovician may represent the first appearance of this ichnogenus in the pelagic realm, as benthic fauna migrated from shallow to deep water. The later emergence of Alcyonidiopsis at Seal Creek than in turbiditic mudstones elsewhere in the world perhaps reflects benthic migration from turbiditic to radiolarian chert facies. Similar chert facies in the Triassic-Jurassic succession of southwest Japan lack the common deep-sea ichnogenus Zoophycos but have peculiar zigzag-shaped burrows that are absent in the Seal Creek chert. This difference in ichnofauna may be an aftereffect of the mass extinction event at the Permian-Triassic boundary.

Abstract An evaluation of the relationship between culture change and the history of volcanic activity from the Witori and Dakataua volcanoes in West New Britain province, Papua New Guinea, demonstrates the importance of studies focusing on long time spans to an understanding of cultural adaptation to volcanic disasters. Using a chronostratigraphy based on several techniques for matching tephras, the cultural responses to five volcanic events are compared and contrasted between the Willaumez Peninsula and Yombon, areas whose environment and proximity to the volcanoes vary significantly. Archaeological analyses of material show that human groups did not immediately adjust to the effects of the most severe volcanic events but abandoned both regions. In contrast, adaptation on a long-term basis may be indicated by the occurrence of a punctuated trend in lithic technology inferred to reflect a decrease in mobility and an increase in the intensification of subsistence practices. This pattern, combined with limited radiocarbon dating, suggests that the length of abandonment decreased after each eruption, probably because of changes in social organization and subsistence practices. The paper demonstrates the value of collaboration between archaeology and geology in the study of long-term human responses to natural hazards.