The submarine hydrothermal activity on and near the Galápagos Rift has been explored with the aid of the deep submersible Alvin. Analyses of water samples from hydrothermal vents reveal that hydrothermal activity provides significant or dominant sources and sinks for several components of seawater; studies of conductive and convective heat transfer suggest that two-thirds of the heat lost from new oceanic lithosphere at the Galápagos Rift in the first million years may be vented from thermal springs, predominantly along the axial ridge within the rift valley. The vent areas are populated by animal communities. They appear to utilize chemosynthesis by sulfur-oxidizing bacteria to derive their entire energy supply from reactions between the seawater and the rocks at high temperatures, rather than photosynthesis.

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Since 1968, cruises of the D.V. Glomar Challenger have created a vast and immensely valuable collection of core samples and geologic data for hundreds of drill sites in all oceans and in the Caribbean, Mediterranean, and Red Seas. This collection represents a large part of the Cenozoic and Mesozoic record of the oceans. The material enables us to reconstruct the geologic history of the ocean basins and improve our understanding of the history of the Earth, the evolution of life, temporal changes in oceanic circulation, and indirectly, the evaluation of the Earth's climate. Regional syntheses are indispensable for effective planning for future ocean drilling. Our study provides a synthesis of the data available for the central equatorial Pacific Ocean, with emphasis on the depositional history of pelagic biogenic sediment and its control by tectonic events and paleoceanographic conditions. AbstractThis study has three distinct but interrelated objectives: to prepare a geological synthesis of Deep Sea Drilling Project data from the central equatorial Pacific Ocean, to interpret this information in terms of the paleoceanographic history of this region, and to evaluate the usefulness of drill data and develop procedures and strategies for future studies of this kind. The investigation is based on primary data contained in the Initial Reports of the Deep Sea Drilling Project and is supported by information from surface cores. The principal data used are the biostratigraphy, lithology, carbonate content, bulk density, and porosity of the cores. From these properties, sedimentation rates, carbonate and carbonate-free accumulation rates, and paleobathymetric histories of the drill sites were derived with the aid of Berggren's chronology. Paleopositions of the drill sites and surface cores were determined from rotation parameters of the Pacific and Cocos plates.The present surface and deep circulation, fertility patterns, and sedimentation of the equatorial Pacific constitute a frame of reference for the paleoceanographic evolution. East-west and north-south lithologic profiles show that a zone of maximum deposition approximately parallel to the Equator has existed at least since middle Eocene time. With increasing age, the axis of this zone is found progressively farther north of the Equator. The profiles illustrate a gradual change from calcareous to siliceous deposits with increasing depth at any time, and they indicate an abrupt change from a dominantly siliceous to a dominantly calcareous depositional regime at the Eocene-Oligocene boundary. Large changes with time in the width and sedimentation rate of the calcareous equatorial zone indicate major variations in depositional conditions since Eocene time.Subsidence with age of the oceanic basement, plate rotation, and changes in spreading rate are closely examined in this study. A northward shift of the equatorial zone of maximum deposition with age and trend and ages of linear volcanic island chains (melting spots) define the rotation of the Pacific plate. This gives...

We explore the hypothesis that the abrupt drainage of Laurentide lakes and associated rapid switch of the North Atlantic thermohaline circulation 8200 yr ago had a catastrophic influence on Neolithic civilisation in large parts of southeastern Europe, Anatolia, Cyprus, and the Near East. The event at 8200 cal yr BP is observed in a large number of high-resolution climate proxies in the Northern Hemisphere, and in many cases corresponds to markedly cold and arid conditions. We identify the relevant archaeological levels of major Neolithic settlements in Central Anatolia, Cyprus, Greece and Bulgaria, and examine published stratigraphic, architectural, cultural and geoarchaeological studies for these sites. The specific archaeological events and processes we observe at a number of these sites during the study interval 8400-8000 cal yr BP lead us to refine some previously established Neolithisation models. The introduction of farming to South-East Europe occurs in all study regions (Thrace, Macedonia, Thessaly, Bulgaria) near 8200 cal yr BP. We observe major disruptions of Neolithic cultures in the Levant, North Syria, South-East Anatolia, Central Anatolia and Cyprus, at the same time. We conclude that the 8200 cal yr BP aridity event triggered the spread of early farmers, by different routes, out of West Asia and the Near East into Greece and Bulgaria.

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It has long been known that pillow basalts are a dominant feature of oceanic volca-