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The relative importance of tectonism in the stratigraphic record should be more clearly expressed during greenhouse times of Earth history due to the lack of overmasking effects of high-frequency and high-amplitude sea-level changes typical for icehouse periods. Establishment of the importance of tectonism, especially at temporal scales comparable to durations of typical transgressive-regressive cycles, has been plagued by poor temporal resolution. Our outcrop and subsurface-based study of a Cenomanian shallow-marine siliciclastic interval, constrained by bentonite-based geochronology and detailed biostratigraphy, examines this problem. In a 2.2 m.y. interval, we identified four tectonically driven erosional surfaces that dominate preserved stratigraphy. Biostratigraphic correlation to a sea-level curve for the Cenomanian--where coeval high-frequency low-amplitude eustatic cyclicity has been demonstrated--allows the first direct comparison of the effects of eustasy and tectonics at temporal scales of hundreds of thousands of years during a global greenhouse time. We suggest that minor tectonic pulses locally overshadow the effects of eustasy and exert the dominant control over preserved stratigraphy. While subtle tectonic control on sedimentation has been documented throughout the Cretaceous Western Interior, the results of this study suggest that much of that deformation occurred at sub-million-year frequencies and at time scales comparable to eustatic transgressive-regressive cycles. Keywords: tectonic controls, Milankovitch theory, sequence stratigraphy, biostratigraphy, erosion surfaces, foreland basins.

A high-resolution pollen record from western Greece shows that the amplitude of millennial-scale oscillations in tree abundance during the last glacial period was subdued, with temperate tree populations surviving throughout the interval This provides evidence for the existence of an area of relative ecological stability, reflecting the influence of continued moisture availability and varied topography. Long-term buffering of populations from climatic extremes, together with genetic isolation at such refugial sites, may have allowed lineage divergence to proceed through the Quaternary. Such ecologically stable areas may be critical not only for the tong-term survival of species, but also for the emergence of new ones., The Pleistocene refugium hypothesis (1) proposed that population fragmentation during individual glacial stages of the Quaternary promoted speciation. A more recent view is that the accentuated environmental instability did not [...]

A temperature spike is reported in the haloclines of three Yucatan sinkholes along a 1 km NW-SE transect from 5 to 4 km inland from the Caribbean coast. The temperature spike decreases in magnitude from ~3.5°C to 0.2°C, approaching the coast. The anomaly does not vary diurnally and does not extend down into the underlying sea water. These conditions are inconsistent with explanations such as radiation absorption within the halocline, in situ microbialfy mediated sulfate reduction within the halocline and the underlying sea water, and sulfide oxidation by photosynthetic purple and green bacteria within the halocline. One explanation consistent with the shape and halocline location of the temperature spike involves a localized sea water convection cell operating near the coast. Cold sea water from the Caribbean Sea enters the coastal limestone at depths of a few hundred meters and heats up because of the geothermal gradient, buoyantly rising in vertical fractures within the unconfined aquifer. Blocked by the less dense fresh water, the movement stops in the halocline where the warm sea water mixes with brackish water. The convection cycle would be completed by the coastward movement of cooling brackish water. The observed temperature anomalies could possibly be snapshots of this warm layer moving coastward., Introduction The northeastern coastal Yucatan Peninsula, adjacent to the Caribbean Sea, is a region of karst topography (Back and Hanshaw 1970) with numerous sinkholes and some of the longest subaquatic [...]

Late Pleistocene organic-rich sediments (sapropels) from the eastern Mediterranean Sea harbor unknown, metabotically active chemoorganotrophic prokaryotes. As compared to the carbon-lean intermediate layers, sapropels exhibit elevated cell numbers, increased activities of hydrolytic exoenzymes, and increased anaerobic glucose degradation rates, suggesting that microbial carbon substrates originate from sapropel layers up to 217,000 years old. 16S ribosomal RNA gene analyses revealed that as-yet-uncultured green nonsulfur bacteria constitute up to 70% of the total microbial biomass. Crenarchaeota constitute a smaller fraction (on average, 16%). A slow but significant turnover of glucose could be detected. Apparently, sapropels are still altered by the metabolic activity of green nonsulfur bacteria and crenarchaeota., Deep-sea sediments of the eastern Mediterranean are characterized by the cyclic occurrence of dark sediment layers, called sapropels. Sapropels differ from most other subsurface environments in that they contain high [...]

Reinvestigations of the cave of Lene Hara in East Timor have yielded new dating evidence showing occupation from before 30,000 BP. These will further fuel the debates on early colonization of the region. Key-words: Indonesia, East Timor, Pleistocene, Middle Palaeolithic, Lene Hara, Timor, the largest of the Lesser Sunda Island chain lying between Java and New Guinea and Australia, has long been recognized as one of the most prospective locations for finding [...]

A major focus of archaeological field investigations over the past four decades in eastern North America has been the excavation of rockshelters. Many of the Southern highland rockshelters investigated during this period yielded evidence of initial occupations by Dalton horizon (10,500 to 10,000 B.P.) hunter-gatherers. Data concerning the Dalton components from a sample of 45 of these shelters are reviewed and discussed in order to identify variability in site functions and to address the question, Why were Dalton peoples the first North American hunter-gatherers to systematically inhabit rockshelters? Factors such as shifts in hunting patterns and mobility strategies appear to have been central to this development in early Holocene landscape utilization., Archaeologists working in North America have become increasingly involved with research into the nature of human adaptation to the environmental changes that took place during the Pleistocene/Holocene transition (Anderson and [...]

The Shed Brook Discontinuity in the western Mohawk Valley region of central New York is an unconformity separating lacustrine beds of the Valley Heads drift (Port Bruce stade) from pre-Valley Heads lacustrine deposits (Nissouri stade). The Little Falls Gravel is a fluvial unit that can be found draped by Valley Heads lacustrine deposits in the Mohawk Valley. The discontinuity and gravel represent subaerial erosion and braided river deposition in response to initial late Wisconsinan ice recession and lake drainage in the Mohawk Valley. These events were followed by Valley Heads lake impoundment and glacial read-vances. The Shed Brook Discontinuity and Little Falls Gravel have a 14C age constrained to 17-14.1 ka on the basis of stratigraphic relationships in central New York and the correlation of paleomagnetic declination records from central New York and the 14C-calibrated New England varve chronology. The Shed Brook Discontinuity and Little Falls Gravel appear to be features equivalent in age to the Erie interstade (about 14.5-16 ka), an interval during which eastward drainage to the Mohawk Valley has been inferred for lakes in the Erie basin. Evidence for a river in the Mohawk Valley (Little Falls Gravel) indicates that it may have served as an eastern outlet for the Erie and Ontario basins, and thus allowed the first eastward diversion of meltwater away from the Mississippi Valley during the last deglaciation. Drainage down the Mohawk Valley entered Lake Albany in the Hudson Valley, which drained into Long Island Sound and not along the present Hudson River course to the New Jersey continental shelf. Meltwater drainage across New York during the latest stages of the Erie interstade may have introduced large volumes of meltwater directly to the western Atlantic, creating a situation that needs to be more fully explored in terms of its possible influence on thermohaline circulation in the North Atlantic and climatic change marked by the Port Bruce stade.

Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps in the evolution of African hominids and other vertebrates are coincident with shifts to more arid, open conditions near 2.8 Ma, 1.7 Ma, and 1.0 Ma, suggesting that some Pliocene (Plio)-Pleistocene speciation events may have been climatically mediated., Detailed records of African paleoclimate change during the Plio-Pleistocene are rare from terrestrial sequences, but deep-sea drilling of marine sedimentary sequences near the continent has recovered several continuous and well-dated [...]

A radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima during the last glaciation at 13,900 to 14,890, 21,000, 23,060, 26,940, 29,600, and ≥33,500 carbon-14 years before present ([sup.14]C yr B.P.) in a cold and wet Subantarctic Parkland environment. The last glaciation ended with massive collapse of ice lobes close to 14,000 [sup.14]C yr B.P., accompanied by an influx of North Patagonian Rain Forest species. In the Southern Alps of New Zealand, additional glacial maxima are registered at 17,720 [sup.14]C yr B.P., and at the beginning of the Younger Dryas at 11,050 [sup.14]C yr B.P. These glacial maxima in mid-latitude mountains rimming the South Pacific were coeval with ice-rafting pulses in the North Atlantic Ocean. Furthermore, the last termination began suddenly and simultaneously in both polar hemispheres before the resumption of the modern mode of deep-water production in the Nordic Seas. Such interhemispheric coupling implies a global atmospheric signal rather than regional climatic changes caused by North Atlantic thermohaline switches or Laurentide ice surges., Detailed oxygen-isotope records from Greenland ice cores show repeated millennial-scale temperature oscillations, called Dansgaard-Oeschger events, between glacial stadials and interstadials[1-3]. Each stadial begins either gradually or with stepwise changes and [...]

Accurate terrestrial glacial chronologies are needed for comparison with the marine record to establish the dynamics of global climate change during transitions from glacial to interglacial regimes. Cosmogenic beryllium-10 measurements in the Wind River Range indicate that the last glacial maximum (marine oxygen isotope stage 2) was achieved there by 21,700 [+ or - ] 700 beryllium-10 years and lasted 5900 years. Ages of a sequence of recessional moraines and striated bedrock surfaces show that the initial deglaciation was rapid and that the entire glacial system retreated 33 kilometers to the cirque basin by 12,100 ± 500 beryllium-10 years., Alpine glacial systems are more responsive than large continental ice sheets to changes in temperature and precipitation. Chronologies of alpine morainal sequences therefore offer the possibility of providing records of [...]

The distribution of food-plants - both potential and actually exploited - reflects the natural history of contact across the seas and through the region, often long before Pleistocene times. The [...]

An element in the changing pattern of Australian archaeology has been the filling-in of great blanks on the archoeological map, once survey and excavation has begun to explore them. The [...]

A central issue in the regional prehistory over the Transition - and therefore of this whole set of papers - is the different life-ways that came to be followed in [...]

The high and low islands of Torres Strait, scattered between the tip of Queensland and the coast of Papua New Guinea, make a unique frontier in later world prehistory: between [...]

A uniform oxygen isotope value of -25 per mil was obtained from old ground water at depths of 20 to 30 meters in a thick deposit of clay in the southern part of the glacial Lake Agassiz basin. The lake occupied parts of North Dakota and southern Manitoba at the end of the last glacial maximum and received water from the ice margin and the interior plains region of Canada. Ground water from thick late Pleistocene-age clay deposits elsewhere, a till in southern Saskatchewan, and a glaciolacustrine deposit in northern Ontario show the same value at similar depths. These sites are at about 50'N latitude, span a distance of 2000 kilometers, and like the Lake Agassiz sites, have a ground-water velocity of less than a few millimeters per year. The value of -25 per mil is characteristic of meltwater impounded in the southern basin of Lake Agassiz. This value corresponds to an estimated air temperature of -16°, compared with the modern temperature of [0degree] for this area., At some locations in the glaciated regions of North America and elsewhere, the stableisotope content of old ground water provides a terrestrial record of pre-Holocene climate. Old ground water is [...]

We live in an ice age: current sea level is some 70 meters below where it would be if the polar regions were warm. However, we live in a warm [...]

Cataclysmic flooding is a geomorphological process of planetary significance. Landforms of flood origin resulted from late Pleistocene ice-dammed lake failures in the Altay Mountains of south-central Siberia. Peak paleoflows, which [...]

Millennial-scale episodes of rapid climate change occurred throughout much of the latter part of the Pleistocene. These oscillations generally occurred with greater regularity and intensity during glacial periods, which are [...]

A detailed record of sea surface temperature from sediments of the Cape Basin in the subtropical South At[antic indicates a previously undocumented progression of marine climate change between 41 and 18 thousand years before the present (ky B.P.), during the last glacial period. Whereas marine records typically indicate a long-term cooling into the Last Glacial Maximum (around 21 ky B.P.) consistent with gradually increasing global ice volume, the Cape Basin record documents an interval of substantial temperate ocean warming from 41 to 25 ky B.P. The pattern is similar to that expected in response to changes in insolation owing to variations in Earth's tilt., The Southern Hemisphere oceans are thought to be an important component of the global climate system, possibly regulating glacial-to-interglacial changes in atmospheric [CO.sub.2] concentrations (1) and, on millennial time scales, [...]

BERKELEY, CALIFORNIA--This quadrennial meeting regularly runs the gamut of life history, but this year's convention, from 26 June to 1 July, featured an emphasis on research with relevance to problems of today, such as invasive species and the decline of coral reefs., Big Clams Make Good Invaders When exotic species invade new territory, trouble may ensue--or it may not. In the sea, some creatures that humans intentionally or unwittingly moved to new [...]

A computer simulation of North American end-Pleistocene human and large herbivore population dynamics correctly predicts the extinction or survival of 32 out of 41 prey species. Slow human population growth rates, random hunting, and low maximum hunting effort are assumed; additional parameters are based on published values. Predictions are close to observed values for overall extinction rates, human population densities, game consumption rates, and the temporal overlap of humans and extinct species. Results are robust to variation in unconstrained parameters. This fully mechanistic model accounts for megafaunal extinction without invoking climate change and secondary ecological effects., More than half of the large mammal biota of the Americas disappeared in a cataclysmic extinction wave at the very end of the Pleistocene (1, 2). This dramatic event, unparalleled [...]

Until the late Pleistocene era, 11,000 to 50,000 years ago, big, exotic mammals and flightless birds roamed the planet. Then, suddenly, they were gone. Who killed the Pleistocene megafauna? So [...]

The current extinction of many of Earth's large terrestrial carnivores has left some extant prey species lacking knowledge about contemporary predators, a situation roughly parallel to that 10,000 to 50,000 years ago, when naive animals first encountered colonizing human hunters. Along present-day carnivore recolonization fronts, brown (also called grizzly) bears killed predator-naive adult moose at disproportionately high rates in Scandinavia, and moose mothers who lost juveniles to recolonizing wolves in North America's Yellowstone region developed hypersensitivity to wolf howls. Although prey that had been unfamiliar with dangerous predators for as few as 50 to 130 years were highly vulnerable to initial encounters, behavioral adjustments to reduce predation transpired within a single generation. The fact that at least one prey species quickly learns to be wary of restored carnivores should negate fears about localized prey extinction., The spectacular post-Pleistocene extinctions of many genera of large animals in areas ranging from Australia to North America have been attributed primarily to human overkill as hunters encountered naive prey--the [...]

Excavation at the site of Picareiro Cave in Portugal provides an important and rare sample of animal remains. Preliminary study shows that late Pleistocene hunter-gatherers hunted rabbits, deer and a wide variety of fauna, perhaps during seasonal occupation of the cave. Key-words: Portugal, subsistence, Picareiro, Pleistocene fauna, fish, hunter-gatherer, Introduction Understanding culture change and continuity at the Pleistocene-Holocene boundary requires subsistence data (see Straus et al. 1996). The paucity of faunal remains, however, limits what is known about subsistence [...]

Archaeological excavations at the site of Dmanisi in the Republic of Georgia have uncovered two partial early Pleistocene hominid crania. The new fossils consist of a relatively complete cranium and a second relatively complete calvaria from the same site and stratigraphic unit that yielded a hominid mandible in 1991. In contrast with the uncertain taxonomic affinity of the mandible, the new fossils are comparable in size and morphology with Homo ergaster from Koobi Fora, Kenya. Paleontological archaeological, geochronological and paleomagnetic data from Dmanisi all indicate an earliest Pleistocene age of about 1.7 million years ago, supporting correlation of the new specimens with the Koobi Fora fossils. The Dmanisi fossils, in contrast with Pleistocene hominids from Western Europe and Eastern Asia, show clear African affinity and may represent the species that first migrated out of Africa., The identity of the first hominid species to disperse out of Africa and the timing of this dispersal remain highly controversial. The earliest known hominid fossils in Europe and Asia [...]

Mechanisms responsible for the initiation of major glaciation in the Northern Hemisphere at about 2.75 million years ago are poorly understood. A laminated terrestrial sequence from Pula maar, Hungary, containing about 320,000 years in annual layers between 3.05 and 2.60 million years ago, provides a detailed record of rates of climatic change across this dramatic transition. An analysis of the record implies that climatic variations at sub-Milankovitch frequencies (less than or equal to 15,000 years) were an important driving force during this transitional interval and that, as the threshold was approached, these increased in frequency and amplitude, possibly providing the final trigger for the amplification of Northern Hemisphere ice sheets., The late Pliocene was a time of major climatic cooling resulting in the growth of large terrestrial ice sheets and the onset of Northern Hemisphere glaciation (NHG) at ~2.75 million [...]

The Wadi Ziqlab Project of University of Toronto conducted survey of river terraces in Wadi Ziqlab and Wadi Taiyiba, two adjacent, small drainage basins in northern Jordan, and made small [...]

Glaciation in the humid tropical Andes is a sensitive indicator of mean annual temperature. Here, we present sedimentological data from lakes beyond the glacial limit in the tropical Andes indicating that deglaciation from the Last Glacial Maximum led substantial warming at high northern latitudes. Deglaciation from glacial maximum positions at Lake Titicaca, Peru/Bolivia (16°S), and Lake Junin, Peru (11°S), occurred 22,000 to 19,500 calendar years before the present, several thousand years before the Bolling-Allerod warming of the Northern Hemisphere and deglaciation of the Sierra Nevada, United States (36.5° to 38°N). The tropical Andes deglaciated while climatic conditions remained regionally wet, which reflects the dominant control of mean annual temperature on tropical glaciation., Maximum late-Pleistocene glaciation in the tropics was associated with an ~800- to 1000-m elevation lowering of glacier equilibrium-line altitudes in response to a 4° to 6°C reduction in mean annual [...]

The Paleomagnetic Field from Equatorial Deep-Sea Sediments: Axial Symmetry and Polarity Asymmetry THE TIME-AVERAGED GEOMAGNETIC field can deviate from the field of a geocentric axial dipole. Although the difference is [...]

The Little Ice Age as Recorded in the Stratigraphy of the Tropical Quelccaya Ice Cap IN 1983 TWO ICE CORES, ONE 154.8-M summit core containing a record of 1350 years [...]

The mineralogy and fossil assemblages of lake beds currently provide the only tool for deciphering pre-Mid-Wisconsin paleoclimatic conditions in the Great Basin. Calcitic veins, which mark the sites of paleoground-water [...]

This history of continental ice sheets and their effect on the composition and climates of the ocean is a pervasive theme in paleoceanography. For example, within the Neogene, much of [...]

Thirty Thousand Years of Human Colonization in Tasmania: New Pleistocene Dates THE DISTRIBUTION OF AUSTRALIAN Pleistone Aboriginal populations has been characterized as wide-spread, with low densities possessing little regional variation [...]

ABSTRACT Research history of the microlithic in northeast Asia reveals that while heavy emphasis has been placed upon reconstructing microblade techniques, little effort has been made in providing a systematic [...]