bluuebunny/crossref_metadata_2025 huggingface dataset:
Middle Wisconsin Stratigraphy and Climatic Reconstruction, Southern Vancouver Island, British Columbia
Authors: Alley Neville F.
Published: July 2006

Interbedded, organic-rich terrestrial and marine sediments exposed along the eastern coastal lowland of Vancouver Island contain an almost continuous record of middle Wisconsin vegetation and climate. The record has been interpreted largely from palynostratigraphic studies at three sites and supported by a study of modern pollen spectra from the three major biogeoclimatic zones of the extant vegetation. Radiocarbon dates from a variety of organic materials in the middle Wisconsin beds reveal that the fossil pollen spectra span an interval ranging from approximately 21,000 yr B.P. to more than 51,000 yr B.P. The spectra are divided into eight major pollen zones encompassing the Olympia Interglaciation and early Fraser Glaciation geologicclimate units of the Pacific Northwest. The Olympia Interglaciation extended from before 51,000 yr B.P. to ca. 29,000 yr B.P. and was characterized by a climate similar to present. During the early Fraser Glaciation, from 29,000 years ago to approximately 21,000 yr B.P., climate deteriorated until tundra like conditions prevailed. These pollen sequences are correlative with those of coastal British Columbia and partly with those from Olympic Peninsula, but apparently are not comparable with events in the Puget Lowland.
Uranium-Series Dating of Lacustrine Limestones from Pan Deposits With Final Acheulian Assemblage at Rooidam, Kimberley District, South Africa
Authors: Szabo B. J. , Butzer K. W.
Published: July 2006

Lacustrine limestone samples from sedimentary pan deposits at Rooidam, near Kimberley, South Africa, that contain late Acheulian (Fauresmith) artifacts have been dated by 230Th/234U and 231Pa/235U methods. Results indicate a minimum age of about 200,000 yr B.P. for the terminal Acheulian in the interior of South Africa.
Late Quaternary Paleoceanography of the Gulf of Aqaba (Elat), Red Sea
Authors: Reiss Z. , Luz B. , Almogi-Labin A. , Halicz E. , Winter A. , Wolf M. , Ross D. A.
Published: July 2006

The quantitative distribution of planktonic foraminifera, pteropods, and coccolithophorids, as well as oxygen-isotope variations were analyzed in four deep-sea cores from the Gulf of Aqaba (Elat) and the northernmost Red Sea. The core record covers about 150,000 yr. Detailed stratigraphic subdivision is facilitated by combining all calcareous plankton groups. Time-stratigraphic correlation and dating beyond the radiocarbon range are possible by comparison of the oxygen-isotope curves. During the glacial maximum salinity rose to more than 50‰, while winter temperature of the upper waters fell by at least 4°C compared to the present. The rise in salinity can be accounted for by sea-strait dynamics and lowering of sea level. The Gulf of Aqaba and the Red Sea were continuously connected through the Straits of Tiran, and there is no indication of desiccation during the glacial maximum.
Surface Circulation of the Indian Ocean during the Last Glacial Maximum, Approximately 18,000 yr B.P.
Authors: Prell Warren L. , Hutson William H. , Williams Douglas F. , Bé Allan W.H. , Geitzenauer Kurt , Molfino Barbara
Published: July 2006

A seasonal reconstruction of the Indian Ocean during the last glacial maximum (∼18,000 yr B.P.) reveals that its surface circulation and sea surface temperature patterns were significantly different from the modern Indian Ocean. This reconstruction is based on the planktonic foraminiferal biogeography and estimated sea surface temperatures in 42 Indian Ocean samples. Compared to modern conditions, the polar front was 5° to 10° latitude further north during the last glacial maximum; the Subtropical Convergence was 2° to 5° latitude further north. The West Australian Current was more intense as part of the West Wind Drift was deflected northward along the coast of Australia. The Agulhas Current was cooler and weaker during the summer and more saline and subtropical during the winter. In general, the low latitudes underwent little temperature change. The western Arabian Sea was warmer which implies less upwelling and a weaker Southwest Monsoon. On the average, the Indian Ocean was 1.9°C cooler in February and 1.7°C cooler in August during the last glacial maximum.
Recent Increased Aridity in Peninsular Florida
Authors: Coleman James M.
Published: July 2006

Precipitation and river-flow data from peninsular Florida show a trend toward increased aridity beginning about 1960. The trend follows by 10–20 yr the onset of Northern Hemispheric cooling and indicates a possible present-day link between this cooling and the recent decrease in precipitation in peninsular Florida. This phenomenon tends to support the hypothesis of a return to cooler and drier conditions, perhaps, similar to those prevailing during the Little Ice Age.
Paleoenvironmental Implications of a Late Glacial Insect Assemblage from Northwestern New York
Authors: Schwert Donald P. , Morgan Alan V.
Published: July 2006

The Winter Gulf site near North Collins, New York is a 0.8-m sequence of organic detritus dated at approximately 12,700 yr B.P. A 260-kg sample produced over 500 identified individuals representing five orders of insects. Three insect zones were recognized, the lowest representing an open mire with sparse numbers of carices and other sedges; aquatic beetles were rare, and no trees were in the vicinity of the sample site. The middle zone indicated an extensive marsh or moist meadow environment with spruce nearby. The upper zone represented a mixed riparian and spruce forest insect assemblage.

The results of the Winter Gulf insect analyses support published hypotheses that the site was probably a protected embayment of early lake Warren. Although the flora at the site has been previously interpreted as representing parkland tundra, temperature analyses of the fauna indicate that the thermal conditions were much warmer than parkland tundra regions of North America today. These results have important significance for the region immediately south of the Laurentide Ice Sheet during this period of the Late Wisconsinan.
Stratigraphy of Late Quaternary Estuarine Deposits and Amino Acid Stereochemistry of Oyster Shells Beneath San Francisco Bay, California
Authors: Atwater Brian F. , Ross Bruce E. , Wehmiller John F.
Published: July 2006

The sequence of Quaternary deposits beneath the floor of San Francisco Bay includes four to seven noncontemporaneous estuarine units intercalated with alluvium and dune sand. Units L (0–10,000 B.P.), M (>40,000 B.P., probably ca. 80,000–140,000 B.P.), and N (older than unit M) are distinctly superposed. The dominant molluscan fossil in each of these three units is Ostrea lurida Carpenter, the native oyster along much of the pacific Coast of North America. Despite a lamellar structure that suggests vulnerability to contamination, O. lurida shells generally yield amino acid enantiomeric ratios that are analytically reproducible and stratigraphically consistent. The kinetics of racemization in O. lurida conceivably resembles that of Protothaca and Saxidomus, other bivalves whose kinetics of racemization are relatively well understood. Assuming such a resemblance, enantiomeric ratios in O. lurida imply that (1) unit M is the same approximate age as estuarine terrace deposits bordering San Pablo Bay and Carquinez Strait, providing that the terrace deposits have been at diagenetic temperatures 1°-2°C warmer than unit M; and (2) the age of unit N is about four times greater than that of unit M, providing that both units have been at the same approximate diagenetic temperature.
Assessing the Global Meltwater Spike
Authors: Jones Glenn A. , Ruddiman William F.
Published: July 2006

L. V. Worthington (1968, Meteorological Monographs 8, 63–67) hypothesized that a low-salinity lid covered the entire world ocean. By deconvolving isotopic curves from the western equatorial Pacific and equatorial Atlantic, W. H. Berger, R. F. Johnson, and J. S. Killingley (1977), Nature (London) 269, 661–663) and W. H. Berger (1978, Deep-Sea Research 25, 473–480) reconstructed “meltwater spikes” similar to those actually observed in the Gulf of Mexico and thus apparently confirmed the Worthington hypothesis. It is shown that this conclusion is unwarranted. The primary flaw in the reconstructed meltwater spikes is that the mixing intensity used in the deconvolution operation is overestimated. As a result, structure recorded in the mixed isotopic record becomes exaggerated in the attempt to restore the original unmixed record. This structure can be attributed to variable ice-volume decay during deglaciation, effects of differential solution on planktonic foraminifera, temporal changes in abundance of the foraminifera carrying the isotopic signal, and analytical error. An alternative geographic view to the global low-salinity lid is offered: a map showing portions of the ocean potentially affected by increased deglacial meltwater at middle and high latitudes and by increased precipitation-induced runoff at low and middle latitudes.
Regional Significance of an Early Holocene Moraine in Enchantment Lakes Basin, North Cascade Range, Washington
Authors: Waitt Richard B. , Yount James C. , Davis P. Thompson
Published: July 2006

The upper Enchantment Lakes basin in the North Cascade Range of Washington displays two moraine belts, each recording an episode of glacier advance after the end of the last glaciation. The inner belt, the Brynhild, 0.1 to 0.5 km beyond existing glaciers, postdates Mount St. Helens Wn tephra (∼450 yr old), which lies only beyond the moraines. The morainal surface is only slightly weathered, is almost barren of lichens, and is devoid of soil, evidence suggesting that the Brynhild moraines are no more than a century old. The outer moraine, the Brisingamen, 0.3 to 0.7 km beyond existing glaciers, is weathered and is covered with large lichens. On and behind the Brisingamen moraine the Mazama ash (6900 yr old) is present beneath the Mount St. Helens Yn and Wn tephras. Despite more than 7 millennia of weathering, the rock surface behind the Brisingamen moraine is measurably less weathered than the surface beyond, which was last glaciated during the Rat Creek advance about 13,000 yr ago. The age of the Brisingamen moraine therefore is probably early Holocene. The Brisingamen moraine evidently correlates with moraines near Glacier Peak, near Mount Rainier, in northeastern and central Oregon, in the southern Canadian Rockies, and in the northern U.S. Rocky Mountains. These regional effects suggest that a climatic episode of cooling or increased snowfall affected the entire region some time during the early Holocene.
Late-Glacial Vegetation Associated with Caribou and Mastodon in Central Indiana
Authors: Whitehead Donald R. , Jackson Stephen T. , Sheehan Mark C. , Leyden Barbara W.
Published: July 2006

The Christensen Mastodon Site, located in central Indiana, contains a rich assemblage of vertebrates (including mastodon, caribou, and giant beaver), invertebrates, and plant macrofossilsin situin lake and bog sediments of late-glacial age. Studies of pollen and plant macrofossils suggest the existence of open, white spruce-dominated boreal forests from > 14,000 yr B.P. to ca. 13,000 yr B.P. The regional decline of spruce, local occurrence of black spruce, white spruce, and larch, immigration of many hardwood taxa (e.g., ash, oak, elm), and the initiation of bog development are recorded beginning about 13,000 yr B.P. Recent reconstructions of late-glacial and early postglacial vegetational changes provide a context for understanding the disappearance of mastodons. The dramatic and rapid restriction of boreal forests along the retreating ice margin from 11,000 to 9000 yr B.P. may have caused a substantial reduction of mastodon populations. A diminished population would be more susceptible to small-scale, stochastic events such as short-term extremes of weather, outbreaks of disease, or predation pressure from paleoindian hunters.
Differential Glacio-Isostatic Uplift of Crustal Blocks at Glen Roy, Scotland
Authors: Sissons J. B. , Cornish R.
Published: July 2006

Detailed measurements of the altitudes of the shorelines of former ice-dammed lakes in Glen Roy and vicinity in the Scottish Highlands prove erroneous the conventional view that former shorelines in areas affected by glacio-isostatic uplift are uniformly tilted and/or gently warped. The measurements demonstrate differential uplift of blocks of the earth's crust. The surfaces of some blocks have no detectable tilt whereas others have gradients up to at least 4.6 m/km and are tilted in different directions. In three areas 0.7–2.0 km long, shorelines are distorted by crustal movements; all these areas have landslides attributed to earthquakes that accompanied the release of stress. In the area of greatest local distortion three shorelines rose about 3 m above their average altitudes for the immediately surrounding area, and a fault scarp was produced. Possibly these local distortions accompanied catastrophic lake drainage by jökulhlaup, analogous to crustal movements associated with man-made lakes. A relationship between crustal movement and the limit of a glacial advance is demonstrated. These findings have implications for other parts of the world affected by glacioisostatic uplift.
Postglacial Temperature Anomalies and Glacial Isostasy
Authors: Tinkler K. J.
Published: July 2006

The isostatic depression of an ice-free land surface, originally caused by glacial ice, ought to be converted into a change in mean annual temperature according to the usual value for the environmental lapse rate, 6.5°C/1000 m. Calculations are undertaken to show the temperature changes, relative to present values at a site, that can be expected from this effect during the retreat of a major continental ice sheet. It is concluded that when restrained rebound is taken into account temperatures relative to the present could vary from 0°C at the start of deglaciation to about +2.32°C at the final disappearance of the Laurentide Ice Sheet. The decay of the warmer-than-present temperatures towards their current values is controlled, in this model, by isostatic recovery of the land surface. Variance estimates are built into the model and suggest that the anomaly might be as small as 0.75°C or as large as 4.0°C depending on the choice of values for crucial components such as maximum ice thickness, the proportion of isostatic deformation, and the amount of restrained rebound achieved by the time a site become ice free.
Time Variations of Erosional Force and Grain Size in Pleistocene Lake Sediments
Authors: Kashiwaya Kenji , Yamamoto Atsuyuki , Fukuyama Kaoru
Published: July 2006

Theoretical investigations on models of the developmental processes of erosional features show that the time variations in erosional force have more sensitive influence on the time fluctuation of eroded material, such as sediments in lakes, than that of the quantity representing erosional features, such as volume of mountains. Time sequences of grain-size distributions from the Pleistocene sediments in Lake Biwa, central Japan indicate dominant periodicities of about 40,000 and 20,000 yr, very close to those predicted from the Milankovitch theory. The time variations of the grain-size parameters which may be indicators of erosional forces are very similar to that of the caloric summer insolation in the Northern Hemisphere.
Paleoenvironmental Changes at the Northern Limit of the Subantarctic Nothofagus Forest, lat 37°S, Argentina
Authors: Markgraf Vera
Published: July 2006

Paleoenvironmental changes dating back to before 10,000 yr B.P. at the northernmost occurrences of Nothofagus forests in Argentina at about latitude 37°S permit the reconstruction of past changes in the intensity of the winter rains, related to the southern westerlies that appear to determine the forest boundary. The paleoenvironmental interpretation is based on changes in the proportions of different Nothofagus species and changes in the ratio betwen forest and steppe taxa. The relatively most diverse and dense Nothofagus forest developed only during the last 4500 yr, prior to human impact during the last 300 yr. Before the middle Holocene, climatic conditions must have been different from the modern ones, with less overall precipitation judging from the overall lower amount of tree pollen and the reduction to primarily Nothfagus pumilio. An interval dated to older than 10,000 yr B.P. is characterized by co-occurrence of Prumnopitys andina, Nothofagus pumilio, and shrub-steppe taxa. Prumnopitys andina is known today only from scattered upper montane forest sites in Chile between 36° and 43°S lat and its ecological requirements are essentially unknown. The taxa combination, however, suggests that late-glacial climate must have been drier, and probably cooler than today. This implies that the winter rains and, consequently, the seasonal shift of the westerly circulation was reduced during the late Pleistocene and did not reach modern levels before 8500 yr B.P.
Importance of the Rossendale Site in Establishing a Deglacial Chronology Along the Southwestern Margin of the Laurentide Ice Sheet
Authors: Teller James T.
Published: July 2006

The timing of deglaciation in the Lake Agassiz basin is critical in establishing the routing of meltwater and precipitation runoff from a 2,000,000-km2region of central North America and in evaluating the influence this water had on rivers and oceans into which it drained. Dates of 12,400 ± 420 and 12,100 ± 160 yr B.P. for moss at the Rossendale site in Manitoba have long been a key for those advocating an “early” deglacial chronology in this region. However, new dates for wood from this site and paleoecological interpretations of ostracods, molluscs, and the dated moss all support a “young” deglacial scenario. Of particular significance is the fact that the dated moss,Scorpidium scorpioides, is a subaquatic type subject to contamination by old carbon dissolved from bedrock. In fact, most subaquatic moss may be unreliable for radiocarbon dating. For these reasons, the 12,400 and 12,100 yr B.P. dates are rejected. New dates of 9600 ± 70 and 9510 ± 90 yr B.P. for wood from the same organic-rich unit containing the dated moss, ostracods, and molluscs fit well with the “young” deglacial chronology of the southwestern Laurentide ice margin advocated by many. In short, the ice margin appears to have retreated into the southern Lake Agassiz basin after 12,000 yr B.P. and north of the Rossendale site by 11,000 yr B.P. About 10,000 yr B.P., following the Moorhead low-water phase, Lake Agassiz rose to the Campbell level. The dated organic matter at Rossendale was deposited in a lagoon behind the Campbell beach.
Glacial/Interglacial Size Variation in Fossil Spotted Hyenas (Crocuta crocuta) from Britain
Authors: Klein Richard G. , Scott Katharine
Published: July 2006

The lower carnassial lengths of spotted hyenas (Crocuta crocuta) in 12 late Pleistocene samples from Britain indicate that, on average, local hyenas of the last (Devensian) glaciation were significantly larger than their last-interglaciation (Ipswichian) counterparts. Together with the tendency for spotted hyena carnassial length to increase with latitude in present-day Africa, this suggests that spotted hyena body size is inversely related to temperature, as predicted by Bergmann's rule. The implication is that spotted hyena carnassial length can be used as an independent gauge of Pleistocene temperature variation, though the combined African and British data imply that the relationship between carnassial length and temperature is curvilinear, such that as temperature declines, equal amounts of further decline produce progressively smaller increases in average carnassial length.
Bagnold's Barchan: A 57-Yr Record of Dune Movement in the Eastern Sahara and Implications for Dune Origin and Paleoclimate Since Neolithic Times
Authors: Haynes C. Vance
Published: July 2006

Discovery in 1980 of Camp 18 of the 1930 Bagnold expedition in northwestern Sudan has resulted in an exceptionally long record of barchan movement from which an average rate of 7.5 m/yr has been calculated. Measurements of the rate of dune advance since 1980 have not varied significantly, indicating a state of quasiequilibrium exists. The dune field is moving over an undulating sand sheet exhibiting various stages of Holocene pedogenesis and containing Neolithic sites. The sand sheet overlies Pleistocene alluvium with stronger stages of pedogenesis. All of these deposits may be a significant source of dune sand. Wind-blown grass fragments trapped by advancing slipfaces mark former slipface positions and indicate late Holocene rainfall events, which can be radiocarbon dated. Parabolic forms (revealed by SPOT images) at the windward ends of the dune fields are transitional to barchans, suggesting sand accumulation in vegetation germinated during a Holocene wet period. In addition, sand streaks from sand-sheet undulations suggest that active eolian erosion of sand sheets contributes to the sand supply of dune fields. Pedogenesis during pluvial periods contributes to silt and clay fractions of bimodal sand sheet sediments. From wind streaks on LANDSAT images and an estimated average rate of dune advance, positions of dune fields during past hyperarid periods can be estimated.
Younger Dryas Climatic Reversal in Northeastern USA? AMS Ages for an Old Problem
Authors: Peteet D. M. , Vogel J. S. , Nelson D. E. , Southon J. R. , Nickmann R. J. , Heusser L. E.
Published: July 2006

Late-glacial macrofossils from a 10-m core from Alpine Swamp, New Jersey, were radiocarbon dated using accelerator mass spectrometry (AMS). The arrival of the first trees to the area following deglaciation is indicated by maximum percentages of spruce pollen and a date of 12,290 ± 440 yr B.P. on a single spruce needle. Subsequent spread of deciduous hardwoods was followed by the expansion of boreal taxa, including spruce (Picea), fir (Abies), larch (Larix laricina), paper birch (Betula papyrifera), and alder (Alnus). Three AMS dates on paper birch seeds and a spruce needle during this boreal expansion indicate that it took place between 11,000 and 10,000 yr B.P. The timing of this vegetational shift and its correlation with late-glacial pollen stratigraphy from many sites in southern New England indicate that a climatic reversal correlative with the Younger Dryas characterized the North Atlantic seaboard of the United States.
Holocene Climatic Change and the Distribution of Peatlands in Western Interior Canada
Authors: Zoltai Stephen C. , Vitt Dale H.
Published: July 2006

Dates of basal fen peat at 52 locations across west-central Canada indicate that peat deposition began <6000 yr B.P. in a broad zone north of the present-day grassland. The isopleth of >6000 yr B.P. basal fen peat parallels the foothills of the Rocky Mountains, and extends eastward along 54°30′ north latitude. The absence of >6000 yr B.P. peat within this zone is attributed to a warmdry early to middle Holocene climate that caused severe seasonal droughts and prevented the establishment of peat-forming fen vegetation. Wetlands west (and probably north) of this line experienced lower water tables, but supported fen vegetation. As the climate became cooler and moister, stable water tables allowed the development of fens and rapid peat accumulation ensued, reaching the modern distribution of fens between 2000 and 3500 yr B.P. Projections of climatic parameters indicate that the mean annual growing degree days were 6 to 21% higher during the early and middle Holocene, and that precipitation was reduced through most of the area, resulting in much higher (by 17 to 29%) aridity than at present.
Late-Pleistocene Eolian Sand Sheets in Alaska
Authors: Lea Peter D. , Waythomas Christopher F.
Published: July 2006

Nonglaciated lowlands in central and southwestern Alaska contain extensive deposits of upper-Quaternary eolian sand, derived largely from major outwash rivers. Although surface dunes are common, deep exposures consistently reveal that subhorizontally stratified sand and silt deposits dominate over dune cross strata. We hypothesize that (1) many of the subhorizontally stratified deposits represent full-glacial eolian sand sheets, formed when sand supply was limited by seasonally variable combinations of ice cementation, snow cover, high groundwater tables, and vegetation, and (2) many surface dunes reflect late-glacial and postglacial reworking under conditions of increased short-term availability of loose sand. The morphology of some surface dunes may therefore reflect mainly the intensity of reworking since the last glacial maximum, rather than full-glacial paleowind vectors or the age of the bulk of the underlying deposits.
Climatic Fluctuations in Northern Patagonia during the Last 1000 Years as Inferred from Tree-Ring Records
Authors: Villalba Ricardo
Published: July 2006

Millennium-old alerce trees (Fitzroya cupressoides (Mol.) Johnst.) have been used to develop a 1120-year reconstruction of the summer temperature departures for the Andes of northern Patagonia in Argentina. Four main climatic episodes can be distinguished in this proxy paleoclimatic record. The first, a cold and moist interval from A.D. 900 to 1070, was followed by a warm-dry period from A.D. 1080 to 1250 correlative with the Medieval warm epoch of Europe. Afterward, a long, cold-moist period followed from A.D. 1270 to 1670, peaking around A.D. 1340 and 1650. These cold maxima are contemporaneous with two principal Little Ice Age events registered in the Northern Hemisphere. Warmer conditions then resumed between A.D. 1720 and 1790. These episodes are supported by glaciological and palynological data in Patagonia. Following a cold period in the early 1800s, tree-ring indices have oscillated around the long-term mean, except for a warmer period from A.D. 1850 to 1890. Correlations between the Rio Alerce reconstruction and the regional weather stations indicate that the tree-ring variations are correlated with a homogeneous summer weather pattern covering Patagonia east of the Andes from 38° to 50°S.
Late Quaternary Glacial History of the South Orkney Plateau, Antarctica
Authors: Herron Margaret J. , Anderson John B.
Published: July 2006

Piston cores from the South Orkney Plateau penetrated overcompacted diamictons in water depths of up to 250 m. Detailed textural and petrological analyses of these diamictons indicate that they are basal tills. Seismic records from the plateau show a widespread surface of glacial erosion and provide additional evidence of an ice cap grounded to a depth of 250 m. Piston cores from the slope of the plateau penetrated diatomaceous muds resting directly on poorly sorted muds with very little to no biogenic material. The ice-rafted debris in these glacial-marine sediments is composed almost exclusively of material derived from the South Orkney Islands. This implies deposition beneath an ice shelf as opposed to iceberg rafting. In contrast, diatomaceous muds contain relatively abundant exotic iceberg-rafted material and reflect a glacial-maritime setting similar to that of today. The sharp contact separating diatomaceous surface sediments from basal tills and sub-ice shelf deposits indicates that the ice cap and ice shelf retreated from the plateau rapidly. Radiocarbon dates for diatomaceous muds from a glacial trough on the plateau indicate that the ice cap and ice shelf retreated from the plateau prior to 6000 to 7000 years ago. The homogeneity of surficial diatomaceous sediments suggests that sea ice conditions over the plateau have not changed radically since that time.
Age and Paleoclimatic Significance of the Stansbury Shoreline of Lake Bonneville, Northeastern Great Basin
Authors: Oviatt Charles G. , Currey Donald R. , Miller David M.
Published: July 2006

The Stansbury shoreline, one of the conspicuous late Pleistocene shorelines of Lake Bonneville, consists of tufa-cemented gravel and barrier beaches within a vertical zone of about 45 m, the lower limit of which is 70 m above the modern average level of Great Salt Lake. Stratigraphic evidence at a number of localities, including new evidence from Crater Island on the west side of the Great Salt Lake Desert, shows that the Stansbury shoreline formed during the transgressive phase of late Pleistocene Lake bonneville (sometime between about 22,000 and 20,000 yr B.P.). Tufa-cemented gravel and barrier beaches were deposited in the Stansbury shorezone during one or more fluctuations in water level with a maximum total amplitude of 45 m. We refer to the fluctuations as the Stansbury oscillation. The Stansbury oscillation cannot have been caused by basin-hypsometric factors, such as stabilization of lake level at an external overflow threshold or by expansion into an interior subbasin, or by changes in drainage basin size. Therefore, changes in climate must have caused the lake level to reverse its general rise, to drop about 45 m in altitude (reducing its surface area by about 18%, 5000 km2), and later to resume its rise. If the sizes of Great Basin lakes are controlled by the mean position of storm tracks and the jetstream, which as recently postulated may be controlled by the size of the continental ice sheets, the Stansbury oscillation may have been caused by a shift in the jetstream during a major interstade of the Laurentide ice sheet.
Paleoclimatic Reconstruction in Northern Oman Based on Carbonates from Hyperalkaline Groundwaters
Authors: Clark Ian D. , Fontes Jean-Charles
Published: July 2006

A paleoclimatic reconstruction for the past 35,000 years for northern Oman is based on an unusual approach using travertines and fracture calcites associated with hyperalkaline springs. High-pH groundwaters (pH up to 11.9) discharge from the mantle sequence of the Oman Ophiolite as the product of modern, low-temperature serpentinization. Under arid climatic conditions, hyperalkaline discharge occurs at the surface. Uptake of atmospheric CO2precipitates characteristic laminated travertines, accompanied by strong kinetic depletion of13C and18O. Pluvial climates supporting a shallow bicarbonate-groundwater flow system and vegetation are recorded by fracture calcites with equilibrium stable isotope contents and calcite-replaced roots and stems. All such carbonates have modern initial14C contents, allowing radiocarbon dating and paleoclimatic reconstruction for the late Pleistocene and Holocene. Our reconstruction shows a dominantly wet late Pleistocene up to 19,000 yr B.P., when a phase of climatic deterioration began, leading to a period of hyperaridity which dominated from ca. 16,300 to 13,000 yr B.P. The early Holocene pluvial occurred from 12,500 to ca. 6500 yr B.P. and was followed by renewed climatic deterioration and the current phase of hyperaridity. Comparison of this paleoclimatic reconstruction with that for lacustrine deposits from the A'Rub al Khali of central Saudi Arabia and the summer insolation-driven monsoon record of east Africa and the Arabian Sea is remarkably good.
Magnetic susceptibility evidence of monsoon variation on the Loess Plateau of central China during the last 130,000 years
Authors: An Zhisheng , Kukla George J. , Porter Stephen C. , Xiao Jule
Published: July 2006

The magnetic susceptibility of loess and paleosols in central China represents a proxy climate index closely related to past changes of precipitation and vegetation, and thus to summer monsoon intensity. Time series of magnetic susceptibility constructed for three loess-paleosol sequences in the southern part of the Chinese Loess Plateau document the history of summer monsoon variation during the last 130,000 yr. They correlate closely with the oxygen isotope record of stages 1 to 5 in deep-sea sediments. Soils were forming during intervals of strong summer monsoon, whereas loess units were deposited at times of reduced monsoon intensity. The Chinese loess-paleosol sequence can thus be viewed as a proxy record of Asian monsoon variability extending over the last 2.5 myr.
ESR ages of middle Pleistocene corals from the Ryukyu islands
Authors: Ikeda Sumiko , Kasuya Masao , Ikeya Motoji
Published: July 2006

Electron spin resonance ages of 11 corals from the lower part of the Ryukyu Group, Japan can be classified into two groups (about 600,000 and 800,000 yr). The result indicates that the lower part of the Ryukyu Group is correlated to at least two of the oxygen isotope stages 15, 17, 19, 21, and 23. Lowermost part of the Ryukyu Group was probably deposited during a large transgression and may be correlated worldwide.
West African Paleoclimates during the Last Climatic Cycle Inferred from an Atlantic Deep-Sea Pollen Record
Authors: Lezine Anne-Marie
Published: July 2006

Pollen studies of marine sediments from Atlantic deep-sea core V22-196 (13°50′ N-18°57′ W; 3728-m water depth) are used to reconstruct paleoclimates of north tropical west Africa since 140,000 yr B.P. High concentration of pollen, mainly from Saharan and arid littoral zones suggests a strengthened tradewind circulation since ca. 60,000 yr B.P. that became even stronger after 40,000 yr B.P. and reached a maximum 17,000 yr B.P. Periods of eolian transport of pollen to the Atlantic occurred about 94,000 and 105,000 yr B.P. and during Termination II. Conversely, high relative values of pollen from Sudanian and Guinean zones and from Mangrove and freshwater vegetation, coincident with maxima of dinocyst concentration, are interpreted as reflecting both strong fluvial inputs and the expansion of humid vegetation on the adjacent continent during wet periods dated between 140,000 and 118,000, 105,000 and 96,000, 92,000 and 73,000, 52,000 and 44,000 yr B.P. and 12,000 yr B.P. and the Holocene. The strong correlation of these results from the eastern tropical Atlantic with those from the Arabian Sea corroborates fluctuations of monsoon climate.
Soil Development, Relative Dating, and Correlation of Late Quaternary Marine Terraces in Southwestern Oregon
Authors: Bockheim James G. , Kelsey Harvey M. , Marshall James G.
Published: July 2006

Flights of tectonically uplifted, late Quaternary marine terraces are preserved at several localities along the Oregon coast. Intervening coastal areas without marine terraces reflect net subsidence. These gaps in the coastal terrace record make it difficult to correlate terraces along the Pacific coast. To test the utility of soils in relative dating and correlation, two flights of marine terraces near Cape Blanco and Cape Arago were investigated. The terraces could be distinguished in each area from soil morphological properties and a quantitative index of soil development derived from field descriptions. The soils in the two areas show a progression in development from spodosols to spodosols underlain by clayey material to ultisols. The lowest two terraces at Cape Blanco, which have reported age estimates of 80,000 and 105,000 yr, are correlative with the lowest two terraces at Cape Arago. The fifth and oldest terrace at Cape Blanco has no equivalent at Cape Arago. Soil development indices for the third and fourth terraces at each area allow two alternative sets of correlations.
Late Holocene Alluvial Chronology and Climate Change in the Central Great Plains
Authors: Martin Charles W.
Published: July 2006

Alluvium in one reach of the Republican River valley, south-central Nebraska, dates to the Holocene. Radiocarbon dating of fills underlying the two terraces in the valley reveals that entrenchment between 4500 and 3700 yr B.P. formed the high terrace. Subsequently, alternating aggradation and stability occurred until sometime between 1800 and 1100 yr B.P. Following another period of alluviation, channel incision formed the low terrace. General synchrony between this chronology and other late Holocene fluvial chronologies of the central Great Plains suggests climatic control of fluvial activity. The episodes of incision are tentatively correlated with different climate regimes, illustrating the difficulty of attributing a given fluvial response to a particular direction of climatic change.
Epidemiology of trauma, post-traumatic stress disorder (PTSD) and co-morbid disorders in Chile
Authors: ZLOTNICK CARON , JOHNSON JENNIFER , KOHN ROBERT , VICENTE BENJAMIN , RIOSECO PEDRO , SALDIVIA SANDRA
Published: July 2006

Background. In this study we examined the prevalence rates of post-traumatic stress disorder (PTSD), types of trauma most often associated with PTSD, the co-morbidity of PTSD with other lifetime psychiatric disorders, which disorders preceded PTSD, and gender differences in PTSD and trauma exposure in a representative sample of Chileans.

Method. The DSM-III-R PTSD and antisocial personality disorder modules from the Diagnostic Interview Schedule (DIS) and modules for a range of DSM-III-R diagnoses from the Composite International Diagnostic Interview (CIDI) were administered to a representative sample of 2390 persons aged 15 to over 64 years in three cities in Chile.

Results. The lifetime prevalence of PTSD was 4·4% (2·5% for men and 6·2% for women). Among persons exposed to trauma, rape was most strongly associated with PTSD. Onset of PTSD significantly increased the risk of developing each of the 10 other tested disorders. Among those exposed to trauma, women were significantly more likely to develop PTSD, after controlling for assaultive violence.

Conclusions. This study highlights the importance of investigating the prevalence of PTSD, patterns of co-morbidity of PTSD, and gender differences in PTSD in non-English-speaking countries.
Learning from Politics? The Causal Interplay between Government Performance and Political Ideology
Authors: KUMLIN STAFFAN
Published: July 2006

Most models of public opinion assign a fundamental role to ideological predispositions. Moreover, the literature usually portrays ideology as a stable phenomenon at the individual-level, one that is mainly shaped by socio-economic class experiences and pre-adult socialisation, and that is likely to grow stronger in intensity – rather than change – over the life-course. However, less is known about the scope of, or reasons for, ideological change in adult life. This paper uses Swedish panel data to investigate the interrelation between evaluations of government performance and ideological left–right related orientations. There is some support for ‘the socialisation school’, in that ideological positions and values display considerable short-term stability, although less stability over a four-year period. Moreover, there is evidence of short-run selective perception, with those close to the government at t1 being more likely than others to form more positive performance perceptions between t1 and t2. Interestingly however, over a four-year period this tendency was not statistically significant. Moreover, there is also clear support for a ‘revisionist’ interpretation of left–right ideology. Such orientations do change at the individual level, according to how people perceive incumbent government performance, an impact which does not depend on political sophistication.
Farmer attitudes towards conservation in Jigme Singye Wangchuck National Park, Bhutan
Authors: WANG SONAM WANGYEL , LASSOIE JAMES P. , CURTIS PAUL D.
Published: July 2006

The attitudes and feelings of people concerning conservation policies and wildlife conflicts affect their behaviour, and understanding this is important in involving local people in conservation planning and decision-making processes. This paper examines these important issues in Jigme Singye Wangchuck National Park, located in central Bhutan. A survey of 274 house-holds was carried out to assess farmers' perceptions of the influence of Park management policies and protection regimes on traditional resource uses, and their attitudes towards the Park and conservation policies set forth in the Forest and Nature Conservation Act of 1995, integrated conservation development programmes (ICDPs) and wildlife conservation, and determine how demographic and socioeconomic variables influence these attitudes. Among local farmers, 52.2% disliked the Park and the Conservation Act, and 67.5% supported exterminating problem wildlife. Negative attitudes were linked to loss of resource use rights, livestock depredation and crop damage, lack of compensation strategies and exclusion of farmers from the Park's planning processes. However, 76.3% of the respondents appreciated the Park's development programmes, the positive attitudes associated with an expectation that significant economic benefits would be available from ICDPs sponsored by the Park. Empowerment of local communities associated with monetary benefits from non-timber forest products and compensation for loss of crops and livestock were emphasized by more than 70% of the respondents. These attitudes were related to age and literacy of the respondents, number of livestock owned and size of land holdings. Though important to the future of Bhutan's parks, study results also have wider applicability to conservation professionals throughout the developing world for resolving human-land use conflicts and involving local farmers in the protection of nature.
Pharmakotherapie und Psychotherapie bei unipolarer Depression
Authors: Sutej Igor , Wiethoff Katja , Neuhaus Kathrin , Bauer Michael
Published: July 2006

Zusammenfassung: Eine kombinierte Behandlung aus Pharmakotherapie und Psychotherapie bei unipolaren depressiven Patienten ist gängige Praxis. Für diese Vorgehensweise liegt allerdings nur wenig empirische Evidenz vor. Der vorliegende Artikel gibt einen Überblick über den gegenwärtigen Stand der Literatur zur Wirksamkeit von Kombinationsbehandlung im Vergleich zu Monotherapie mit Pharmako- oder Psychotherapie. Berücksichtigt werden vorrangig Studien zur Akuttherapie, Erhaltungstherapie sowie zur Rezidivprophylaxe depressiver Episoden. Zusammenfassend lässt sich sagen, dass von einer kombinierten Behandlung insbesondere Patienten mit schweren Verläufen der Depression in der Akutbehandlung sowie Patienten mit rezidivierenden und chronischen Verläufen der Depression profitieren.
Pharmakologische und psycho- therapeutische Behandlung der Borderline-Störung
Authors: Remmel Andreas , Bohus Martin
Published: July 2006

Zusammenfassung: Trotz erheblicher Fortschritte in jüngster Zeit ist die wissenschaftliche Basis für die evidenzbasierte Behandlung der Borderline-Störung immer noch sehr schmal. Obgleich im klinischen Alltag häufig Kombinationen von Psychotherapie und psychopharmakologischer Behandlung zur Anwendung kommen, liegen zu dieser Verfahrensweise gerade zwei publizierte Studien mit unterschiedlichen Ergebnissen vor. Auf Seiten der Psychotherapie gilt derzeit die dialektisch-behaviorale Therapie (DBT) nachLinehan als am besten evaluiertes Verfahren. Auch die Studienlage zur Pharmakotherapie bessert sich. Wirksamkeitsnachweise wurden u. a. für Serotonin-Reuptake-Hemmer, atypische Neuroleptika und Stimmungs-Stabilisatoren erbracht. Allerdings liegen ausschließlich Daten zum monotherapeutischen Einsatz vor, was nicht die klinische Praxis widerspiegelt. Da sich der Einsatz der Psychopharmaka zumeist an der jeweils individuellen Symptomausprägung orientiert, kommen sehr häufig Kombinationen von verschiedenen Substanzklassen zum Einsatz, deren Wirksamkeit bislang nicht untersucht wurde.
Aggression-Related Characteristics and the Selection of Media Violence
Authors: Rosaen Sarah F. , Boyson Aaron R. , Smith Stacy L.
Published: July 2006

Abstract. A survey of 341 undergraduate students (118 males, 223 females) assessed five aggression-related personality characteristics and their relationships to the preference for violent media. Positive relationships were predicted for aggression, impulsivity and sensation seeking with exposure to media violence and negative relationships for empathy and guilt. Hierarchical regression analyses revealed consistent results only for aggression, where significant positive relationships existed with the frequency of consuming violent media. Sex was also found to be a significant moderator of the relationship between sensation seeking, impulsivity, guilt and violent media and suggests that women may derive much different value from media violence. These findings are predicted and interpreted using a selective exposure theory perspective. Generally, the present study suggests that a general predisposition toward anger, hostility and aggression is the best, albeit small, predictor of who chooses to consume media violence.
Stationary self‐focusing of Gaussian electromagnetic beams in the ionosphere
Authors: Sodha Mahendra Singh , Sharma Ashutosh
Published: July 2006

The self‐focusing of a Gaussian electromagnetic beam in the ionosphere has been investigated in the paraxial approximation, when the wave frequency is much higher than the electron collision frequency and the electron cyclotron frequency; the radial redistribution of the electron/ion density on account of nonuniform Ohmic heating by the Gaussian beam is taken as the dominant self‐focusing mechanism. Using the energy balance equation (considering the solar radiation) and the available database for the midlatitude daytime ionosphere, the irradiance, corresponding to different values of the electron temperature has been evaluated. A curve fit yields (at a given height) a relatively simple analytical representation of the electron temperature as a function of irradiance. This expression has been used to obtain an analytical equation for the critical curve (the relation between initial beam width versus initial axial irradiance for propagation without change in beam width). It is seen that the critical curve has two humps, which implies that there may be none, one, two, three, or four values of critical axial irradiance, corresponding to a given beam width; such a possibility has not been pointed out before. The beam width–beam power plane may be divided into three regions, corresponding to self‐focusing, oscillatory divergence, and steady divergence of the beam. The dependence of the beam width parameter on the distance of propagation has been obtained for three typical points in the three regions. The numerical results correspond to horizontal propagation at a height of 150 km in the daytime midlatitude ionosphere for the wave frequency ω = 5 × 107 s−1 and duration less than the electron concentration relaxation time, during which the electron density remains almost unaffected by the enhanced electron temperature.
Atmospheric dynamics over northwest Africa and linkages with Sahelian rainfall
Authors: Tourre Yves M. , Paz Shlomit , Cassou Christophe , Kutiel Haim
Published: July 2006

The variability of sea level pressure (SLP) anomalies over Northwest Africa (NA) that is, one of the two poles of the NAWA index identified by Paz et al. (2003), and its relationship with Sahelian summer rainfall is investigated during the 1950–1998 period. Significant positive linear correlations of 0.55 (0.60) are found first between spring (summer) SLP anomalies of the southernmost grid‐points of the NA pole and Sahelian summer rainfall of the same year. Moreover, by tracking the location of the center of the Azores anticyclone it is argued that the thickness of the Sahara/Sahel thermal low and the latitudinal position of the ITCZ during springtime, are important parameters/predictors modulating ensuing Sahelian precipitation on different time‐scales. Other factors such as natural penta‐decadal climate variability, local increase in greenhouse gases concentrations, and sea surface temperature or neighboring oceans might modify global SLP fields and contribute as well to low‐frequency Sahelian summer rainfall variability.