bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimized 1D double quantum filter NMR experiments
Authors: Ramesh V. , Chandrakumar N.
Published: July 2006

We propose and demonstrate a 1D pulse sequence to convert double quantum coherence (DQC) of y phase with optimal efficiency, relying on single transition selection. Our sequence has a larger high‐sensitivity bandwidth with respect to the coupling, compared to other reconversion strategies. A modified version of the new pulse sequence provides the missing chemical shift and coupling information, at minor cost in sensitivity. Application to 1D 13C INADEQUATE is demonstrated.

Our new sequence is also applied to quadrupole coupled spin‐1 systems, such as 2H in lyotropic phase. Performance of the sequence may be fine‐tuned by pulse flip angle optimization, taking into account relaxation effects. Copyright © 2006 John Wiley & Sons, Ltd.
Millions of missing girls: from fetal sexing to high technology sex selection in India
Authors: George Sabu M.
Published: July 2006

The morality and acceptability of using prenatal diagnosis for sex selection is being extensively debated around the world as advances in assisted reproductive technologies (ART) and embryology have enabled selective implantation of embryos of the desired sex (George and Dahiya, 1998; Savulescu, 1999; Raphael, 2002; Harris, 2005; Robertson, 2005; Snider, 2005). Sophisticated methods of separation of semen, originally developed for cattle breeding, are being used for human sex selection. Recently, non‐invasive methods of fetal sex determination in the first trimester (from 6 weeks) of pregnancy have also emerged (Hahn and Chitty, 2005). Market forces that promote sex selection along with libertarian ideologues have assisted in blurring the ethical limits (Paul, 2001; President's Council on Bioethics, 2003). The widespread misuse of sex selection for eliminating girls before birth in India and among the Indian diaspora needs to be brought into the global ‘intellectual discourse’. It is imperative that Western ethicists recognize the genocidal nature of sex selection taking place in certain Asian countries. Even if they believe that these trends will not affect mainstream Western societies, the promotion or tolerance of sex selection amounts to a ‘crime of silence’ against this ongoing genocide in China and India. I have been concerned with issues of the girl child in India for over two decades and sex selection among Asian Indians in North America (George et al., 1992; George et al., 1993; George and Dahiya, 1998). This article examines the missing millions of girls, but will not consider the 1980s campaign against fetal sex determination, Indian feminists' recognition of sex selection as violence against women (unlike several Western feminists, Moazam, 2004), or the Government's response to regulate prenatal diagnostic techniques in 1994 (George and Dahiya, 1998; George, 2002). Copyright © 2006 John Wiley & Sons, Ltd.
Crystallization and melting of polyethylene copolymers: Differential scanning calorimetry and atomic force microscopy studies
Authors: Mirabella Francis M.
Published: July 2006

The Hoffman–Lauritzen theory of secondary, surface nucleation and growth was primarily relied upon for about 40 years after its introduction in about 1960 to rationalize the crystallization of flexible chain polymers into lamellar crystals. However, in about 1998, Strobl and coworkers introduced a different model for crystallization, based on the stage‐wise formation of lamellae. Two major components of this model were as follows: (1) the concept of the formation of a mesomorphic melt as a precursor to crystallization and (2) the control of the melting temperature range of lamellar crystals of homogeneous polyolefin copolymers by an inner degree of order or perfection rather than on the crystal thickness. The first concept is in disagreement with the HL theory and the second with the Gibbs‐Thomson theory, which associates melting temperature with lamella thickness. In the present study, differential scanning calorimetry and atomic force microscopy were successfully employed to monitor thein situquiescent crystallization of polyethylene homopolymer and copolymer. In the present study, evidence was not found to support the concept of lamellae with equal thickness melting over a broad temperature range. Some evidence was found that might be interpreted to support the concept of a mesomorphic melt as a precursor to crystallization. At present, the model promoted by Strobl and coworkers appears to be at an uncertain stage at which strong proof or disproof are not available. However, this alternative model has injected a new vitality into the study of crystallization of flexible chain polymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2369–2388, 2006
Objective and subjective stressors and the psychological adjustment of melanoma survivors
Authors: Hamama‐Raz Y. , Solomon Z. , Schachter J. , Azizi E.
Published: July 2006

This study of 300 melanoma survivors examines the relative contributions of objective illness‐related factors (stage of illness at diagnosis, time since diagnosis, and change in physical condition) and of subjective factors (cognitive appraisal) to their psychological adjustment. The findings show that lower appraisal of their situation as a threat, higher appraisal of it as a challenge, and higher appraisal of their subjective ability to cope with it all increased their well‐being, while lower threat appraisal and higher appraisal of subjective ability to cope also reduced their distress. These findings, which are consistent with Lazarus and Folkman's stress coping theory, suggest that subjective factors may be more important than objective medical factors in predicting patients' adjustment. With this, more advanced stage at diagnosis contributed to reducing distress, while being married contributed both to higher well‐being and reduced distress. Copyright © 2006 John Wiley & Sons, Ltd.
Late Quaternary glacio- and Hydro-Isostasy, on a Layered Earth
Authors: Chappell J.
Published: July 2006

Isostatic response of the Earth to changes in Quaternary Times of ice and water loads is partly elastic, and partly involves viscous mantle flow. The relaxation spectrum of the Earth, critical for estimation of the mantle flow component, is estimated from published determinations of Fennoscandian and Laurentide rebound, and of the nontidal acceleration of the Earth's rotation. The spectrum is consistent with an asthenosphere viscosity around 1021P, and a viscosity around 1023P below 400 km depth. Calculation of relaxation effects is done by convoluting the load history with the response function in spherical harmonics for global effects, and in rectangular or cylindrical transforms for smaller regional effects. Broad-scale deformation of the globe, resulting from the last deglaciation and sea level rise, is calculated to have involved an average depression of ocean basins of about 8 m, and mean upward movement of continents of about 16 m, relative to the center of the Earth, in the last 7000 yr. Deflection in the ocean margin “hinge zone” varies with continental shelf geometry and rigidity of the underlying lithosphere: predictions are made for different model cases. The computational methods is checked by predicting Fennoscandian and Laurentide postglacial warping, from published estimates of icecap histories, with good results. The depth variations of shorelines formed around 17,000 BP (e.g., North America, 90–130 m; Australia, 130–170 m), are largely explainable in terms of combined elastic and relaxation isostasy. Differences between Holocene eustatic records from oceanic islands (Micronesia, Bermuda), and continental coasts (eastern North America, Australia), are largely but not entirely explained in the same terms.
Man's Interaction with Holocene Environments on the Plains
Authors: Frison George C.
Published: July 2006

The Northwestern Plains provide evidence of human occupation from Clovis times. The human groups involved were not spectacular and operated at the band level as hunters and gatherers. Changes in climate during the Altithermal Period may have caused some shifts in animal populations as a result of aridity with concomitant shifts in human occupations. The human groups were not adapted to storage of large quantities of food and as a result were operating in close harmony with the environment. Interdisciplinary efforts are needed to further resolve the past activities of human groups on the Plains.
The Contemporary Distribution of Pollen in Eastern North America: A Comparison with the Vegetation
Authors: Davis Ronald B. , Webb Thompson
Published: July 2006

By mapping and summarizing 478 pollen counts from surface samples at 406 locations in eastern North America, this study documents the relationships between the distributions of pollen and vegetation on a continental scale. The most common pollen types in this region are pine, birch, oak, and spruce. Maps showing isopercentage contours or isopolls for 13 important pollen types reflect the general N-S zonation of the vegetation. The maps and tabulations of average pollen spectra for the six major vegetational regions indicate high values for the following pollen types in each region: (1) tundra-nonarboreal birch, sedge, and alder; (2) forest/tundra-spruce, nonarboreal birch and alder; (3) boreal forest-spruce, jack pine (type), and arboreal birch with fir in the southeastern part; (4) conifer/hardwood forest-white pine, arboreal birch, and hemlock with beech, maple, and oak in the southern part; (5) deciduous forest-oak, pine, hickory, and elm, with beech and maple in the northern part, and highest values of oak and hickory west of the Appalachian crest; and (6) southeastern forest-pine, oak, hickory, tupelo, and Myricaceae. In some cases, less abundant pollen types are diagnostic for the region, e.g., bald cypress in the southeast. In the conifer-hardwood region and southward, pollen of weeds associated with deforestation and agriculture is abundant. The maps also show that much of southeastern U.S. and the area just to the east of Hudson Bay are in need of additional sampling. At 51 of the sites, absolute pollen frequencies (APF; grains/ml lake sediment) were obtained. These confirm the major conclusions from the percentage data, but differences are evident, e.g., the percentages of alder pollen peak in the tundra whereas alder APFs peak in the boreal forest, and spruce percentages peak in the forest-tundra whereas spruce APFs peak in the boreal forest. Because the APF data reflect the patterns of absolute abundance of individual taxa in the vegetation as well as the overall forest densities, future counts of modern pollen should include APF determinations. The effects of sedimentation processes on APF quantities indicate that APF samples should be obtained from moderate size lakes of similar morphology and hydrology and that, in each lake, several samples from the profundal zone should be pooled to create a sample representative of that lake.
Effects of Holocene Climatic Change on some Tropical Geomorphic Processes
Authors: Fairbridge Rhodes W.
Published: July 2006

Man's interference with the landscape process places him in the role of a “paraglacial” agent: He tends to duplicate ice-age stresses such as deforestation, accelerated erosion, and climate alteration. Against a background climatic control dictated by the Milankovich mechanisms, the 10,000-year history of the Holocene has seen very large secondary modulations that must be better understood so that they may be distinguished from anthropogenic effects. If they are exogenetically controlled, as it seems, then they are probably predictable from astronomic data. Four geomorphic type areas are selected for demonstrating Holocene changes in tropical regions, because they have been somewhat neglected within the framework of Quaternary science and because they include some of the most fragile and easily disrupted environments: lakes, semiarid desert margins, coastlines, and coral reefs. In a nutshell, the tropical Holocene has seen three major changes: (a) the evolution from the hyperaridity of the last pleniglacial stage to the “postglacial pluvial”; (b) the “climatic optimum,” which was highly diachronous and strongly retarded as it shifted from low latitudes to high; (c) the postoptimum “deterioration” that has involved desiccation of lakes, readvances of the deserts, fall of sea level, and truncation of coral reefs. While this deterioration is predictable in terms of an interglacial-glacial climatic transition, strong natural climatic oscillations, not yet well understood, together with man's activities, make the future a cause for concern.
Holocene Glacial and Tree-Line Variations in the White River Valley and Skolai Pass, Alaska and Yukon Territory
Authors: Denton George H. , Karlén Wibjörn
Published: July 2006

Complex glacier and tree-line fluctuations in the White River valley on the northern flank of the St. Elias and Wrangell Mountains in southern Alaska and Yukon Territory are recognized by detailed moraine maps and drift stratigraphy, and are dated by dendrochronology, lichenometry,14C ages, and stratigraphic relations of drift to the eastern (123014C yr BP) and northern (198014C yr BP) lobes of the White River Ash. The results show two major intervals of expansion, one concurrent with the well-known and widespread Little Ice Age and the other dated between 2900 and 210014C yr BP, with a culmination about 2600 and 280014C yr BP. Here, the ages of Little Ice Age moraines suggest fluctuating glacier expansion between ad 1500 and the early 20th century. Much of the 20th century has experienced glacier recession, but probably it would be premature to declare the Little Ice Age over. The complex moraine systems of the older expansion interval lie immediately downvalley from Little Ice Age moraines, suggesting that the two expansion intervals represent similar events in the Holocene, and hence that the Little Ice Age is not unique. Another very short-lived advance occurred about 1230 to 105014C yr BP. Spruce immigrated into the valley to a minimum altitude of 3500 ft (1067 m), about 600 ft (183 m) below the current spruce tree line of 4100 ft (1250 m), at least by 802014C yr BP. Subsequent intervals of high tree line were in accord with glacier recession; in fact, several spruce-wood deposits above current tree line occur bedded between Holocene tills. High deposits of fossil wood range up to 76 m above present tree line and are dated at about 5250, 3600 to 3000, and 2100 to 123014C yr BP. St. Elias glacial and tree-line fluctuations, which probably are controlled predominantly by summer temperature and by length of the growing and ablation seasons, correlate closely with a detailed Holocene tree-ring curve from California, suggesting a degree of synchronism of Holocene summer-temperature changes between the two areas. This synchronism is strengthened by comparison with the glacier record from British Columbia and Mt. Rainier. Likewise, broad synchronism of Holocene events exists across the Arctic between the St. Elias Mountains and Swedish Lappland. Finally, two sequences from the Southern Hemisphere show similar records, in so far as dating allows. Hence, we believe that a preliminary case can be made for broad synchronism of Holocene climatic fluctuations in several regions, although further data are needed and several areas, particularly Colorado and Baffin Island, show major differences in the regional pattern.
Late-Pleistocene and Holocene Remains of Hysterocarpus traski (Tule Perch) from Clear Lake, California, and Inferred Holocene Temperature Fluctuations
Authors: Casteel Richard W. , Adam David P. , Sims John D.
Published: July 2006

The remains of scales of Hysterocarpus traski Gibbons (Tule perch) were found throughout a 27.44-m core from Clear Lake. Most scales occurred between the mud surface and deposits approximately 11,000 years old. Changes in growth rates of the animals were examined by measuring scale annuli and applying an empirically established regression of fish length on scale radius. The data indicate a pattern of accelerating growth rates, reaching a peak between ⋍4000 and 2800 BP. After ⋍2800 BP, growth rates decline markedly. Because the growth rates of these animals are essentially dependent on temperature, the changes observed in the patterns of growth probably reflect changes in climate in the northern Coast Range. The general pattern of inferred temperature increase during the early and middle Holocene, ending between ⋍4000 and 2800 BP, is consistent with evidence from tree-line studies and palynology indicating higher temperatures in parts of the western United States during this period.
Polygonal Patterned Ground in Central New Jersey
Authors: Walters James C.
Published: July 2006

Polygonal patterned ground and associated sediment-filled wedges occur in thin-bedded shale in central New Jersey. During a dry growing season, numerous areas of polygonal ground were visible owing to differential growth of vegetation over the sediment-filled fractures. Construction sites where material was removed from the surface prior to excavation also revealed areas of polygonal ground. Measurements of the patterns show networks of polygons with diameters ranging from about 3 m to over 30 m, with an average of approximately 20 m. The wedges examined in vertical exposures range in depth from 25 to 260 cm (average, 125 cm) and in width from 10 to 240 cm (average, 50 cm). The infilling material of the wedges is mostly a sandy loam, although this material is not homogeneous throughout the wedges. The presence of ventifacts and frosted sand grains within the wedges indicates eolian activity during the formation of these features. The polygonal ground and wedge structures exhibit several characteristics similar to those of ice-wedge casts, and available evidence suggests they may have originated as ice-wedge polygons during the last glacial maximum.
Environmental Changes During the Past 2000 Years in North-Central Wisconsin: Analysis of Pollen, Charcoal, and Seeds from Varved Lake Sediments
Authors: Swain Albert M.
Published: July 2006

A 2000-year accumulation of varved sediments from Hell's Kitchen Lake in north-central Wisconsin was analyzed for pollen, charcoal, and seeds. The varves provided an accurate time scale for the study. The pollen record indicates changes on two different time scales. Short-term changes lasting several decades appear to be superimposed on long-term changes lasting several centuries. The short-term changes are related to individual fires, and the long-term changes result from increases or decreases in the frequency of these perturbations. From 2000 to 1150 years ago the average interval between fires was about 100 years, and from 1150 to 120 years ago the interval increased to about 140 years. Evidence from pollen, seeds, and charcoal at Hell's Kitchen Lake suggests that at least two “moist” intervals occurred during the past 2000 years, one between 2000 and 1700 years ago and the other between 600 and 100 years ago. A third but minor “moist” period occurred about 1150 to 850 years ago. A pollen and seed diagram shows that these intervals are characterized by increased percentages of white pine pollen, hemlock pollen, and yellow birch seeds, and by decreased levels of charcoal. The “dry” interval of 1700 to 1150 years ago is characterized by increased percentages of paper birch seeds, oak pollen, and aspen pollen, along with high levels of charcoal. The times of climatic change indicated at Hell's Kitchen Lake are nearly synchronous with those based on studies of tree rings, soils, glacial activity, and other pollen studies from various regions of North America, but the direction of these inferred changes is not always the same. This result suggests that the long-wave pattern of the general circulation has been variable during the past 2000 years.
Changing Patterns in the Late Pleistocene/Early Holocene Prehistory of Southern Africa as Seen from the Nelson Bay Cave Stone Artifact Sequence
Authors: Deacon Janette
Published: July 2006

The dating of the Stone Age sequence in southern Africa has been considerably revised over the last decade, and one of the anomalies which has resulted is that the Middle Stone Age, now dated to beyond 30,000 B.P., does not immediately precede the Later Stone Agesensu stricto. The excavation and analysis of occupation horizons dating between the most recent Middle Stone Age assemblages and the Holocene is therefore of particular interest. Nelson Bay Cave, situated on the southern coast of South Africa, contains deposits which partly fill the “gap” between the Middle and Later Stone Ages, and the occupation horizons dating between about 18,000 and 5000 years ago are described in this paper. Changes in the habitat in the vicinity of the site caused by sea-level and vegetation changes coincident with the amelioration of temperatures at the end of the Pleistocene are clearly marked in the faunal remains at the site. Largely correlated with the faunal changes (which includes the introduction of marine resources to the cave at about 12,000 B.P.) are changes in the stone artifact assemblages. Three industries are recognized in the sequence: the Robberg, characterized by microbladelets produced from bladelet cores and a few small scrapers and backed tools; the Albany, characterized by large scrapers and an absence of backed tools; and the Wilton, characterized by a variety of Formal Tools including relatively large numbers of small scrapers and backed tools. These changes in artifact-manufacturing traditions are interpreted as signaling adjustments to changing environmental conditions. An explanation for these adjustments is not sought in a simple cause-and-effect relationship between the environment and the cultural response; artifact changes are seen instead as the result of a twofold process, with the environment acting as an external stimulus to change, and the direction of the artifact change governed by the selection of a range of possibilities offered by the technology of the Later Stone Agesensu latothat was widespread in subequatorial Africa during the last 20,000 years.
A Method for Quantitative Evaluation of Carbonate Dissolution in Deep-Sea Sediments and its Application to Paleoceanographic Reconstruction
Authors: Ku Teh-Lung , Oba Tadamichi
Published: July 2006

A method is proposed by which the degree of attrition of the tests of certain foraminifera species, such asGloborotalia menardiiandGloborotalia tumida, is used to “scale” the amount of CaCO3that has been dissolved from sediment. The scale is calibrated experimentally in the laboratory. The method has been applied to three calcareous cores from the Pacific and the Indian Oceans. It is shown that the original CaCO3contents in these cores were high (82–95%) and relatively uniform compared to the present down-core values. About 65 to 85% of the originally deposited CaCO3has been dissolved, corresponding to dissolution rates on the order of 0.1-0.3 moles/cm2/yr. These results indicate that appreciable solution could have occurred on sea floor rich in calcareous sediments and that the variation in CaCO3content in a core may have resulted largely from dissolution. The difference in the degree of solution between glacial and interglacial sediments in these cores is not so distinct, with ⋍ 10% less intense dissolution during glacial times on the average. However, the dissolution minimum occurring around the late Wisconsin glaciation (10,000–20,000 yr B.P.) previously noted in several cores elsewhere is confirmed. At that time, near the site of core M70 PC-20 in the southwest Pacific, the CO32−concentration of the bottom water is estimated to have been approximately 5% higher than the present value, and the calcite lysocline was about 300 m deeper. To evaluate possible variations in CaCO3deposition rate across the glacial-interglacial transitions requires precise age control, which the present study lacks.
Uplift rates of the Loyalty Islands as Determined by 230Th/234U Dating of Raised Coral Terraces
Authors: Marshall John F. , Launay Jean
Published: July 2006

Uplift rates of the Loyalty Islands (S.W. Pacific) have been determined from 230Th/234U dating of raised coral terraces standing 2 to 7.5 m above sea level. The ages of the terraces on Ouvéa and Lifou correspond closely to previously documented periods of high sea levels at 120,000 and 180,000 yr BP. A +2-m terrace on Beautemps-Beaupré is considered to be beyond the range of the dating technique. The uplift rates of the various islands show a decrease toward the west. This lends support to the hypothesis of a lithospheric bulge of the leading edge of the Australian plate prior to its subduction at the level of the New Hebrides trench.
Aspartic Acid Racemization in Late Wisconsin Lake Ontario Sediments
Authors: Schroeder Roy Allen , Bada Jeffrey L.
Published: July 2006

We have determined aspartic acid racemization and [14C] ages in sediment from a 17-m piston core recovered from Lake Ontario. This core represents a depositional record extending back into the Late Wisconsin. Total organic radiocarbon ages of the glaciolacustrine lower section of the core are older than the true depositional age. Hence we suggest that these ages do not represent time elapsed since deposition but rather may be up to several thousand years too old due to mixing with 14C-depleted organic matter and possibly also D-amino acids contained by the glacier and deposited as the glacier receded. Further studies are suggested that might test this hypothesis as well as establish the general applicability of racemization dating to clay sediments.
Late Pleistocene Glacial Chronology of the Taylor Valley, Antarctica, and the Global Climate
Authors: Hendy C. H. , Healy T. R. , Rayner E. M. , Shaw J. , Wilson A. T.
Published: July 2006

Carbonate-rich lacustrine and deltaic deposits, containing thin beds of finely laminated carbonates and thick beds of silt, crop out at several sites in the Taylor Valley and have been encountered in cores obtained by the Dry Valley Drilling Project (DVDP). Fragments of the more indurated carbonate beds have widespread occurrence as part of the desert “lag gravel” which covers much of the valley floor. Analysis of the carbonates suggests that they were deposited as algal limestones from waters derived from the East Antarctic Ice Sheet via the Taylor Glacier at times which correspond to the previous three global interglacial periods, as evidenced by the ice volumes deduced from oxygen-isotopic analysis of oceanic cores. The lacustrine carbonates have been found up to 30 km beyond the present terminus of the Taylor Glacier, and up to 100 m above the level of Lake Bonney, into which the Taylor Glacier at present discharges. It is concluded that the Taylor Glacier has advanced during each of the previous three interglaciations, and it is suggested that this has been caused by a thickening of the East Antarctic Ice Sheet during the interglaciations.
Water Balance of Britain, 50,000 yr B.P. to the Present Day
Authors: Lockwood John G.
Published: July 2006

Estimates made of lowland precipitation and evaporation in Britain during the last (Devensian) glaciation suggest that during the cold periods of the Devensian precipitation was probably low, between 260 and 370 mm/thermal maximum of the Upton Warren Interstadial lowland precipitation was probably in the range 450 to 650 mm/year. Two summer precipitation regimes are identified during the cold periods, one with high values and the other with low. The high summer precipitation variant leads to moist conditions with July and August precipitation values similar to those at the present day, and global circulation models suggest that the moist regime may have existed at the time of the maximum advance of the ice sheets. On the other hand, the low summer precipitation variant leads to a dry summer with wind action creating aeolian deposits, and this variant probably existed at earlier times in the glacial period. About 6500 yr B.P., in the Atlantic period, forest conditions probably caused increased evaporation which more than compensated for the increased precipitation of the time, causing low runoff conditions. The clearance of British forests by man since 6500 yr B.P. has probably led to an absolute increase in runoff values even though precipitation values have fallen.
Testing a Simulation Model for Reconstruction of Prehistoric Forest-Stand Dynamics
Authors: Solomon Allen M. , Delcourt Hazel R. , West Darrell C. , Blasing T. J.
Published: July 2006

Three characteristics of the output of a forest-stand simulation model were matched to pollen records of actual vegetation in central Tennessee. Temporal shifts of individual pollen taxon frequencies were compared to shifts of individual plant species frequencies in simulated biomass for the last 16,000 yr. Individual pollen profiles (temporally ordered species frequencies) were also compared to simulated biomass profiles during that period. Modern ratios of pollen to vegetation composition (Rvalues) were compared with those calculated from simulated biomass percentages and fossil pollen percentages. The model output was similar to the comparable characteristics of the pollen record. The model output is therefore a plausible description of vegetation characteristics at the site of pollen deposition in central Tennessee. The model produced information unavailable from other sets of prehistoric data. This information describes the invasion and growth of the yellow-poplar which produces no windborne pollen, and of palynologically indistinguishable oak and pine species. These results suggest that many paleoecological questions can be answered through appropriate simulation modeling studies.
Holocene Variations of Monsoon Rainfall in Rajasthan
Authors: Bryson R. A. , Swain A. M.
Published: July 2006

Two reconstructed histories of the monsoon rainfall in Rajasthan show that the monsoon was weak or absent in latest glacial time. With the advent of Holocene climatic patterns, fresh water lakes formed in dune fields and the pollen rain preserved in these reservoirs provides a basis for the reconstruction of the monsoon history. The two reconstructions, separated by only 150 km, have some features in common and some striking differences. Both show maximum monsoon amounts in the early Holocene, with a roughly two-thirds decrease to the present. Both show salinization in sub-Boreal time. Both show long intervals of near complete desiccation in the last four millennia. The shorter term variations, however, are not closely parallel. These shorter term variations may be explained in terms of the behavior of the present day interannual variability.
Holocene Changes in Tropical Wind Intensity and Rainfall: Evidence from Southeast Ghana
Authors: Talbot M. R.
Published: July 2006

Remnants of a fixed aeolian dune ridge occur along the southeast coast of Ghana, just behind the present shoreline. Aeolian sands also cover extensive areas of the Accra Plains. No dunes are present here, the sands mainly occurring as sheets which blanket an early Holocene landscape. The sediments are of mid-Holocene age and were deposited during the interval 4500 B.P.–3800 yr B.P., when the southwesterly winds were stronger than they are at present and much of tropical Africa seems to have been subject to marked aridity. The onset of drier, windier conditions around 4500 yr B.P. brought to an end the more equable climates than had characterized much of West Africa during the earlier Holocene. Aridity, intensified winds, and desert expansion between 4500 and 3800 yr B.P. parallel environmental conditions in tropical continental areas at the height of the Late Pleistocene glaciation.
A Record of Late Quaternary Vegetation from Davis Lake, Southern Puget Lowland, Washington
Authors: Barnosky Cathy W.
Published: July 2006

Pollen and macrofossil analyses of a core spanning 26,000 yr from Davis Lake reveal late Pleistocene and Holocene vegetational patterns in the Puget Lowland. The core ranges lithologically from a basal inorganic clay to a detritus gyttja to an upper fibrous peat and includes eight tephra units. The late Pleistocene pollen sequence records two intervals of tundra-parkland vegetation. The earlier of these has high percentages ofPicea, Gramineae, andArtemisiapollen and represents the vegetation during the Evans Creek Stade (Fraser Glaciation) (ca. 25,000–17,000 yr B.P.). The later parkland interval is dominated byPicea, Tsuga mertensiana, and Gramineae. It corresponds to the maximum ice advance in the Puget Lowland during the Vashon Stade (Fraser Glaciation) (ca. 14,000 yr B.P.). An increase inPinus ontortapollen between the two tundra-parkland intervals suggests a temporary rise in treeline during an unnamed interstade. After 13,500 yr B.P., a mixed woodland of subalpine and lowland conifers grew at Davis Lake during a period of rapid climatic amelioration. In the early Holocene, the prolonged expansion ofPseudotsugaandAlnuswoodland suggests dry, temperate conditions similar to those of present rainshadow sites in the Puget Lowland. More-mesic forests ofTsuga eterophylla, Thuja plicata, andPseudotsuga, similar to present lowland vegetation, appeared in the late Holocene (ca. 5500 yr B.P.).
Contribution de l'étude exoscopique des quartz à la reconstitution paléogéographique des derniers épisodes du Quaternaire littoral du Congo
Authors: Giresse Pierre , le Ribault Loïc
Published: July 2006

The paleogeographic and particularly palaeoclimatic evolution in the Congo at the end of the Quatemary has been investigated thoroughly with a study of grain surfaces using the scanning electron microscope. The succession of distinct physicochemical environment marks is characterized with the help of other methods (radiocarbon, micropaleontology). During a still-existing tropical climate, arid periods are contemporaneous with regressive phases (eolian, fluviatile, or pedogenetic reliefs of the grains) and humid periods correspond to transgressive phases (infratidal, Intertidal, deltaic, lagoonal marks).
Vegetation and Climate during the Last Glacial Maximum in Japan
Authors: Tsukada Matsuo
Published: July 2006

The Japanese Archipelago was almost entirely covered by coniferous forests during the last glacial maximum. Northern Hokkaido was distinguished by coniferous parkland and tundra vegetation, while southern Hokkaido and northernmost Honshu were covered by northern boreal coniferous forests consisting mainly of Picea jezoensis, Picea glehnii, Abies sachalinensis, and Larix gmelinii; Tsuga was missing from the forest. More diverse boreal forests including species from Sakhalin and northern Japan grew together in northeastern Honshu. Central Honshu and the mountains of southwestern Japan supported subalpine coniferous forests which are now mainly restricted in distribution to the central mountains. Temperate coniferous forests (Picea polita, Abies firma, and Tsuga sieboldii) existed principally in the modern mid-temperate and evergreen laurel-oak forest regions. Haploxylon pine and tree birch were also abundant in the boreal and cool-temperate zones, as was Diploxylon in the southern temperate zone. Significant populations of Fagus were found along the Pacific coasts of Kyushu and Shikoku, but they were too small to be defined as a beech forest zone. Quercetum mixtum (Quercus, Ulmus, and Tilia) was more common in the coastal lowlands of southwestern Japan than those of northeastern Honshu; it was completely eliminated from Hokkaido. The reduced mean August temperature inferred from the floral assemblages showed a latitudinal gradient 20,000 yr ago; it was 8–9°C in northern Hokkaido, 7.7–8.7°C in northernmost Honshu, 7.2–8.4°C in the central mountains, 6.5°C in the Chugoku District, and 5–6°C in Kyushu. The probable annual precipitation ranged from 1050 to 1300 mm along coasts in southwestern Japan during the culmination of the last glaciation.
Radiocarbon dating of Danube Delta Deposits
Authors: Panin Nicolae , Panin Stefana , Herz Norman , Noakes John E.
Published: July 2006

The Holocene history of the Danube Delta has been studied using 14C analyses of faunal material. The principal phases of development include: (1) initial Letea Caroarman spit, 11,700–9800 yr B.P. in its central part, 8800-5500 yr B.P. in its southern part; (2) Sf. Gheorghe I Delta, 8900-7200 yr B.P.; (3) Sulina Delta, 7200-2000 yr B.P., and (4) Sf. Gheorghe II Delta-Chilia Delta 2000 yr B.P.-present. Other smaller-scale features have also been dated, including secondary deltas (Coşna and Sinoe Deltas) and littoral bars. Age determinations carried out on whole samples were erratic and it was found that individual species had to be separated and dated. In all cases, the older dates were of transported material whereas the younger dates gave the true age of the formation.
Late Weichselian Environmental History in Southeastern Sweden during the Deglaciation of the Scandinavian Ice Sheet
Authors: Björck Svante , Möller Per
Published: July 2006

Late Weichselian litho-, bio-, and chronostratigraphy (14C and varves) in southeastern Sweden provide a detailed picture of the deglaciation pattern and dynamics, shore displacement, late-glacial sedimentation, and history of the landscape, vegetation, and climate. Two plausible glacial models were tested against lithologic, chronologic, and climatic data. Permafrost at and outside the ice margin and topographic conditions beneath the ice apparently caused inward spread of frozen glacier-bed conditions. This led to a buildup of a large zone of debris-rich basal ice. A climatic amelioration about 12,700 yr B.P. changed the temperature profile in the ice sheet. Deposition of basal melt-out till began at the previously frozen glacier bed, and a rapid recession of the clean ice set in; thin exposed debris-rich basal ice which was separated from the active ice margin about 150 yr later. In this zone of stagnant ice there followed a 200– 300-yr period marked by subglacial and supraglacial melt-out and resedimentation, forming a large hummocky/transverse moraine. The mild climate favored rapid plant immigration, and a park-tundra was established. The gradual closing of the landscape was interrupted by a 100- to 150-yr period of tundra vegetation and a cool, dry climate, with local vegetational differences caused by differences in soil moisture. About 12,000 yr B.P. a second climatic amelioration set in, and during the next 1000 yr a birch (and pine) woodland gradually developed. Soils stabilized andEmpetrumheaths became abundant as the climate gradually deteriorated at the end of this period. By 11,000 yr B.P. the area had become a tundra again with scattered birch stands, dominated by herbs such asArtemisia, Chenopodiaceae, grasses, and sedges. Some 500 yr later a birch/pine woodland again succeeded, and within about 500 yr the vegetation changed to a rather closed woodland as the climate ameliorated further. However, the time lag between climatic and vegetation change was considerable.
Systematics, Phylogenetic Relationships, and Dispersal of the Chamois (Rupicapra spp.)
Authors: Masini Federico , Lovari Sandro
Published: July 2006

The Rupicaprini originated during the Miocene in Asia and dispersed during the late Miocene-early Pliocene, the Villafranchian, and the middle Pleistocene. Rupicapra and Oreamnos spread respectively to Europe and to North America in the middle Pleistocene. The Villafranchian Procamptoceras may be considered to be the closest known form to Rupicapra's ancestor. Rupicapra evolved during the middle and late Pleistocene in west Eurasia. At the beginning of the Würm glaciation the two closely related species R. pyrenaica and R. rupicapra were in existence. The former was already geographically split into Spanish-Pyrenean and central-southern Apennines groups, while the latter species ranged from the Caucasus to the Alpine Arch. R. pyrenaica shows more conservative features and possibly differentiated directly in western Europe from older representatives of the genus that migrated to western Europe in the middle Pleistocene. The cold-adapted Alpine chamois may have differentiated in eastern Europe and then migrated west-ward because of the advent of dry climates in the east Mediterranean and Pontic regions. The Alpine chamois failed to spread to the warmer southernmost regions of Europe that became a refugium area for R. pyrenaica. This dispersal hypothesis explains the morphologic, biometric, electrophoretic, and behavioral differences among modern chamois populations.
Late Quaternary Evolution of the Northern Aegean Shelf
Authors: Perissoratis C. , Mitropoulos D.
Published: July 2006

A dense network of 3.5 kHz and Uniboom seismic profiles revealed the geological evolution of the Ierissos-Alexandroupolis Shelf area of the northern Aegean during the latest sea-level rise. Near the end of the Pleistocene, ca. 14,000 yr B.P., the sea was at about − 120 m, and almost 5300 km2 of shelf was exposed to subaerial erosion. Two permanet lakes existed in the Ierissos and Kavalla Gulfs, as well as a number of ephemeral lakes scattered throughout the rest of the area. Kavalla Gulf was drained by the Nestos River which joined the Strymon River at the outer Strymonikos Plateau. On the flat Samothraki Plateau were dune fields, marshes, and a number of minor seasonal rivers, while the Evros River flowed east of the plateau. By ca. 13,000 yr B.P. the sea had risen to − 70 m and covered 30% of the previously exposed shelf. The lakes at Ierissos and Strymonikos Gulfs were shallower and the sea approached to within about 5 km of them. Kavalla Gulf and the adjacent eastern Strymonikos Plateau lay 10 m above sea level, while the sea intruded along river mouths at the Samothraki Plateau. During this transgression of the sea river-bed gravels and sands were covered by silts and clays. At the Pleistocene-Holocene transition, ca. 10,500 yr B.P., the sea lay at about − 50 m and in areas of steep slope the coast was close to its present position. At Kavalla Gulf, the sea advanced along the paleochannel of the Nestos River, and the island of Samothraki was separated from the mainland. By ca. 7500 yr B.P. the sea was only 15 m below its present level and the northeastern Aegean shelf assumed nearly its present morphology. The Nestos River changed course to the east and Thassos Island was separated from the mainland. Coarse sediment formed wedges nearshore, whereas fine-grained sediments were distributed widely by current action. In many areas, relict sediments are present.
Radiocarbon Dates on Deglaciation, Cordillera Central, Northern Peruvian Andes
Authors: Birkeland P.W. , Rodbell D.T. , Short S.K.
Published: July 2006

Three radiocarbon dates along with relative-dating criteria place limits on the deglaciation history of Manachaque Valley, Cordillera Central. Ice retreated from the late-glacial maximum by at least 12,100 yr B.P. During ice retreat numerous moraines were deposited throughout the valley. Glacier cover was reduced to about half that of the last glacial maximum by at least 9700 yr B.P. and to less than a tenth by at least 6450 yr B.P. Because all dates are minimum, the dates and field data are consistent with little or no ice remaining by early Holocene. No unambiguous Younger Dryas moraines are present.
The Late Pleistocene Laurentide Glacier: Th/U Dating of its Major Fluctuations and δ18O Range of the Ice
Authors: Hillaire-Marcel Claude , Causse Christiane
Published: July 2006

Direct information on the isotopic composition and timing of the now-vanished Laurentide glacier can be found in subglacial calcite or in early diagenetic concretions from glaciolacustrine deposits. Th/U isotopic measurements on early diagenetic concretions frome Lake Deschaillons varves (St. Lawrence Lowland, Québec) date the early Wisconsinan major ice advance at ca. 80,000 yr (isotopic stage 5a/4 transition). Significant retreat occurred at ca. 46,000 yr (isotopic stage 3) as indicated by Th/U isochrones on early diagenetic concretions from Lake Gayhurst varves in the Appalachian foothills of Québec. During the maximum extension of the ice, which is dated at ca. 22,000 yr by Th/U measurements on subglacial calcite at Cantley (northern margin of the St. Lawrence Lowland), δ18O values (vs PDB) ranging from −16/−19‰ (surficial ice) to ca. −30‰ (basal ice) are inferred for the Laurentide ice isotopic composition. Superimposition of two phases of carbonate precipitation does not prevent the establishment of their respective age and isotopic composition through correlation of independent parameters and calculation of mixing lines.
The Use of Total Lake-Surface Area as an Indicator of Climatic Change: Examples from the Lahontan Basin
Authors: Benson L.V. , Paillet F.L.
Published: July 2006

Variation in the size of lakes in the Lahontan basin is topographically constrained. River diversion also has played a major role in regulating lake size in Lahontan subbasins. The proper gage of lake response to change in the hydrologic balance is neither lake depth (level) nor lake volume but instead lake-surface area. Normalization of surface area is necessary when comparing surface areas of lakes in basins having different topographies. To a first approximation, normalization can be accomplished by dividing the paleosurface area of a lake by its mean-historical, reconstructed surface area.
Quaternary Marine Transgressions and Paleoclimate in the Yangtze River Delta Region
Authors: Lin Jingxing , Zhang Shanlin , Qiu Jinbo , Wu Biaoyun , Huang Huanzhong , Huang Huizhen , Xi Jianguo , Tang Baogen , Cai Zuren , He Yubao
Published: July 2006

Eight marine transgressions have been recognized from more than 30 deep drill holes (ca. 300 m deep) through Quaternary sequences in the Yangtze River delta region. These are, in ascending order, the Rugao and Zhoupe transgressions (early Pleistocene); the Shanghai, Jiading, and Wangdian transgressions in the middle Pleistocene; the Jiangyin and Gehu transgressions in the late Pleistocene; and the Zhenjiang transgression in the Holocene. The transgressions correspond to warm periods and regressions to cold periods. The younger transgressions were not only of shorter duartion, but also of larger magnitude. The findings verify that there were five moderately warm periods during the early to middle Pleistocene and two very warm periods during the late Pleistocene in the Yangtze River delta region.
Dating Geomorphologic Surfaces Using Cosmogenic 3He
Authors: Cerling T. E.
Published: July 2006

Cosmogenically produced 3He in rocks can be used to date geomorphologic surfaces. Using the Late Pleistocene Bonneville flood event, the subsequent development of the Provo shoreline, and associated volcanic rocks, a production rate of 432 atoms/g/yr in olivine is determined for 38°56′ N latitude (present geomagnetic latitude 46.5°) at 1445 m altitude integrated over the last 14,400 years. Measurements of cosmogenic helium in flood deposits, on river-scoured surfaces, and lava flows show that it is possible to date directly large-scale events such as volcanic eruptions and catastrophic floods. Olivine and pyroxene are both satisfactory minerals for cosmogenic dating by the 3He method. However, in most cases, plagioclase and quartz are unsuitable because they do not quantitatively retain helium isotopes in their lattices.
Reconstruction of Past Erosional Force from Tree Ring Information around the Rokko Mountains, Japan
Authors: Kashiwaya Kenji , Okimura Takashi
Published: July 2006

Torrential rainfalls in the Rokko Mountains have often triggered severe landslides and debris flows, but few such phenomena have occurred in the area just to the north of the mountains during the same rainfall events. The periodicity of 25–30 years in excess rainfall data (i.e., the annual summation of heavy rainfall of more than 100 mm/day during the past 100 years) around the mountains correlates with the increased frequency of landslides and debris flows. Analyses of tree-ring widths that span the past 50–240 years in samples taken from various areas in the mountains and the area just to the north indicate that most sequences have a dominant periodicity of about 25–30 years, the ring series in the mountain areas having a more conspicuous periodicity than those from the area just to the north. These results lead to the conclusion that excess rainfall may provide a first approximation of erosional force in areas affected by slope movement, and that tree-ring width may be used as a proxy for erosional force.