bluuebunny/crossref_metadata_2025 huggingface dataset:
Sorption as a Factor in the Transport of Major Cations by Meltwaters from an Alpine Glacier
Authors: Lorrain R.D. , Souchez R.A.
Published: December 2004

In meltwater derived from the Moiry Glacier (Switzerland), sorption of major cations on suspended sediments can be a significant factor in chemical transport. In meq/100 g, especially for calcium and potassium, sorption on suspended particles is more important in the waters resulting from percolation through morainic deposits than in subglacial waters. Sorption of major cations should not be neglected, either in quantitative studies of chemical denudation or in studies related to the glacial melt-water environment.
Dynamics of the Ocean-Cryosphere System: Barbados Data
Authors: Matthews R.K.
Published: December 2004

Renewed development of the Laurentide and Scandinavian ice sheets would have large effects on global climate. By one model, growth of a new ice sheet would be slow and would begin with systematic and easily measurable changes in remote regions of Northeastern Canada. By another model, growth of a new ice sheet would begin rapidly with the development of thin ice cover over a large area. Clearly, immediate global impact would be much greater with the second model than with the first.

Because sea level fluctuations are the reciprocal of change in ice volume, interaction between Pleistocene coral reefs and sea level events provides an estimate of the dynamics of the ocean-cryosphere system. The data suggest rapid growth of continental sheets.
Fire in the Boreal Forest
Authors: Rowe J.S. , Scotter G.W.
Published: December 2004

The boreal forest in North America owes much of its floristic and faunistic diversity to periodic fires ignited by lightning and by man since he appeared on the scene. The indirect evidences of buring in vegetation and soils, and recent direct observations of fires, are reviewed. Fire is shown to exert a significant effect on vegetational composition, on soil chemical properties and thermal regime, and on animal populations through the particular mosaic of habitats created. In turn, fire is itselt influenced by the nature of geographic landscape ecosystems according to their surface forms, accumulations of organic materials, and susceptibility to drought. It is concluded that fire should be viewed as a normal ecological process in the boreal forest. A thorough understanding of its long-term role in terrestrial and aquatic ecosystems is needed.
Paleoclimatic Investigation of a Late Pleistocene Caribbean Deep-Sea Core: Comparison of Isotopic and Faunal Methods
Authors: Imbrie John , van Donk Jan , Kipp Nilva G.
Published: December 2004

A simplified and more accurate version of the quantitative paleoenvironmental method proposed by Imbrie and Kipp (1971) is described, which is based on untransformed rather than transformed species per cent data. The method yields faunal indices (Ts, Tw, S), useful both as objective measures of paleontological properties and as estimates of Pleistocene sea-surface summer and winter temperatures (Ts, Tw) and salinity (S). Similarly, the oxygen-isotope method yields objective measurements of δ O18, useful stratigraphically and as indications of past changes in isotopic water composition and temperature.

Laboratory errors of the two methods have about the same magnitude relative to ranges observed in V12-122. Accuracy of faunal indices as estimates of oceanic conditions is evaluated by study of modern oceanographic data and sea-bed samples. Under favorable conditions, accuracy is apparently limited primarily by the degree of ecological control exercised by the estimated parameter. Accuracy of the isotopic paleotemperature estimates is limited primarily by uncertainty as to the magnitude of the water-correction term in the isotope equation, a value which combines global ice-volume and local evaporation-precipitation effects.

Curves of δ O13 and S in V12-122 record all or part of seven major climatic cycles, and display a fundamental periodicity of about 85,000 years. Ts and Tw curves show small but significant differences: two phase shifts in estimated temperature minima, and a long-term increasing trend.

Amplitude-frequency histograms of Tw and δ O18 indicate that only two percent of the time during the past 450,000 years have Caribbean temperatures been as warm and isotopic ratios as low as they are today.

A comparison of the magnitude of δ O18 change (2.2%.) during the shift from late-glacial to post-glacial times, with that of the faunally estimated change in average temperature (2.2°C), provides a basis for estimating the associated change in isotopic water composition (1.8%.) by back-calculation in the isotope equation. At least 0.4%. of this change in A is attributed to an evaporation-precipitation effect, and the balance (≤1.4%.) to an icevolume effect.

Isotopic and faunal methods monitor different responses to global climatic change. Used in conjunction, they provide deeper insights into the past than either could achieve alone.
Oxygen Isotope and Palaeomagnetic Stratigraphy of Equatorial Pacific Core V28-238: Oxygen Isotope Temperatures and Ice Volumes on a 105 Year and 106 Year Scale
Authors: Shackleton Nicholas John , Opdyke Neil D.
Published: December 2004

Core Vema 28-238 preserves an excellent oxygen isotope and magnetic stratigraphy and is shown to contain undisturbed sediments deposited continuously through the past 870,000 yr. Detailed correlation with sequences described by Emiliani in the Caribbean and Atlantic Ocean is demonstrated. The boundaries of 22 stages representing alternating times of high and low Northern Hemisphere ice volume are recognized and dated. The record is interpreted in terms of Northern Hemisphere ice accumulation, and is used to estimate the range of temperature variation in the Caribbean.
Late Pleistocene-Holocene Oceanographic Changes in the Northeastern Pacific
Authors: Moore Ted C.
Published: December 2004

The distributions of the radiolarian assemblages in the Northeastern Pacific Ocean were determined and correlated with the average summer temperature of the near surface waters of this region. These assemblages were compared with those in three sediment cores taken beneath the Transition Zone waters. This comparison indicates that the assemblage off Oregon at the last maximum cold interval (24,000 yr B.P.) was like that now found off southern Alaska. The correlation of the radiolarian assemblages with temperature gives an estimate of 11°C for the average summer temperature at that time. This is approximately 4°C cooler than present day conditions in the area. Superimposed on the general warming trend that began 24,000 y.a., there are minor oscillations in the assemblages which correspond to estimates of temperature change of about 2°C in the Pleistocene and about 1°C in the Holocene. In the Holocene, these minor warm intervals appear to be approximately synchronous with advances in mountain glaciers.
Climate of the American Tropics and Subtropics in the 1960s and Possible Comparisons With Climatic Variations of the Last Millenium
Authors: Sanchez W.A. , Kutzbach J.E.
Published: December 2004

Departures of mean annual precipitation and temperature for the decade 1961–1970 from the 1931–1960 averages are illustrated on maps of the tropical and subtropical portions of the American continents. Certain features of midlatitude climatic anomalies appear to be associated with concurrent anomalies in the tropics. There is an apparent southward shift of circulation features in this longitudinal sector of both hemispheres. A review of selected literature on latitudinal climatic shifts and atmosphere-ocean interaction suggests some similarities between the patterns of climate in the 1960s and the climate of the Little Ice Age.
Radiolaria as Paleoclimatic Indicators: Pleistocene Climatic Fluctuations in the Equatorial Pacific Ocean
Authors: Johnson David A. , Knoll Andrew H.
Published: December 2004

Late Pleistocene radiolarian assemblages were examined in two cores (V24-58 and RC11-209) from the eastern equatorial Pacific Ocean, using Nigrini's 1970 method of recurrent group analysis. The radiolarian “climatic index” curves obtained by this analysis were in close agreement with fluctuations in carbonate levels established previously for the same cores. This correspondence suggests that equatorial radiolarian assemblages changed significantly in response to Pleistocene climatic oscillations. The radiolarian “climatic indices” of the two cores showed close agreement with each other. Our data indicate that equatorial radiolarian assemblages may prove useful for regional correlations between cores, and for paleoclimatic interpretations.
The Barents Ice Sheet as a Relay Regulator of Glacial-Interglacial Alternation
Authors: Kvasov D. D.
Published: December 2004

A slight cooling can induce the formation of ice sheets in the Scandinavian mountains and in the American Arctic. The increasing albedo and the appearance of cold air masses above the glaciers cause glaciation to spread over a vast area. As a result, the sea level lowers and a large part of the Barents and Kara seabeds dries up. Ice sheets are formed there, which spread over the northeastern part of the Kola Peninsula, the Pechora River basin, and over northwestern Siberia. The glacier barrier extending nearly from the North Pole to central Europe hinders latitudinal atmospheric circulation. Precipitation decreases sharply in the areas east and southeast of the glaciers. As a consequence, glaciers in the mid-latitudes retreat and sea level rises. Increased iceberg formation is induced in the periphery of the Barents Ice Sheet, causing it to disappear. An interglacial sets in.
Hawaiian Glacial Ages
Authors: Porter Stephen C.
Published: December 2004

Four glacial drifts that are interstratified with lava flows and tephra layers on the upper slopes of Mauna Kea demonstrate that an ice cap formed repeatedly at the summit of the volcano during the middle and late Pleistocene. The oldest drift (Pohakuloa Formation) probably was deposited shortly after eruption of a lava flow having a K/Ar age of 278,500 ± 68,500 yr. Drift of the Waihu Formation, marked by a belt of subdued end moraines, is correlated with hyaloclastite cones and associated lava flows that were erupted beneath an ice cap about 170,000–175,000 yr ago. One of four younger subglacially erupted lavas at the crest of the volcano has a K/Ar age of 41,300 ± 8300 yr. Tephra layers that antedate the last glaciation are about 29,700 to 37,20014C yr old and underlie dune sand that is believed to correlate with drift of the Makanaka Formation deposited during the last ice advance. The late Makanaka ice cap, which covered an area of about 70 km2and was as much as 100 m thick, is reconstructed from end moraines and limits of erratic stones that encircle the summit region. The ice cap disappeared from the summit before about 9080 yr ago. Postglacial lavas and tephra overlie the youngest drift on the upper south flank of the mountain and buried a widespread post-Makanaka soil on the lower south rift zone about 450014C yr ago. The island of Hawaii is subsiding isostatically due to crustal loading by Quaternary volcanic rocks, with subsidence near the midpoint of Mauna Kea estimated as about 2.5 ± 0.5 mm/yr. A curve depicting an inferred long-term subsidence rate has been used to adjust equilibrium-line altitudes (ELAs) of former ice caps that are calculated on the basis of reconstructed glacier topography and an assumed accumulation-area ratio of 0.6 ± 0.05. The results indicate that ELA depression was greatest during Waihu glaciation, least during Pohakuloa glaciation, and that the ELA during late Makanaka glaciation was somewhat lower than that of the early Makanaka advance. Available radiometric dates show that late Makanaka glaciation correlates with stage 2 of the marine oxygen-isotope record, and suggest that early Makanaka, Waihu, and Pohakuloa glaciations correlate, respectively, with isotope stages 4, 6, and 8. Because ice caps could have formed on Mauna Kea only after the snowline was lowered many hundreds of meters below its inferred present level, episodes of Hawaiian glaciation probably were restricted to times of maximum ice volume on the continents. The asymmetry of the late Makanaka ice cap and the southeast-descending gradient of its equilibrium line are consistent with a southeast (tradewinds) source of precipitation during the last glaciation. Although departures of glacial-age temperature and precipitation from present values are difficult to assess quantitatively, growth of former ice caps on Mauna Kea most likely was due to enhanced winter snowfall and to reduced ablation rates brought about by lower air temperature and increased cloudiness.
Ice Ages and Orbital Variations: Some Simple Theory and Modeling
Authors: Schneider Stephen H. , Thompson Starley L.
Published: December 2004

Possible physical mechanisms relating orbital-element variations (i.e., the “Milankovitch mechanism” of insolation regime changes) to Quaternary glacial/interglacial transitions are explored quantitatively. These include the seasonal cycle of albedo and the zonal distribution of thermal inertia. These mechanisms can interact with the perturbations to zonal average and seasonal average insolation caused by orbital-element variations to cause a global annual temperature residual, even though such variations can cause only a negligible change in global annual insolation.

Numerical model experiments with a zonal energy balance model show that the relative interactions between insolation regime changes and seasonally and latitudinally varying albedo and latitudinally varying thermal inertia are roughly of comparable magnitude. Encouraging agreements between model experiments and data are evident, but these (and others') simulations are still a long way away from providing a satisfying explanation of the physical processes that could fully explain the apparent connections between orbital-element variations and Quaternary glaciations.

It seems likely that no single physical process can be identified as predominate, and rather, the hypothesized physical connection between insolation regime changes and glacial/interglacial transitions will have to be built on the interactions of a number of processes on both short and long time scales.
Holocene Vegetation History of the Okanogan Valley, Washington
Authors: Mack Richard N. , Rutter N.W. , Valastro S.
Published: December 2004

Haploxylon pine(s) andArtemisiadominated the initial vegetation in front of the receding Okanogan Lobe until ca. 10,000 yr B.P., as revealed by two pollen records in north-central Washington. After 10,000 yr B.P. the macroclimate became warmer throughout the Okanogan drainage as diploxylon pines andArtemisiaincreased. The Mount Mazama eruption at ca. 6700 yr B.P. is recorded as two stratigraphically separate and petrographically distinct tephra units at Bonaparte Meadows. While there are apparent short-term changes in the vegetation coincident with the ashfall(s),Artemisiacontinues to dominate the Okanogan Valley until ca. 5000 yr B.P. By 4700 yr B.P. the modern vegetation, dominated byPseudotsuga menziesii, had become established around Bonaparte Meadows.
Late Quaternary Glacial and Vegetation Changes, Little Cottonwood Canyon Area, Wasatch Mountains, Utah
Authors: Madsen David B. , Currey Donald R.
Published: December 2004

Glacial geology and14C dating in the central Wasatch Mountains indicate: an early canyon-mouth glaciation (Dry Creek till), probably during isotope stage 6; on that till, a paleosol (Majestic Canyon soil) dated at about 26,000 yr B.P.; overriding that soil, a later canyon-mouth glaciation (Bells Canyon till) probably beginning prior to about 19,000 yr B.P.; a midcanyon deglacial pause (Hogum Fork till) prior to 12,300 yr B.P.; an upper-canyon deglacial pause (Devils Castle till) prior to 7500 yr B.P.; and late Holocene periglaciation. Pollen ratios from bog profiles in the mid to upper reaches of the canyon suggest that temperatures cooler than the Holocene average occurred until after about 8000 yr B.P. Warmer and dryer than average conditions were initiated about 8000 to 7500 yr B.P. During the later portion of this Altithermal period conditions became relatively warm and wet. Two subsequent episodes of cooler than average temperatures correspond chronologically to the initial stades of Neoglaciation elsewhere in the Rocky Mountains. However, there is no geomorphic evidence of corresponding glacial activity in the canyon area. Relative moisture during these two periods differs significantly, suggesting that Neoglacial conditions were controlled primarily by changes in summer temperature.
Quaternary Antarctic Bottom-Water History: Deep-Sea Benthonic Foraminiferal Evidence from the Southeast Indian Ocean
Authors: Corliss Bruce H.
Published: December 2004

Distinct assemblages of Recent deep-sea benthonic foraminifera from the southeast Indian Ocean have been shown to be associated with Antarctic Bottom Water (AABW) and Indian Bottom Water (IBW). The AABW assemblage is divided into two groups. One is dominated by Epistominella umbonifera and is associated with AABW having temperatures between −0.2° and 0.4°C. The second group is dominated by Globocassidulina subglobosa and is associated with AABW having temperatures between 0.6° and 0.8°C. The IBW assemblage is marked by the strong dominance of Uvigerina spp. and Epistominella exigua. The faunal-water-mass relationships have been used to infer the history of bottom-water circulation over the last 500,000 yr in this region using faunal data from four Eltanin cores. One core was taken from the Southeast Indian Ridge in association with IBW, and three were taken from the flank of the ridge associated with AABW flowing within a western boundary contour current in the South Australian Basin. Little faunal variation exists in the core beneath IBW (E48-22), indicating that IBW was present on the Southeast Indian Ridge during the last 300,000 yr. A record of the intensity of AABW circulation during the last 500,000 yr is inferred from the benthonic foraminiferal data in the three cores located within the western boundary contour current. Marked oscillations in the relative proportions of AABW and IBW faunal assemblages are found in one core, E48-03. The faunal variations are inferred to have resulted from variation in intensity of AABW circulation between 500,000 and 195,000 yr B.P. In E48-03, the AABW assemblage was present most of the time between 500,000 and 195,000 yr B.P., with low intensity of AABW circulation occurring primarily during the equivalent of stages 8 and 7 (t = 305,000 to 195,000 yr B.P.). The intensity of AABW circulation varied, with a maximum occurring during the equivalent of stage 11 (t = 420,000 yr B.P.). Two additional cores, E45-27 and E45–74, show relatively constant intensity of AABW circulation from 195,000 yr B.P. to the present. The intensity of AABW circulation at the present appears to be intermediate between a maximum during the equivalent of stage 11 (t = 420,000 yr B.P.) and the minimum during the equivalent of stage 8 (t = 275,000 yr B.P.). AABW production has occurred during both glacial and interglacial episodes. Bottom-water productivity has been suggested to play an important role in glacial/interglacial oscillations during the late Quaternary (Weyl, 1968; Newell, 1974). In this study, the relationship between bottom-water circulation and climatic fluctuations appears to be more complex than had been previously suggested, since a simple relationship between Quaternary bottom-water circulation and paleoclimatic fluctuations is not shown.
Comparison of 105Years of Oxygen Isotope and Insoluble Impurity Profiles from the Devon Island and Camp Century Ice Cores
Authors: Fisher David A.
Published: December 2004

Oxygen-isotope profiles for the Devon Island ice cap and Camp Century Greenland are affected by a number of variables, some of which must have been the same for both sites. The two δ(18O) records spanning about 120,000 years are brought into relative alignment by comparison of major δ features, and subsequent verification that the insoluble particulate concentration records were also in phase for this alignment. The difference between the δ profiles is shown to be mainly a function of the altitude of the accumulation area for Camp Century. This altitude seems to have been higher than present for the last 100,000 years, suggesting the present flow line through the site has never been shorter. The maximum altitude for the Camp Century accumulation area is 1500 m above the present site and is almost synchronous with the maximum in particulate concentration that occurs at 16,000 yr B.P. The synchronism is likely due to the maximum sea-level lowering that exposed vast areas of continental shelf to wind erosion.
Eastern Mediterranean Sea during the Last Glacial Maximum; an 18,000-years B.P. Reconstruction
Authors: Thunell Robert C.
Published: December 2004

An ecological transfer function based on the distribution of planktonic foraminifera in 66 Mediterranean and 8 North Atlantic surface-sediment samples is used to estimate sea-surface temperatures and salinities for the eastern Mediterranean during the last glacial maximum (18,000 yr B.P.). The present-day distribution of planktonic foraminifera can be explained by four faunal assemblages, each of which has diagnostic environmental preferences. Factor 1 is a tropical-subtropical assemblage; factor 2 is a transitional assemblage; factor 3 is a low-salinity assemblage; and factor 4 is a subpolar assemblage. The geographic distribution of these faunal assemblages reflect the variation in overlying hydrographic conditions. The 18,000-yr B.P. samples were selected based on total faunal stratigraphy, oxygen-isotope stratigraphy, and previously determined radiometric dates for eastern Mediterranean volcanic ash layers. Estimated temperature and salinity patterns show that the greatest change between present-day and 18,000-yr B.P. sea-surface conditions existed in the Aegean Sea and immediately south of Crete. The winter temperature anomaly (18,000 yr B.P.-present) within the Aegean Sea is 6°C cooler than present. In contrast to this, the maximum summer temperature anomaly exists to the south of Crete, where sea-surface temperatures were 4°C cooler than present. Estimated sea-surface salinities also show that the greatest change took place within the Aegean Sea, being 5‰ less saline than present. The estimated temperature and salinity patterns seem to reflect changing drainage patterns during glacial times and the diversion of cool, low-salinity water into the Aegean Sea. The source of this glacial runoff appears to be large freshwater lakes that existed during this time over parts of eastern Europe and western Siberia.
Global Maps of Lake-Level Fluctuations since 30,000 yr B.P.
Authors: Street F. Alayne , Grove A. T.
Published: December 2004

This paper presents selected world maps of lake-level fluctuations since 30,000 yr B.P. These are based on a literature survey of 141 lake basins with radiocarbon-dated chronologies. The resulting patterns are subcontinental in scale and show orderly variations in space and time. They reflect substantial changes in continental precipitation, evaporation, and runoff, which are due to glacial/interglacial fluctuations in the atmospheric and oceanic circulations. In the tropics, high lake levels are essentially an interglacial or interstadial phenomenon, although there are important exceptions. Since extensive lakes during the Holocene corresponded with relatively high sea-surface temperatures, and therefore presumably with high evaporation rates on land, they are interpreted as the result of higher precipitation. Tropical aridity culminated in most areas at, or just after, the glacial maximum, although the present day is also characterized by a below-average abundance of surface water. In extratropical regions the mapped patterns are more complex. They vary markedly with latitude and proximity to major ice sheets. In these areas, evidence is at present insufficient to evaluate the relative contributions of precipitation and temperature to the observed lake-level record.
Rapid Ice-Sheet Growth and Initiation of the Last Glaciation
Authors: Johnson R.G. , Andrews J.T.
Published: December 2004

Calculations based on temperature-corrected oxygen-isotope ratios from deep-sea cores yield a glacioeustatic sea-level fall in excess of 50 m during the first 10,000 yr of the last glaciation, and generally support the local regression of about 70 m inferred from tectonically rising New Guinea beaches. We propose that this rapid glacial buildup depended on high-latitude cooling, and large increases of high-latitude regional winter precipitation in the Laurentide and the Fennoscandian-Barents Sea areas, and that these factors were caused by a critical alteration of North Atlantic Drift currents and their associated subpolar atmospheric circulation. In support of this, faunal data from northeast North Atlantic deep-sea cores show that the glacial buildup was accompanied by a sudden loss of most of the North Atlantic Drift from the Greenland-Norwegian Sea, a factor favoring reduced heat input into the higher latitudes. Subpolar mollusk and foraminifera fauna from elevated marine deposits on the Baffin Island coast, and northwest North Atlantic core data suggest a continuation or an associated restoration of subpolar water west of Greenland as far north as Baffin Bay, a factor favoring precipitation in the northeast Canadian region. Heat transport and atmospheric circulation considerations suggest that the loss of the northeast North Atlantic Drift was itself a major instrument of high-latitude climate change, and probably marked the initiation of major new ice-sheet growth.
Surge Moraines of the Klutlan Glacier, Yukon Territory, Canada: Origin, Wastage, Vegetation Succession, Lake Development, and Application to the Late-Glacial of Minnesota
Authors: Wright H. E.
Published: December 2004

The Klutlan Glacier in the St. Elias Mountains of the Yukon Territory has surged repeatedly during the last few hundred years, and its drift-covered stagnant ice provides an analog for the downwastage, landform development, vegetational succession, and lake formation on Late Wisconsin moraines of Minnesota. Melting of the buried ice caused collapse of the drift mantle and the formation of lakes, which become filled with sediment that slumps in from receding ice walls. Topographic reversals are common, as the sediment cover of drained lakes inhibits local under-melting, and collapse occurs elsewhere. As the drift mantle thickens the land surface becomes stabilized and pioneer herbs are succeeded by shrubs and then by white spruce. The oldest moraines (600–1200 yr old) have a multiple-generation spruce forest, yet melting of buried ice still locally forms young lakes. Cores of organic sediment from the oldest lakes contain a stratigraphic sequence of pollen, diatoms and cladocerans that record the early stages in lake and landscape succession.
Wastage of the Klutlan Ice-Cored Moraines, Yukon Territory, Canada
Authors: Driscoll Fletcher G.
Published: December 2004

A series of ice-cored Neoglacial moraines at the terminus of the Klutlan Glacier covers an area of 90 km2. Studies were made to determine empirically how long ice persisted in the Klutlan moraines and to develop models that can accurately predict wastage rates under current climatic conditions. A meltout curve based on climatological data reflects the sum of three melting processes: surficial melting, melting by lake water, and melting by geothermal heat. About 950 yr are required to melt 180 m of ice with a debris concentration of 1%, or about 1200 yr for a 1.5% debris load. Another meltout curve, based on seismic data, suggests total meltout in about 875 yr. When all geologic factors are considered, the empirical meltout curve is remarkably similar to that derived by considering the major heat-flux parameters. Meltout rates can be predicted if (1) the fundamental climatic parameters can be ascertained, and (2) the sediment concentration in the ice is known.
Modern Pollen Assemblages and Vegetational History of the Moraines of the Klutlan Glacier and Its Surroundings, Yukon Territory, Canada
Authors: Birks H. J. B.
Published: December 2004

Modern pollen assemblages have been studied from surficial lake muds and moss polsters collected from five vegetated ice-cored moraines of the Klutlan Glacier. The youngest vegetated moraine (K-II) is characterized by high pollen values for Salix and Hedysarum, K-III by high Salix and Shepherdia canadensis and low Hedysarum and Picea, K-IV by high Betula, Salix, and Shepherdia, and K-V and the Harris Creek moraine (HCM) by high Picea. Variations are summarized by canonical variates analysis. A percentage pollen diagram from Gull Lake on the upland east of the glacier records vegetational development since the deposition of the White River volcanic ash 1220 14C yr ago. An initial species-rich treeless vegetation was replaced by birch-alder-willow shrub-tundra, and this by open Picea glauca forest similar to present vegetation around the lake. Sites on HCM show two basic stratigraphies. Triangle Lake reflects vegetational succession from Salix-Shepherdia canadensis scrub similar to that on K-III today, through open Picea woodland of K-IV type, to closed Picea forests of K-V and HCM. Heart Lake and Cotton Pond reflect vegetational development following melting of ice underlying the spruce forests of HCM. These two types are summarized by positioning the fossil spectra on the first two canonical variate axes of the modern surface spectra.
A Reported Early-Man Site Adjacent to Southern Alaska's Continental Shelf: A Geologic Solution to an Archeologic Enigma
Authors: Thorson Robert M. , Plaskett David C. , Dixon E.James
Published: December 2004

An extensive ancient archeologic site containing lithic artifacts and associated with mammoth remains was reported at Chinitna Bay, southern Alaska in 1943. The presence of such a site adjacent to the continental shelf at the base of the rugged Aleutian Range suggested that humans may have inhabited the inner shelf environment during the late Pleistocene at times of lowered sea level. Because of the site's potential significance, an interdisciplinary research team relocated and reinvestigated the area in 1978, but failed to find evidence of prehistoric human habitation. Geologic studies and radiocarbon dating indicate that the strata reported at the site are intertidal in origin, very late Holocene in age, and have undergone significant tectonic movement in the recent past. These observations indicate that the previously published observations of the Chinitna Bay site are probably invalid.
Radiocarbon Dating of the Rate of Movement of Two Solifluction Lobes in the Ruby Range, Yukon Territory
Authors: Alexander Charles S. , Price Larry W.
Published: December 2004

The rates of solifluction of two lobes in the Ruby Range have been determined by 14C dates of samples taken from buried organic layers in the lobes. Twenty-one dates are available from one lobe, and seven from another. When plotted against distance back from control points at the lobe fronts the dates show considerable scatter. In part the scatter is thought to be due to a potential age range of 340 ± 100 yr in the organic layers. Linear and polynomial regressions were calculated for the time/distance relationships shown by the dates. The rates of lobe advance established by these means for the lobe with seven dates are not thought to be reliable. Reasonably good estimates of movement rate were determined for the second lobe by both the linear and polynomial methods. However, the rates established by the two methods are quite similar. Because of this and other uncertainties it is difficult to draw inferences of climatic change from the changes in movement rate shown by the polynomial solution.
Holocene Vegetational History of the Kootenai River Valley, Montana
Authors: Mack Richard N. , Rutter N. W. , Valastro S.
Published: December 2004

Pollen records in the Kootenai and Fisher River drainages in western Montana reveal a fivezone sequence of Holocene vegetation change. Deposition of Glacier Peak Ash-Layer G (ca. 10,540 ± 660 yr B.P.) in the lowermost sediments (clay intermixed with pebbles) at Tepee Lake gives a minimum date for the initiation of sedimentation. Initial vegetation on the newly deglaciated terrain was dominated by Pinus (probably white bark pine) with small amounts of Gramineae, Picea and Abies, reflecting a relatively cool, moist macroclimate. Two vegetation units appear to contribute to Pollen Zone II (ca. 11,000–7100 yr B.P.): arboreal communities with pines, along with Pseudotsuga or Larix, or both, and treeless vegetation dominated by Artemisia. Pollen Zone II represents an overall warmer macroclimate than occurred upon ice withdrawal. After ca. 7100 yr B.P. (Pollen Zone III) diploxylon pines became a major pollen contributor near both Tepee Lake and McKillop Creek Pond, indicating an expansion of xerophytic forest (P. contorta and P. ponderosa) along with an increase in the prominence of Pseudotsuga menziesii or Larix occidentalis, or both. Artemisia briefly expanded coverage near Tepee Lake concomitant with the Mazama ashfall ca. 6700 yr B.P. A short-term climatic trend with more available water began after ca. 4000 yr B.P. as Abies (probably A. grandis) along with Picea engelmannii became a more regular component of the forest surrounding both sites. Emergence of the modern macroclimate is indicated primarily with the first regular appearance of Tsuga heterophylla in the pollen record by ca. 2700 yr B.P., synchronous with the development of western hemlock forest within the same latitudes in northern Idaho and northeastern Washington.
Pollen Analysis of the 1973 Ice Core from Devon Island Glacier, Canada
Authors: McAndrews John H.
Published: December 2004

Meltwater from a 299-m-long ice core was filtered and analyzed for fossil pollen and spores. Pollen concentration was higher in the late Holocene and interglacial intervals (ca. 7 liter−1) than in the early Holocene and Wisconsinan (ca. 1–2 liter−1) ones. The late Holocene and interglacial assemblages were dominated byAlnus(alder), whereas the early Holocene and Wisconsinan ones were dominated byBetula(birch) andArtemisia(sage). During the Holocene and probably the last interglaciation, most of the pollen and spores were blown a minimum of 1000 km from low arctic shrub tundra and adjacent subarcticPicea(spruce) forest; these areas were dominated by the arctic air mass during the summer pollinating season. During the Wisconsinan-early Holocene, glacier ice and arctic air were more widespread and pollen sources were more distant; thus, at this time relatively little pollen was incorporated into the ice.

The Devon ice-core data suggest that there should have been pollen in the continental ice sheet of Wisconsin time. When the ice sheet retreated this pollen would be carried by meltwater and redeposited with silt and clay together with contemporary pollen, producing an ecologically anomalous assemblage.
Buried Trees, Water Table Fluctuations, and 3000 Years of Changing Climate in West-Central Oklahoma
Authors: Hall Stephen A. , Lintz Christopher
Published: December 2004

A sequence of radiocarbon-dated buried trees, buried soils, a carbonate zone, and a molluscan fauna from Carnegie Canyon indicate that between 3200 and 2600 yr B.P. the climate of west-central Oklahoma was drier than today. A high water table accompanied a period of moister climate 2000 to 1000 yr B.P. The water table dropped after 1000 yr B.P. due to a change toward dry conditions.
Dating Quaternary Fault Scarps Formed in Alluvium Using Morphologic Parameters
Authors: Mayer Larry
Published: December 2004

Ages of fault scarps, as well as those other types of transport-limited slopes, can be estimated by comparing their morphology with the morphology of scarps of known age. Age estimates are derived by fitting the scarp profiles to synthetic profiles generated using a diffusion equation or, alternatively, by classification using a linear discriminant function. The usefulness of morphology-derived age estimates depends on the relative importance of non-age-related morphologic variation. Data from more than 200 scarp profiles demonstrate that morphologic variation not related to scarp age can introduce significant uncertainties into morphology-derived age estimates.
Context and Environment in Taphonomic Analysis: Examples from Alaska's Porcupine River Caves
Authors: Dixon E. James
Published: December 2004

Field investigations of caves along Alaska's Porcupine River document three major mechanisms which modify bone in patterns similar to alterations produced by man: (1) carnivore fracture; (2) rodent gnawing; and (3) rock fall and rubble scarring. A late Wisconsin faunal assemblage composed of Equus sp., Rangifer tarandus, Ovis dalli, Bison sp., proboscidean, numerous small mammal species, birds, and fish is well documented. This faunal assemblage suggests a mosaic environment of grassland-tundra-forest in the immediate vicinity of these caves and implies that the late Wisconsin environment in north-central Alaska may have been characterized by a number of microenvironments and colder, dryer, steppe conditions. Taphonomic data which have historically been interpreted to support human occupation of eastern Beringia during the Pleistocene are critically examined and the context of these discoveries (not the specimens themselves) provides the test essential to document the antiquity of man in North America prior to 12,000 yr ago.
The Last Interglacial Ocean
Authors: Cline Rose Marie L. , Hays James D. , Prell Warren L. , Ruddiman William F. , Moore Ted C. , Kipp Nilva G. , Molfino Barbara E. , Denton George H. , Hughes Terence J. , Balsam William L. , Brunner Charlotte A. , Duplessy Jean-Claude , Esmay Ann G. , Fastook James L. , Imbrie John , Keigwin Lloyd D. , Kellogg Thomas B. , McIntyre Andrew , Matthews Robley K. , Mix Alan C. , Morley Joseph J. , Shackleton Nicholas J. , Streeter S. Stephen , Thompson Peter R.
Published: December 2004

The final effort of the CLIMAP project was a study of the last interglaciation, a time of minimum ice volume some 122,000 yr ago coincident with the Substage 5e oxygen isotopic minimum. Based on detailed oxygen isotope analyses and biotic census counts in 52 cores across the world ocean, last interglacial sea-surface temperatures (SST) were compared with those today. There are small SST departures in the mid-latitude North Atlantic (warmer) and the Gulf of Mexico (cooler). The eastern boundary currents of the South Atlantic and Pacific oceans are marked by large SST anomalies in individual cores, but their interpretations are precluded by no-analog problems and by discordancies among estimates from different biotic groups. In general, the last interglacial ocean was not significantly different from the modern ocean. The relative sequencing of ice decay versus oceanic warming on the Stage 6/5 oxygen isotopic transition and of ice growth versus oceanic cooling on the Stage 5e/5d transition was also studied. In most of the Southern Hemisphere, the oceanic response marked by the biotic census counts preceded (led) the global ice-volume response marked by the oxygen-isotope signal by several thousand years. The reverse pattern is evident in the North Atlantic Ocean and the Gulf of Mexico, where the oceanic response lagged that of global ice volume by several thousand years. As a result, the very warm temperatures associated with the last interglaciation were regionally diachronous by several thousand years. These regional lead-lag relationships agree with those observed on other transitions and in long-term phase relationships; they cannot be explained simply as artifacts of bioturbational translations of the original signals.
13C Record of Benthic Foraminifera in the Last Interglacial Ocean: Implications for the Carbon Cycle and the Global Deep Water Circulation
Authors: Duplessy Jean-Claude , Shackleton Nicholas J. , Matthews Robley K. , Prell Warren , Ruddiman William F. , Caralp Michèle , Hendy Chris H.
Published: December 2004

The 13C/12C ratios of Upper Holocene benthic foraminiferal tests (genera Cibicides and Uvigerina) of deep sea cores from the various world ocean basins have been compared with those of the modern total carbon dioxide (TCO2) measured during the GEOSECS program. The δ13C difference between benthic foraminifera and TCO2 is 0.07 ± 0.04‰ for Cibicides and −0.83 ± 0.07‰ for Uvigerina at the 95% confidence level. δ13C analyses of the benthic foraminifera that lived during the last interglaciation (isotopic substage 5e, about 120,000 yr ago) show that the bulk of the TCO2 in the world ocean had a δ13C value 0.15 ± 0.12‰ lower than the modern one at the 95% confidence level, reflecting a depletion, compared to the present value, of the global organic carbon reservoir. Regional differences in δ13C between the various oceanic basins are explained by a pattern of deep water circulation different from the modern one: the Antarctic Bottom Water production was higher than today during the last interglaciation, but the eastward transport in the Circumpolar Deep Water was lower.
Late Pleistocene Climate and Water Budget of the South American Altiplano
Authors: Hastenrath Stefan , Kutzbach John
Published: December 2004

Geomorphic evidence from the Peruvian-Bolivian Altiplano indicates that during episodes prior to 28,000 and around 12,500-11,000 yr B.P., lakes covered an area about six and four times as large as at present, respectively. Within the constraints of the heat and water budget, model calculations are used to estimate the precipitation rate that would allow hydrologic equilibrium. On this basis it is suggested that rainfall on the Altiplano during the episodes of enlarged lakes was, respectively, some 300 and 200 mm annum−1 larger than at present, representing increases of about 75 and 50%, respectively. Field evidence suggests that the episodes of enlarged lakes on the Altiplano may have preceded or coincided with periods of maximum glaciation in the neigh-boring Andes. In this region with high elevation of the ice equilibrium line, increased precipitation is particularly conducive to glaciation.
A Hypothesis for the Sawlike Pattern of World Sea-Level Fluctuations
Authors: Kazanskiy A. B.
Published: December 2004

A theory of the world's sea-level fluctuations during late Pleistocene time, based on the analysis of the general equation of the mass balance between ocean water and inland water, suggests that the exchange of water masses between the ocean and the land, where at continental glaciation periods water is stored as ice, occurs only as a result of global climatic changes. The tectonic effect is considered insignificant for late Pleistocene time. The proposed theory explains the asymmetric character and the sawlike shape of the curve of the main cycles of sea-level fluctuations. The theory also makes it possible to construct a diagram of sea-level fluctuations from the last glacial maximum to the present time. This diagram is governed by two parameters, the amount of the average “effective” evaporation from the world's ocean surface (evaporation minus rainfall) and the rate of the sea-level rise at the present time. The resulting theoretical curve agrees well with known estimates of sea level within the time span being considered. The comparison of the theoretical curve with these estimates eliminates the apparent discrepancy between data obtained by different methods: measurements of old coastline and the isotopic composition of bottom sediments.
The Distribution of 230Th/234U Ages in Corals and the Number of Last Interglacial High-sea Stands
Authors: Kaufman Aaron
Published: December 2004

The 104 available [230Th/234U] analyses of unrecrystallized corals from stable emerged terraces indicate that the last interglacial period occurred approximately 125,000 yr ago. An estimate is made of the exact duration of this period by accounting for the surprisingly small distribution width observed among the 80 most reliable analyses. This distribution width is compared with those obtained for model populations generated by assuming various characteristic analytical errors and various lengths of the last interglacial period. The results show that (1) if there was only a single rise in sea level, it probably lasted no more than 12,000 yr, in agreement with previous estimates; and (2) if there were two separate rises of sea level, the gap between them must have been less than 7500 yr and not 12,200 as proposed by some authors.
Dynamics of Periglacial Sorted Circles in Western Spitsbergen
Authors: Hallet Bernard , Prestrud Suzanne
Published: December 2004

A working hypothesis for the development and maintenance of sorted circles, which are finegrained soil domains delineated by borders of coarser material, involves clast motion relative to soil and intermittent circulatory motion of soil in the active layer. The hypothesis is compatible with the observed size, regularity, sorting, microtopography, surface soil motion, vegetation cover, and subsurface organic carbon content of soil patterns studied in Spitsbergen. Theoretical considerations of buoyancy-driven convection suggest that intermittent convection of thawed soils is plausible, and that the requisite bulk density decrease with depth arises naturally from moisture gradients that develop during the thaw consolidation of ice-rich soils. These considerations also help in understanding the dependence of sorted circles on soil characteristics and on moisture. Moreover, they point to the possible use of sorted patterns as paleoclimatic indicators based on the expected relation between pattern size and active layer depth.
Carnivore Size and Quaternary Climatic Change in Southern Africa
Authors: Klein Richard G.
Published: December 2004

The relationship between carnassial length and latitude south is analyzed for 17 African carnivore species to determine if individuals tend to be larger in cooler climates, as predicted by Bergmann's Rule. With modern data in support, middle and late Quaternary temperatures might then be inferred from mean carnassial length in fossil samples, such as those from Equus Cave, Elandsfontein, Sea Harvest. Duinefontein, and Swartklip in the Cape Province of South Africa. One problematic aspect of the study is the use of carnassial length and latitude as necessary but imperfect substitutes for body size and temperature, respectively. For some species, another difficulty is the relatively small number of available modern specimens, combined with their uneven latitudinal spread. Still, in 14 of the species, carnassial length does tend to increase with latitude south, while mean carnassial length in the same species tends to be greater in those fossil samples which accumulated under relatively cool conditions, as inferred from sedimentologic, palynological, or geochemical data. Given larger modern samples from a wide variety of latitudes, refinement of the mathematical relationship between carnassial length and latitude in various species may even permit quantitative estimates of past temperatures in southern Africa.