bluuebunny/crossref_metadata_2025 huggingface dataset:
Paleoenvironments along the Eastern Laurentide Ice Sheet Margin and Timing of the Last Ice Maximum and Retreat
Authors: de Vernal Anne , Hillaire-Marcel Claude
Published: July 2012

Palynological and isotopic analysis in a few deep-sea cores from the Labrador Sea reveals strong environmental changes related to the Late Pleistocene glacial fluctuations over eastern Canada. On the whole, the Labrador Sea was characterized by strong exchanges between North Atlantic water masses, Arctic outflows, and meltwater discharges from Laurentide, Greenland and lnuitian ice sheets. The penetration of temperate Atlantic waters persisted throughout most of the Late Pleistocene, with a brief interruption during the Late Wisconsinan. During this glacial substage, a slight but continuous meltwater runoff from the Laurentide ice margins grounded on the northern Labrador Shelf is indicated by relatively low 18O values and low-salinity (< 30‰) dinocyst assemblages. The calving of the ice margin, the melwater outflow and the subsequent dilution of surface waters offshore Labrador probably contributed to the dispersal of floating ice and, consequently, to a southward displacement of the polar front restraining the penetration of North Atlantic waters into the Labrador Sea. The advection of southern air masses along the Laurentide ice margins, shown by pollen assemblages, was favourable to abundant precipitation and therefore, high ice accumulation rates, especially over northern Labrador during the Late Wisconsinan. The déglaciation is marked by a brief, but significant, melting event of northern Laurentide ice shortly after 17 ka. The main glacial retreat occurred after ca. 11 ka. It allowed restoration of WSW-ENE atmospheric trajectories, increased phytoplanktonic productivity, and penetration of North Atlantic water masses into the Labrador Sea.
Conditions for Growth and Retreat of the Laurentide Ice Sheet
Authors: Budd William F. , Smith Ian N.
Published: July 2012

Results of three dimensional numerical modelling of the North American ice sheets in response to the Earth's orbital radiation variations are reviewed in relation to the conditions for formation and retreat of the ice sheets. The last interglacial develops as a clear result of the preceding high summer radiation levels and is not very dependent on the climatic paramaterisation. The magnitude and timing of the last glacial maximum provides a means of fine tuning the climatic parameterisation. In between these two periods the extent of ice sheet advances and retreat is strongly sensitive to the magnitude of the ice sheet albedo feedback parameter. The time changes of the radiation, climate, ice sheet cover and bedrock depression are out of phase and as a result equilibrium is not attained. The distribution of land surface elevation plays a key role in the pattern of seeding of the ice sheet growth and the subsequent advances, coalescence and retreat. The dispersal pattern of bedrock in till can be expected to reflect the growth and advance phases of the ice sheet development rather than the maximum configuration. Finally, the cycles of ice ages over the last 500,000 years from the modelling follows the occurrence of extreme summer radiation levels over a wide latitude band of 40-80°N due to coincidence of obliquity and perihelion features superimposed on the hysteresis effects of the ice cover.
The Effects of the Laurentide Ice Sheet on North American Climate during the Last Glacial Maximum
Authors: Broccoli A. J. , Manabe S.
Published: July 2012

A climate model, consisting of an atmospheric general circulation model coupled with a simple model of the oceanic mixed layer, is used to investigate the effects of the continental ice distribution of the last glacial maximum (LGM) on North American climate. This model has previously been used to simulate the LGM climate, producing temperature changes reasonably in agreement with paleoclimatic data. The LGM distribution of continental ice according to the maximum reconstruction of HUGHES et al. (1981) is used as input to the model. In response to the incorporation of the expanded continental ice of the LGM, the model produces major changes in the climate of North America. The ice sheet exerts an orographic effect on the tropospheric flow, resulting in a splitting of the midlatitude westerlies in all seasons but summer. Winter temperatures are greatly reduced over a wide region south of the Laurentide ice sheet, although summer cooling is less extensive. An area of reduced soil moisture develops in the interior of North America just south of the ice margin. At the same time, precipitation increases in a belt extending from the extreme southeastern portion of the ice sheet eastward into the North Atlantic. Some of these findings are similar to paleoclimatic inferences based on geological evidence.
The Geomorphology of Glaciomarine Sediments in a High Arctic Fiord
Authors: Bednarski Jan
Published: July 2012

A general geomorphic model describing marine transgressions and regressions under non-glacial conditions is applied to the glacial environment. The general model recognizes two variables: i) the rate of relative sea level change, and ii) the rate of sedimentation at the coastline. The interaction of the two variables determines the nature of transgression or regression at a particular shoreline. In glaciated areas both sedimentation rates and relative sea level changes are controlled mainly by glacioclimatic responses of the ice. This is best illustrated along arctic coastlines where glacioisostatic loading caused extensive marine inundations during, and immediately after, the last glaciation. Subsequent emergence in the early Holocene has exposed extensive raised marine deposits. Clements Markham Inlet, on the northernmost coast of Ellesmere Island, Northwest Territories, contains raised marine deposits which have a definite spatial and sequential distribution related to the glacial history. The general geomorphic model is used to explain the distribution and geomorphology of this sediment. As the glacial cycle proceeds the balance between fluxes of sediment input and rate of sea level rise or fall will have a direct bearing on the type of stratigraphie sequence found in a particular area.
Note sur les variations du niveau marin relatif à l’Holocène, à Rivière-Ouelle, côte sud du Saint-Laurent
Authors: Dionne Jean-Claude
Published: July 2012

À Rivière-Ouelle, sur la rive sud du moyen estuaire du Saint-Laurent, une coupe le long de la rivière révèle l'existence d'un bas niveau marin relatif antérieurement à 6000 ans BP, suivi d'une transgression de 8-9 m. On y observe trois unités distinctes: à la base, l'argile de la mer de Goldthwait taillée en une surface d'érosion ; au-dessus, une séquence alluviale comprenant deux faciès, l'un estuarien (sable fin et limon), l'autre fluviatile (sable et gravier); au sommet, un dépôt de zone intertidale composé de sable fin et limon stratifiés en lits minces. Ces nouvelles données corroborent celles de trois autres sites: rivière Boyer, Montmagny-Cap-Saint-Ignace et Saint-Fabien-sur-Mer, et renseignent sur les modalités du relèvement isostatique de la côte sud du Saint-Laurent.
Notes on the Morphology and Genesis of Mud Polygons on Mount Kenya, East Africa
Authors: Mahaney William C. , Boyer Michael G.
Published: July 2012

Mud polygons forming in a valley train deposit in Teleki Valley on Mount Kenya were studied with respect to their physical, mineralogical, chemical and biological characteristics. Developing in fine-grained alluvium of postglacial age, those polygonal systems are composed of numerous, and nearly isomorphous units, that appear close to existing drainages in areas stripped of vegetation cover. Stream erosion and animal activity (particularly rodents and Mount Kenya hyrax, e.g. cony) appear to be primarily responsible for the loss of plant cover. Field tests show that periodic wetting and drying results in closure and reopening of polygonal cracks; freeze thaw activity was not observed to assist in developing polygonal ground shape. Subsequent laboratory tests on several samples confirm that the lack of expandable clay minerals might inhibit wetting-drying activity in individual polygon samples.
De l’aéropalynologie aux paléocirculations atmosphériques : cas des travertins holocènes
Authors: Geurts Marie-Anne
Published: July 2012

L'étude de la genèse et de la stratigraphie des travertins en Belgique a démontré que : 1) la sursaturation des eaux augmente en période chaude et sèche dans le climat tempéré océanique de Belgique; 2) c'est au Boréal (chaud et sec) que se sont édifiés les dépôts les plus épais en accord avec les conditions physico-chimiques optimales; 3) grâce à une vitesse de sédimentation élevée, ces dépôts ont enregistré des variations polliniques et climatiques de courte durée (quelques siècles) à la fin du Préboréal et au Boréal. Les études aéropalynologiques permettent maintenant d'expliquer les variations à court terme des spectres polliniques comme des modifications de production pollinique en fonction des types de temps dominants, et donc de la circulation atmosphérique, et cela sans faire appel à une modification du couvert végétal arborescent.
A New Framework for the Pleistocene Stratigraphy of the Central St. Lawrence Lowland, Southern Québec
Authors: Lamothe Michel
Published: July 2012

For three decades, a stratigraphic framework involving one glaciation with two major ice advances (represented by the Bécancour Till and Gentilly Till), separated by one brief interstade (represented by the St. Pierre Sediments), has been invoked to explain the lithostratigraphic succession of Pleistocene sediments exposed in the St. Lawrence Lowland of southern Québec. New exposures found along the bluffs of the St. Lawrence River and recent borehole data provide evidence that the Pleistocene depositional sequence is the result of three glacial advances and two nonglacial events, each represented by organic-bearing units. Two lithostratigraphic units (Lotbinière Sand and Lévrard Till) and three climatostratigraphic units (St. Lawrence Stade, Grondines Interstade and Les Becquets Interstade) are introduced in the stratigraphie nomenclature. No definite age can be assigned to the lowermost till (Bécancour?) but it is now believed to be pre-Sangamonian. Field observations and geochronological data suggest the lower and upper interstadial sediments, and an intervening glacial unit represent brief but severe environmental changes that occurred at the beginning of the Wisconsin Glaciation, ca. 90-70 ka BP. This sequence may correlate with marine isotope stage 5a, stage 4, and the earliest part of stage 3. The age of the onset of the last glacial advance (Gentilly Till) is problematic, possibly ranging from 60 to 30 ka BP.
Fiord to Deep Sea Sediment Transfers along the Northeastern Canadian Continental Margin: Models and Data
Authors: Andrews John T.
Published: July 2012

In Alaskan fiords, sedimentation rates are high; during a glacial advance fiord-basin sediments are transported to the ice front to form a shoal which reduces the calving rate. Thus, during successive glacial cycles, sediment is initially stored and then removed from fiord basins. In the fiords of eastern Baffin Island sedimentation rates are, and were, much lower (< 1000 Kg/m2 ka). and fiord-basin fills may span several glacial cycles. This hypothesis is in keeping with the relatively low sedimentation rates on the adjacent shelf (50 to 500 kg/m2 ka) and deep-sea plain (< = 50 kg/m2 ka). The advance of outlet glaciers through these arctic fiords may be explained by the in situ growth of a floating ice-shelf, grounded at the mouth of the fiord. The extent of late Foxe Glaciation in McBeth and ltirbilung fiords can be delimited by raised marine deltas (50-85 m asl) with 14C dates on in situ shells and whalebone of >54 ka. Holocene raised beaches are lower and date <10 ka. These data, plus the absence of tills in raised marine sections along the outer coast, make it difficult to extend grounded ice onto the shelf during the 18 ka global maximum. Piston cores from Tingin. ltirbilung and McBeth fiords vary between 4 and 11 m in length, but only sample a proportion of the total basin-fills.
Paleosols of the Interglacial Climates in Canada
Authors: Tarnocai Charles
Published: July 2012

Although paleosols are useful indicators of paleoclimates. it is first necessary to establish the relationships between the northern limits of the various contemporary soils and the pertinent climatic parameters. It is then necessary to determine the age of the various paleosols and, if possible, their northern limits. Comparison of the distribution and northern limits of the contemporary soils with the distribution and northern limits of the analogous paleosols then permits the reconstruction of the paleoenvironments. For the purposes of comparison the mean annual temperature of the Old Crow area during the Pliocene epoch was also determined (about 4°C) even though this was not an interglacial period. It was found that during the pre-lllinoian interglacial periods the central Yukon had a mean annual temperature of about 7°C while during the Sangamonian interglacial period it had a mean annual temperature of about - 3°C. During the Holocene epoch, the current interglacial period, the climate has been similar to or only slightly cooler than that existing during the Sangamonian interglacial period. The fluctuating position of the arctic tree line (and associated forest soils) during the Holocene epoch, however, indicates that the climate has also been fluctuating during this time. The paleoclimatic reconstruction presented in this paper also relies heavily on both diagnostic soil features and the soil development during the various interglacial periods.
A Conceptual Model for Growth and Decay of the Cordilleran Ice Sheet
Authors: Fulton Robert  J.
Published: July 2012

A conceptual model for growth and decay of the Cordilleran Ice Sheet has evolved over 100 years of Quaternary research in British Columbia. Physiography and location relative to prevailing westerly winds were the main factors controlling the style of glacier build up. The pattern of decay was controlled mainly by physiography. With cooling at the beginning of glaciation, mountain glaciers expanded to become valley glaciers and eventually coalesced on adjacent plateaus or shelves to form an ice sheet. At glacial maximum, this sheet extended from the western margin of the continental shelf to the eastern edge of the Rocky Mountains and from the Columbia Plateau to the central Yukon. The central (highest) part of the ice sheet was hemmed in by mountains, consequently, snowline had to rise nearly to its present elevation before shrinking of the central core could begin. This meant that mountain glaciers which initiated growth of the ice sheet were reduced to near their present dimensions before significant recession could take place in the core area of the ice sheet. As a consequence, large ice masses in the interior of British Columbia stagnated and then shrank to remnants occupying major valleys and eventually were reduced to dead ice blocks buried in glacial debris. This pattern of retreat contrasts with that of ice masses centred on mountain blocks, such as the Alps, where rising of the snowline resulted in recession of ice cap margins back towards original accumulation areas in the central core of the mountains.
Glacier Physics of the Puget Lobe, Southwest Cordilleran Ice Sheet
Authors: Booth Derek  B.
Published: July 2012

The Puget lobe, the southwest-most extension of the Cordilleran ice sheet, provides an excellent opportunity to examine the connection between glacier physics and the resulting products of glaciation. The action of water, at and within the sediments of the glacier bed, is particularly significant for the geologic record of this ice sheet. Physical data and inferred mass balance relationships constrain lobe reconstruction and predict sliding velocities in excess of 500 m/a and water discharges of nearly 1 * 10" m3/a. This sub-glacial water produced a dendritic channel pattern well predicted by static analysis of sub-glacial hydrology. Near to the eastern ice margin, a much larger single channel drained subglacially and episodically, with tributary ice-dammed lakes releasing their water as jokulhlaups. Basal meltwater generated near-hydrostatic water pressures and very low till strengths at the base of the ice sheet. Water pressure dropped only close to the ice margin, allowing normal stresses to rise to significant fractions of the total ice overburden. Thus marginal and interior zones impose contrasting bed conditions. Although observation of sub-glacial deposits will reflect the late-stage passage of the marginal zone, conditions within the ice-sheet interior, far more significant to glacier history and behavior, may be substantially different.
Climatic Conditions in the Western and Northern Cordillera During the Last Glaciation: Paleoecological Evidence
Authors: Mathewes Rolf  W.
Published: July 2012

In the southern Cordillera, paleoecological evidence suggests that climate was variable, from cooler than present by up to 3°C, to possibly similar to modern during the Olympia non-glacial interval (> 59 TO 25-29 ka). The development of open subalpine parkland vegetation in lowlands after 25 ka reflects slow cooling to glacial conditions. Assumptions about continuously cold and dry glacial conditions are tested and disputed. Between 18-19 ka, pollen, plant macrofossil and beetle evidence suggest relatively warm and moist conditions in the Fraser/Puget Lowlands. A tentative correlation can be inferred with the recently defined "Hanging Lake thermal event" around 18-22 ka in the unglaciated Yukon. Further work should be done to test this inference. Paleobotanical data suggest that increasing moisture, rather than increased cooling, was responsible for the late Vashon ice advance in the southwestern Cordillera. The controversy regarding the nature of the vegetation cover in eastern Beringia, north of the main Cordilleran ice sheet, is not yet settled, although evidence to date favours a complex mosaic of tundra and "steppe-tundra" plant communities supporting a greater diversity of grazing large mammals than exist in the area today.
The Cordilleran Ice Sheet and the Glacial Geomorphology of Southern and Central British Colombia
Authors: Ryder June M. , Fulton Robert J. , Clague John J.
Published: July 2012

This paper reviews the current state of knowledge about the Cordilleran Ice Sheet in southern and central British Columbia. Reconstructions of the ice sheet and the styles of ice expansion and déglaciation are based on extensive and varied glacigenic sediments and landforms that date from Late Wisconsinan (Fraser) Glaciation. Late-glacial lakes and sea level changes are also described and related to isostatic and eustatic effects. The timing of ice expansion and recession during Fraser Glaciation was markedly asymmetric: ice build-up commenced about 29 000 years BP, culminated between 14 500 and 14 000 years BP1 and déglaciation was largely completed by 11 500 years BP. Most of this interval appears to have been dominated by montane glaciation, which produced striking erosional landforms. A Cordilleran Ice Sheet existed from only about 19 000 to 13 500 years BP. An older glaciation, probably of Early Wisconsinan age, has been recognized from widespread exposures of drift that underlies Middle Wisconsinan non-glacial sediments. Pre-Wisconsinan drift is present near Vancouver. Drifts of late Tertiary to Middle Pleistocene age have been dated by association with volcanic sequences in the southern Coast Mountains and the central Interior, and by paleomagnetic studies in the southern Interior.
Seismostratigraphy of the Middle St. Lawrence Esturary: A Late Quaternary Glacial Marine to Estuarine Depositional/Erosional Record
Authors: Praeg Dan , d’Anglejan Bruno , Syvitski James  P. M.
Published: July 2012

A buried bedrock trough 350 m deep extends 100 km above Saguenay Fjord beneath the North Channel of the middle estuary. Four of five regional seismostratigraphic units are recognized in and adjacent to the trough; unit 1 (glacial ice-contact) and older sediments might also be present beneath the largely unpenetrated trough axis. Units 2 and 3 represent thick glacial marine sediments deposited in the >550 m deep waters of the Goldthwait Sea after glacial withdrawal ca. 13 ka BP: lower draped muds 10-20 m thick (unit 2) suggest deposition proximal to a retreating ice margin, while upper onlapping muds > 290 m thick (unit 3) record distal basin-filling; lateral transition to a coarse-grained proximal wedge 5*260 m thick (unit 2) is indicated by unit 3 reflectors rising and strengthening towards the Saguenay entrance, where a stable ice-margin ca. 13-11 ka BP supplied sediment to the lower and middle estuary. Unit 4 corresponds to lobes over 30 m thick on both sides of the upper North Channel, recording marginal input from glacial fluvio-deltaic sources. Unit 5 (estuarine sands, gravels and muds =£30 m thick) unconformably overlies glacial units. A smooth unconformity surface records erosion (at least 15 m, to axial depths >150m) by strong currents; irregular relief above depths of 25-50 m might relate to relative sea levels below present ca. 7-6 ka BP. Sand bedforms (apparently inactive) occur at the estuary floor, and possibly buried beneath estuarine muds; buried bedforms would imply an early Holocene genesis. Greatest thicknesses of estuarine mud coincide with adjacent fluvial discharges. Sandy/gravelly veneers form the estuary floor in most places. Mass displacement has disturbed units 3 and 5 along the northern, and locally southern, walls of the North Channel.
Étude dendrochronologique de l’érosion associée aux crues du Saint-Laurent, Saint-Antoine-de-Tilly, Québec
Authors: Desrosiers Marc , Bégin Yves
Published: July 2012

Les phases d'activité littorale dans un site de la rive sud du Saint-Laurent ont été étudiées à l'aide de la dendrochronologie. L'analyse des dates de formation de bois de réaction chez les arbres déstabilisés sous l'effet de décrochements mineurs survenus au pied des versants forestiers a permis d'établir le cadre spatio-temporel de la reprise d'érosion associée aux débordements récents du fleuve. Deux périodes de hauts niveaux de l'eau semblent avoir particulièrement marqué révolution des rives, les décennies 1920 et 1970, au cours desquelles une régression des franges forestières se serait produite en raison d'une érosion accrue. Lors des périodes intercalaires de bas niveaux, soit autour de la décennie 1910 et de 1930 à 1950, la forêt se serait rapprochée du fleuve en colonisant les sédiments de plage. Depuis 1970, l'amplitude et la fréquence des débordements ont considérablement augmenté. Ce changement de régime du fleuve implique de fréquents débordements d'hiver associés aux variations des conditions pluvio-thermiques, aux ouvrages de rétention des grands lacs et au contrôle de débit par des barrages. Les débordements hivernaux contribuent à favoriser une forte activité glacielle sur le littoral.
La modélisation fractale et la variabilité spatiale des phénomènes naturels
Authors: Robert André , Roy André  G.
Published: July 2012

Le modèle fractal a suscité beaucoup d'intérêt récemment en sciences naturelles. Cette théorie de Benoit Mandelbrot s'avère particulièrement pertinente en géographie, puisque le modèle fractal traite de la variabilité spatiale des phénomènes naturels, de l'échelle d'observation de ces phénomènes et des propriétés géométriques résultantes. La première partie de cette revue consiste en une description du modèle fractal et des méthodes qui peuvent être utilisées pour estimer la dimension de Hausdorff et de l'intérêt immédiat des fractales en sciences naturelles. La deuxième partie traite, de façon générale, de l'application des fractales à la variabilité spatiale de divers phénomènes (pédologie, réseaux hydrographiques, turbulence, etc.). Une imbrication de différents niveaux de variation est généralement observée et un des intérêts du modèle provient de la variation de la dimension fractionnaire avec l'étendue d'échelles considérée. La troisième partie est consacrée à l'analyse des surfaces topographiques, de la microéchelle (quelques millimètres) à l'échelle des bassins-versants. Différents types d'utilisation du modèle fractal pour l'analyse des surfaces topographiques sont présentés. Plus particulièrement, il s'agit de l'utilisation des surfaces fractales comme surface initiale pour l'étude des processus géomorphologiques, de même que l'utilisation de la dimension fractionnaire pour caractériser la rugosité des surfaces topographiques (pour des études hydrauliques ou hydrologiques). Cette revue se termine en considérant brièvement les conséquences en géographie physique et en géomorphologie des découvertes récentes de la théorie du chaos. L'outil fractal est privilégié dans l'étude du comportement des systèmes dynamiques.
The Quaternary History of Cumberland Sound, Southeastern Baffin Island: The Marine Evidence
Authors: Jennings Anne  E.
Published: July 2012

Acoustic and core data from Cumberland Sound show that glacial ice derived from the Foxe Sector (Amadjuak Dome) of the Laurentide Ice Sheet advanced to the continental shelf at the mouth of the sound during a late phase of the Foxe Glaciation. The basal lithofacies/acoustic unit (Ai/BUD) in the sound is a massive, black diamicton. On the basis of strati-graphic, acoustic, lithologie and faunal evidence, this unit is interpreted as till. The till is overlain by an ice proximal to ice distal glacial-marine sediment sequence termed the Davis Strait Silt (DSS). The influence of ice retreat is reflected in the foraminiferal assemblages of the DSS. Rapid sedimentation rates in the sound prevailed during deposition of the DSS as shown by the conformable geometry of the DSS. Accelerator Mass Spectrometry dates on molluscs and foraminifera and a single conventional 14C date on disseminated organic material from ice proximal sediment of the DSS (lithofacies B and lower lithofacies C) indicate that the ice retreated rapidly from its probable maximum position on the shelf no earlier than ca. 13,400 BP and into the fiords along the coast of the sound by ca. 8900 BP. Deposition of ice-distal glacial marine sediments (lower lithofacies D) continued in the sound until ca. 7600 BP as the ice margin rapidly retreated into the fiords. Between ca. 8900 BP and ca. 8000 BP, the foraminiferal fauna show that the influence of glacial ice is remote and that "Atlantic Water" impinges on the seafloor. Postglacial sedimentation began in the sound at ca. 7600 BP. Retreat of the ice margin onto land made the fiord basins available as sediment catchments. The reduced sedimentation rates in the sound during this interval are indicated by the change to onlapping basin fill geometry of the Tiniktartuq Silt and Clay (TS&C). Calcareous foraminifera disappear from the sediments by ca. 6300 BP and are replaced by agglutinated foraminifera reflecting "Arctic Water" conditions at the seafloor. The TS&C is presently being deposited in the sound.
Structural Elements and Neotectonics of Prince Edward County, Southern Ontario
Authors: McFall Gail  H.
Published: July 2012

The seismically active Clarendon-Linden Fault of western New York State appears to connect with the Salmon River Fault and possibly with the Picton Fault, both of which cut through Prince Edward County, southern Ontario. Bedrock exposures display a variety of structural features including faults, fractures, and pop-ups which indicate that the region has been subjected to repeated tectonism since the Middle Ordovician. Thus, despite the general perception that Prince Edward County and the rest of the Lake Ontario region is one of low seismic potential, geological and geophysical data suggest otherwise.
Les coulées de pierres glacées : un nouveau type de coulées de pierraille sur les talus d’éboulis
Authors: Hétu Bernard , Van Steijn Henk , Vandelac Pierre
Published: July 2012

Un nouveau type de coulées de pierraille, les coulées de pierres glacées (CPG), a été observé en activité sur un long talus d'éboulis (640 m) de schiste du nord de la Gaspésie. Située en contexte maritime, par 50° de latitude nord, la région possède un climat tempéré humide à hiver froid. Les CPG correspondent à des coulées de pierraille superficielles, sans matrice (openwork), dont la progression est facilitée par l'existence d'une mince pellicule de glace autour des pierres, réduisant ainsi le frottement. Du point de vue dynamique, les CPG s'apparentent aux grain flows. Leur dynamique a été reconstituée grâce : (1) à l'observation de CPG déclenchées artificiellement; (2) à l'étude de CPG naturelles observées en mouvement au cours de l'hiver 1989-90; (3) à l'analyse morphosédimentologique détaillée des dépôts qui en résultent (cartographie à grande échelle, granulomere, fabriques). Déclenchées le plus souvent par les pierres qui mitraillent le haut du talus, elles démarrent juste au pied de la paroi, sur des pentes comprises entre 40° et 42°. Larges de 1 à 3 m, elles avancent par vagues successives à raison de 4,5 m • sec"' en moyenne. Observées à six reprises au cours de l'hiver 1989-90, elles se produisent quand les talus sont déneigés et que les températures quotidiennes oscillent autour du point de congélation. Les plus longues, survenues au printemps, ont parcouru plus de 500 m, pénétrant sur une centaine de mètres dans la forêt qui recouvre la partie inférieure du talus d'éboulis. Elles se sont arrêtées dans un secteur où la pente générale du versant est de 28°-30°. Les CPG façonnent à la surface du talus des chenaux peu profonds, bordés de levées, prolongés par des lobes terminaux à galets fortement imbriqués. En 1989-90, les CPG ont touché 40 % de la surface totale du talus étudié, soit 65 000 m2 environ. Traduit en flux, le volume de débris mobilisé en 1989-90 atteint 4,7 m3-m"'.
Stable Isotopic Variability within Modern Travertines
Authors: Chafetz Henry S. , Lawrence James R.
Published: July 2012

Six hot and two ambient water travertine systems were sampled to determine the relationships between the stable isotopic composition of the travertines and the waters from which they were deposited. This was conducted in order to evaluate the use of geochemical analyses of ancient travertines for the interpretation of the composition of the waters from which they precipitated, climatic conditions at time of formation, etc. The waters displayed down-flow trends of progressively higher (^ 8'3C values, in all 8 systems, and (H) 618O values, in all 6 hot water systems. Whereas the stable isotopic values of the mineral precipitates sometimes showed similar trends, the magnitude of the downflow changes commonly was quite different than that exhibited by the water data. Additionally, different types of precipitates, which formed within centimeters of each other, commonly had different stable isotopic compositions, e.g., crusts which formed at the air/water interface always had higher 813C and 8'8O values than constituents which formed within the immediately subjacent water column. The lack of a simple relationship between stable isotopic composition of the water and the precipitate is due to the fact that the stable isotopic composition of the precipitates are controlled by a number of variables, including the water's composition, temperature, level of saturation, etc. And these variables can change dramatically within very short distances and at the same spot within very short time intervals. Thus, as demonstrated by the stable isotope data, attempting to interpret the composition of the water from the composition of the deposit is a highly risky venture.
The Eastern Canadian Arctic at ca. 6 ka BP: A Time of Transition
Authors: Williams Kerstin M. , Short Susan K. , Andrews John T. , Jennings Anne E. , Mode William N. , Syvitski James P.M.
Published: July 2012

The middle Holocene was a time of definite environmental transition in the Eastern Canadian Arctic. Based on several proxy indicators (pollen, diatoms, foraminifera, molluscs and nearshore sedimentation rates), it appears that a thermal maximum occurred around middle Holocene (6-4 ka), several thousand years after the insolation maximum — a lag caused by the thermal inertia of the earlier massive ice sheet. Terrestrial records indicate that a warming began around 6 ka, both in the subarctic (Labrador - Ungava) and on Baffin Island. Marine records, on the other hand, suggested major water structure changes around 6 ka both in the Northeastern Canadian Arctic and also along the East Greenland coast with evidence of a marine surface water temperature maximum at 8 ka. We hypothesize that the marine circulation changes, both along the Baffin Island and along the East Greenland coasts, were primarily driven by glacio-isostatic uplift of the Arctic Channels. With the cessation of water flow of Atlantic (warmer) origin, and decrease in water volume from the deeper parts of the Arctic Ocean through the Arctic Channels, the export through the Fram and Denmark straits increased and the water column changed. Changes in the concentration and duration of sea ice along the eastern Canadian coast would have had important repercussions on the biota of the coastal marine and terrestrial ecosystems.
Vegetation and Climate of Maritime Canada 6000 Years BP: A Synthesis
Authors: Jetté Hélène , Mott Robert J.
Published: July 2012

Environmental conditions (vegetation and climate) of Maritime Canada are reconstructed as a regional contribution to a national synthesis on the paleoenvironment of Canada 6000 yr BP. Ten new sites, including three complete sequences and seven short sequences bracketing the 6 ka period, are added to the existing pollen dataset for this region. The vegetation prevalent 6000 yr BP in New Brunswick was a mixed coniferous-deciduous forest with pine, mostly white pine (Pinus strobus) in the northwest, and a mixed coniferous-deciduous forest with hemlock (Tsuga canadensis) in the south and southeast. In the northwest, fir (Abies) replaced pine at high elevations and a boreal forest grew on the New Brunswick Highlands. The dominant vegetation at 6000 yr BP in Prince Edward Island and Nova Scotia was a mixed coniferous-deciduous forest with hemlock dominating. Cape Breton Island was covered by a mixed coniferous-deciduous forest with pine and/or fir, except for the southern part of the Island where hemlock was probably present. Analysis of the fossil sites indicate that a warm-dry period influenced the composition of the vegetation 6000 yr BP.
A 6 ka BP Reconstruction for the Island of Newfoundland from a Synthesis of Holocene Lake-Sediment Pollen Records
Authors: Brown MacPherson Joyce
Published: July 2012

A 6 ka reconstruction for the island of Newfoundland is presented in the context of a synthesis of Holocene pollen records for twelve sites within or at the margin of the boreal forest, five of which are new. Climatic reconstruction is based primarily on representation of the major boreal taxa: balsam fir, spruce, birch and pine, with charcoal data for some sites. The period of greatest Holocene warmth began at 6 ka. Although temperatures at inland sites were at or close to modern values as early as 8.5-8.0 ka, it was not until 6 ka on the Avalon Peninsula, in the southeast, and 5.5 ka in the north, that coastal sites registered expansion of more thermophilous taxa. Thus oceanic warming lagged terrestrial warming. Temperatures during the period of greatest warmth were no more than 1.0°C higher than modern, based on fluctuations of the upper forest limit and post-Hypsithermal contraction of the range of indicator taxa. Fire importance increased after 6 ka as pine expanded, but moisture availability also increased. The first indications of cooling occurred on the coast at 4.5-4.0 ka, but at different times after 4.0 ka inland; thus oceanic cooling led terrestrial cooling. The latest Holocene has been cool, moist and relatively free from fire.
Early Postglacial Sedimentation of Lower Seymour Valley, Southwestern British Columbia
Authors: Lian Olav B. , Hickin Edward J.
Published: July 2012

In lower Seymour Valley, much of the sediment derived from the erosion of valley-side drift (paraglacial sediments) remains in storage in the form of alluvial fans and aprons. Fluvial incision into these features has exposed sections for lithostratigraphic and chronological study. Radiocarbon dating of organic-rich beds within these deposits indicate that paraglacial sedimentation of lower Seymour Valley commenced before 11.4 ka, was periodic, and was essentially complete by about 9 ka; Seymour River had incised to its present vertical position by about 5 ka. Furthermore, our radiocarbon ages indicate that, although paraglacial sedimentation commenced shortly following deglaciation when the climate was cool and moist, a significant amount of sedimentation occurred during a transition from wet and moist climate to warm and dry (xerothermic) conditions (ca. 10 ka). Charcoal-rich beds indicate that some erosional events may have been a result of slope instability caused by fire.
La sous-séquence des sédiments de Saint-Pierre — rythmites du Saint-Maurice — Sables des Vieilles-Forges, Pléistocène supérieur, vallée du Saint-Laurent, Québec
Authors: Clet Martine , Occhietti Serge
Published: July 2012

Le Quaternaire de la vallée et de l'estuaire moyen du Saint-Laurent est caractérisé par des séquences sédimentaires emboîtées. La séquence supérieure est la mieux représentée. Elle comprend des dépôts non glaciaires inférieurs, associés notamment à l'Interstade des Becquets, le Till wisconsinien de Gentilly et les sédiments des mers de Champlain et de Goldthwait. La base de cette séquence est emboîtée dans l'Argile de La Pérade (Mer de Cartier, Sangamonien supérieur) dont le contenu pollinique témoigne de la recolonisation végétale des surfaces déglacées et d'un bref épisode de réchauffement avant l'implantation de la forêt boréale. Au-dessus de la surface d'emboîtement, les Sédiments fluviatiles de Saint-Pierre ont un contenu pollinique qui indique le maintien d'une forêt boréale. Les Rythmites du Saint-Maurice, sus-jacentes, représentent au moins 1000 ans de sédimentation dans le Lac de La Vérendrye. Le contenu pollinique et les macrorestes de la zone inférieure de ces rythmites indiquent l'inondation, dans les basses terres, d'une sapinière associée à des essences thermophiles plus abondantes que dans les sédiments fluviatiles antérieurs. La zone supérieure évoque le retour à une pessière avec diminution des espèces thermophiles. Au-dessus, les Sables des Vieilles-Forges comprennent trois lithozones : sable fin lacustre, sable deltaïque et dépôts proglaciaires. Leur contenu pollinique témoigne de la détérioration du climat : la forêt boréale à Picea évolue progressivement vers une toundra forestière. Les zones supérieures sont stériles. Cette palynostratigraphie permet d'établir des corrélations entre les différents sites répartis sur plus de 400 km dans la vallée du Saint-Laurent et de différencier des unités et des séquences qui semblaient similaires.
Chronologie de la déglaciation en Gaspésie : nouvelles données et implications
Authors: Richard Pierre J. H. , Veillette Jean J. , Larouche Alayn C. , Hétu Bernard , Gray James T. , Gangloff Pierre
Published: July 2012

De nouvelles datations à l'accélérateur de particules des premiers macrorestes végétaux terricoles accumulés dans les sédiments postglaciaires d'une douzaine de lacs répartis en Gaspésie et au Bas-Saint-Laurent bouleversent entièrement la chronologie générale de la déglaciation de ces régions. Ces données indiquent que la Gaspésie est restée sous l'emprise des glaces jusque vers 10 500-10 000 ans BP sauf en bordure de la péninsule, notamment le long de la côte septentrionale où la déglaciation de l'arrière-pays date d'au moins 12 500 ans BP par endroits. La déglaciation finale se serait produite vers 9500-9000 ans BP dans la région de Murdochville. La chronologie de déglaciation qui se dégage de ces données s'accorde maintenant avec celle des provinces maritimes, notamment pour ce qui est de l'existence de masses glaciaires actives durant l'épisode du Dryas récent. Les conséquences sont importantes, tant pour la modélisation du retrait des glaces, la colonisation végétale et l'accessibilité du territoire aux populations humaines que pour les reconstitutions climatiques.
La politique imaginaire de Joseph Roth
Authors: Robin Régine
Published: July 2012

II s'agit de montrer comment fonctionne la «toute-puissance» de l'écrivain non seulement dans la littérature, mais dans la vie transformée en fiction. L'auteure interroge les lieux où se met en place, à travers le mythe de l'Empire des Habsbourg, la constitution imaginaire de soi comme sujet et comme sujet d'une politique imaginaire qui va permettre aux fantasmes de prendre corps dans l'écriture à la fois autobiographique, fïctionnelle et aussi dans la correspondance. Les multiples personnalités de Joseph Roth, que ce soit à travers ses propres métamorphoses ou celles de ses personnages, inaugurent l'éclatement postmoderne des identités, question qui nous concerne au premier chef aujourd'hui.
Dans les marges du texte : l’annotation des Météores de Michel Tournier
Authors: Besa Carles
Published: July 2012

Analyse des notes infrapaginales incluses dans Les Météores de Tournier. Cette pratique peu courante dans le domaine de la fiction tend à laisser supposer l'existence d'un Lecteur Modèle capable de coopérer à l'actualisation textuelle de la façon dont l'auteur a agi générativement. L'ensemble du récit participe d'une multiplicité de formes et d'une orchestration audacieuse qui innove par rapport aux romans précédents de Tournier.
Germaine Guèvremont (1900‑1968)
Authors: Roy Gabrielle
Published: July 2012

Éloge funèbre de Germaine Guèvremont, écrit en 1969 pour la Société royale
Anti-heroes of the Canadian Expeditionary Force
Authors: Cook Tim
Published: July 2012

The civilian-soldiers that formed the ranks of the Canadian Corps created a unique soldiers’ culture composed of songs, poetry, doggerel, cartoons, and newspapers during the course of the war to cope with the strain of service. This unique soldiers’ culture offers keen insight into soldiers’ experience. The antihero was one of the most important themes running through soldiers’ culture. In a war where soldiers were elevated to heroes by civilians, the soldiers in turn often chose instead to emphasis the antiheroic in their cultural products. There were several antihero archetypes in Canadian soldiers’ culture, and this essay will examine three: British cartoonist Bruce Bairnsfather’s Old Bill, “old soldiers,” and malingers. While these archetypes were separate, with identifiable qualities, they also bled into one another, creating a rich tapestry of anti-heroic cultural products and icons. These antiheroes provided a voice to the soldiers, even at times a language by which the soldiers could make sense of their war experience. The antiheroes were not always emulated, but their unheroic actions resonated with the trench warriors.
Visual Interpretations, Cartoons, and Caricatures of Student and Youth Cultures in University Yearbooks, 1898–19301
Authors: Panayotidis E. Lisa , Stortz Paul
Published: July 2012

Students have always been integral in the development of the university in Canada. Driven by personal, professional, and political agendas, student experiences, understandings, and narratives helped construct the academic and intellectual cultures of universities. In their relationships with professors, administrators, and the spaces they inhabit, students crucially contributed to the university as a historically vibrant idea and social institution. As cast by the students, the university was clearly expressed in variant and creative ways through the annual yearbook. In particular, within the yearbook, the practice of parody in cartoons and caricatures was powerful in depicting the imagined worlds of academe as seen through the students’ eyes, and importantly how the students saw themselves and their life on campus. Using yearbooks from three universities — Toronto, Alberta, and British Columbia – visual images are studied that reveal underlying intentions to comment, marginalize, ridicule, and esteem groups of students according to both ascribed and self-imposed socialized hierarchical structures and codes of expectations and behaviour. Among the universities, the visual satire was consistent in tone and image, exposing the historic place and activities of students in the early university and in society, the contingent formation of student identities, and the nature of the pursuit of academic knowledge and credentials by youth in early-twentieth Century Canada.
The Refugee ritual: Sopron students in Canada
Authors: Madokoro Laura
Published: July 2012

In the power politics of international migration, the relationship between migrants and the states that receive them are inherently uneven. This is particularly true of the international refugee regime and the manner in which refugees have been identified and resettled in the postwar period. This paper traces the journey of 200 student refugees from Sopron University in Hungary to the University of British Columbia in 1956, following the failure of the Hungarian Revolution. It argues that the manner in which the Sopron students were selected and then settled in Canada assumed ritualistic characteristics with which the federal government attempted to shape their identity and normalize their entry into Canadian society. Tracing the Sopron students’ refugee experience beginning with their flight from Hungary to their graduation from the University of British Columbia, this paper identifies four components to the refugee ritual: selection, movement, settlement and commemoration and argues that because the Sopron forestry students migrated as a group, they experienced the ritual experience to a far greater degree than other student refugees in Canada.
To Visit and to Cut Down: Tourism, Forestry, and the Social Construction of Nature in Twentieth-Century Northeastern Ontario
Authors: Thorpe Jocelyn
Published: July 2012

This paper relies on the insights of social nature scholarship to trace the historical forest conservationist and tourism discourses through which Temagami, Ontario, became famous as a site of wild forest nature. The discursive practices associated with Temagami tourism and forest conservation in the early twentieth century did not merely reflect a self-evident wilderness, but rather constituted the region as a wild place for non-Native people both to visit and to extract for profit. The social construction of Temagami wilderness came to appear natural through the erasure of the Teme-Augama Anishnabai’s claim to the Temagami region, an erasure that persisted in environmentalists’ struggle to “save” the Temagami wilderness in the late 1980s. Revealing the histories and power relationships embedded in wilderness is part of the struggle toward greater justice.