Amérique du Nord ; Circulation atmosphérique ; Great Lakes ; Géographie physique ; LakeSuperior ; Pression atmosphérique ; Température ; Variation climatique
Variations in atmospheric circulation and spatial and temporal patterns of sea-level pressure anomalies over eastern North America are highly correlated in time with temperature trends in the LakeSuperior area. LakeSuperiorregion temperature
trends have not been the same for all seasons. January and July temperatures were highest in the mid-1930s| those for April and October culminated later. Differences in the timing of temperature peaks within the LakeSuperiorregion are related mainly
mainly the temperatures over the eastern part of region. About seventy to eighty percent of the temperature variance for the LakeSuperiorregion is related to about twenty-five to thirty percent of the pressure variance for eastern North America.
to variations in pressure anomalies over western Canada and with associated anomalous air flow components across the Lake. Pressure anomalies over the southwestern United States and opposite anomalies to the east have been less important and they have affected
Seismic reflection study of recessional moraines beneath LakeSuperior and their relationship to regional deglaciation
Amérique du Nord ; Déglaciation ; Glaciaire ; Great Lakes ; Géographie de l'Amérique ; Holocène ; LakeSuperior ; Moraine de retrait ; Quaternaire zones moyennes ; Sismique réflexion
An offlapping sequence of glacial and glacial-lacustrine sediments overlying bedrock is recognized in west-central LakeSuperior that is progressively younger to the northeast. Four facies are recognized on the basis of geomorphologic and acoustic
), and basal till (facies D). The prominent moraines of facies B are unusually thick and are believed to mark the ice-margin shorelines of successive major proglacial lakes that formerly occupied parts of western LakeSuperior. The moraines are tentatively
correlated with Glacial Lake Duluth (unit 1), Glacial Lake Washburn (unit 2), and Glacial Lake Beaver Bay (unit 3), the most prominent of lakes drained via the progressively lower outlets via the Moose Lake/Brule-St. Croix Rivers, the Huron Mountains
, and the Au Train-Whitefish regions, respectively.
Regeneration dynamics and genetic variability of sugar maple (Acer saccharum (Marsh.)) seedlings at the species'northern growth limit, LakeSuperior Provincial Park, Canada
The AA. examine the demographics and genetic properties of Acer saccharum seedlings across the regional and local vegetation transition in LakeSuperior Provincial Park, LSPP. Objectives are to determine if density age, size, growth and gene
frequencies varied across the regional and local transitions, and to examine the relationship between growth and regional temperature and precipitation. Genetic variability is great with no chort preference for topographic position detected.
. Cependant, dans la partie nord du Lac Supérieur, la sédimentation rythmique s'est continuée jusqu'à 8 200 B. P. et jusqu'à plus ou moins 8 000 B. P. dans la région de la baie Nipigon.
Animaux à fourrure ; Chasse ; East North Central States ; Ecologie ; Ecologie humaine ; Environnement ; Etats-Unis ; Faune ; Fourrure ; Great Plains ; Géographie de l'Amérique ; Géographie historique ; Indiens, ethnies ; LakeSuperior, région
Calcareous till facies north of LakeSuperior, Ontario : implications for Laurentide ice streaming
Etude de la texture, de la teneur en carbonate et de la composition lithologique de la fraction grossière des tills carbonatés des régions de Geraldton et Hemlo. Leur présence et leur uniformité sur de grandes étendues témoignent d'un important
into the Lake Michigan basin about 11,700 BP, and an advance into the LakeSuperior basin about 9 900 BP. In addition, the beginning of late Wisconsinan glaciation, before 20,000 BP, is fairly well documented. None of the fluctuations in the western part
Impact of lake-level and climate changes on microbial communities in a terrestrial permafrost sequence of the El'gygytgyn Crater, Far East Russian Arctic
Arctic Region ; Asian part of Russia ; Carbon cycle ; Climatic change ; Ecosystem ; Holocene ; Lake level ; Micro-organism ; Palaeobiogeography ; Periglacial features ; Permafrost ; Quaternary ; Upper Pleistocene
Cambio climático ; Ciclo del carbono ; Cuaternario ; Ecosistema ; Holoceno ; Microorganismo ; Nivel lacustre ; Paleobiogeografía ; Pergelisol ; Periglaciar ; Pleistoceno superior ; Rusia de Asia ; Ártica
The AA. investigated the changing distribution of permafrost microorganisms in response to climate and lake-level changes. The permafrost core was drilled at the near shore of Lake El'gygytgyn, and a combined microbiological and lipid biomarker
the Allerød, the abundance of Bacteria and Archaea started to increase and the lake-level change is evidenced by the relative proportion of archaeal biomarkers. After a small decrease during the colder Younger Dryas, the TOC content and the microbial signals
in Louisiana, Belgians in Wisconsin, Danes in Iowa and Minnesota, Norwegians in Wisconsin, Finns in the LakeSuperiorRegion, German-Russian Mennonites in Manitoba, Czechs in South Dakota, Ukranians in Western Canada, Navajo in the American Southwest, Spanish
this ecotone zone. Within LakeSuperior Provincial Park, Ontario, they characterize the regeneration status of tree species at and near the northern limit of sugar maple, and identify temporal colonization patterns of dominant tree species to determine
In light of regional warming trends over the past 100 years and projections for even warmer conditions in the future, the AA. sought to characterize the current age structure and regeneration status of both sugar maple and boreal tree species within
El Cretacico Superior y la morfologia estructural en la costa sur del seno Skyring (Magallanes)
Analyse de la composition pétrographique et de la structure géologique d'une petite région sise à l'extrême sud du Chili. L'A. avance quelques hypothèses relatives à l'origine des formations locales. (OP).
zone is postulated with mean July temperatures in the range 11 to 14C. If the cold environment was restricted, however, the climate may have been similar to that of the LakeSuperiorregion with a mean July temperature of 17C.
. Included in this group is the weevil Vitavitus thulius, known only from two localities in Northwest Territories. The sedimentary environment indicated by the beetles was a small lake, rich in aquatic and semi-aquatic vegetation. The margins were
characterized by open areas and spruce woodland. Species with arctic-alpine distributions indicate a cold environment, but whether it was regional or local in extent could not be determined. If regional, a climate similar to that of the tundra forest transition
Late Pleistocene and late Holocene lake highstands in the Pyramid Lake subbasin of Lake Lahontan, Nevada, USA
C 14 dating ; Lake ; Lake level ; Nevada ; Palaeoclimate ; Quaternary ; Shoreline ; Stratigraphy ; United States of America
subbasin. The AA. briefly compare their findings to previously published post-highstand Lahontan lake-level curves and other regional paleoclimate indicators.
Shoreline geomorphology, shoreline stratigraphic position, and radiocarbon dates of organic material obtained from trench and quarry exposures provide evidence for 2 significant post-Lahontan highstand lake transgressions in the Pyramid Lake
Lake Michigan beach-ridge and dune development, lake level, and variability in regional water balance
Aerial photography ; C 14 dating ; Dune ; Holocene ; Lake ; Lake level ; Michigan ; Palaeoclimatology ; Quaternary ; United States of America ; Water balance
This paper reports the results of AMS radiocarbon dates of plant macrofossils associated with dune formation and growth, determines the historical relationships among beach-ridge formation, lake-level fluctuation, and regional climatic variation
, and finally provides an interpretation of lake-level and regional climate history based on dune morphology and the radiocarbon chronology of ridge formation.
Stream geomorphology in a mountain lake district : hydraulic geometry, sediment sources and sinks, and downstream lake effects
Channel geometry ; Drainage network ; Glacial lake ; Idaho ; Lake ; Mountain ; Stream ; United States of America ; Watershed
downstream patterns in channel form including analyses of sediment entrainment and hydraulic geometry in one catchment with a lake. Furthermore, they collected data from 33 stream reaches throughout the region to compare channel form and functions among
Lakes in the Sawtooth Mountains, Idaho, were created during glaciation and the AA. sought to understand how and to what extent glacial morphology and lake disruption of fluxes control stream physical form and functions. First, they described
catchments with lakes, meadows (filled lakes), and present lakes. The results suggest that sediment sinks, such as lakes, in addition to sources, such as tributaries, are important local controls on mountain drainage networks.
A influência atlântica no clima da Estremadura portuguesa durante o Paleolítico superior : os resultados geoquímicos da gruta do Caldeirão
Etude de l'influence atlantique dans le climat de l'Estremadura, d'après les données géochimiques obtenues dans une grotte de cette région portugaise. - (CAM)
Estudio del Terciario superior y del Quaternario del Campo de Calatrava, Ciudad Real
La région étudiée est située au S des monts de Tolède. On en analyse tant la topographie que le climat, en les situant dans le contexte de la Meseta méridionale. Distingue finalement 4 entités morphologiques. (A. Garcia Ballesteros).