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Hilary H Birks - One of the best experts on this subject based on the ideXlab platform.

  • full Glacial upland tundra vegetation preserved under tephra in the beringia national park seward peninsula alaska
    Quaternary Science Reviews, 2001
    Co-Authors: Victoria G Goetcheus, Hilary H Birks
    Abstract:

    The nature of the full-Glacial vegetation of Beringia has been the subject of a great deal of investigation and debate. Here we present a reconstruction of an intact example of the full-Glacial upland vegetation of part of the northern Seward Peninsula at one point in time. The area was blanketed by more than 1 m of tephra ca. 18,000 14C BP (ca. 21,500 cal. BP), and the former land-surface was preserved in the permafrost. The discovery of the land-surface provides a unique opportunity to study a fossil ecosystem preserved in situ. Macrofossils were used to reconstruct the vegetation growing at several sites on the buried land-surface. The macrofossil assemblages indicate a vegetation characterized by graminoids and forbs, with the occasional occurrence of Salix arctica. The vegetation was dominated by Kobresia myosuroides, other sedges (Carex), and grasses, with a "ne-scale mosaic related to snow accumulation and moisture availability. Overall, the vegetation was a closed, dry, herb-rich tundra-grassland with a continuous moss layer, growing on calcareous soil that was continuously supplied with loess. Nutrient renewal by loess deposition was probably responsible for the relatively fertile vegetation, and the occurrence of a continuous mat of acrocarpous mosses. Good physiognomic analogues can be suggested, but no exact modern vegetational analogues have been found, probably because the full-Glacial Environment and climate with loess deposition do not occur today. ( 2000 Elsevier Science Ltd. All rights reserved.

Simona Fratianni - One of the best experts on this subject based on the ideXlab platform.

  • climate variations in a high altitude alpine basin and their effects on a Glacial Environment italian western alps
    Atmosfera, 2015
    Co-Authors: Elisa Giaccone, Nicola Colombo, Fiorella Acquaotta, Luca Paro, Simona Fratianni
    Abstract:

    The main objective of this study is to evaluate the variations of climatic parameters (temperature, rain and snow) measured by two weather stations (Formazza and Sabbione) that have never been analyzed before, located in a high Glacial catchment (the Sabbione basin in the Italian Western Alps). The study highlights the climatic evolution of the Alpine basin during the last 60 years (1950-2012): climate change has caused a pronounced Glacial decline originated by ablation augmentation, due mainly to increasing air temperatures and to reduced alimentation caused by a fresh snow decrease. The cross-correlation test shows that temperatures affect the Glacial retreat dynamics more than snowfall. PeriGlacial and permafrost landforms (e.g., patterned grounds, rock glaciers) have been identified within the Little Ice Age (LIA) Glacial deposits, which indicate the ongoing transition from Glacial/proGlacial to periGlacial Environments. Furthermore, in order to better identify the periGlacial domain in the basin, a map of mean annual air temperature (MAAT) was produced based on climatic analysis.

  • climate variations in a high altitude alpine basin and their effects on a Glacial Environment italian western alps
    Argumentos, 2015
    Co-Authors: Elisa Giaccone, Nicola Colombo, Fiorella Acquaotta, Luca Paro, Simona Fratianni
    Abstract:

    Resumen en: The main objective of this study is to evaluate the variations of climatic parameters (temperature, rain and snow) measured by two weather stations (Form...

Paul A Mayewski - One of the best experts on this subject based on the ideXlab platform.

  • climatic and tectonic significance of taboche lake khumbu region nepal
    iScience, 2021
    Co-Authors: Ananta Prasad Gajurel, Mary Hubbard, Bibek Giri, Aurora C Elmore, Sanjit Maka, Patrick A Rafter, Aaron E Putnam, Sandra Elvin, Alex Tait, Paul A Mayewski
    Abstract:

    Summary The Everest region is characterized by its alpine Glacial Environment. In an effort to understand Environmental change and tectonic activity, our team cored Taboche Lake, situated at 4,712 m along the western margin of the Ngozumpa Glacier. This research catalogs past earthquakes using geological records of the lake core that are important for the assessment of future earthquake hazards in the region and provides information for tectonic risk of Glacial lake floods. Core grain size characteristics and internal sedimentary structures from computed tomographic scan were coupled with radiocarbon dating of organic matter preserved in the core to reconstruct the Environmental history of the area. The 58-cm-long core consists of laminated silty sands and sandy silts with particle diameters

  • climatic and tectonic significance of taboche lake khumbu region nepal
    Social Science Research Network, 2020
    Co-Authors: Ananta Prasad Gajurel, Mary Hubbard, Bibek Giri, Aurora C Elmore, Sanjit Maka, Patrick A Rafter, Aaron E Putnam, Sandra Elvin, Alex Tait, Paul A Mayewski
    Abstract:

    The Mount Everest region is characterized by its alpine Glacial Environment. In an effort to understand Environmental change in the area, our team cored Taboche Lake, situated at 4,712 m along the western margin of the lateral moraine of the Ngozumpa Glacier. This research catalogues past earthquakes using geological records of the lake core that are important for the assessment of future earthquake hazards in the region. To achieve the aims of the study, core grain size characteristics and internal sedimentary structures from CT scan tomography, were coupled with radiocarbon dating of organic matter preserved in the core to reconstruct the Environmental history of Loboche Lake. The 58 cm-long core consists of laminated silty sands and sandy silts with particle diameters less than 2 mm, covering  ∼ 2,000 years of sedimentation history. Syn-sedimentary deformational structure, folding of sediments, rhythmically alternating dark- and light-coloured laminations, and turbidites are discussed in terms of their origins as past climatic and tectonic indicators.

Chienlu Ping - One of the best experts on this subject based on the ideXlab platform.

  • the full Glacial Environment of the northern seward peninsula alaska reconstructed from the 21 500 year old kitluk paleosol
    Quaternary Research, 2000
    Co-Authors: Claudia Hofle, Mary E Edwards, David M Hopkins, Daniel H Mann, Chienlu Ping
    Abstract:

    PaleoEnvironmental conditions are reconstructed from soils buried under volcanic ash ca. 21,500 years ago on the Seward Peninsula. Soil development was minimal, reflecting the continuous regional deposition of loess, which originated from river floodplains and the exposed Chukchi shelf. Cryoturbated soil horizons, ice wedges, and ice-lens formation indicate a permafrost Environment and mean annual temperatures below −6° to −8°C. Shallow active layers (average 45 cm), minimal evidence for chemical leaching of soils, and the presence of earthen hummocks indicate a cold and seasonally dry climate. Neither steppe nor polar desert soils are appropriate analogues for these zonal soils of loess-covered central Beringia. No exact analogues are known; however, soils underlying dry tundra near the arctic coast of northern Yakutia, Russia, and under moist, nonacidic tundra of the Alaskan North Slope have properties in common with the buried soils.

Jane K Hart - One of the best experts on this subject based on the ideXlab platform.

  • Glacial Environment monitoring using sensor networks
    2005
    Co-Authors: Paritosh Padhy, Kirk Martinez, Alistair Riddoch, H Royan L Ong, Jane K Hart
    Abstract:

    This paper reports on the implementation, design and results from GlacsWeb, an Environmental sensor network for glaciers installed in Summer 2004 at Briksdalsbreen, Norway. The importance of design factors that influenced the development of the overall system, its general architecture and communication systems are highlighted.

  • the interrelation of glaciotectonic and glaciodepositional processes within the Glacial Environment
    Quaternary Science Reviews, 1991
    Co-Authors: Jane K Hart, G S Boulton
    Abstract:

    Abstract In recent years it has been recognised that ice/sediment coupling occurred beneath the Quaternary ice sheets that advanced over the soft sediments of lowland areas. This paper looks in detail at the effects of this coupling on the sediments, which results in glaciotectonic deformation, and also discusses the interaction of deformation and deposition within the subGlacial Environment. Two types of glaciotectonic deformation are discussed that are produced by the active movement of ice: (1) proGlacial tectonics at the margin, which include compressive fold styles such as listric thrusts and faults and open folding; (2) subGlacial tectonics formed beneath the glacier, which include fold styles resulting from simple shear and represent a soft rock purely dynamic shear zone. Styles of deformation associated with stagnant ice are also investigated. We argue that glaciotectonic deformation is a common phenomenon and an integral part of geological record from continental ice sheets. It is suggested that zones of deformation within the sediment are related to similar zones of strain in the ice sheet, and complex deformation sequences are produced by the superimposition of these differing styles upon one another as the ice sheet advances and retreats. It is also argued that subGlacial deposition and deformation are related and that on soft beds underformed till is rare, whilst deformed till is very common.