نتایج جستجو برای: glacial geology

تعداد نتایج: 21695  

2017
S. Cauvy-Fraunié T. Condom A. Rabatel M. Villacis D. Jacobsen

Worldwide, the rapid shrinking of glaciers in response to ongoing climate change is modifying the glacial meltwater contribution to hydrosystems in glacierized catchments. Determining the influence of glacial runoff to streams is therefore of critical importance to evaluate potential impact of glacier retreat on water quality and aquatic biota. This task has challenged both glacier hydrologists...

Journal: :Nature 1871

2006
Robert S. Anderson Peter Molnar Mark A. Kessler

[1] Glacial occupation of alpine valleys results in a distinct signature in the long-valley profile, including steepening of the profile in the headwaters, flattening at lower elevations, and a step in the profile at the convergence of headwater tributaries. We present analytic results for glacial erosion patterns by making the following assumptions: (1) the initial profile is linear, (2) the w...

2006
Peter Huybers

An agemodel not relying upon orbital assumptions is estimated over the last 2Ma using depth in marine sediment cores as a proxy for time. Agemodel uncertainty averages 10Ka in the early Pleistocene ( 2–1Ma) and 7Ka in the late Pleistocene ( 1Ma to the present). Twelve benthic and five planktic d O records are pinned to the agemodel and averaged together to provide a record of glacial variabilit...

Journal: :Molecular ecology 2008
Tyler S Zemlak Evelyn M Habit Sandra J Walde Miguel A Battini Emily D M Adams Daniel E Ruzzante

We employed DNA sequence variation at two mitochondrial (control region, COI) regions from 212 individuals of Galaxias platei (Pisces, Galaxiidae) collected throughout Patagonia (25 lakes/rivers) to examine how Andean orogeny and the climatic cycles throughout the Quaternary affected the genetic diversity and phylogeography of this species. Phylogenetic analyses revealed four deep genealogical ...

2008
Jason P. Briner Gifford H. Miller Robert Finkel Dale P. Hess

Organized conduits of fast ice flow at the fringe of present and past ice sheets move the majority of ice from ice sheet interior to periphery. These relatively narrow corridors play a critical role in feedbacks between landscape evolution and ice sheet dynamics. Here we combine bedrock Be concentrations with distribution of lakes on Baffin Island, Arctic Canada, to constrain the pattern of gla...

2016
Gabriele Casazza Fabrizio Grassi Giovanni Zecca Luigi Minuto

Quaternary glaciations and mostly last glacial maximum have shaped the contemporary distribution of many species in the Alps. However, in the Maritime and Ligurian Alps a more complex picture is suggested by the presence of many Tertiary paleoendemisms and by the divergence time between lineages in one endemic species predating the Late Pleistocene glaciation. The low number of endemic species ...

Journal: :American journal of botany 2015
Karen B Barnard-Kubow Catherine L Debban Laura F Galloway

PREMISE OF THE STUDY Glacial cycles have influenced the genetic structure of many species. In addition to facilitating genetic divergence, isolation in multiple glacial refugia may have contributed to the development of genetic incompatibility and reproductive isolation. We examined the phylogeography of Campanulastrum americanum, a monocarpic herbaceous plant that exhibits strong intraspecific...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2005
Joy K Ward John M Harris Thure E Cerling Alex Wiedenhoeft Michael J Lott Maria-Denise Dearing Joan B Coltrain James R Ehleringer

The Rancho La Brea tar pit fossil collection includes Juniperus (C3) wood specimens that 14C date between 7.7 and 55 thousand years (kyr) B.P., providing a constrained record of plant response for southern California during the last glacial period. Atmospheric CO2 concentration ([CO2]) ranged between 180 and 220 ppm during glacial periods, rose to approximately 280 ppm before the industrial per...

2011
T. Tadono S. Kawamoto T. Yamanokuchi J. Ukita N. Tomiyama H. Yabuki

This study is describe to development of glacial lake inventory in the Bhutan Himalayas using the Panchromatic Remote Sensing Instrument for Stereo Mapping (PRISM) and the Advanced Visible and Near Infrared Radiometer type-2 (AVNIR-2) onboard the Advanced Land Observing Satellite (ALOS, nicknamed “Daichi”) to contribute to the evaluation of potential Glacial Lake Outburst Floods (GLOFs) and the...

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