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526 full-text articles. Page 11 of 14.

Evolution With Depth From Detrital To Authigenic Smectites In Sediments From And-2a Drill Core (Mcmurdo Sound, Antarctica), Francesco Iacoviello, Giovanna Giorgetti, Fernando Nieto, Isabella Turbanti Memmi 2012 Università degli Studi di Siena

Evolution With Depth From Detrital To Authigenic Smectites In Sediments From And-2a Drill Core (Mcmurdo Sound, Antarctica), Francesco Iacoviello, Giovanna Giorgetti, Fernando Nieto, Isabella Turbanti Memmi

ANDRILL Research and Publications

We have examined the nature and origin of smectites in glaciomarine sediments of the AND-2A drill core (McMurdo Sound, Antarctica) by means of X-ray diffraction (XRD) analyses on the clay fraction, field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM) observations and SEM-EDS microanalyses on smectite particles. Relying on the smectite variation throughout the drill core it was possible to split the sequence into three units. Smectites throughout the core are either detrital or authigenic. Detrital smectites are close to montmorillonite-beidellite in composition while newly-formed smectites frequently have higher Fe-Mg contents and intermediate compositions between the saponite and nontronite ...


Late Pleistocene And Holocene Aged Glacial And Climatic Reconstructions In The Goat Rocks Wilderness, Washington, United States, Joshua Andrews Heard 2012 Portland State University

Late Pleistocene And Holocene Aged Glacial And Climatic Reconstructions In The Goat Rocks Wilderness, Washington, United States, Joshua Andrews Heard

Dissertations and Theses

Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred downstream from these glaciers. Closest to modern glacier termini are Little Ice Age (LIA) moraines that were deposited between 1870 and 1899 AD, according to the lichenometric analysis. They are characterized by sharp, minimally eroded crests, little to no soil cover, and minimal vegetation cover. Glacier reconstructions indicate that LIA glaciers covered 8.29 km2, 76% more area than modern ice coverage. The average LIA equilibrium ...


Glacier-Bed Geomorphic Processes And Hydrologic Conditions Relevant To Nuclear Waste Disposal, Neal R. Iverson, Mark Person 2011 Iowa State University

Glacier-Bed Geomorphic Processes And Hydrologic Conditions Relevant To Nuclear Waste Disposal, Neal R. Iverson, Mark Person

Geological and Atmospheric Sciences Publications

Characterizing glaciotectonic deformation, glacial erosion and sedimentation, and basal hydrologic conditions of ice sheets is vital for selecting sites for nuclear waste repositories at high latitudes. Glaciotectonic deformation is enhanced by excess pore pressures that commonly persist near ice sheet margins. Depths of such deformation can extend locally to a few tens of meters, with depths up to approximately 300 m in exceptional cases. Rates of glacial erosion are highly variable (0.05–15 mm a−1), but ratesa−1 are expected in tectonically quiescent regions. Total erosion probably not exceeding several tens of meters is expected during a glacial ...


A New Laboratory Device For Study Of Subglacial Processes: First Results On Ice–Bed Separation During Sliding, Neal R. Iverson, Ben B. Petersen 2011 Iowa State University

A New Laboratory Device For Study Of Subglacial Processes: First Results On Ice–Bed Separation During Sliding, Neal R. Iverson, Ben B. Petersen

Geological and Atmospheric Sciences Publications

A new ring-shear device allows basal slip and related processes to be studied in laboratory experiments for the cases of hard or soft beds. The device rotates a confined ring of ice (0.9 m outside diameter) across a horizontal bed at a constant velocity or drag, while a vertical stress is applied and basal water pressure is controlled. A bath with circulating fluid regulated to ∼0.01°C surrounds the ice chamber and keeps the ice at its pressure-melting temperature. In a first experiment with a stepped rigid bed and zero basal water pressure, steady lengths of step cavities ...


High-Resolution Study Of Layering Within The Percolation And Soaked Facies Of The Greenland Ice Sheet, Joel Brown, Joel T. Harper, W. Tad Pfeffer, Neil Humphrey, John H. Bradford 2011 University of Montana - Missoula

High-Resolution Study Of Layering Within The Percolation And Soaked Facies Of The Greenland Ice Sheet, Joel Brown, Joel T. Harper, W. Tad Pfeffer, Neil Humphrey, John H. Bradford

Geosciences Faculty Publications

Within the percolation and soaked facies of the Greenland ice sheet, the relationship between radar-derived internal reflection horizons and the layered structure of the firm column is unclear. We conducted two small-scale ground-penetrating radar (GPR) surveys in conjunction with 10 m firm cores that we colleced within the percolation and soaked facies of the Greenland ice sheet. The two surveys were separated by the distance of about 50 km and about 340 m of elevation leading to about 40 days of difference in the duration of average annual melt. At the higher site (about 1997 ma.s.l.), which receives ...


Flow Dynamics Of An Accumulation Basin: A Case Study Of Upper Kahiltna Glacier, Mount Mckinley, Alaska, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone 2011 University of Maine

Flow Dynamics Of An Accumulation Basin: A Case Study Of Upper Kahiltna Glacier, Mount Mckinley, Alaska, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone

Open Dartmouth: Faculty Open Access Articles

We interpreted flow dynamics of the Kahiltna Pass Basin accumulation zone on Mount McKinley, Alaska, USA, using 40, 100 and 900 MHz ground-penetrating radar profiles and GPS surface velocity measurements. We found dipping, englacial surface-conformable strata that experienced vertical thickening as the glacier flowed westward from a steep, higher-velocity (60 m a−1) region into flat terrain associated with a 90° bend in the glacier and lower velocities (15 m a−1) to the south. Stratigraphy near the western side of the basin was surface-conformable to ∼170 m depth and thinned as flow diverged southward, down-glacier. We found complex strata ...


Geogram 2011, David J. Keeling Editor, WKU Department of Geography and Geology 2011 Western Kentucky University

Geogram 2011, David J. Keeling Editor, Wku Department Of Geography And Geology

Geography and Geology Publications

No abstract provided.


Above The Mukpa: The Shifting Ground Of Khumbu's Sacred Geography, Noah Brautigam 2011 SIT Study Abroad

Above The Mukpa: The Shifting Ground Of Khumbu's Sacred Geography, Noah Brautigam

Independent Study Project (ISP) Collection

The Himalayan region is suffering from global warming,2 and the effects are felt at all scales, from the local to the global. Himalayan glaciers feed ten major Asian rivers, and 1.3 billion people in southern and southeast Asia reside in those river basins (Eriksson, et al. 2009:1). Global warming is melting these glaciers at a rapid rate, with retreat ranging from 10 to 60 meters per year on average, and many smaller glaciers already disappearing (Mool, Bajracharya and Shrestha 2008:1). This research is a study of local perceptions of global warming and glacial melt among the ...


Collaborative Research: Microparticle/Tephra Analysis Of The Wais Divide Ice Core, Karl J. Kreutz, Andrei V. Kurbatov, Mark Wells, Paul Andrew Mayewski 2011 Principal Investigator; University of Maine, Orono

Collaborative Research: Microparticle/Tephra Analysis Of The Wais Divide Ice Core, Karl J. Kreutz, Andrei V. Kurbatov, Mark Wells, Paul Andrew Mayewski

University of Maine Office of Research and Sponsored Programs: Grant Reports

This award supports a project to perform continuous microparticle concentration and size distribution measurements (using coulter counter and state-of-the-art laser detector methods), analysis of biologically relevant trace elements associated with microparticles (Fe, Zn, Co, Cd, Cu), and tephra measurements on the WAIS Divide ice core. This initial three-year project includes analysis of ice core spanning the instrumental (~1850-present) to mid- Holocene (~5000 years BP) period, with sample resolution ranging from subannual to decadal. The intellectual merit of the project is that it will help in establishing the relationships among climate, atmospheric aerosols from terrestrial and volcanic sources, ocean biogeochemistry, and ...


Melt Regimes, Stratigraphy, Flow Dynamics And Glaciochemistry Of Three Glaciers In The Alaska Range, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone 2011 University of Maine

Melt Regimes, Stratigraphy, Flow Dynamics And Glaciochemistry Of Three Glaciers In The Alaska Range, Seth Campbell, Karl Kreutz, Erich Osterberg, Steven Arcone

Open Dartmouth: Faculty Open Access Articles

We used ground-penetrating radar (GPR), GPS and glaciochemistry to evaluate melt regimes and ice depths, important variables for mass-balance and ice-volume studies, of Upper Yentna Glacier, Upper Kahiltna Glacier and the Mount Hunter ice divide, Alaska. We show the wet, percolation and dry snow zones located below 2700ma.s.l., at 2700 to 3900ma.s.l. and above 3900ma.s.l., respectively. We successfully imaged glacier ice depths upwards of 480m using 40–100MHz GPR frequencies. This depth is nearly double previous depth measurements reached using mid-frequency GPR systems on temperate glaciers. Few Holocene-length climate records are available in Alaska ...


Ice-Movement History And Kimberlite Indicator Mineral Dispersal Study, Pelly Bay, Lower Boothia Peninsula, And Wager Plateau Areas, Nunavut, Canada, Carl Ozyer 2011 The University of Western Ontario

Ice-Movement History And Kimberlite Indicator Mineral Dispersal Study, Pelly Bay, Lower Boothia Peninsula, And Wager Plateau Areas, Nunavut, Canada, Carl Ozyer

Electronic Thesis and Dissertation Repository

This study reconstructs the ice flow history of the eastern portion of the Keewatin sector of the Laurentide Ice Sheet by integrating field work, remote imagery, and work by others. The study reveals at least seven ice flow phases during the Wisconsinan, including ice streams. A model was developed using inverse distance weighed (IDW) interpolation with GIS to identify and isolate potential kimberlite bedrock sources in kimberlite indicator mineral-rich areas in the Pelly Bay area, Nunavut. Kimberlite indicator mineral (KIM) data were normalized by “peer size” to better understand how KIM grains from three kimberlite sources are distributed within three ...


Quantifying 20th Century Glacier Change In The Sierra Nevada, California, Andrew G. Fountain, Hassan J. Basagic 2011 Portland State University

Quantifying 20th Century Glacier Change In The Sierra Nevada, California, Andrew G. Fountain, Hassan J. Basagic

Geology Faculty Publications and Presentations

Numerous small alpine glaciers occupy the high elevation regions of the central and southern Sierra Nevada, California. An inventory based on 1:24,000 topographic maps revealed 1719 glaciers and perennial snowfields for a total area of 39.15 +/- 0.13 km(2). The number of 'true' glaciers, versus non-moving ice, is estimated to be 122 covering 14.89 +/- 0.08 km(2) or 38% of the ice-covered area. Historic photographs, geologic evidence, and field mapping were used to determine the magnitude of area change over the past century at 14 glaciers. The area change between 1903 and 2004 ranged ...


An Ice-Core Proxy For Northerly Air Mass Incursions Into West Antarctica, Daniel D. Dixon, Paul Andrew Mayewski, Ian D. Goodwin, Gareth J. Marshall, Rhaelene Freeman, Kirk A. Maasch, Sharon B. Sneed 2011 University of Maine

An Ice-Core Proxy For Northerly Air Mass Incursions Into West Antarctica, Daniel D. Dixon, Paul Andrew Mayewski, Ian D. Goodwin, Gareth J. Marshall, Rhaelene Freeman, Kirk A. Maasch, Sharon B. Sneed

Earth Science Faculty Scholarship

A 200-year proxy for northerly air mass incursions (NAMI) into central and western West Antarctica is developed from the examination of 19 shallow (21–150 m deep) Antarctic ice-core non-sea-salt (nss) Ca2+ concentration records. The NAMI proxy reveals a significant rise in recent decades. This rise is unprecedented for at least the past 200 years and is coincident with anthropogenically driven changes in other large-scale Southern Hemisphere (SH) environmental phenomena such as greenhouse gas (GHG) induced warming, ozone depletion, and the associated intensification of the SH westerlies. The Hysplit trajectory model is used to examine air mass transport pathways into ...


Roosevelt Island Climate Evolution Project (Rice): Us Deep Ice Core Glaciochemistry Contribution (2011- 2014), Paul Andrew Mayewski, Karl J. Kreutz, Andrei V. Kurbatov 2011 Principal Investigator; University of Maine, Orono

Roosevelt Island Climate Evolution Project (Rice): Us Deep Ice Core Glaciochemistry Contribution (2011- 2014), Paul Andrew Mayewski, Karl J. Kreutz, Andrei V. Kurbatov

University of Maine Office of Research and Sponsored Programs: Grant Reports

This award supports a project to analyze a deep ice core which will be drilled by a New Zealand research team at Roosevelt Island. The objectives are to process the ice core at very high resolution to (a) better understand phasing sequences in Arctic/Antarctic abrupt climate change, even at the level of individual storm events; (b) determine the impact of changes in the Westerlies and the Amundsen Sea Low on past/present/future climate change; (c) determine how sea ice extent has varied in the area; (d) compare the response of West Antarctica climate to other regions during glacial ...


An Emerging Technique: Multi-Ice-Core Multi-Parameter Correlations With Antarctic Sea-Ice Extent, Sharon B. Sneed, Paul Andrew Mayewski, Daniel A. Dixon 2011 University of Maine

An Emerging Technique: Multi-Ice-Core Multi-Parameter Correlations With Antarctic Sea-Ice Extent, Sharon B. Sneed, Paul Andrew Mayewski, Daniel A. Dixon

Earth Science Faculty Scholarship

ABSTRACT. Using results stemming from the International Trans-Antarctic Scientific Expedition (ITASE) ice-core array plus data from ice cores from the South Pole and Siple Dome we investigate the use of sodium (Na+), non-sea-salt sulfate (nssSO4 2–) and methylsulfonate (MS–) as proxies for Antarctic sea-ice extent (SIE). Maximum and mean annual chemistry concentrations for these three species correlate significantly with maximum, mean and minimum annual SIE, offering more information and clarification than single ice-core and single species approaches. Significant correlations greater than 90% exist between Na+ and maximum SIE; nssSO4 2– with minimum and mean SIE; and MS– with mean SIE ...


Recent Increase In Black Carbon Concentrations From A Mt. Everest Ice Core Spanning 1860–2000 Ad, S. D. Kaspari, M. Schwikowski, M. Gysel, M. G. Flanner, Kang Shichang, S. Hou, Paul A. Mayewski 2011 The University of Maine

Recent Increase In Black Carbon Concentrations From A Mt. Everest Ice Core Spanning 1860–2000 Ad, S. D. Kaspari, M. Schwikowski, M. Gysel, M. G. Flanner, Kang Shichang, S. Hou, Paul A. Mayewski

Climate Change Institute Faculty Scholarship

A Mt. Everest ice core spanning 1860–2000 AD and analyzed at high resolution for black carbon (BC) using a Single Particle Soot Photometer (SP2) demonstrates strong seasonality, with peak concentrations during the winter-spring, and low concentrations during the summer monsoon season. BC concentrations from 1975–2000 relative to 1860–1975 have increased approximately threefold, indicating that BC from anthropogenic sources is being transported to high elevation regions of the Himalaya. The timing of the increase in BC is consistent with BC emission inventory data from South Asia and the Middle East, however since 1990 the ice core BC record ...


Effect Of A Cold Margin On Ice Flow At The Terminus Of Storglacïaren, Sweden: Implications For Sediment Transport, Peter Lindsay Moore, Neal R. Iverson, Keith A. Brugger, Denis Cohen, Thomas S. Hooyer, Peter Jansson 2011 Iowa State University

Effect Of A Cold Margin On Ice Flow At The Terminus Of Storglacïaren, Sweden: Implications For Sediment Transport, Peter Lindsay Moore, Neal R. Iverson, Keith A. Brugger, Denis Cohen, Thomas S. Hooyer, Peter Jansson

Geological and Atmospheric Sciences Publications

The cold-based termini of polythermal glaciers are usually assumed to adhere strongly to an immobile substrate and thereby supply significant resistance to the flow of warm-based ice upglacier. This compressive environment is commonly thought to uplift basal sediment to the surface of the glacier by folding and thrust faulting. We present model and field evidence from the terminus of Storglacïaren, Sweden, showing that the cold margin provides limited resistance to flow from up-glacier. Ice temperatures indicate that basal freezing occurs in this zone at 10–1 – 10–2 ma–1, but model results indicate that basal motion at rates greater ...


Final Evaluation Report, SageFox Consulting Group 2011 University of Massachusetts Amherst

Final Evaluation Report, Sagefox Consulting Group

IPY STEM Polar Connections

No abstract provided.


Photonic Non-Destructive Measurement Methods For Investigating The Evolution Of Polar Firn And Ice, Daniel James Breton 2011 The University of Maine

Photonic Non-Destructive Measurement Methods For Investigating The Evolution Of Polar Firn And Ice, Daniel James Breton

Electronic Theses and Dissertations

When snow falls on glaciers or ice sheets, it persists for many tens, hundreds and sometimes thousands of years before becoming ice. The granular material in between fresh snow and glacial ice is known as firn and is generally 50 to 100 m thick over polar ice sheets. The compaction mechanism of firn into ice (called densification) has important glaciological ramifications in determination of ice sheet stability and related sea level rise effects via remote sensing altimetry. Firn densification is also important for correctly interpreting ice core paleoclimate records, especially those analyzing gases trapped in air bubbles within the glacial ...


Effect Of A Cold Margin On Ice Flow At The Terminus Of Storglaciaren, Sweden: Implications For Sediment Transfer, Keith A. Brugger, Peter L. Moore, Neal R. Iverson, Denis Cohen, Thomas S. Hooyer, Peter Jansson 2011 University of Minnesota, Morris

Effect Of A Cold Margin On Ice Flow At The Terminus Of Storglaciaren, Sweden: Implications For Sediment Transfer, Keith A. Brugger, Peter L. Moore, Neal R. Iverson, Denis Cohen, Thomas S. Hooyer, Peter Jansson

Geology Publications

The cold-based termini of polythermal glaciers are usually assumed to adhere strongly to an immobile substrate and thereby supply significant resistance to the flow of warm-based ice upglacier. This compressive environment is commonly thought to uplift basal sediment to the surface of the glacier by folding and thrust faulting. We present model and field evidence from the terminus of Storglaciaren, Sweden, showing that the cold margin provides limited resistance to flow from up-glacier. Ice temperatures indicate that basal freezing occurs in this zone at 10−1 –10−2 ma−1, but model results indicate that basal motion at rates greater ...


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