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Shear Resistance And Continuity Of Subglacial Till: Hydrology Rules, Neal R. Iverson 2017 Iowa State University

Shear Resistance And Continuity Of Subglacial Till: Hydrology Rules, Neal R. Iverson

Neal Iverson

The field observations of G.S. Boulton stimulated widespread interest in deformable beds. Shear resistance of till in its critical state is insensitive to strain rate and increases linearly with effective pressure. During unsteady deformation, pseudo-viscous shear resistance can be caused by dilation of consolidated tills and resultant pore-pressure decline. This effect is probably uncommon, however, because susceptible tills of low hydraulic diffusivity are also those least likely to consolidate significantly during effective-pressure transients. Stick–slip motion at Whillans Ice Stream, Antarctica, indicates that its basal till must weaken during rapid slip and strengthen during longer periods of slower slip ...


Debris-Bed Friction Of Hard-Bedded Glaciers, Denis Cohen, Neal R. Iverson, T. S. Hooyer, U. H. Fischer, M. Jackson, Peter Lindsay Moore 2017 Iowa State University

Debris-Bed Friction Of Hard-Bedded Glaciers, Denis Cohen, Neal R. Iverson, T. S. Hooyer, U. H. Fischer, M. Jackson, Peter Lindsay Moore

Neal Iverson

Field measurements of debris-bed friction on a smooth rock tablet at the bed of Engabreen, a hard-bedded, temperate glacier in northern Norway, indicated that basal ice containing 10% debris by volume exerted local shear traction of up to 500 kPa. The corresponding bulk friction coefficient between the dirty basal ice and the tablet was between 0.05 and 0.08. A model of friction in which nonrotating spherical rock particles are held in frictional contact with the bed by bed-normal ice flow can account for these measurements if the power law exponent for ice flowing past large clasts is 1 ...


Glacier Slip And Seismicity Induced By Surface Melt, Peter Lindsay Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Mark E. Mathison, Denis Cohen 2017 Iowa State University

Glacier Slip And Seismicity Induced By Surface Melt, Peter Lindsay Moore, J. Paul Winberry, Neal R. Iverson, Knut A. Christianson, Sridhar Anandakrishnan, Mark E. Mathison, Denis Cohen

Neal Iverson

Many of the key processes governing fast glacier flow involve interaction between a glacier and its basal hydrological system, which is hidden from direct observation. Passive seismic monitoring has shown promise as a tool for remotely monitoring basal processes, but lack of glacier-bed access prevents clear understanding of the relationships between subglacial processes and corresponding seismic emissions. Here we describe direct measurements of basal hydrology, sliding, and broadband seismicity made in a unique subglacial facility in Norway during the onset of two summer melt seasons. In the most pronounced of these episodes, rapid delivery of surface meltwater to the bed ...


Permafrost, Ice Sheets, And Sea Level, Beth Caissie, Julie Brigham-Grette 2017 Iowa State University

Permafrost, Ice Sheets, And Sea Level, Beth Caissie, Julie Brigham-Grette

Beth Caissie

Sea level rise and inhabited coastlines. Ice shelves and sea ice do not contribute to sea level but they can buttress the land ice sheets from rapid retreat. Causes of Sea Level Rise: •Melting of glaciers, ice caps, ice sheets •Thermal expansion of sea water ••Small scale changes due to anthropogenic land water storage (damming rivers, over-pumping of water and fuels, wetland and forest destruction) •Relative changes in sea level due to tectonic movements (land subsidence or rebound)


Sea Ice Food Webs—Hands On Sampler Teacher Guide, Beth Caissie 2017 Iowa State University

Sea Ice Food Webs—Hands On Sampler Teacher Guide, Beth Caissie

Beth Caissie

This activity is a variation on a food web game that I’ve seen played many times before, but it is adapted to reflect a sea ice food web and show the many organisms that are intimately connected to polar bears.


Brine Rejection Activity, Beth Caissie, Rob Snyder 2017 Iowa State University

Brine Rejection Activity, Beth Caissie, Rob Snyder

Beth Caissie

As salt water freezes, the salt is pushed out of solution through channels in the ice. This process is called brine rejection or brine exclusion. These channels are often used as microhabitats by ice algae, zooplankton, and even tiny fish. You can easily demonstrate what these channels look like.


Polar Remote Sensing, Beth Caissie 2017 Iowa State University

Polar Remote Sensing, Beth Caissie

Beth Caissie

•Satellite sensors specialize in collecting data about specific wavelengths The Geostationary Operational Environment Satellites (GOES) operated by NASA, NOAA, and the U.S. Department of Commerce provide continuous monitoring of weather conditions. Orbiting the Earth’s equatorial plane at a speed exactly matching the planet’s rotation, satellites in the GOES network seem to hover over fixed spots. They monitor atmospheric conditions that lead to hurricanes, flash floods, tornadoes, and hail storms.


Glacier Goo Activity, Beth Caissie 2017 Iowa State University

Glacier Goo Activity, Beth Caissie

Beth Caissie

We provided the students with background information about what a glacier is, where they are, how they move. Then split the students into four groups each tasked with a question to answer through experimentation Group s 1 and 2: How does temperature change the way a glacier flows? (we provided frozen, and room temperature goo, and a microwave for heating the goo) Groups 3 and 4: How does friction or obstacles change the way a glacier flows? (we provided different pvc tubes—tubes with nothing done to them, tubes with paintable sand applied to them, and tubes with rocks glued ...


Atmospheric Co2 And Temperature. What Is Normal?, Beth Caissie, Julie Brigham-Grette 2017 Iowa State University

Atmospheric Co2 And Temperature. What Is Normal?, Beth Caissie, Julie Brigham-Grette

Beth Caissie

–How much of a change in CO2 concentration and other GHGs is natural? –What is the normal range of CO2 and temperature variability? How is normal defined in this context? –What is the relationship between CO2 and global temperatures?


Play Doh Coring Sampler Teacher Guide, Beth Caissie 2017 Iowa State University

Play Doh Coring Sampler Teacher Guide, Beth Caissie

Beth Caissie

Sediment cores are one of the most valuable types of samples for researchers who would like to learn about past climate or ecological changes. Cores can be retrieved from lakes, marshes, swamps, fields, and the ocean. The layers often reveal striking changes in color (see photos) reflecting changing sediment composition (i.e. more clay deposition or more microfossil s). This easy activity illustrates the basic geologic principle that horizontal layers of sediment become older the deeper you go below the Earth’s surface (Law of Superposition). Each layer contains sediment, fossils and organic matter etc. that can inform us about ...


Toward The Development Of A 10be Chronology Of Glaciation In The Mosquito Range, Colorado: A Progress Report, Noah Bensen, Keith A. Brugger 2017 University of Minnesota, Morris

Toward The Development Of A 10be Chronology Of Glaciation In The Mosquito Range, Colorado: A Progress Report, Noah Bensen, Keith A. Brugger

Undergraduate Research Symposium 2017

The Last Glacial Maximum (LGM) in the Rocky Mountain region occurred about 21 ka (20,000 years before present). However, dated glacial chronologies suggest that while LGM glacier advances in individual ranges in Colorado were somewhat synchronous, retreat from their maximum extents was asynchronous, varying between ~20 and 15 ka or later. The precise timing and spatial variation of glacier advance and retreat provides insights into LGM climate change and is necessary to calibrate climate models. To better understand the timing of the LGM in the Mosquito Range in Colorado, we collected 12 samples from granitic boulders on moraine crests ...


Assessing Seasonal And Spatial Variability In The Hydrogeochemistry Of Glacial Meltwater In Iceland, Anisha Tuladhar 2017 Western Kentucky University

Assessing Seasonal And Spatial Variability In The Hydrogeochemistry Of Glacial Meltwater In Iceland, Anisha Tuladhar

Masters Theses & Specialist Projects

A detailed comparative geochemical characterization of three different types of Iceland glacial systems was conducted during June, August, and October, 2016. The study was carried out at a total of 11 outlet glacier rivers flowing from the icecaps Vatnajökull, Eyjafjallajökull, and Mýrdalsjökull. A total of 75 grab samples were collected (25 for each sampling period). The hydrogeochemical variations of Icelandic glacial meltwater are influenced by volcanic activity, temporal changes, and geographical location, which differed between the sampling sites within the glaciers and icecaps. Lower pH range, and comparatively higher and variable specific conductivity, SO4, S and F is linked to ...


Gravity And Passive Seismic Methods Used Jointly For Understanding The Subsurface In A Glaciated Terrain: Dowling And Maple Grove Quadrangles, Barry County, Michigan, Scott A. Feldpausch 2017 Western Michigan University

Gravity And Passive Seismic Methods Used Jointly For Understanding The Subsurface In A Glaciated Terrain: Dowling And Maple Grove Quadrangles, Barry County, Michigan, Scott A. Feldpausch

Master's Theses

The Horizontal to Vertical Spectral Ratio (HVSR) passive, single sensor seismic technique has been used together with gravimetry to study the topography hidden below the glacial drift of two 7.5’ quadrangles in Barry Co., MI. 265 stations were observed with both instruments along roads at nominal spacings of about 0.4 to 0.8 km. Occasional water wells and oil wells with documented penetrations of the base of glacial were used to calibrate the local power law regression calibration. This was also compared with the statewide calibration curve previously established. Results are presented as maps of Simple Bouguer Anomaly ...


Regional Greenland Accumulation Variability From Operation Icebridge Airborne Accumulation Rradar, Gabriel Lewis, Erich Osterberg, Robert Hawley, Brian Whitmore 2017 Dartmouth College

Regional Greenland Accumulation Variability From Operation Icebridge Airborne Accumulation Rradar, Gabriel Lewis, Erich Osterberg, Robert Hawley, Brian Whitmore

Open Dartmouth: Faculty Open Access Articles

The mass balance of the Greenland Ice Sheet (GrIS) in a warming climate is of critical interest to scientists and the general public in the context of future sea-level rise. An improved understanding of temporal and spatial variability of snow accumulation will reduce uncertainties in GrIS mass balance models and improve projections of Greenland's contribution to sea-level rise, currently estimated at 0.089 ± 0.03 m by 2100. Here we analyze 25 NASA Operation IceBridge accumulation radar flights totaling  >  17 700 km from 2013 to 2014 to determine snow accumulation in the GrIS dry snow and percolation zones over ...


Analyzing Glacier Surface Motion Using Lidar Data, Jennifer W. Tellig, Craig Glennie, Andrew G. Fountain, David C. Finnegan 2017 University of Houston

Analyzing Glacier Surface Motion Using Lidar Data, Jennifer W. Tellig, Craig Glennie, Andrew G. Fountain, David C. Finnegan

Geology Faculty Publications and Presentations

Understanding glacier motion is key to understanding how glaciers are growing, shrinking, and responding to changing environmental conditions. In situ observations are often difficult to collect and offer an analysis of glacier surface motion only at a few discrete points. Using light detection and ranging (LiDAR) data collected from surveys over six glaciers in Greenland and Antarctica, particle image velocimetry (PIV) was applied to temporally-spaced point clouds to detect and measure surface motion. The type and distribution of surface features, surface roughness, and spatial and temporal resolution of the data were all found to be important factors, which limited the ...


Assessment Of Nasa Airborne Laser Altimetry Data Using Ground-Based Gps Data Near Summit Station, Greenland, Kelly M. Brunt, Robert L. Hawley, Eric R. Lutz, Michael Studinger 2017 University of Maryland at College Park

Assessment Of Nasa Airborne Laser Altimetry Data Using Ground-Based Gps Data Near Summit Station, Greenland, Kelly M. Brunt, Robert L. Hawley, Eric R. Lutz, Michael Studinger

Open Dartmouth: Faculty Open Access Articles

A series of NASA airborne lidars have been used in support of satellite laser altimetry missions. These airborne laser altimeters have been deployed for satellite instrument development, for spaceborne data validation, and to bridge the data gap between satellite missions. We used data from ground-based Global Positioning System (GPS) surveys of an 11 km long track near Summit Station, Greenland, to assess the surface–elevation bias and measurement precision of three airborne laser altimeters including the Airborne Topographic Mapper (ATM), the Land, Vegetation, and Ice Sensor (LVIS), and the Multiple Altimeter Beam Experimental Lidar (MABEL). Ground-based GPS data from the ...


Novel Methods For Quantifying Spatio-Temporal Change In Glaciated And Subaqueous Environments, Jordan Mertes 2017 Michigan Technological University

Novel Methods For Quantifying Spatio-Temporal Change In Glaciated And Subaqueous Environments, Jordan Mertes

Dissertations, Master's Theses and Master's Reports

In many scientific fields, it is important to actively develop new approaches to monitoring and quantifying changes within different systems. Often adapting existing tools or applying techniques from alternative fields can greatly improve our ability to monitor spatial and temporal changes. In this dissertation, I present four studies aimed at demonstrating new innovative ways at improving our ability to observe and quantify changes occurring on glaciers, submerged cultural resources (SCRs) and supraglacial lakes by using technology such as Structure from Motion + Multi-view stereo photogrammetry (SfM) and ground penetrating radar (GPR) surveying combined with facies analysis.

I have successfully reconstructed highly ...


A New Data Set For Assessing The Cold Content Of The Rocky Mountain West Snowpack, Jeffrey Schmidt 2017 University of Colorado, Boulder

A New Data Set For Assessing The Cold Content Of The Rocky Mountain West Snowpack, Jeffrey Schmidt

Undergraduate Honors Theses

Abstract

Snowpack cold content (CCsnow) is the energy required to bring a snowpack to an isothermal temperature of 0.0°C. CCsnow is a snow characteristic that integrates the response of a snowpack to components of the snow-cover energy balance. An improved understanding of the spatiotemporal variability of CCsnow may provide insight into dynamics and sensitivity of the snowpack to climate change. In this study, snowpit observations of snow water equivalent (SWE), snow temperature (Tsnow) and snow density (⍴snow) from the United States Geologic Survey Rocky Mountain Snowpack Chemistry Program (USGS RMS) were used to evaluate ...


Utilizing Remote And Numerical Methods To Provide Constraints For The Seasonal Development And Topographic Profiles Of Rock Glaciers, Brett Oliver 2017 University of Colorado, Boulder

Utilizing Remote And Numerical Methods To Provide Constraints For The Seasonal Development And Topographic Profiles Of Rock Glaciers, Brett Oliver

Undergraduate Honors Theses

Rock glaciers represent the dynamic interaction between rock and ice in many alpine settings that lie below the Equilibrium Line Altitude (ELA). These periglacial systems are formed by avalanched snow and debris from an overlying headwall, and are adorned with distinct topographic lobes collectively known as rumples. The central rock glacier of Mount Sopris presents a clear expression of rumples, where the structures are well-defined throughout the 1.8 km long glacier. In addition to clearly-expressed rumples, the accumulation area is constrained to a narrow bowl at the base of the headwall that is easy to identify. To inform our ...


Hall Basin And The Petermann Glacier, Nw Greenland: A Late Quaternary Provenance Glacial History, Blythe Befus 2017 University of Colorado, Boulder

Hall Basin And The Petermann Glacier, Nw Greenland: A Late Quaternary Provenance Glacial History, Blythe Befus

Undergraduate Honors Theses

The Petermann Ice Tongue, located in the northwest region of Greenland, has experienced large caving events since 2010. It is one of the few remaining ice tongues and or ice shelves still present in Greenland. The Petermann Glacier and its ice tongue are important to study as little is known about their glacial history since the deglaciation that likely began in the early Holocene. Through analyzing two cores, 18GC in Hall Basin and 003TC/41GC/003PC in the Petermann Fjord, in conjunction with prior analysis of the HLY03-05GC core in Hall Basin (Jennings et al., 2011), a relative glacial history ...


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