A Theoretical Model Of Drumlin Formation Based On Observations At Múlajökull, Iceland, 2017 Iowa State University
A Theoretical Model Of Drumlin Formation Based On Observations At Múlajökull, Iceland, Neal R. Iverson, R. G. Mccracken, L. K. Zoet, Í. Ö. Benediktsson, A. Schomacker, M. D. Johnson, J. Woodard
Geological and Atmospheric Sciences Publications
The drumlin field at the surge‐type glacier, Múlajökull, provides an unusual opportunity to build a model of drumlin formation based on field observations in a modern drumlin‐forming environment. These observations indicate that surges deposit till layers that drape the glacier forefield, conform to drumlin surfaces, and are deposited in shear. Observations also indicate that erosion helps create drumlin relief, effective stresses in subglacial till are highest between drumlins, and during quiescent flow, crevasses on the glacier surface overlie drumlins while subglacial channels occupy intervening swales. In the model, we consider gentle undulations on the bed bounded by subglacial ...
Arctic And North Atlantic Paleo-Environmental Reconstructions From Lake Sediments, 2017 University of Massachusetts Amherst
Arctic And North Atlantic Paleo-Environmental Reconstructions From Lake Sediments, Gregory A. De Wet
ARCTIC AND NORTH ATLANTIC PALEO-ENVIRONMENTAL RECONSTRUCTIONS FROM LAKE SEDIMENTS
GREGORY A. DE WET, B.Sc., BATES COLLEGE
M.Sc., UNIVERSITY OF MASSSCHUSETTS, AMHERST
Ph.D., UNIVERSITY OF MASSACHUSETTS, AMHERST
Directed by: Drs. Raymond S. Bradley and Isla S. Castañeda
There are few fields in the discipline of Earth Science that hold more relevancy in 2017 than studies of earth’s climate. Called the “perfect problem” considering its complexity and magnitude, climate change will continue to be one of the greatest challenges humanity will face in the 21st century. And while numerical models provide valuable information on ...
Raritan Formation (Upper Cretaceous), Long Island, New York: Sedimentological And Geochemical Assessment, Nazrul I. Khandaker, Arif Sikder, Stanley Schleifer, Xin-Chen Liu, Carlos E. Castano Londano, Joseph B. Mcgee Turner
Publications and Research
The lithology of the Upper Cretaceous Raritan Formation (RF) consists of two members: an upper clay member (Raritan clay) and a lower unit, the Lloyd Sand Member. RF is unconformably overlain by upper Pleistocene glacial deposits. The RF consists of stratified white, light- to dark-gray, and red beds and lenses of clay, silt, and sand; lignite and pyrite are common. Variegated, thin to thickly-bedded Lloyd sandstone (LS) is considered to be one of the extensive regional aquifers in Long Island and interpreted to be nearshore, fluvio-deltaic deposit. Proximity to fluvial axes and active deltaic lobes plays an important role in ...
Giovanni Badino (1953-2017), 2017 International Union of speleology
Giovanni Badino (1953-2017), Arrigo Cigna, Paolo Forti
International Journal of Speleology
Short obituary of Giovanni Badino.
Odu Scientists Address Antarctic Ice Melt Affecting Sea Levels, 2017 Old Dominion University
Odu Scientists Address Antarctic Ice Melt Affecting Sea Levels, Miasia Osbey
No abstract provided.
The Uppermost Mantle Seismic Velocity And Viscosity Structure Of Central West Antarctica, 2017 University of Leeds
The Uppermost Mantle Seismic Velocity And Viscosity Structure Of Central West Antarctica, J. P. O'Donnell, K. Selway, A. A. Nyblade, R. A. Brazier, D. A. Wiens, S. Anandakrishnan, R. C. Aster, Audrey D. Huerta, T. Wilson, J. Paul Winberry
All Faculty Scholarship for the College of the Sciences
Accurately monitoring and predicting the evolution of the West Antarctic Ice Sheet via secular changes in the Earth's gravity field requires knowledge of the underlying upper mantle viscosity structure. Published seismic models show the West Antarctic lithosphere to be ∼70–100 km thick and underlain by a low velocity zone extending to at least ∼200 km. Mantle viscosity is dependent on factors including temperature, grain size, the hydrogen content of olivine, the presence of partial melt and applied stress. As seismic wave propagation is particularly sensitive to thermal variations, seismic velocity provides a means of gauging mantle temperature. In ...
The Geography Of Glaciers And Perennial Snowfields In The American West, 2017 Portland State University
The Geography Of Glaciers And Perennial Snowfields In The American West, Andrew G. Fountain, Bryce Glenn, Hassan J. Basagic
Geology Faculty Publications and Presentations
A comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey 1:24,000 topographic maps based on aerial photographs acquired during 35 years, 1955–1990, of which the first 20 years or more was a cool period with little glacier change. The mapped features were filtered for those greater than 0.01 km2. Results show that 5036 G&PS (672 km2, 14 km3) populate eight states, of which about 1276 (554 km2, 12 km3) are glaciers. Uncertainty is ...
Microfeatures Of Modern Sea-Ice-Rafted Sediment And Implications For Paleo-Sea-Ice Reconstructions, 2017 James Madison University
Microfeatures Of Modern Sea-Ice-Rafted Sediment And Implications For Paleo-Sea-Ice Reconstructions, Kristen E. St. John, Sandra Passchier, Brooke Tantillo, Dennis Darby, Lance Kearns
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
Distinguishing sea-ice-rafted debris (SIRD) from iceberg-rafted debris is crucial to an interpretation of ice-rafting history; however, there are few paleo-sea-ice proxies. This study characterizes quartz grain microfeatures of modern SIRD from the Arctic Ocean, and compares these results with microfeatures from representative glacial deposits to potentially differentiate SIRD from ice-rafted sediments which have been recently subjected to glacial processes. This allows us to evaluate the use of grain microfeatures as a paleo-sea-ice proxy. SIRD grains were largely subrounded, with medium relief, pervasive silica dissolution and a high abundance of breakage blocks and microlayering. The glacial grains were more angular, with ...
The Potential Effects Of Percolating Snowmelt On Palynological Records From Firn And Glacier Ice, 2017 University of Southern Mississippi
The Potential Effects Of Percolating Snowmelt On Palynological Records From Firn And Glacier Ice, Michael E. Ewin, Carl A. Reese, Matthew A. Nolan
The effects of meltwater percolation on pollen in snow, firn and glacial ice are not fully understood and currently hamper the use of pollen in ice-core studies of paleoclimate. Several studies have suggested that, due to grain size, pollen is not mobilized by meltwater transport. However, these findings contradict many ice-core pollen studies that show pollen concentrations in snow and firn are much higher than concentrations found in the ice layers they eventually form. This study addresses one aspect of this question by investigating whether meltwater percolation can effectively transport pollen within a snowpack. We used nine Styrofoam coolers filled ...
Evidence For Late Pliocene Deglacial Megafloods From Giant Sediment Waves In The Northern Gulf Of Mexico, 2017 Western Kentucky University
Evidence For Late Pliocene Deglacial Megafloods From Giant Sediment Waves In The Northern Gulf Of Mexico, Zexuan Wang
Masters Theses & Specialist Projects
Laurentide Ice Sheet outburst floods to the Gulf of Mexico have been mainly documented based on deep-sea cores, especially the megafloods, only during the last several interglacial episodes in the late Pleistocene. The paleoclimatic significance of giant sedimentary structures developed under unconfined Froude-supercritical turbidity currents in subaqueous settings is considerably under-examined. This research extensively documents >20-km-wide and 200-m-thick Plio-Pleistocene giant sediment waves for the first time on the northern Gulf of Mexico continental slope using 3D seismic data, which show waveform morphology in unprecedented detail. The results suggest that such large-scale bedforms were formed under sheet-like unconfined Froudesupercritical turbidity currents ...
Toward The Development Of A 10be Chronology Of Glaciation In The Mosquito Range, Colorado: A Progress Report, 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, 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, Feldpausch
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
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, 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, 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
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 ...
Field-Trip Guide To Mafic Volcanism Of The Cascade Range In Central Oregon— A Volcanic, Tectonic, Hydrologic, And Geomorphic Journey, Natalia I. Deligne, Daniele Mckay, Richard M. Conrey, Gordon E. Grant, Emily R. Johnson, Jim O'Connor, Kristin Sweeney
Environmental Studies Faculty Publications and Presentations
The Cascade Range in central Oregon has been shaped by tectonics, volcanism, and hydrology, as well as geomorphic forces that include glaciations. As a result of the rich interplay between these forces, mafic volcanism here can have surprising manifestations, which include relatively large tephra footprints and extensive lava flows, as well as water shortages, transportation and agricultural disruption, and forest fires. Although the focus of this multidisciplinary field trip will be on mafic volcanism, we will also look at the hydrology, geomorphology, and ecology of the area, and we will examine how these elements both influence and are influenced by ...
Tidal And Structural Controls On Seismic Events Near The Grounding Line At Beardmore Glacier, Antarctica, 2017 Central Washington University
Tidal And Structural Controls On Seismic Events Near The Grounding Line At Beardmore Glacier, Antarctica, Jade Cooley
All Master's Theses
Here I report seismic events occurring over a three-week period during the 2013-2014 austral summer near the grounding line of Beardmore Glacier, Antarctica. The ~24000 events over this time frame had a noticeable temporal pattern that correlates well with the principally diurnal tides of Antarctica. Falling and rising tide each accounted for nearly equal occurrence of events, and most (~42%) events occurred in the last third of any tidal cycle. Event epicenters were located using beamforming, and display a spatial pattern of two distinct clusters. Appearance of event location clusters differ on rising and falling tide. I theorize that, due ...
Novel Methods For Quantifying Spatio-Temporal Change In Glaciated And Subaqueous Environments, 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 ...
Greenland Subglacial Drainage Evolution Regulated By Weakly Connected Regions Of The Bed, 2016 Fluid Dynamics and Solid Mechanics Group, Los Alamos National Laboratory
Greenland Subglacial Drainage Evolution Regulated By Weakly Connected Regions Of The Bed, Matthew J. Hoffman, Lauren C. Andrews, Stephen A. Price, Ginny A. Catania, Thomas A. Neumann, Martin P. Luthi, Jason Gulley, Claudia Ryser, Robert L. Hawley, Blaine Morris
Penetration of surface meltwater to the bed of the Greenland Ice Sheet each summer causes an initial increase in ice speed due to elevated basal water pressure, followed by slowdown in late summer that continues into fall and winter. While this seasonal pattern is commonly explained by an evolution of the subglacial drainage system from an inefficient distributed to efficient channelized configuration, mounting evidence indicates that subglacial channels are unable to explain important aspects of hydrodynamic coupling in late summer and fall. Here we use numerical models of subglacial drainage and ice flow to show that limited, gradual leakage of ...