Glaciology Commons^™

Mountain Evolution And Environmental Changes Of Huangshan, China, P.-H. Huang, Robert F. Diffendal Jr., M. Yang, Patricia E. Helland

Department of Earth and Atmospheric Sciences: Faculty Publications

Huangshan (Yellow Mountain) is located in southern part of the lower reaches of the Yangtze River. The highest Lotus Flower peak is 1,864 m above sea level. Formative ages of the Huangshan and its granite, process of mountain geomorphic evolution from the Eocene to Quaternary, environmental changes of Quaternary, formative origin of beautiful peaks and fascinating rocks were studied and questionable "Pleistocene glaciation" was also discussed in this paper.

Mapping Subglacial Surfaces Of Temperate Valley Glaciers By Two-Pass Migration Of A Radio-Echo Sounding Survey, Brian C. Welch, W. Tad Pfeffer, Joel T. Harper, Neil F. Humphrey

Geosciences Faculty Publications

High-resolution maps of the glacier bed are developed through a pseudo-three-dimensional migration of a dense array of radio-echo sounding profiles. Resolution of three-dimensional maps of sub-glacial surfaces is determined by the radio-echo sounding wavelength, data spacing in the field, and migration. Based on synthetic radio-echo sounding profile experiments, the maximum resolution of the final map cannot exceed one half-wavelength. A methodology of field and processing techniques is outlined to develop a maximum-resolution map of the glacier bed. The field and processing techniques valley glacier in south-central Alaska. The field techniques and the processing steps used on the glacier result in …

Quartzite Fabric Transition In A Cordilleran Metamorphic Core Complex, Allen J. Mcgrew, Martin Casey

Department of Earth, Environment and Sustainability Faculty Publications

Photomicrographs 143A-143F record fabric variations in quartzite with increasing structural depth in a > 1 km thick, amphibolite-facies, normal-sense shear zone in the East Humboldt metamorphic core complex, Nevada (Figure 143.1). This shear zone and the overlying detachment system unroofed an infrastructure of high-grade, migmatitic gneiss during Oligocene to early Miocene extension (Dallmeyer and others, 1986; Wright and Snoke, 1993; McGrew and Snee, 1994). Thermobarometric constraints from near the base of the mylonitic zone record deformation conditions of 550°- 620°C and 300-400 MPa (Hurlow and others, 1991). Sample WBC6 (l43A and 143B) characterizes the mylonitic zone, whereas sample 8706-1 (143C and …

Crevasse Patterns And The Strain-Rate Tensor: A High-Resolution Comparison, Joel T. Harper, Neil Humphrey, W. Tad Pfeffer

Geosciences Faculty Publications

Values of the strain-rate tensor represented at a 20 m length scale are found to explain the pattern and orientation of crevasses in a 0.13 km² reach of Worthington Glacier, Alaska, U.S.A. The flow field of the reach is constructed from surveyed displacements of 110 markers spaced 20-30 m apart. A velocity gradient method is then used to calculate values of the principal strain-rate axes at the nodes of a 20 m x 20 m orthogonal grid. Crevasses in the study reach are of two types, splaying and transverse, and are everywhere normal to the trajectories of greatest (most …

Lead Isotopes And Selected Metals In Ice From Law Dome, Antarctica, K. J. R. Rosman, W. Chisholm, C. F. Boutron, S. Hong, R. Edwards, Vin Morgan, Peter N. Sedwick

OES Faculty Publications

The isotopic composition. of Pb and the concentrations of Pb, Ba and Bi were measured in selected ice-core samples from Law Dome, East Antarctica, to a depth of 1196 m. The range of concentrations found in decontaminated ice was 0.03-1.5 pg g^-1 for Pb, 0.9-6.1 pg g^-1 for Ba and 0.4-17 fg g^-1 for Bi, excluding the deepest sample which contained ∼1 ppm of rock dust. The abundances of all four stable lead isotopes were measured and gave ²⁰⁶Pb/²⁰⁷Pb ratios ≤ ∼1.23. A value of ²⁰⁸Pb/²⁰⁷Pb = 2.78 was measured in …

On The Strain-Rate Sensitivity Of Columnar Ice, M. E. Manley, E. M. Schulson

Dartmouth Scholarship

A power law relation between stress and strain rate of the form σ ∝ ε̇1/n was used to describe the response to strain rate of S1 ice loaded across the columns at -10°C. The rate exponent, n, decreased with increasing strain from about 4.6 at an observed peak on the load displacement curve to approximately 2.6 at a shortening of 2%. Analysis of these results and of the results of other authors on different forms of ice deformed at the same temperature suggests that the power law exponent, n, is proportional to Fc/Fg. The parameter Fc/Fg is the far-field basal …

Researchers Pool Knowledge About Antarctic Dry Valleys, Andrew G. Fountain, Sarah Spaulding

Geology Faculty Publications and Presentations

Most of us think of ice when we think of the Antarctic, and rightly so, considering that only 5% of it is ice-free. Dry valleys--the ice-free areas--have sandy, rocky valley floors, ice-covered lakes, and streams that flow only two months of the year. The McMurdo Dry Valleys (78øS 163øE) are the largest of these regions.

Across-Column Cracks And Axial Splits In S2 Saline Ice Under Compression, E. M. Schulson, S. Qi, J. S. Melton, E. T. Gratz

Dartmouth Scholarship

Experiments on plate-like specimens have established that across-column cracks from within S2 (columnar) salt-water ice when compressed uniaxially along a direction inclined to the long axis of the grains. Wing cracks initiate from the across-column cracks and lengthen into axial splits when the ice is rapidly deformed; correspondingly; the macroscopic behavior changes from ductile to brittle. The across-column cracking is attributed to grain-boundary sliding, and the splitting to the suppression of crack-tip creep.

Sem Analysis Of Quartz Sand Grain Surface Textures Indicates Alluvial/Colluvial Origin Of The Quaternary "Glacial" Boulder Clays At Huangshan (Yellow Mountain), East-Central China, P. E. Helland, Pei-Hua Huang, Robert F. Diffendal Jr.

School of Natural Resources: Faculty Publications

Geomorphic features and Pleistocene deposits on Huangshan have been attributed to glaciation. Recent reassessment questions this interpretation. As part of the reassessment, quartz sand grains from deposits identified as glacial boulder clays (till composed of boulders in a clay or silt matrix) were analyzed by scanning electron microscope for evidence of their sedimentary history. Surface textures found on the boulder-clay grains were compared with those on grains with known sedimentary histories including glacial, grus, colluvial, and alluvial grains. The analysis shows that the grains lack typical glacial textures. The surface textures present indicate a complex history. Non-uniformly weathered grain surfaces …

A Strategy For Monitoring Glaciers, Andrew G. Fountain, Robert M. Krimmel, Dennis C. Trabant

Geography Faculty Publications and Presentations

Glaciers are important features in the hydrologic cycle and affect the volume, variability, and water quality of runoff. Assessing and predicting the effect of glaciers on water resources require a monitoring program to provide basic data for this understanding. The monitoring program of the U.S. Geological Survey employs a nested approach whereby an intensively studied glacier is surrounded by less intensively studied glaciers and those monitored solely by remote sensing. Ideally, each glacierized region of the United States would have such a network of glaciers. The intensively studied glacier provides a detailed understanding of the physical processes and their temporal …

Grand Tour-Part 2: Petrogenesis And Thermal Evolution Of Deep Continental-Crust: The Record From The East Humboldt Range, Nevada, Allen J. Mcgrew, Mark T. Peters

Department of Earth, Environment and Sustainability Faculty Publications

The northern part of the East Humboldt Range, Nevada, provides a rare opportunity to explore the petrogenetic environment of deep levels in the middle crust during both large-scale Mesozoic contraction and Cenozoic regional extension. On this segment of the field trip, we will explore evidence bearing on the character of the metamorphic and magmatic history of this terrane, and attempt to link these constraints to the rheology and tectonic evolution of the middle crust during the Mesozoic and Cenozoic.

The Grand Tour Of The Ruby-East Humboldt Metamorphic Core Complex, Northeastern Nevada: Part 1-Introduction & Road Log, Arthur W. Snoke, Keith A. Howard, Allen J. Mcgrew, Bradford R. Burton, Calvin G. Barnes, Mark T. Peters, James E. Wright

Department of Earth, Environment and Sustainability Faculty Publications

The purpose of this geological excursion is to provide an overview of the multiphase developmental history of the Ruby Mountains and East Humboldt Range, northeastern Nevada. Although these mountain ranges are commonly cited as a classic example of a Cordilleran metamorphic core complex developed through large-magnitude, mid-Tertiary crustal extension, a preceding polyphase Mesozoic contractional history is also well preserved in the ranges. An early phase of this history involved Late Jurassic two-mica granitic magmatism, high-temperature but relatively low-pressure metamorphism, and polyphase deformation in the central Ruby Mountains. In the northern Ruby Mountains and East Humboldt Range, a Late Cretaceous history …

Nearly Synchronous Climate Change In The Northern Hemisphere During The Last Glacial Termination, Larry V. Benson, James Burdett, Steve Lund, Michaele Kashgarian, Scott Mensing

United States Geological Survey: Staff Publications

The climate of the North Atlantic region underwent a series of abrupt cold/warm oscillations when the ice sheets of the Northern Hemisphere retreated during the last glacial termination (17,700–11,500 years ago). Evidence for these oscillations, which are recorded in European terrestrial sediments as the Oldest Dryas/Bølling/ Older Dryas/Allerød/Younger Dryas vegetational sequence, has been found in Greenland ice cores. The geographical extent of many of these oscillations is not well known, but the last major cold event (the Younger Dryas) seems to have been global in extent. Here we present evidence of four major oscillations in the hydrological balance of the …

The Impact Of Glacier Recession Upon The Discharge Of The Bow River Above Banff, Alberta, 1951-1993, Christopher Dennis Hopkinson

Theses and Dissertations (Comprehensive)

Three methods have been used to explore the volumetric change of glaciers in the Bow Basin above Banff for the years 1951 to 1993. Using aerial photography, the extent of glacier covers for the two years were mapped at a scale of 1:50,000. The first volumetric calculation of glacier loss was based on inventory criteria; the second a hyposgraphic curve method based on Young’s investigations in Mistaya Basin (1991) and the third stereo air photogrammetry and DEM comparisons using computer software. These methods were applied to the highly glacierized Hector Lake catchment within the Bow Valley and then extrapolated up …

Hydrogeology And Stable Isotope Investigations Of A Landfill Impacted Site In Southwest Michigan, Eliot Anong Atekwana

Dissertations

The Cork Street landfill in the City of Kalamazoo is unlined and constructed in glacial drift material. Although water quality in some of the landfill monitoring wells is poor, the degree of the landfill’s influence to groundwater, wetlands and Davis Creek located downgradient of the landfill is unknown. The objective of this study is to evaluate the degree of the landfill’s impact in this region through hydrologic and stable isotope analysis.

Site characterization using geophysical surveys and specific conductance measurements indicates highly conductive shallow groundwater probably attributable to groundwater contamination. Hydrologic evaluation of this region shows that groundwater flows towards …

Using Digital Elevation Models To Measure The Surface And Volumetric Change Of Athabasca Glacier, Alberta, Canada, 1919-1979, James Robb Reynolds

Theses and Dissertations (Comprehensive)

The Athabasca Glacier (52˚12'N, 117˚14'W) located at the Alberta-British Columbia border was studied to quantify its volumetric, area and elevation changes below 2400 m between 1919 and 1979. The data sources consist of maps produced using aerial and terrestrial photogrammetry in the years between 1919 and 1979. The maps were digitized and converted into raster digital elevation models (DEMs), the manipulation of which allowed values of surface and volumetric change to be calculated. These DEMs showed that between 1919 and 1979 the glacier lost 2.344 x 108m3 of volume and receded more than 1 km. Each of the source maps …

A Wellhead Protection Study Of A Small Agricultural Community In Glaciated Terrain, As A Model For Wellhead Protection Efforts By Similar Communities, Cole Kevan Lovett

Dissertations

The purpose of this study was to create a wellhead protection approach for a small town in a rural watershed that could be used by other, similar, communities.

Lacustrine clay and melt-out till interbedded in outwash sands and fine gravel, separate an unconfined aquifer from a deeper aquifer. The lower aquifer was determined to be semiconfined due to (a) high vertical conductivity, (b) lack of continuity in the clay/till, (c) absence of significant seasonal water level changes, and (d) tritium levels above 1-2 tritium units in deep wells.

Tritium level falls and water age rises along flowpaths. A low-high-low pattern …

Hydrometeorological Investigations On A Small Valley Glacier In The Sawtooth Range, Ellesmere Island, Northwest Territories, Paul Michael Wolfe

Theses and Dissertations (Comprehensive)

Hydrometeorological techniques were employed during the summer of 1993 to study a small (4.7km2) valley glacier in the Sawtooth Range, Fosheim Peninsula, Ellesmere Island, Northwest Territories. The annual 1992-93 mass balance for Quviagivaa Glacier (unofficial name), and for the adjacent Nirukittuq Glacier (unofficial name) was -532mm and -530mm water equivalent respectively. The equilibrium line altitude was above the upper limit of the glaciers due to the exceptional warmth of the summer. Slight marginal shrinking in the areal extent of Quviagivaa Glacier since 1959 suggests that strongly negative mass balances such as those recorded in 1993 are not indicative of the …

The Volumetric Change Of The Peyto Glacier, Alberta, Canada, 1896-1966, Alistair Lennox Wallace

Theses and Dissertations (Comprehensive)

The historical information concerning the Peyto Glacier is plentiful, especially with regards to terrestrial photographs. The information available dates from 1896 to present day. The glacier has been studied intensively since the 1960’s. The purpose of this thesis is to document a comprehensive historical record and determine volumetric changes of the Peyto Glacier, 1896-1966.

Changes in the extent of Peyto Glacier, Alberta are determined for the period 1896-1966. Data sources used include terrestrial photographs of Peyto Glacier from 1896, 1902 and 1917, the 1917 Alberta-British Columbia Interprovincial Boundary Commission Survey map and the 1966 map of the Peyto Glacier produced …

Subsurface Glacial Geology Of The Area Between The Tekonsha And Kalamazoo Moraines, Kalamazoo County, Michigan, Kim Finkbeiner

Masters Theses

Cross sections profiling the stratigraphy of the glacial sediments were created using the geological logs recorded on water well records. Glacial sediments in the study area comprise a large outwash complex between two moraines. The surficial landforms are the result of the last Wisconsinan advance and retreat through the area.

Cross sections contructed for this project reveal at least three major till units. An additional till unit contains a weathered soil sequence. Therefore, it is possible that this paleosol represents the Sangamon Interglacial period between the Wisconsinan and Illinoian stages. No obvious evidence of movement of the Saginaw Lobe remains …

Ductile Saline Ice, G. A. Kuehn, E. M. Schulson

Dartmouth Scholarship

Experiments have shown that tensile ductility of about 5% or more can be imparted to columnar, saline ice by pre-compressing the material by about 3.5%. This effect is similar to that observed in granular, fresh-water ice and is attributed to the operation of both dislocation creep and diffusion creep within that part of the matrix which recrystallized during the pre-compressive deformation.

Probable Glacial Climatic Conditions In Source Areas During Deposition Of Parts Of The Ash Hollow Formation, Ogallala Group (Late Tertiary), Of Western Nebraska, Patricia E. Helland, Robert F. Diffendal Jr.

Robert F. Diffendal, Jr., Publications

Evidence of the climatic conditions in the mountain sediment source areas for the late Tertiary Ash Hollow Formation of the Ogallala Group in western Nebraska has been sought in an SEM (scanning electron microscope) study of surface features on detrital quartz grains from these deposits. The following lines of indirect evidence raised the possibility of glacial conditions: uplift of up to 3500 m in the source areas, paleohydrologic parameters indicative of a transport system analogous to the modern North Saskatchewan River, and possible cold climate surface features on cobbles from the deposits. SEM analysis shows that five of the nine …

Brittle Compressive Failure Of Salt-Water Columnar Ice Under Biaxial Loading, T. R. Smith, E. M. Schulson

Dartmouth Scholarship

The brittle failure of saline columnar ice was investigated under biaxial compression at and −10° and −40°C over the range 0 ≤ R A < 1 where R A is the ratio of the intermediate to major principal compressive stress. The major principal stress and the intermediate (confining) stress were orthogonal to the columnar axes (type-A confinement); both stresses and the c-axes of the grains were co-planar. The results confirm earlier work by Hausier (1981) and Timco and Frederking (1983, 1986) on saline ice and follow similar behavior to fresh-water columnar ice found by Smith and Schulson (1993) and Frederking (1977). Failure stress and failure mode are sensitive to the confinement and two regimes of behavior are found: the failure stress first rapidly increases with R A in the range 0 ≤ R A < R T and then tends to decrease for R A > R t. The transition stress ratio, R t changes from ≈0.2 at −10°C to ≈0.1 at −40°C. The failure mode changes from axial splitting to shear faulting in the loading plane for 0 < R A < R t. Above R t failure changes to a combined mode of splitting across the columns and shear faulting out of the loading plane. The failure-stress envelope is of a truncated Coulomb-type. Damage studies show wing cracks and local fragmentation of grains involving the brine pockets. The results are explained in terms of Coulombic sliding and Hertzian crack mechanics.

The Origin And Evolution Of The Southern Snake Range Decollement, East Central Nevada, Allen J. Mcgrew

Department of Earth, Environment and Sustainability Faculty Publications

Regional and local stratigraphic, metamorphic, and structural constraints permit reconstruction of the southern Snake Range extensional deformational system in east central Nevada. The dominant structure of the range, the southern Snake Range décollement (SSRD), operated during Oligocene and Miocene extensional deformation to exhume a footwall of multiply deformed metasedimentary and plutonic rocks. Intrusion of three plutons (∼160 Ma, 79.1 ± 0.5 Ma, and 36 ± 1 Ma, respectively) and development of two cleavages preceded the onset of extensional deformation. Plastic deformation of lower plate metasedimentary rocks accompanied the early phases of regional extension and produced bedding-parallel grain shape foliations and …

Ages Of The Whitewater And Fairhaven Tills In Southwestern Ohio And Southeastern Indiana, Barry B. Miller, William D. Mccoy, William J. Wayne, C. Scott Brockman

Department of Earth and Atmospheric Sciences: Faculty Publications

Alloisoleucine/isoleucine (aIle/Ile) ratios obtained from fossil mollusc shells collected at localities in southwestern Ohio and southeastern Indiana, where they occur in silt beds associated with the Whitewater and Fairhaven tills, indicate a pre-Wisconsinan age for these tills, which had previously been thought to be early or middle Wisconsinan.

The aIle/Ile ratios in shells from beneath the buried soil (Sidney soil) and till exposed near Sidney, Ohio, are most similar to values in shells obtained from Illinoian sediments at Clough Creek in Hamilton County, Ohio; Mechanicsburg southwest, Illinois; and Trousdale Mine in Vermillion Co., Indiana. The first well-developed weathering profile in …

The Fracture Of Ice On Scales Large And Small: Arctic Leads And Wing Cracks, E. M. Schulson, W. D. Hibler

Dartmouth Scholarship

From observations and calculations of crack patterns in ice, it is suggested that a similar mechanism may account for cracking over a wide range of scales.

Ice-Wedge Casts Of Wisconsinan Age In Eastern Nebraska, William J. Wayne

Department of Earth and Atmospheric Sciences: Faculty Publications

Sand-filled, wedge-shaped structures beneath a thin layer of aeolian sand penetrate a preIllinoian till and gravel in northeastern Nebraska. Interpreted to be relic thermal contraction crack wedges, they provide the first definite evidence in this State of the former presence of permafrost. The wedges are 5- 7 m apart, 1.8-2.8 m deep and 0.6-0.9 m across at the top, taper downward to a crack and intersect to form polygons. They are filled with medium sand that contains mostly rounded and frosted grains. Vertical fabric is present in each wedge. Ventifacts lie along the top of the till, which is covered …

Determination Of Morphologic And Volumetric Change, Peyto Glacier, Alberta, 1966-1989, Peter J. Glenday

Theses and Dissertations (Comprehensive)

During the summer months of July and August 1989, approximately 23 years after a photogrammetric survey on August 22, 1966, Peyto Glacier, a glacier selected for study during the International Hydrologic Decade (IHD) 1965-74, was re-surveyed using terrestrial geodetic surveying techniques. The volumetric and morphologic change of Peyto Glacier, Alberta from 1966 to 1989 is estimated through a combined application of digital cartometry, digital geodetic survey and Triangulated Irregular Network (TIN) digital terrain modeling and analysis. Changes in glacial volume, areal extent, teriminus position, percentage basin glaciation, slope, and aspect for the 23 year interval are shown. Additionally, a 1:10000 …

A Notch-Strengthening Effect In Fresh-Water Ice, Wilfrid A. Nixon, Erland M. Schulson

Dartmouth Scholarship

Tensile tests have been performed onnotched and unnotched cylindrical samples of randomlyoriented polycrystalline ice of controlled grain-size (between2.2 and 7.3mm) at a loading rate of lOOPaS-l and at a temperature of -10 0c. In the notched samples, the notch-root diameter was 80% of the base diameter. Anotch-strengthening effect was observed in the large-grained ice, with fracture stresses being up to 50% higher than that for unnotched samples of the same grain-size. This notch-strengthening effect diminished as grain-size decreased, disappearing at a grain-size of "'3 mm. The notch-strengthening effect is explained in terms of the triaxial stress constraint at the notch …

Water Quality Dynamics In Meltwaters Draining Peyto Glacier, Alberta, Christopher Bradley

Theses and Dissertations (Comprehensive)

Variations in the quantity and quality of meltwaters draining Peyto Glacier, Alberta, are assessed to examine to what extent meltwater characteristics might be indicative of any distinctive source and routing of water through a glacierised drainage basin. Continuous monitoring of solute concentrations of the principle melt-stream, Peyto Creek, was undertaken for significant periods in 1982, 1984 and 1987, coupled with measurements of suspended sediment concentration at the glacier terminus. Discharge of meltwater was determined for periods in 1982 and 1987. Supplementary monitoring of hydrogen-ion variation and total solute concentration was undertaken at additional sites within the basin, at a stream …