Physical Sciences and Mathematics Commons^™

The Upper Ocean At The End Of An Ice Age: Using Proxies In Benthic Foraminifera To Investigate Intermediate Water Changes During The Last Glacial Termination, Cassandre R. Stirpe

Electronic Theses and Dissertations

The ocean is an important component of the global climate system and plays a key role as a storage reservoir for heat and carbon. Under glacial conditions, the ocean sequestered carbon from the atmosphere, contributing to a cooler global climate. During the last glacial termination, that carbon was released back into the atmosphere, but the exact timing and mechanisms of this transfer are still not fully understood. This study examines waters from the intermediate depths of the Southern Ocean to gain insight into deglacial processes. Intermediate waters are capable of reacting to climate change on decadal timescales, making them a …

Variations In The Southern Hemisphere Westerlies Over The Last 23,000 Years From Lake Records In The Falkland Islands, Meghan M. Spoth

Electronic Theses and Dissertations

The Southern Hemisphere Westerlies (SHW) are an important driver of climate in the mid-latitudes of the Southern Hemisphere. Abrupt latitudinal migration of this coupled atmospheric-oceanic system is thought to be linked to the onset of the Termination at the end of the last ice age and to subsequent climatic variation through the late-glacial period and Holocene. However, the timing and spatial extent of these shifts, as well as variations in wind intensity, are poorly constrained, hindering our understanding of abrupt climate change in the Southern Hemisphere. In addition, future changes in the position and intensity of the SHW are a …

An Algorithm To Estimate Suspended Particulate Matter Concentrations And Associated Uncertainties From Remote Sensing Reflectance In Coastal Environments, Juliana Tavora

Electronic Theses and Dissertations

Suspended Particulate Matter (SPM) is a major constituent in coastal waters, involved in processes such as light attenuation, pollutant propagation, and waterways blockage. The spatial distribution of SPM is an indicator of deposition and erosion patterns in estuaries and coastal zones and a necessary input to estimate the material fluxes from the land through rivers to the sea. In-situ methods to estimate SPM provide limited spatial data in comparison to the coverage that can be obtained remotely. Ocean color remote sensing complements field measurements by providing estimates of the spatial distributions of surface SPM concentration in natural waters, with high …

How Acidic Sediments And Seawater Affect Interactive Effects Of Predation On Survival, Growth, And Recruitment Of Wild And Cultured Soft-Shell Clams, Mya Arenaria L., Along A Tidal Gradient At Two Intertidal Sites In Eastern Maine, Brian F. Beal, William Otto

Miscellaneous Publications

No abstract provided.

High Net Loss Of Intertidal Wetland Coverage In A Maine Estuary By Year 2100, Jack R. Mclachlan

Biology and Ecology Faculty Scholarship

Rising sea levels and coastal land use are predicted to synergistically impact coastal wetlands by reducing their extent and ecosystem functioning through a process known as “coastal squeeze”. Impervious surfaces associated with coastal development prevent the natural process of wetland migration, whereby intertidal wetland area is lost at its seaward edge to rising low water lines, but is replaced by eroding uplands and accumulating new wetland at its landward edge. As these constructed surfaces prevent the replacement of lost wetland, intertidal wetlands are “squeezed” by rising sea levels until they disappear. This study uses geographic information system (GIS) to predict …

Sediment Accumulations Patterns In The Damariscotta River Estuary, Emily A. Chandler

Electronic Theses and Dissertations

The tidally dominated Damariscotta River estuary is located on the south-central Maine coast. The elongate, north-south orientation of the estuary is characteristic of the indented shoreline in this region and a consequence of the bedrock structural framework, comprised of Paleozoic high-grade metasedimentary rocks. Pegmatite sills form bedrock constriction points that divide the estuary into seven distinct basins. The narrow, bending geometry and sill and basin morphology impact the distribution of sediment within the estuary and the hydrodynamics of the system. This study employs multibeam bathymetry surveys, sediment grab samples and radionuclide analysis (²¹⁰Pb and ¹³⁷Cs) of sediment …

Fluvial Deposition, El Nino And Landscape Construction In Northern Coastal Peru, Paul M. Pluta

Electronic Theses and Dissertations

The El Nino global climate anomaly is a major cause of weather variation that can have far-reaching effects on human populations around the world. Northern coastal Peru is an area of historically major impacts where strong El Nino events have resulted in catastrophic flooding and mass wasting, leading to significant social disruption. There is a growing body of literature on the prehistoric chronology of El Nino and how it affected human populations of the past, but more work is needed. In order to address the timing and characteristics of past El Nino events I investigated the alluvial sedimentary sequences at …

Estimating Particle Size In The Ocean From High-Frequency Variability In In-Situ Optics, Mary Jane Perry

University of Maine Office of Research Administration: Grant Reports

During this 3-year NESSF fellowship and seven-month no-cost extension, I published two papers as first author (Briggs et al. 2011; Briggs et al. 2013) and two papers as a co-author (Alkire et al. 2012; Cetinic et al. 2012). I am also co-author on one submitted paper and have worked on five additional papers that are in preparation (two as first author). I have given talks at four international oceanographic conferences: The 2012 and 2014 Ocean Sciences Meetings in Salt Lake City and Honolulu, the 2012 Ocean Optics meeting in Glasgow, Scotland, and the 2013 Liege Colloquium in Liege, Belgium. I …

The Characteristics That Control The Stability Of Eroding Coastal Bluffs In Maine, Corinn C. Keblinsky

Electronic Theses and Dissertations

Bluffs of glacigenic sediment exist along 53% of the tidal shoreline of Maine. Under the current regime of rising sea level, waves, groundwater, and sub-aerial processes easily erode these materials. The hazardous nature of the bluffs is not widely recognized by the public, and new homeowners are often shocked to find out that their property is disappearing. To better educate the public, the Maine Geological Survey is mapping the stability of coastal bluffs. This report utilizes that database along with other available data to determine what controls the relative stability of bluffs. A geographic information system (GIs) was used to …

Formation And Age Of Raised Marine Beaches, Northern Scott Coast, Antarctica, Nathan Gardner

Electronic Theses and Dissertations

The stability of the West Antarctic Ice Sheet (WAIS) is a key problem because of its potential effect on global sea level and climate. Some geologic evidence suggests that the ice sheet has collapsed in the past, which, if correct, implies that future disintegration is possible. Isolation of the mechanism(s) that have affected WAIS behavior since the last glacial maximum (LGM) may yield information about factors that control it today. Previous studies have indicated thatrecession of the WAIS from the LGM position occurred in the middle to late Holocene. However, the data come fiom points too far south to assess …

Distribution Of Patterned Ground And Surficial Deposits On A Debris-Covered Glacier Surface In Mullins Valley And Upper Beacon Valley, Antarctica, Andrew M. Lorrey

Electronic Theses and Dissertations

Beacon Valley is located in the western Dry Valleys, Antarctica, adjacent to the East Antarctic Ice Sheet (EAIS). The surficial material on the floor of Beacon Valley is segmented into large polygonal landforms separated by trenches. Buried beneath the polygons and surficial material is massive ground ice. One hypothesis is that the buried ice in upper Beacon Valley is glacier ice originating from local debris-covered glaciers. The networks of polygons and trenches form as the buried ice undergoes thermal contraction and sublimation. Contraction cracks that penetrate the surficial material and buried ice in Beacon Valley contain Late Miocene age volcanic …

Evolution Of Seabed Pockmarks In Penobscot Bay, Maine, Allen M. Gontz

Electronic Theses and Dissertations

Seafloor depressions, called pockmarks, have been known to exist in Penobscot Bay, Maine since the mid 1980's (Knebel and Scanlon, 1985). Earlier workers (Ostericher, 1965) recognized "channels" on sonoprobe records that are in the sanle area as the pockmarks recognized by Knebel and Scanlon (1985). Their origins and pathways of evolution are unknown. Much speculation about the sources of pore fluids, levels of activity, and evolutionary pathways has occurred since their discovery. Two surveys of Belfast Bay, in 1998 and 1989, have shown differences in the pockmark field population. Over the course of a decade, 36% of the field's 1998 …

Evolution Of Sprague Neck Bar, Machias Bay, Maine, Rebecca A. Nestor

Electronic Theses and Dissertations

Sprague Neck Bar is a recurved barrier spit located in Machias Bay, Maine. Principle geomorphic features associated with Sprague Neck Bar include bedrock, coastal bluffs, till in grounding line (the Pond Ridge Moraine) and washboard moraines, mudflats, sand and gravel beaches, and a salt marsh. Sprague Neck Bar is attached to the western end of the Pond Ridge Moraine (Sprague Neck) and extends northward toward the head of Machias Bay for 845 meters before the system recurves to the southeast for 232 meters. The recurve system forms a broad tidal flat with evidence for northward and eastward migration of the …

Collaborative Research: Long Records Of Paleoclimate From Florida, George L. Jacobson, Heather Almquist

University of Maine Office of Research Administration: Grant Reports

Long Records of Paleoclimate from Florida Recent research on a continuous 50,000-year sediment record from eastern North America has revealed a striking correlation between Heinrich events (large surges in flow of ice streams feeding from the Laurentide ice sheet into the North Atlantic) and major changes in vegetation in peninsular Florida. These events are expressed at Lake Tulane, Florida, as abrupt shifts between pine-dominated and oak-dominated communities, which likely correspond with times of moist climate alternating with periods of extreme drought. Those results suggest that the Heinrich events involved important changes in ocean-atmosphere circulation, and thus forcing other than internal …

Ice-Core Dating And Chemistry By Direct-Current Electrical Conductivity, Kenorick Taylor, Richard Alley, Joe Fiacco, Pieter Grootes, Gregg Lamorey, Paul Andrew Mayewski, Mary Jo Spencer

Earth Science Faculty Scholarship

Although quantitative interpretation of the low-frequency electrical conductivity of ice cores from central Greenland is complicated by temperature variations of the measured core, annual layers can be recognized in sections of the core that are not impacted by non-seasonal features. Ambiguities in counting of annual layers can be minimized by comparing the electrical conductivity measurements to measurements of dust concentration and visual stratigraphy. A non-linear relationship between applied voltage and the current measured across two electrodes complicates the quantitative comparison of measurements made with different equipment, but does not affect the overall shape of the observed features .

The Glaciochemistry Of Snowpits From Quelccaya Ice Cap, Peru, 1982, W. Berry Lyons, Paul Andrew Mayewski, Lonnie G. Thompson, Boyd Allen Iii

Earth Science Faculty Scholarship

We present glaciochemical data from a pilot study of two snow-pits from Quelccaya ice cap, Peruvian Andes. These are the first samples to be analyzed from Quelccaya for nitrate and sulfate by ion chromatography (IC), for nitrate-plus-nitrite, reactive silicate and reactive iron by colorimetry, and for sodium by atomic absorption spectrophotometry. The 3 m pits used in this study represent a one year record of mass accumulation and the 29 samples collected provide the first glaciochemical data from this area which can be compared with glaciochemical studies from other locations.

Reactive iron, reactive silicate and sodium, and the profiles of …

Geochemical And Glacio-Geomorphic Implications Of Basalt Weathering In The Queen Maud Mountains, Antarctica, R. W. Talkington, Paul Andrew Mayewski, H. E. Gaudette

Earth Science Faculty Scholarship

Summary. The weathering of a suite of basalt clasts. that have been transported by mass wasting downslope in the Cumulus Hills region of the Queen Maud Mountains. Antarctica. is examined from both geochemical and glacio-geomorphic viewpoints. Chemical weathering. predominantly oxidation and hydration. increases in severity from clast core to rim for the suite. These weathering processes and concomitant formation of a weathering rind are suggested to be an accumulative process. culminating in the disaggregation of the rock due in part both to the chemical breakdown of the interstitial and intersertal basaltic glass and to physical weathering processes. Mass wasting rates …

Dickey-Lincoln School Lakes Project Environmental Impact Statement: Appendix A: Geology And Seismology (Supplement), Walter A. Anderson, New England Division, United States Army Engineer Division

Dickey-Lincoln School Lakes Project

The plan was prepared for a close working relationship between the evaluation teams and the immediate availability of geochemical and geophysical data to the geologic mapping team. Those samples determined in the field to be anomalously high in heavy metals by cold extractable procedures were sent to North American Laboratories where metal content determinations were made through: atomic absorption and spectrophotometry after hot acid digestion techniques.

Weathering Stages Of A Tholeiitic Basalt (Dolerite), Queen Maud Mountains, Paul Andrew Mayewski

Earth Science Faculty Scholarship

The sparsity of datable material and key horizons throughout most of the Transantarctic Mountains requires that much of the mapping and correlation of glacial deposits, especially moraines, be based primarily on qualitative techniques. One qualitative method is to characterize the degree of weathering of clasts covering these deposits (Behling, 1971; Calkin, 1971; Nichols, 1971; and Mayewski, 1975). Lacking, however, is a detailed understanding of the role and method of weathering. To help solve this problem, soil studies have been made by Claridge and Campbell (1968) in the Shackleton Glacier region and Everett and Behling (1968), Linkletter (1972), Behling (1971), and …

Glacial Geology Near Mcmurdo Sound And Comparison With The Central Transantarctic Mountains, Paul Andrew Mayewski

Earth Science Faculty Scholarship

(From summary, pp. 105-106) In the central Transantarctic Mountains, the Sirius Formation consists of both a lower massive till and an upper assemblage of interlayered till and stratified lenses. Deposits of the Sirius Formation found in the McMurdo region contain only the lower massive till. The lower massive till of the Sirius Formation is thought to be a basal till because of extremely strong fabric, high concentration of faceted and striated pebbles, and heterogeneous particle sizes (clay to boulders). Fabrics observed in the basal till indicate that the ice that deposited the Sirius Formation, although displaying a much higher surface …