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Articles 1 - 10 of 10
Full-Text Articles in Entire DC Network
Ecological Interactions Affecting Diatom Climate Reconstructions In Prairie Saline Lakes Of The Northern Great Plains (Usa), Courtney R. Wigdahl
Ecological Interactions Affecting Diatom Climate Reconstructions In Prairie Saline Lakes Of The Northern Great Plains (Usa), Courtney R. Wigdahl
Electronic Theses and Dissertations
Sedimentary diatom profiles from saline lakes are frequently used to reconstruct lakewater salinity as an indicator of drought. However, diatom-inferred salinity reconstructions (DI-salinity) from geographically-close sites in the Great Plains (USA) have yielded disparate results. Here, I explore how within-lake ecological processes, such as physical changes in lake habitat and zooplankton grazing pressure, may affect the accuracy of diatom-based salinity reconstructions. I examined how relationships differed among drought, lake-level change, and diatom community structure over the last century by developing three-dimensional models of planktic:benthic habitat (P:B) relationships with lake level change. I explored the potential for zooplankton grazing influence by …
Kinematic Vorticity Gauges And The Rheology Of Mylonitic Shear Zones, Scott E. Johnson
Kinematic Vorticity Gauges And The Rheology Of Mylonitic Shear Zones, Scott E. Johnson
University of Maine Office of Research Administration: Grant Reports
Many hazards encountered by humans, including earthquakes, volcanic eruptions and tsunamis, result from plate tectonics. How tectonic plates move and interact with one another, and how deformation that occurs at their interacting boundaries is localized into structures like the San Andreas fault in California, are first-order questions in the Earth Sciences. At active tectonic plate boundaries, GPS data have allowed a much clearer understanding of plate interactions, localization of deformation, and relations to seismic and volcanic hazards. However, such data provide little information about plate interaction and deformation at great depth. The most direct way to study these deeper processes …
Collaborative Research: High-Resolution Studies Of Glacier Dynamics At Two Major Outlet Glaciers In East Greenland, Gordon S. Hamilton
Collaborative Research: High-Resolution Studies Of Glacier Dynamics At Two Major Outlet Glaciers In East Greenland, Gordon S. Hamilton
University of Maine Office of Research Administration: Grant Reports
The Principal Investigators request support for an interdisciplinary, high-resolution study involving remote sensing and field investigations at two of Greenland's largest outlet glaciers. The study of the Helheim and Kangerdlugssuaq Glaciers will integrate seismological, glaciological, and geodetic observations to build an understanding of flow dynamics at major outlet glaciers, which represent a critical junction between the atmosphere, cryosphere, and hydrosphere. The project would be the first long-term occupation of an outlet glacier by a GPS receiver network, and would address questions of flow variation on earthquake to interannual time scales. Recent discoveries have made it clear that our understanding of …
Collaborative Research: Dynamics At The Base Of A Pseudotachylyte-Bearing Fault System, Scott E. Johnson, Peter O. Koons
Collaborative Research: Dynamics At The Base Of A Pseudotachylyte-Bearing Fault System, Scott E. Johnson, Peter O. Koons
University of Maine Office of Research Administration: Grant Reports
A concerted effort through EarthScope is currently underway to better understand seismicity along the San Andreas Fault, which poses serious threats to society from large-magnitude earthquakes. The San Andreas Fault Observatory at Depth features an instrumented drill hole, allowing characterization of the rocks, fluids, kinematics, and stress orientations and magnitudes within the fault zone to depths of approximately 3 km. These studies are designed partly to investigate the strength of the San Andreas Fault, which is critical for seismic forecasting. In conjunction with these studies it is important that we locate and study appropriate exhumed examples of similar faults at …
Ice Dynamics And Surface Glaciology Along Us Itase Traverse Routes In East Antarctica, Gordon Hamilton
Ice Dynamics And Surface Glaciology Along Us Itase Traverse Routes In East Antarctica, Gordon Hamilton
University of Maine Office of Research Administration: Grant Reports
This award supports a series of field measurements that will improve our understanding of the East Antarctic ice sheet. The objectives of this project are to take advantage of the overland traverse logistics framework provided by US ITASE and to collaborate with other US ITASE investigators to calculate rates of ice sheet thickness change (mass balance) on domes, along elevation contours and along flow lines in East Antarctica using precise global positioning system methods. In addition, the variability (both spatial and temporal) in snow accumulation rates will be assessed using shallow ice cores and ground-penetrating radar profiling, and will provide …
Dirigo In The Arctic: Donald B. Macmillan, Harrison J. Hunt, And The Crocker Land Expedition, 1913-1917, Charles H. Lagerbom
Dirigo In The Arctic: Donald B. Macmillan, Harrison J. Hunt, And The Crocker Land Expedition, 1913-1917, Charles H. Lagerbom
Maine History
The polar careers of three Maine men intersected in the far reaches of the northern Arctic Ocean at a specific geographic spot on the globe: 83° North Latitude, 100° West Longitude. Called Crocker Land, it had been sighted by polar explorer and Maine resident Robert E. Peary on June 24, 1906. In 1913, Mainer Donald B. MacMillan organized the Crocker Land expedition to explore this land that Peary had sighted. Another Mainer, Harrison J. Hunt, signed on as doctor for MacMillan’s venture in 1913. Crocker Land tied them all together, but only one of the three actually stood where it …
Rapid: Assessing Tsunami Impacts On The Benthic Community Of Robinson Crusoe Island, Richard Wahle, Peter Petraitis
Rapid: Assessing Tsunami Impacts On The Benthic Community Of Robinson Crusoe Island, Richard Wahle, Peter Petraitis
University of Maine Office of Research Administration: Grant Reports
This RAPID project will assess the subtidal ecological impacts of the tsunami that struck Robinson Crusoe Island on 27 February 2010 with support from the Biological Oceanography Program and the Office of International Science and Engineering/Americas. It will take advantage of baseline data collected as part of an ongoing Chilean research project. Robinson Crusoe Island belongs to the Juan Fernandez archipelago, some 600 km west of the coast of Chile in the southeast Pacific. The island group is unique for its high level of marine and terrestrial endemism, including a fishery for the prized Robinson Crusoe Island lobster, Jasus frontalis. …
Structure And Rheology Of The Sandhill Corner Shear Zone, Norumbega Fault System, Maine: A Study Of A Fault From The Base Of The Seismogenic Zone, Nancy Ann Price
Structure And Rheology Of The Sandhill Corner Shear Zone, Norumbega Fault System, Maine: A Study Of A Fault From The Base Of The Seismogenic Zone, Nancy Ann Price
Electronic Theses and Dissertations
Determining the structure and rheology of a seismogenic fault at frictional-to-viscous transition (FVT) depths is vital for understanding its strength and behavior. Few studies describe a fault from within this depth level, so the architecture of a shear zone at these depths as well as the effect of transient coseismic and postseismic deformation on the rheology of the shear zone is poorly-understood. The Sandhill Corner strand of the Paleozoic Norumbega fault system of Maine is the one of the few known examples of a subvertical, strike-slip fault exhumed from FVT depths. Using a suite of samples collected from the Sandhill …
The Hydrological And Geochemical Role Of The C Horizon In A Glacial Till Mantled Headwater Catchment, Margaret A. Burns
The Hydrological And Geochemical Role Of The C Horizon In A Glacial Till Mantled Headwater Catchment, Margaret A. Burns
Honors College
The C horizon is the deepest soil layer that is technically unweathered, similar to the rest of the regolith beneath the bottom of the pedon. In New England, the C horizon formed from the retreat of the glaciers eroding bedrock and depositing an unsorted and unstratified glacial till on the surface. This research evaluated the hydrologic and chemical role of the C horizon, inclusive of underlying regolith, in a forested watershed at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire. Results suggest that the C horizon at HBEF is extensive and heterogeneous. Traditional concepts of basal till offer a …
Heterogeneous Deformation Of Gabbroic Rocks, Calvin Mako
Heterogeneous Deformation Of Gabbroic Rocks, Calvin Mako
Honors College
The Grenville province is the exhumed remains of a more than 1 billion year old orogen. Mid to lower crustal rocks of this orogen are now exposed at the surface, affording the opportunity to examine deeper crustal processes during orogeny. I have studied an outcrop of anorthositic gabbro from the Central Metasedimentary Belt boundary thrust zone (CMBbtz) in the Grenville province of southern Ontario. The CMBbtz is a region that separates two major lithotectonic domains of this part of the Grenville province and is thought to have accommodated large scale thrusting in the mesoproterozoic era. The CMBbtz comprises large crystalline …