Date of Award

August 2018

Degree Name

Master of Science (MS)

Department

Earth Sciences

Advisor(s)

Gregory D. Hoke

Keywords

Cosmogenic Nuclides, Forward Modeling, Glacial Erosion Rates, New York, Pleistocene

Subject Categories

Physical Sciences and Mathematics

Abstract

Throughout the Pleistocene the northern hemisphere was subject to alternating ice-free and ice accumulation periods. Today’s glacial landscapes, composed of a mix of erosive and depositional geomorphological features, reflect the integrated impacts of successive Pleistocene glaciations. In North America such impacts include the formation of the Great Lakes, the reorganization of river networks and the deposition of till sheets, erratic boulders, and moraines. Nearly all of New York State was covered by ice; however, the impact of the successive glaciations on the landscape varies throughout the state. An examination of the regional topography reveals relatively undissected, streamlined landforms of the Finger Lakes area, while adjacent areas retain a largely remnant dissected fluvial landscape. This variation implies differences in the erosive effect of glaciers on modifying the landscape and this study explores that variation. The earliest work in the area hypothesized that the first glacial episode exploited the differences in rock competence related to the facies of the Appalachian Basin in order to create today’s physiographic differences, preparing a path for subsequent advances to follow with no further erosion. This study uses the cosmogenic nuclide 10Be to constrain the magnitude of glacial erosion in the Finger Lakes and adjacent areas. Exploiting a stratigraphically continuous sandstone layer, the Devonian Oriskany Sandstone, an estimate of the amount of glacial erosion experienced by the landscape over the last million years is determined using the concentration 10Be produced at depth by the muon production mechanism. This thesis explores a family of plausible erosion scenarios by forward modeling of the accumulation of 10Be concentrations as successive glacial erosion events exhumes the sandstone layer towards the surface. The model output as well as calculated erosion rates and effective ages are used to make determinations about each of the sites in the context of elevation and topography, including interpretations based on the presence of various glacial erosive features. In an east - west transect across the Finger Lakes Region, increasing site elevation correlates with older effective ages and low erosion rates, with one exception whose high elevation is secondary to its proximity to areas of focused glacial erosion.

Access

Open Access

Available for download on Monday, September 14, 2020

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