Award Date

1-1-2003

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Geoscience

First Committee Member

Richard L. Orndorff

Number of Pages

225

Abstract

Limited research has been conducted on the paleoclimatic significance of glacial and periglacial features in the Great Basin. Glacial features in the range were first recognized and described by early explorers (Gilbert, 1875; Simpson; 1876 and Russell, 1884) and subsequent authors have continued to substantiate and elaborate on earlier reports (Heald, 1956; Kramer, 1962; Currey, 1969; Peigat, 1980; Osborn and Bevis, 2001). Since this early reconnaissance work, few studies have focused on the Late Quaternary evolution and paleoclimatic implications of glacial and periglacial landforms in the Great Basin (Wayne, 1983; Osborn, 1989; Bevis, 1995; and Osborn and Bevis, 2001). Wayne (1984) describes relict rock glaciers, sorted circles, debris islands, solifluction lobes and sorted stripes in the Ruby, Schell Creek, and Snake ranges. While Currey (1969) and Osborn and Bevis, (2001) discuss the distribution of rock glaciers in numerous ranges throughout the Great Basin, including the Snake Range, and the surrounding regions; This study presents new data on the glacial and periglacial Late Quaternary conditions in the interior Great Basin based on studies carried out in the Snake Range, located in east-central Nevada. I propose the Lehman rock glacier is an ice-cemented landform that evolved via a recessional genesis, contrary to present glacial or periglacial models that primarily propose constructional geneses for rock glaciers. Preliminary GPR evidence suggests the Lehman rock glacier may retain interstitial lenses of ice; remnant ice that has stagnated under modern climate conditions; The spatial distribution of both glacial and periglacial landforms provides paleoclimatic information derived using field evidence and computer modeling. Neoglacial temperature depression estimates calculated using modern freezing and thawing indices for relict rock glaciers, range from -0.25°C to -1.00°C while temperature estimates calculated using the methodology described by Frauenfelder and Kaab, (2000) and Frauenfelder et al., (2001) are 0.35 to 0.97 degrees lower than those calculated using freezing and thawing indices. Full Glacial MAAT depression estimates range from approximately -5.16°C to -6.61°C calculated using periglacial landforms, to approximately -4.55°C to -5.77°C, calculated from reconstructed Angel Lake equilibrium line altitudes (ELAs); Finally, using scanning electron microscopy, it is possible to differentiate between a glacial and non-glacial origin for pebbles and cobbles entrained in enigmatic sedimentary deposits is a useful tool. Each depositional environment creates distinct micro-features that can be identified and used to establish a glacial or non-glacial history.

Keywords

Environment; Glacial; Late; Nevada; Periglacial; Quaternary; Range; Rock Glaciers; Snake; Snake Range

Controlled Subject

Geology; Environmental sciences

File Format

pdf

File Size

11294.72 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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