Thesis (MS)--Montana State University--Bozeman, 2008. / Typescript. Chairperson, Graduate Committee: Mark L. Skidmore. Includes bibliographical references.

The upland soils of Randolph County, Indiana were studied for the following purposes: to provide an additional characterization of these soils, to identify a set of soil parameters that could delineate the extent of Late Wisconsinan glaciation in that county and to determine if there were any geographic trends in silt cap thickness. The study was prompted from observations by the recent Randolph County Soil Survey team that high clay content soils commonly associated with the county's Late Wisconsinan till (Lagro Formation) were found south of its previously mapped boundary.The only soil parameters that were effective in mapping the extent of Late Wisconsinan glaciation were: particle size analyses and some combinations of particle size analysis data with other soil parameters. The data support the previously mapped boundary of the Late Wisconsinan sediments in Randolph County, Indiana.Silt cap thickness was identified to be greatest in three areas of the county. However, the source(s) of these silts could not be determined. / Department of Geology

A palaeoenvironmental record for the Wisconsin Later Glacial is provided from ten sites in the Magellan Region, southern Chile. Palynological and lithostratigraphical evidence provided by the sites was correlated with other palaeoenvironmental data from the Magellan region using ¹⁴C dating and tephrochronology. This enabled the construction of a regional record of environmental change that was compared with records in northern Patagonia and the Southern Hemisphere. Deglaciation of the Strait of Magellan began sometime before 16,590 yrs BP. A large Late Glacial ice advance believed to have occurred in the Strait of Magellan and contemporary with ice advances in northern Patagonia (c. 15,000-14,000 yrs BP) is not compatible with the ¹⁴C dating evidence. However, a Late Glacial ice advance along the Strait of Magellan was indicated by the glaciotectonic deformation of, and deposition of glaciolacustrine sediments above the Volcan Reclus tephra layer. Eight ¹⁴C dates provided the mean age estimate of 12,010±55 yrs BP for the deposition of the tephra. The erosion of a raised beach into the glaciolacustrine sediments after 7,950±60yrs BP provided the minimum age for the ice advance. Palynological evidence suggested that cold climatic conditions prevailed throughout the Wisconsin Late Glacial. The dominance of eurythermic pollen taxa, components of Patagonian steppe and glacial tundra vegetation, makes it difficult to infer a detailed climatic signal for the Wisconsin Late Glacial. However, a probable climatic deterioration occurred between c. 15,850-14,900 yrs BP. This may have been contemporary with an ice advance in northern Patagonia. A controversial climatic cooling correlated to the Northern Hemisphere Younger Dryas was not evident in the pollen record. The expansion of <I>Nothofagus</I> forest at c. 10,000 yrs BP indicated a change to a warmer environment contemporary with an intense arid phase. Therefore, it is likely that the large Late Glacial ice advance in the Strait of Magellan occurred between c. 12,000-10,000 yrs BP.

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). One map in pocket. Includes bibliographical references (leaves 131-145). Also available via the World Wide Web.

Thesis (M.Sc.)-- Memorial University of Newfoundland, 1992. / Typescript. Bibliography: leaves 179-194. Also available online.

Thesis (Ph. D.)--University of Washington, 1996. / Accompanying maps: Plate 1: Quaternary geologic map of the Hoh, Queets, and lower Clearwater valley, Washington. Plate 2: Stratigraphic cross-section, Hoh River to Raft River. Vita. Includes bibliographical references (leaves [131]-139).

The Younger Dryas was the last period during which glaciers shaped large parts of the Scottish landscape. Reconstructing the palaeoclimate and glacial processes that operated during this time is crucial for the understanding of past atmosphere-cryosphere interactions and predicting future climate change. This thesis presents results from geomorphological and geological mapping in the NW Highlands of Scotland that have resulted in the reconstruction of a Younger Dryas ice cap. Reconstruction of equilibrium-line altitudes and palaeo-precipitation values suggest that the Scottish west coast was wetter than at present. Detailed sedimentological analyses of "hummocky moraines" allow the modes of moraine formation to be reconstructed in great detail and existing models to be tested. "Hummocky moraines" largely represent terrestrial ice-contact fans consisting of supraglacial debris flows and intercalated glaciofluvial units indicating an ice-marginal mode of formation. Different stages of deformation in these fans indicate highly dynamic glaciers that oscillated during retreat, partly or completely overriding previously formed landforms during readvances. Clast shape analyses reveal that debris was mostly subglacially derived and transported. The evidence is incompatible with a morphological model according to which the moraines could be formed by englacial thrusting. Comparison with modem glacial landsystems indicates the following similarities with Scottish Younger Dryas glaciers. Low winter temperatures are similar to those on Svalbard, the marginal response of Younger Dryas glaciers to temperate environments and the modes of deposition to less responsive debris-covered glaciers. High precipitation along the Scottish west coast probably suppressed continuous permafrost development and caused high mass turnover and very dynamic, dominantly temperate Younger Dryas glaciers. Only a narrow zone around the margins appears to have been frozen to the ground, aiding elevation of basal debris and rapid deposition near the snout. The specific climatic and glaciological conditions during the Younger Dryas appear not to have a single modem analogue.

By only considering records of climate and glaciers over the period that humans have been monitoring them, one might think that climate normally changes quite rapidly, and that glaciers have always been small. But in the not-so-distant past, an ice sheet covered the Southern Andes, flowing across the southern tip of the continent, and in some places, even terminating into the Atlantic Ocean. Glaciers rewrite the surfaces they inhabit, leaving behind indicators of their past behavior. By studying the landforms they create, we can reconstruct climates of the past. Here I present unique and novel glacier-climate reconstructions over southern and central Patagonia using a state-of-the-art dating approach tied to high resolution spatial mapping and glaciological modeling. The main goal of this thesis is to constrain the precise timing and character of the past advances of three glaciers in Patagonia. To this end, I present new precise 10Be surface exposure datasets from two paleo outlet glacier lobes (at 45°S and 53°S), totaling 71 new moraine boulder ages. In these two valleys, I am able to reconstruct the last three major glaciations (MIS 6, 4, 2), as well as provide a constraint for the last two terminations (T1, T2). At a third site, I create a novel dataset to reconstruct the behavior of the Calluqueo glacier (48°S) from ~7,000 years ago to the present. All three sites are eastwards of the main Andes mountain range, spanning from southernmost Patagonia (53°S) to central Patagonia (45°S). To achieve my thesis objectives, I employed recent improvements in the 10Be exposure dating method, and tied the geochronological studies to new, high resolution maps of the glacial geomorphology created by the former glaciers and associated processes. We find in central Patagonia, the Ñirehuao glacier lobe was most extensive potentially during Marine Isotope Stage (MIS) 8, but certainly prior to MIS 6, followed by a major advance during MIS 6. This study presents one of the first directly dated records of a MIS 6 glacier expansion in Patagonia at 153±5.1 ka, where the glacier may have been in retreat at 137±4.2 ka. During the last glacial cycle, the glacier was most extensive during the middle of MIS 2, at 23.6±0.9 ka. The southernmost section of the Ice Sheet, at Estrecho de Magallanes, was more extensive during Marine Isotope Stage 4 (MIS 4) than during MIS 2, representing the first direct dating of the MIS 4 glacier culmination in South America. Similar to the MIS 2 glacial maximum, within MIS 4 there were multiple advances that we date (6 samples) to between 67.5±2.1 and 62.1±2.0 ka. Inboard of the MIS 4 moraine complex, we date a sequence of geomorphically distinct MIS 2 moraines that represent separate major periods of glacial stability. The MIS 2 maximum extent occurred by 27.4±0.8 ka and was followed by at least four more full glacial culminations over a hundred miles beyond the Andes mountains. About 18 km inboard of the main MIS 2 landforms, the sequence is followed by smaller-scale recessional moraine crests that we date to 18.0±0.8 ka, indicating the glacier was in net retreat at this time. In order to estimate the climate conditions necessary to drive the glacier advances that we date and map, we apply the University of Maine Ice Sheet Model to the Estrecho de Magallanes and Ñirehuao records. Tentative results suggest that the Magallanes lobe may have reached mapped inner and outer MIS 2 moraines with a climate that had approximately 4.5°C and 5.5°C cooler summers, respectively, assuming about 25% less annual precipitation relative to modern conditions. A new record at Calluqueo, in central Patagonia, allows us to reconstruct Holocene (interglacial) glacier changes. Using 33 new 10Be ages with unprecedented precision, geomorphic mapping and historical imagery, we find that the Calluqueo glacier sat at its mid-Holocene maximum extent from ~6,900 until ~6,700 years before the present. Major moraine forming advances subsequently culminated at least seven more times, averaging every 500±31 years, between 5,620±203 and 3,120±106 years ago. A hiatus in moraine formation occurred from 3,120±106 until 1,160±50 years ago (860 CE). Major retreat occurred between 1600-1800 CE, followed by stability from 1800-1940 CE, and pronounced ongoing retreat since after 1940 CE. For the Holocene period, this record represents one of the first precise, directly-dated glacier histories from central Patagonia, and one of the few available for all of Patagonia. The timing of advances of the Calluqueo glacier has little in common with the glacial histories from the Northern Hemisphere, suggesting an inter-hemispheric asynchronicity. All together, we reconstruct the timing of glacial maxima at three sites in terrestrial Patagonia from 53°S to 45°S, with unprecedented precision, from pre-MIS 6 to the present day.

We use sedimentary structures, fossil evidence, sediment petrophysical properties, and geochemistry to investigate past climate. In the first two chapters, we outline a toolkit to identify the presence of ice rafted debris in lake sediments using a combination of grain size analysis, computed tomography and image analysis. We apply this toolkit to sediments from the early Mesozoic, paleo-Arctic Junggar Basin, and describe the first evidence of continental freezing from this time period. We also discuss characteristics of algae rafted debris; clusters of coarse sediment suspended in a fine sediment matrix can be deposited without freezing conditions and may be a confounding factor in the geological record. In chapters three and four, we examine sediment cores from the coast of New York and the effects of sea level rise after the last deglaciation. New AMS radiocarbon dates from submerged terrestrial sediments on the US Atlantic continental shelf provide key constraints on the timing of marine transgression following the retreat of the Laurentide Ice Sheet. We use sediment elevation tables (SETs) and sediment cores to measure the accretion rate in a Hudson River tidal wetland to determine its vulnerability to sea level rise. We find that SETs overestimate accretion and underestimate vulnerability on timescales relevant to coastal flooding risk. Together, these chapters outline novel tools and approaches in imaging, geochemistry, and micro-stratigraphy broadly applicable for investigations on paleoclimate research through time and space.

No description available.