Browsing by Subject "glacier"
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Item A geological framework for temporal sedimentary dynamics(2009-05-15) Noll, Christian JohnGeophysical, geochemical and geotechnical methods were used to investigate the spatial and temporal aspects of sediment distribution, accumulation, post-depositional alterations, and seafloor response and recovery to major events in a temperate, paraglacial, turbid outwash fjord. The goals of this study are to generate a complete geological model and compare the results to the global distribution of fjords. The over arching theme of this study is that the ratio of the area of the watershed to the area of the receiving basin can provide a first order indicator of many factors including glacial mass; the timing of glacial retreat; sediment input, accumulation, and preservation; and other factors. Temporal observations reveal the change of this fjord from a glaciated basin to and estuarine environment. These observations become important when viewed in the context of global climate change and the continued loss of ice. Preserved strata provide a 2800 yr record of changing modes of sedimentation as the system evolved from a glaciated basin to a non-glaciated fjord revealing a detailed chronology of change between end-member systems which can be used to infer changes as glaciers retreat from other fjords. Short lived radio isotopes were used to investigate post-depositional alteration of modern sediments. Without an understanding of how biological and physical processes work to modify sedimentary fabric during preservation, changes seen in sediment and rock core data cannot be accurately resolved. Physical processes can cause erosion and lateral transport; winnowing and armoring; and instantaneous sedimentation, all of which may be preserved. Biological processes can modulate the preservation of strata by destroying sedimentary fabric and integrating signals. The final fundamental need is to investigate the seafloor response and recovery to these events. Massive earthquakes are frequent in the study area and cause perturbations to sediment input and preservation. By understanding how lakes and deltas modulate sediment discharge after the event; how shorelines are modified after the event; and where sediment is deposited we can determine the influence these changes have on the environment and on humans.Item Analysis of Glacier Recession in the Cordillera Apolobamba, Bolivia 1975-2010(2012-02-14) Latterman, LaDonnaThe tropical glaciers in the Bolivian Andes Mountains are small and respond quickly to changes in their climate. They are also a major source of freshwater year-round for nearby communities. Monitoring the glacial changes taking place in these glaciers has become increasingly important as they have been retreating over the past century. These glaciers are remote and the terrain treacherous making it potentially dangerous to gather data through field work. For this reason and because of advances in remote sensing technologies the use of satellite images has become the primary means to study these tropical glaciers in detail. This research study focuses on the Cordillera Apolobamba range located on the Peruvian-Bolivian border. It is an example of the methodology applied to assess the area covered by glaciers in this and other regions around the world. Using Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) images from 1985 to 2010, as well as the Glacier Inventory of Bolivia, the glacier extents of the Apolobamba are mapped. From 1975 to 2010 the portion of the range located within Bolivia's border lost 110.76 km^2 of surface ice lowering its total area from 240.36 km^2 to 129.60 km2, a 46.08% reduction. From the 1985 to 2010 the entire Apolobamba range lost 102.72 km^2 of ice lowering its total area from 261.07 km^2 to 158.35 km^2, a 39.35% reduction. An analysis of atmospheric conditions was conducted at the 500 hPa level for various climate variables using NCEP/NCAR reanalysis data. Between time period one (1975-1986) and two (1987-1995) the climate variables exhibiting a statistically significant change are air temperature with an increase of .165 degrees C and geopotential height with an increase of 2.967 m. Between time period two and three (1996-2005) the climate variables exhibiting a statistically significant change are freezing level with a 50.017 m increase, precipitation with an 60.604 mm/month decrease and wind velocity with an increase of .373 m/sec. According to the analysis conducted using the Oceanic Nino Index, the monthly sea surface temperatures exhibit no statistically significant change from 1975-2005.Item Warmly Debated: The Little Ice Age and the Construction of Historical Climatic Regimes, 1650-1950(2011-08-08) Gilson, Christopher R.Climatic change has been the subject of investigation and spirited debate for more than three centuries. One important element of this debate has been the search for and definition of unique, impermanent climatic regimes measurable by historic time. The Medieval Warm Period and the Little Ice Age are the two most commonly referenced and discussed of such regimes. This thesis examines the theories and debates that preceded and surrounded the formal definition of the Little Ice Age as an historic period of approximately 1550-1850 AD. This thesis begins by describing early attempts to measure and record climatic conditions during the late seventeenth and early eighteenth centuries while also demonstrating that climatic change and climatic influence were matters of concern for both the scientific and philosophical elite and the public. By the first decade of the nineteenth century, however, discussion of climatic change had begun to center on comparisons of the medieval past and the cooler present. Climatic change itself often intruded on debates about past climates during the early nineteenth century. By 1900, however, both scholars and laymen had begun to recognize that some form of climatic change had occurred in the sixteenth century. Early twentieth century scholars such as Otto Pettersson, Charles Rabot, and Ellsworth Huntington helped define the boundaries and significance of historical climatic regimes. When Francois Matthes wrote of a "little ice-age" in 1939, he was not creating a wholly new idea; he was instead engaging in a centuries-old debate over the climatic conditions of the last millennium.