Thesis (LL. M.)--Judge Advocate General's School, U.S. Army, 1958. / "April 1958." Typescript. Includes bibliographical references. Also issued in microfiche.

Thesis--University of Wisconsin. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 181-187).

archives@tulane.edu / I present research that improves our understanding of the glacial history of the Antarctic Ice Sheet and advances the method of in situ 14C exposure dating. Firstly, I present research investigating deglaciation in the Weddell Sea Embayment (WSE) sector of the Antarctic Ice Sheet. Large spatial gaps exist in our knowledge of the former configuration of the ice sheet in the WSE because previous studies observe cosmogenic nuclide exposure ages indicative of either significantly thicker ice than present at the Last Glacial Maximum (LGM) or limited (<100 m) thickening. The resulting pattern of past ice thickness is glaciologically unlikely. By measuring the short-lived cosmogenic nuclide in situ 14C in many of the same samples as previous studies, I show that ice at locations thought to have experienced limited thickening was at least 300 to 800 m thicker than present. These new constraints will help future modelling studies in their efforts to simulate the ice sheet and narrow down the contribution to deglacial sea level rise. Next, I present an investigation into the source of elevated in situ 14C measurements observed from samples that were processed using a mineral separation technique called froth flotation. Multiple organic compounds are required for the use of froth flotation. With modern carbon sources, these organic compounds could introduce carbon contamination to samples. I find that froth flotation introduces modern carbon to samples and contaminant 14C is released with the in situ component. I then outline a procedure that demonstrably removes carbon contamination that can be followed by those isolating quartz for in situ 14C analysis. Finally, I present an evaluation of the results of numerical ice sheet models using a compilation of exposure ages from the WSE. I use all published post-LGM 10Be and in situ 14C exposure ages from the WSE to assess how well models predict ice thinning histories evidenced by the cosmogenic nuclide measurements. Whilst most models are consistent with minimum geologic constraints for the thickness of the ice sheet, the timing and rate of the majority of post-LGM ice thinning predicted by ice sheet models is often both premature and more rapid than indicated by exposure ages. / 1 / Keir Nichols

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Thesis--Wisconsin. / Includes bibliographical references (leaves 58-59).

Habilitationsschrift - Freiburg.

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

The Southern Ocean has unique seasonal qualities due to the Antarctic Circumpolar Current (ACC) thermo-isolating the Antarctic continent. During summer months, surface primary productivity from algal blooms is very high. In the winter months, limited daylight hours (4 in winter) and formation of sea ice prevents sun light from reaching surface waters, therefore limiting productivity. The short seasons of productivity and long winters in Antarctica combined with seasonal changes in deep ocean temperatures, salinity, and fluxes of organic matter impact foraminiferal population dynamics. Fluctuations in surface primary productivity, as well as living foraminiferal assemblages have been documented around the Antarctica Peninsula, but the impact on benthic foraminiferal assemblages is poorly understood. This is a study of seasonal affects on benthic foraminiferal assemblages in the southern Bransfield-northern Gerlache Straits of the Southern Ocean. Surface sediment samples from 600 meters and 1200 meters water depth were collected during two seasonal cruises: early April to record the productivity of the end-of-summer bloom and late June to sample the less-productive winter period. Three hundred and sixty samples were collected from 7 sites and processed using standard techniques. To identify living foraminifera, samples were treated with Rose Bengal, and CellTracker Green on a select set of samples for comparison. Ninety total species were identified; seventy species from June and seventy-one from April, fifteen species of foraminifera unique to April, thirteen to June and two unique species in the CellTracker Green samples. The abundance of total living (stained tests) opportunistic benthic foraminiferal species from the 7 sampled sites show distinct temporal differences related to seasonality. An assemblage of deep water species was also found, as well as an assemblage of shallow water species. ANOVA and post hoc Tukey tests showed that the full cores must be analyzed to determine seasonal species assemblage changes. Cluster analysis and species abundances in CellTracker Green samples showed a marked difference from the Rose Bengal samples, consistent with literature that suggests the two methods differ. Fluctuating populations of foraminifera in fossil samples can be interpreted as changes in local or global climate. This study stands as a modern analog for fossil foraminiferal assemblages, and provides important information to help interpret paleoenvironmental conditions related to seasonality by defining seasonally and geographically distinct species assemblages.