Poster Number 112
Sunday, 5 October 2008
George R. Brown Convention Center, Exhibit Hall E
The Hogup Bar quadrangle of northwestern Utah is a region with a diverse and rich archive of multiple coastal shorelines and landforms developed during the Late Pleistocene Lake Bonneville. Within the quadrangle multiple regressive and transgressive shorelines record the lakes elevations that are then related to patterns of paleoclimatic change. The lakes minor transgressive and regressive shorelines amid the major shorelines are still poorly understood due to the convoluted effects of isostatic rebound, past morphology, sediment sources, and potential climatic factors that drove the deposition and erosion of these laterally not continuous shorelines. An EDMAP sponsored geologic mapping project for the quadrangle has allowed the researchers to complete a detailed investigation of these shorelines in the Hogup Bar quadrangle. This mapping illustrates the complex relation of the both the transgressive and regressive shorelines and give a relative chronology of these minor shorelines in relation to the current understanding of the lakes history. The dating of these shorelines via radiocarbon and optically stimulated luminescence is currently underway in order to quantitatively improve the chronology of these less known aspects of the lake's history and how it relates to Late Pleistocene climate changes. In addition, the significant shoreline expressions seen in the bedrock platforms and depositional landforms within the quadrangle suggest that strong northerly wind events were frequent during the Late Pleistocene and could be due to a katabatic effect caused by the presence of the large continental ice sheet to the north of the lake.