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RESEARCH PROJECTS
My PhD dissertation research will focus on the Clyde Foreland Formation, a sequence of glaciomarine and marine sediments exposed in the sea cliffs on the northeast coast of Baffin Island. The oldest of these sediments are thought to be nearly 2.5 million years in age. These cliffs contain the longest record of erosion by the Laurentide Ice Sheet anywhere in the eastern Canadian Arctic. I'm using a variety of techniques to date (amino acid racemization of molluscs and cosmogenic radionuclide burial dating of sediment) and extract a record of erosion (till mineralogy and geochemistry, including radiogenic isotope tracers, and meteoric 10Be, among other tools) from these sediments to examine changes in ice sheet flow lines through time and to test the deformable-bed (aka Clark and Pollard's "Regolith Hypothesis") for the Mid-Pleistocene Transition. This research is supported by a Graduate Research Grant from the Geological Society, a Beverly Sears Student Research Grant from the CU Graduate School, and a Shell Research Award from the CU Department of Geological Sciences.
PROBING THE AGE AND SPELEOGENESIS OF THE HIGH-ELEVATION
CAVES Marble Mountain, in the Sangre de Cristo Mountains of south-central Colorado, holds a legendary cave network that contain what are likely the highest solution caves in the United States, ranging in elevation from ~3,200 and 3,650 m. In addition to being unusually high, these caves are situated within a summit ridge that is less than 1 km wide at the elevation of the majority of the passages. Given this unique setting, common mechanisms of speleogenesis cannot be called upon to explain the formation these caves. I'm using cosmogenic radionuclide burial dating to place minimum age constraints on the age of different levels of this cave system. This research is supported by the Ralph W. Stone Graduate Research Fellowship from the National Speleological Society.
In this project we will investigate the climate of south-central Colorado during the Last Glacial Maximum. The extent of glaciers which occupied selected valleys across the range were mapped in the summer of 2006, focusing on the Hunts Creek and South Rock Creek drainages at the northern end of the range, Black Canyon and Lake Creek drainages farther south, South Colony and Crestone drainages in the central part of the range, South Zapata and Huefano drainages on Blanca Massif, and North Vallejos drainage in the Culebra Range. Additional mapping of other drainages on private property on the Blanca Massif and in the Culebra Range will be completed using air photos, topographic maps, and DEMs. Ice surface reconstructions will be created from these mapped ice extents, and from the reconstructions, former equilibrium line altitudes will be calculated. This research is supported by grants from the American Alpine Club and the Colorado Scientific Society.
GLACIAL AND PALEOCLIMATE HISTORY OF THE UINTA MOUNTAINS Beginning in 2004, I began working with the Uinta Mountains Research Group and focusing my research on the southwestern part of the range. The upper Provo River drainage was glaciated repeatedly throughout the late Pleistocene, and unlike glaciers farther west in the range, glaciers in the western end of the range eminated from an ice field which covered all but the highest peaks at the west end of the range. To further investigate the glaciation of this area, the timing of the local Last Glacial Maximum, and the associated climate at the time, we used a combination of field mapping, cosmogenic surface-exposure dating, and inverse glacier modeling. See Refsnider et al. (2007, AAAR), Refsnider et al. (2008, Quaternary Research), and Laabs et al. (2007, AAAR).
ROCK GLACIERS IN CENTRAL COLORADO In an investigation of the paleoclimatic importance of
rock glaciers in central Colorado (Elk and Sawatch ranges),, we used
lichenometry to date rock glacier deposits. Though the correlation of
the age of these deposits and periods of regional neoglacial cooling
identified using other paleoclimate proxies, we show that rock glaciers
can be used as important paleoclimate indicators in alpine regions.
See Refsnider and Brugger (2007, AAAR).
RABOTS GLACIAR, NORTHERN SWEDEN During thse summer of 2003, we completed the first detailed survey of the surface of Rabots Glaciär using differential GPS techniques. Comparisons of the 2003 ice surface elevation and margin position were compared to previous survey data. The results, which are also supported by numerical modeling, suggest that in the absence of concurrent climate change, Rabots Glaciär should be: (1) essentially half-way through its response to earlier climate warming (1°C warming that occurred around 1910), and (2) currently experiencing a rate of volume change comparable to that measured. We also have been using a degree-day model to simulate mass-balance changes for this glacier, and recently, the focus of this part of the project has been to try to improve the degree-day factors by measuring snow and ice melt rates across the glacier's surface. See Brugger et al. (2006, Annals of Glaciology).
PUBLICATIONS PEER-REVIEWED PUBLICATIONS Refsnider, K.A., Brugger, K.A., Leonard, E.M., McCalpin, J.P., and Armstrong, P. Last Glacial Maximum equilibrium line altitude trends in the Sangre de Cristo Mountains, southern Colorado, U.S.A. In review (Boreas). Refsnider, K.A., Laabs, B.J.C., Plummer, M.A., Singer, B.S., Mickelson, D.M., and Caffee, M.W., 2008. Last glacial maximum climate inferences from cosmogenic dating and glacier modeling of the Western Uinta ice field, Uinta Mountains, Utah. Quaternary Research, v. 59, p. 130-144. Refsnider, K.A., Laabs, B.J.C., and Mickelson, D.M., 2007. Glacial geology and equilibrium line altitude reconstructions for the Provo River drainage, Uinta Mountains, Utah, U.S.A. Arctic, Antarctic, and Alpine Research, v. 39, n. 4, p. 529-536. Laabs, B.J.C., Munroe, J.S., Rosenbaum, J.G., Refsnider, K.A., Mickelson, D.M., Singer, B.S., and Caffee, M.W., 2007. Latest Pleistocene Glaciation of the Upper Bear River Basin, Utah. Arctic, Antarctic, and Alpine Research, v. 39, n. 4, p. 537-548. Refsnider, K.A. and Brugger, K.A., 2007. Rock glaciers in central Colorado as indicators of late-Holocene climate change: a lichenometric study using Rhizocarpon subgenus Rhizocarpon: Arctic, Antarctic, and Alpine Research, v. 39, p. 127-136. Munroe, J.S., Laabs, B.J.C., Shakun, J.D., Singer, B.S.,
Mickelson, D.M., Refsnider, K.A., and Caffee, M.W., 2006. Latest
Pleistocene advance of alpine glaciers in the southwestern Uinta Mountains,
northeastern Utah, USA: Evidence for the influence of local moisture
sources: Geology, v. 34, p. 841-844.
Refsnider, K.A., 2006, Late Quaternary glacial
and climate history of the Provo River drainage, Uinta Mountains, Utah.
[Unpublished M.S. thesis]: University of Wisconsin - Madison, 121 p.
Refsnider, K.A., Brugger, K.A., Leonard, E.M., McCalpin, J.M., and Armstrong, P., 2007. Late Pleistocene equilibrium line altitude trends and precipitation distribution in the Sangre de Cristo Range, Colorado, v. 39. Brugger, K.A., Refsnider, K.A., Leonard, E.M., and McCalpin, J.M., 2007. Late Pleistocene equilibrium-line altitudes on the Blanca Massif, Sangre de Cristo Range, Colorado: Geological Society of America Abstracts with Program, v. 39. Colgan, P.M., Zhou Shangzhe, Liubing Xu, Douglass, D.R., Refsnider, K.A., Mickelson, D.M., and Munroe, J.S., 2006. Cosmogenic radionuclide 10Be exposure ages for two glacial advances in the Boduizangbu and Palongzangbu river valleys of the southeastern Tibetan Plateau: Geological Society of America Abstracts with Program, v. 38, p. 06-6. Laabs, B.J.C., Refsnider, K.A., and Plummer, M.A., 2006. Glacial climates in the Wasatch and Uinta Mountains inferred from glacier modeling: AMQUA Program with Abstracts. Laabs, B.J.C., Munroe, J.S., Rosenbaum, J.G., and Refsnider,
K.A., 2006. New cosmogenic beryllium-10 exposure-age limits on terminal
moraines of the last glaciation in the Bear River drainage, Uinta Mountains,
Utah: EOS Trans. AGU, 87(52), Fall Meeting Supplement, Abstract C21B-1159.
Refsnider, K.A.
and Brugger, K.A., 2005. Rock glaciers in central Colorado as indicators
of late-Holocene climate change: Geological Society of America Abstracts
with Program, v. 37. |
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