Surface Processes & Numerical Modeling
The realization that in-situ and near in-situ ashfall up to 15 million years in age rest directly on the modern Dry Valleys landscape has prompted us to take a closer look at the range of periglacial processes operating in region. As part of this effort, we have deployed meteorological sensors (Onsett HOBO® data loggers) throughout the valleys in order to determine the spatial distribution and magnitude of microclimate variation, and to assess the resultant surface processes/ landforms that are endemic to each microclimate zone.
On the basis of measured variations in summertime atmospheric temperature and relative humidity (RH), soil temperature, average wind speed/direction, and soil moisture, we divide the region into three microclimate zones: a coastal thaw zone (CTZ), in which elevated soil temperatures and seasonally-moist soils foster development of saturated active layers; an inland-mixed zone (IMZ), in which abundant surface water and saturated active layers are restricted to the margins of melting snowbanks, ephemeral streams, and thawed-lake margins; and, a stable-upland zone (SUZ), in which atmospheric and soil temperatures are too cold and dry to permit the development of traditional, saturated active layers.
Equilibrium landforms are those that are endemic to, and in balance with, local microclimate conditions in each zone. Our assemblage of equilibrium landforms in the CTZ includes tafoni, solifluction lobes, thermokarst, ice-wedge polygons, and low-gradient slopes with mature, low-density gullies. In the IMZ, equilibrium landforms include gelifluction lobes, sand-wedge and composite polygons, desert pavements with wind-polished cobbles, and immature, closely spaced gullies. Finally, equilibrium landforms that best characterize the SUZ include sublimation polygons, debris-covered glaciers, pitted surface cobbles, salt-cemented duricrusts, and puzzle rocks.
Of particular interest are the unusual landforms and surface processes endemic to the SUZ, in which environmental conditions are among the most Mars-like on earth (click here for more details on our Mars-Antarctic analog studies). Within the SUZ, we have studied, and modeled, the formation of sublimation polygons, the magnitude of warming that would initiate slope failures (e.g., shallow planar slides that today occur in the CTZ), and the rate of vapor-diffusion from buried-ice surfaces to the atmosphere. For the latter, we have shown that buried-ice deposits in the SUZ sublimate at an average rate of 0.1 mm a-1, with rates reduced to <0.001 mm a-1 if summertime temperatures drop by ~3°.
NSF Award Abstract
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(* Student Advisee)
*Kowalewski, D.E., Marchant, D.R., Head, J.W., and Jackson, D.W., 2012. A 2D model for characterizing
first-order variablility in sublimation of buried glacier ice, Antarctica: assessing the influence of polygon
troughs, desert pavements, and shallow-subsurface salts. Permafrost and Periglacial Processes 23, 1-14.
Head, J.W., Kreslavsky, M.A., and Marchant, D.R., 2011. Pitted rock surfaces on Mars: a mechanism of formation by transient melting of snow and ice. Journal of Geophysical Research, Volume 116. doi:10.1029/2011JE003826
*Kowalewski, D.E., Marchant, D.R., Swanger, K.M., and Head, J.W., 2011. Modeling vapor diffusion within cold and dry supraglacial tills of Antarctica: Implications for the preservation of ancient ice. Geomorphology 126, 159-173. doi:10.1016/j.geomorph.2010.11.001
*Swanger, K.M., Marchant, D.R., Kowalewski, D.E., and Head, J.W. 2010. Viscous flow lobes in central Taylor Valley, Antarctica: Origin as remnant buried glacial ice. Geomorphology 120, 174-185. doi:10.1016/j.geomorph.2010.03.024
Levy, J.S., Marchant, D.R., and Head, J.W. 2010. Thermal contraction crack polygons on Mars: A synthesis from HiRISE, Phoenix and terrestrial analog studies. Icarus 206, 229-252. doi:10.1016/j.icarus.2009.09.005.
Levy, J.S., Head, J.W., and Marchant, D.R. 2009. Cold and Dry Processes in the Martian Arctic: Geomorphic Observations at the Phoenix Landing Site and Comparisons with Terrestrial Cold Desert Landforms. Geophysical Research Letters36, L21203. doi:10.1029/2009GL040634.
Levy, J.S., Head, J.W., and Marchant, D.R. 2009. Thermal Contraction Crack Polygons on Mars: Classification, Distribution, and Climate Implications from HiRISE Observations. Journal of Geophysical Research 114, E01007, doi:10.1029/2008JE003273.
Levy, J.S., Head, J.W., Marchant, D.R., Dickson, J.L., and Morgan, G.A. 2009. Geologically recent gully-polygon relationships on Mars: Insights from the Antarctic Dry Valleys on the roles of permafrost, microclimates, and water sources for surface flow. Icarus 201, 113-126. doi:10.1016/j.icarus.2008.12.043
Levy, J.S., Head, J.W., and Marchant, D.R. 2008. The role of thermal contraction crack polygons in cold-desert fluvial systems. Antarctic Science 20(6), 565-579.
*Swanger, K.M. and Marchant, D.R. 2007. Sensitivity of ice-cemented Antarctic soils to greenhouse-induced thawing: are terrestrial archives at risk? Earth and Planetary Science Letters 259, 347-359.
Levy, J.S., Marchant, D.R., and Head, J.W., III. 2006. Distribution and origin of patterned ground on Mullins Valley debris-covered glacier, Antarctica: the role of ice flow and sublimation. Antarctic Science 18, 385-398.
*Kowalewski, D. E., Marchant, D.R., Levy, J.S., and Head, J.W. III. 2006. Quantifying low rates of summertime sublimation for buried glacier ice in Beacon Valley, Antarctica. Antarctic Science 18, 421-428.
*Lewis, A.R., Marchant, D.R., Baldwin, S.L, and Webb, L.E. 2006. The age and origin of the Labyrinth, western Dry Valleys, Antarctica: evidence for extensive middle Miocene subglacial floods and freshwater discharge to the Southern Ocean. Geology 34 (7), 513-516.
Marchant, D.R., *Lewis, A., Phillips, W.C., *Moore, E.J., Souchez, R., and Landis, G. P. 2002. Formation of patterned-ground and sublimation till over Miocene glacier ice in Beacon Valley, Antarctica. Geological Society of America Bulletin 114, 718-730.
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