01707nam a2200205 4500008004100000020001800041245013400059210006900193260001300262520102300275653001501298653001701313653001201330653001201342653001801354653000901372100002401381700002101405856007501426 2021 eng d a978012820245600aThe McMurdo Dry Valleys of Antarctica: A geological, environmental, and ecological analog to the Martian surface and near surface0 aMcMurdo Dry Valleys of Antarctica A geological environmental and bElsevier3 a

The surface of Mars is universally thought to have experienced widespread cold and dry environmental conditions for at least the last half of its geologic history, with more modern studies suggesting relatively cold and dry conditions early in its geologic history as well. However, the paucity of liquid water and mean annual temperatures well below the freezing point of water do not necessarily mean a complete cessation of all water-related geologic activity at the Martian surface. Over the past several decades, investigations in the McMurdo Dry Valleys (MDV) of Antarctica have revealed a dynamic geological, environmental, and ecological system resulting from locally optimized conditions operating over repeated, albeit brief, intervals during summer months. In this chapter, we compare the hyper-arid and hypo-thermal environments of the MDV and the modern Martian surface and discuss three unique enigmas that demonstrate how the Antarctic is a valuable analog to better understand processes on Mars.

10aAntarctica10aastrobiology10aclimate10ageology10ageomorphology10aMars1 aSalvatore, Mark, R.1 aLevy, Joseph, S. uhttps://www.sciencedirect.com/science/article/pii/B978012820245600011202542nas a2200181 4500008004100000022001300041245006800054210006300122260001200185300001200197490000800209520181900217100002402036700002102060700002502081700002402106856023002130 2014 eng d a0169555X00aThe McMurdo Dry Valleys: A landscape on the threshold of change0 aMcMurdo Dry Valleys A landscape on the threshold of change c11/2014 a25 - 350 v2253 a

Field observations of coastal and lowland regions in the McMurdo Dry Valleys suggest they are on the threshold of rapid topographic change, in contrast to the high elevation upland landscape that represents some of the lowest rates of surface change on Earth. A number of landscapes have undergone dramatic and unprecedented landscape changes over the past decade including, the Wright Lower Glacier (Wright Valley) — ablated several tens of meters, the Garwood River (Garwood Valley) has incised > 3 m into massive ice permafrost, smaller streams in Taylor Valley (Crescent, Lawson, and Lost Seal Streams) have experienced extensive down-cutting and/or bank undercutting, and Canada Glacier (Taylor Valley) has formed sheer, > 4 meter deep canyons. The commonality between all these landscape changes appears to be sediment on ice acting as a catalyst for melting, including ice-cement permafrost thaw. We attribute these changes to increasing solar radiation over the past decade despite no significant trend in summer air temperature. To infer possible future landscape changes in the McMurdo Dry Valleys, due to anticipated climate warming, we map ‘at risk’ landscapes defined as those with buried massive ice in relative warm regions of the valleys. Results show that large regions of the valley bottoms are ‘at risk’. Changes in surface topography will trigger important responses in hydrology, geochemistry, and biological community structure and function.

1 aFountain, Andrew, G1 aLevy, Joseph, S.1 aGooseff, Michael, N.1 aVan Horn, David, J. uhttp://linkinghub.elsevier.com/retrieve/pii/S0169555X14001780http://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/plain