1079 - Lunar and Planetary Science XXXVI(2005 1079...

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STRATIGRAPHIC ANALYSIS OF THE NORTH POLAR CAP OF MARS: RECENT CLIMATE HISTORY. Sarah M. Milkovich and James W. Head, Department of Geological Sciences, Brown University, Providence, Rhode Island 02912 USA [email protected] Introduction: The northern polar cap of Mars is characterized by spiraling troughs cutting through the cap surface. Horizontal and subhorizontal layers ex- posed on the walls of these troughs are thought to con- tain varying ratios of water ice and dust. These polar layered deposits (PLD), first observed in Mariner 9 im- ages [1, 2] and later studied in detail with the Viking orbiters [e. g. 3, 4, 5, 6], extend throughout the cap. . Recent images from Mars Global Surveyor (MGS) show that the layers have a range of thicknesses and albedos [7, 8]. Formation theories regard the layers as products of climate change due to orbital cycles [9, 4, 5], similar to climate changes caused by Milankovitch cycles on Earth [e.g., 10], although the details of the formation processes remain unknown. As a first step in unraveling the relationship be- tween the polar layered deposits and climate, it is nec- essary to understand and quantify the characteristics of the layers themselves in individual sections. Then it is necessary to establish whether there are any correlations between adjacent sections as well as any regional or cap-wide correlations. Finally, it is important to estab- lish if and how such correlation is consistent with depth in the vertical sections representing changes with geo- logical time. Once the signals encoded in the layers and their lateral and vertical correlations are known, then their relationships to climate change can be assessed. The results reported here are part of an ongoing effort to characterize quantitatively the layers both vertically, by looking for patterns in vertical stratigraphy, and hori- zontally, by examining variations in layer continuity on
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This note was uploaded on 04/15/2008 for the course HIST 101 taught by Professor Wormer during the Spring '08 term at Arizona.

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1079 - Lunar and Planetary Science XXXVI(2005 1079...

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