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The Residual Polar Caps of Mars: Geological Differences and Possible ConsequencesThe Martian polar regions have been known to have thick layered sequences (presumed to consist of silicates and ice), CO2 seasonal frost, and residual frosts that remain through the summer: H2O in the north, largely CO2 in the south. The relationship of the residual frosts to the underlying layered deposits could not be determined from Viking images. The Mars Orbiter Camera on Mars Global Surveyor has provided a 50-fold increase in resolution that shows more differences between the two poles. The north residual cap surface has rough topography of pits, cracks, and knobs, suggestive of ablational forms. This topography is less than a few meters in height, and grades in to surfaces exposing the layers underneath. In contrast, the south residual cap has distinctive collapse and possibly ablational topography emplaced in four or more layers, each approx. two meters thick. The top surface has polygonal depressions suggestive of thermal contraction cracks. The collapse and erosional forms include circular and cycloidal depressions, long sinuous troughs, and nearly parallel sets of troughs. The distinctive topography occurs throughout the residual cap area, but not outside it. Unconformities exposed in polar layers, or other layered materials, do not approximate the topography seen on the south residual cap. The coincidence of a distinct geologic feature, several layers modified by collapse, ablation, and mass movement with the residual cap indicates a distinct composition and/or climate compared to both the remainder of the south polar layered units and those in the north.
Document ID
20010002509
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Thomas, P. C.
(Cornell Univ. Ithaca, NY United States)
Sullivan, R.
(Cornell Univ. Ithaca, NY United States)
Ingersoll, A. P.
(California Inst. of Tech. Pasadena, CA United States)
Murray, B. C.
(California Inst. of Tech. Pasadena, CA United States)
Danielson, G. E.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA United States)
Herkenhoff, K. E.
(Geological Survey Flagstaff, AZ United States)
Soderblom, L.
(Geological Survey Flagstaff, AZ United States)
Malin, M. C.
(Malin Space Science Systems San Diego, CA United States)
Edgett, K. S.
(Malin Space Science Systems San Diego, CA United States)
James, P. B.
(Toledo Univ. OH United States)
Date Acquired
August 20, 2013
Publication Date
August 1, 2000
Publication Information
Publication: International Conference on Mars Polar Science and Exploration
Subject Category
Lunar And Planetary Science And Exploration
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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