title: North-south geological differences between the residual polar caps on Mars.
abstract: Polar processes can be sensitive indicators of global climate, and the geological features associated with polar ice caps can therefore indicate evolution of climate with time. The polar regions on Mars have distinctive morphologic and climatologic features: thick layered deposits, seasonal CO2 frost caps extending to mid latitudes, and near-polar residual frost deposits that survive the summer. The relationship of the seasonal and residual frost caps to the layered deposits has been poorly constrained, mainly by the limited spatial resolution of the available data. In particular, it has not been known if the residual caps represent simple thin frost cover or substantial geologic features. Here we show that the residual cap on the south pole is a distinct geologic unit with striking collapse and erosional topography; this is very different from the residual cap on the north pole, which grades into the underlying layered materials. These findings indicate that the differences between the caps are substantial (rather than reflecting short-lived differences in frost cover), and so support the idea of long-term asymmetry in the polar climates of Mars.
authors.affiliation: Center for Radiophysics and Space Research, Cornell University, Ithaca, New York 14853, USA. thomas@cuspif.tn.cornell.edu
authors.forename: P C
authors.initials: PC
authors.lastname: Thomas
authors.forename: M C
authors.initials: MC
authors.lastname: Malin
authors.forename: K S
authors.initials: KS
authors.lastname: Edgett
authors.forename: M H
authors.initials: MH
authors.lastname: Carr
authors.forename: W K
authors.initials: WK
authors.lastname: Hartmann
authors.forename: A P
authors.initials: AP
authors.lastname: Ingersoll
authors.forename: P B
authors.initials: PB
authors.lastname: James
authors.forename: L A
authors.initials: LA
authors.lastname: Soderblom
authors.forename: J
authors.initials: J
authors.lastname: Veverka
authors.forename: R
authors.initials: R
authors.lastname: Sullivan
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis; D019419:Evolution, Planetary; D005118:Extraterrestrial Environment; D018535:Mars
chemical_list: D002245:Carbon Dioxide