The role of eolian processes in forming surface features of the Martian polar layered deposits

The major topographic features of the martian polar layered deposits includ e the conspicuous spiral troughs, subtle undulations, broad reentrants (cha sma), steep, arcuate scarps, and dune fields. A prominent role for eolian p rocesses in the formation of all of these features is proposed. Strong kata batic winds occur on the north polar cap, producing widespread frost streak s. These cold drainage winds are analogous to those on the terrestrial Anta rctic cap. In the chasmae convergent katabatic winds create yardangs and er ode arcuate scarps in the layered deposits that are also the source for loc al dune fields migrating outward from the polar cap. The chasmae are postul ated to originate by long-term erosion by katabatic wind. Wind plays a role in formation of the troughs and scarps primarily through removal of dust f reed from exposed layered deposits by ablation of ice on defrosted equator- facing slopes. The undulations are created by interaction between surface e rosion or deposition of perennial ice and standing waves in the shallow kat abatic wind-flow The south polar layered deposits exhibit topographic featu res similar to those at the north polar cap, but erosion and depositional p rocesses creating these features may be inactive during the current epoch b ecause of the lack of an extensive perennial ice cover and associated katab atic wind. (C) 2000 Academic Press.