Abstract
1 The surfaces of the Martian north and south polar residual caps
are marked by unusual ice features: Dark spiralesque troughs up to
1 km deep, 10 km wide, and 300 km long appear on both ice caps, and
circular pits that make up the "Swiss cheese'' terrain appear on
the south polar cap. Both types of features are of interest to researchers
as a potential means of understanding ice composition and flow rates.
Some glaciers of the McMurdo dry valleys have surface features unknown
elsewhere on terrestrial glaciers, including canyons over 6 km long,
100 m wide, and tens of meters deep and basins up to 100 m across.
High sublimation, dust accumulation, and very little melting is key
to their origin. These processes and ice landforms are suggested
as terrestrial analogs for the sublimation behavior of Martian ice
caps, where dust accumulation and sublimation are significant but
surface melting is absent. We have developed a solar radiation model
of canyon formation and have applied it to the Martian polar caps.
The modeled processes do well to describe direct and reflected radiation
within V grooves, a process that may be significant in the development
of the spiral troughs and Swiss cheese terrain. The model fails to
reproduce the low observed slopes of the Martian troughs. The grooves
are too shallow, with opening angles of similar to165degrees compared
with model predictions of similar to90degrees. The reason for the
failure may be that we have not included creep closure, which should
flatten their slopes.
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