Mars Astrobiology: Recent Status and Progress - Planetary Exploration and Science: Recent Results and Advances - page 164

Fig. 8.8 Cross section of a portion of the north polar ice cap of Mars, derived from satellite radar
sounding - Mars Reconnaissance Orbiter ( http://photojournal.jpl.nasa.gov/catalog/PIA13164 -
NASA/JPL-Caltech/Italian Space Agency, 2010)

Many researchers have attempted to use this layering to attempt to understand the
structure, history, and flow properties of the caps, although their interpretation is not
straightforward.
Lake Vostok in Antarctica may have implications for liquid water still existing
on Mars because if water existed before the polar ice caps on Mars, it is possible
that there is still liquid water below the ice caps.

8.3.5.4 Ground Ice

For many years, various scientists have suggested that some Martian surfaces look
like periglacial regions on Earth. By analogy with these terrestrial features, it has
been argued for many years that these are regions of permafrost. This would suggest
that frozen water lies right beneath the surface. A common feature in the higher
latitudes, patterned ground, can occur in a number of shapes, including stripes and
polygons. On Earth, these shapes are caused by the freezing and thawing of soil.
There are other types of evidence for large amounts of frozen water under
the surface of Mars, such as terrain softening, which rounds sharp topographical
features. Theoretical calculations and analysis have tended to bear out the possibility
that these features are formed by the effects of ground ice. Evidence from Mars
Odyssey's gamma ray spectrometer and direct measurements with the Phoenix
lander have corroborated that many of these features are intimately associated with
the presence of ground ice.
Some areas of Mars are covered with cones that resemble those on Earth where
lava has flowed on top of frozen ground. The heat of the lava melts the ice and then
changes it into steam. The powerful force of the steam works its way through the