theory to account for how glaciers could form so far from the poles
relates, again, to the idea that Mars' obliquity fluctuated extremely
in the past.
were formed from snow brought from the polar regions," says
Brown University planetary geologist James Head. "A few million
years ago, Mars had a different tilt. The poles were pointing more
closely toward the Sun, so the polar ice caps released massive amounts
of water vapor into the atmosphere. Wind carried the vapor south,
up and over the slopes of the Tharsis Montes volcanoes and Olympus
Mons, the solar system's largest volcano. The vapor cooled, condensed
and fell as snow. The snow turned to ice over time and formed glaciers.