Today, it is too cold and the atmospheric pressure
is too low for liquid water to exist on the surface of Mars. However,
more than three billion years ago, Mars may have experienced some
of the biggest floods in the Solar System. Water from these floods
may have pooled into lakes, oceans and rivers.
Evidence of liquid water on the surface of an ancient Mars is plentiful. We have
seen images of what look like dry river beds, deltas, streamlined islands, and
possibly even shorelines. We have also seen evidence of the possibility of water
trapped under the surface of Mars gushing out through the steep walls of canyons
and craters to form gullies. Although these gullies are considered recent, they
might still be millions of years old. |
