This drawing shows the possible geography of Martian water. Click on image for full size version (40K GIF)

The unusual global geography of Mars helps to explain the fact that water has been drawn from the southern hemisphere to the northern hemisphere of the planet through all of Martian history (that is, from higher ground to lower ground, where lower ground is in the northern hemisphere of the planet).

On a cold planet water can be trapped, frozen, within the ground, providing a source of flowing water on the ground only when the water is melted. The question is, what causes the frozen ground water to be melted and released to the surface? Opening of the aquifer can occur in a number of ways. Among them are

• volcanism, where ice is melted along the slopes of the volcano during volcanic events,
• climatary warming, where near surface ice is catastrophically released during periods of warmer temperatures.

Much of the evidence for running water on Mars shows that the water is being drawn to lower latitudes, including evidence that water flowed down the edges of the steep slopes at the boundary between the Martian highlands and the Martian lowlands. This evidence is in the form of icy flows, i.e. glacial features, suggesting that there is icy flow towards the lowlands from the highlands.

This drawing shows the possible geography of Martian water. Click on image for full size version (40K GIF)

On Mars, the water is trapped, frozen, within the ground. Nevertheless, there is evidence for running water on Mars.

When the water is melted and released to the surface, it will run from higher ground to lower ground. Because the geography of Mars is so unusual, where the south of the planet is high ground, while the north of the planet is lower ground, scientist think that this means that water has been drawn slowly from the south to the north of the planet through all of Martian history.

This is a very different pattern of circulation of water than is found on the Earth.

This drawing shows the possible geography of Martian water. Click on image for full size version (40K GIF)

On Mars, the water is trapped, frozen, within the ground. Nevertheless, there is evidence for running water on Mars.

When the water is melted and released to the surface, it will run from higher ground to lower ground.

Because this water transfer can only take place when the water melts, however, the water transfer takes a very long time.