Mars Geology

The primary driver of modern Martian geology is its atmosphere, which is mostly made of carbon dioxide, nitrogen, and argon. By Earth standards, the air is preposterously thin; air pressure atop Mount Everest is about 50 times higher than it is at the Martian surface. Despite the thin air, Martian breezes can gust up to 60 miles an hour, kicking up dust that fuels huge dust storms and massive fields of alien sand dunes.Once upon a time, though, wind and water flowed across the red planet. Robotic rovers have found clear evidence that billions of years ago, lakes and rivers of liquid water coursed across the red planet's surface. This means that at some point in the distant past, Mars's atmosphere was sufficiently dense and retained enough heat for water to remain liquid on the red planet's surface. Not so today: though water ice abounds under the Martian surface and in its polar ice caps, there are no large bodies of liquid water on the surface there today.