Eruptions at Mars’ volcanic plateau possibly pushed the whole planet
Around four billion years ago, Mars must have looked like it was trying to propel itself with a set of volcanic rocket-boosters. Three of the solar system’s largest volcanoes, collectively known as the Tharsis Montes, were spewing enough lava to have not only altered at least 3,106 square miles of terrain, but possibly the climate and rotation of the entire Red Planet. While these three volcanoes are now clustered up on Mar’s equator (near Olympus Mons, for the sightseers out there,) it appears that they weren’t originally in that location. The equator used to be home to rivers and valleys before the volcanoes knocked the planet’s axis off kilter.
Rocking the ring of rivers
The Tharsis region is part of a huge volcanic plateau, long thought to have caused serious deformation of Mars’ surface, creating a bulge six miles thick. The severity of the volcanic activity to create such multiple volcanoes over 49,000 feet tall was assumed to have reshaped other river and valley networks near the planet’s equator. Recent analysis noted that those rivers actually formed a ring around the planet, slightly misaligned with the equator, prompting the idea that they used to sit right on it. It was possible that when the Tharsis plateau was then created, it didn’t just push on the terrain locally, it pushed the whole planet over nearly 42°. On Earth, this would be like tilting the planet until Paris, France sat at the North Pole.
Proven with previous poles
This kind of dramatic shift would have seriously altered the terrain of Mars, but scientists were still able to find supporting evidence of the original orientation to support this hypothesis. As predicted, they found collections of ancient ice at the original north pole, plus geologic evidence of now-missing ice at the original south pole. With this in mind, the topographical history of the planet was rewritten a bit, since the river and valley networks that once surrounded the equator must have existed before, or been created during, the volcanic activity that created Tharsis and knocked the planet sideways.
With this in mind, researchers are now looking at what this might have done to the Red Planet’s climate. Those equatorial rivers are thought to have originally been home to rather wet, nearly tropical conditions. Tipping them out of the equator may have then disrupted this weather system, potentially leading to the cooler and drier planet we find today.
Source: Volcanic mount spun Mars around and rearranged its rivers by Rebecca Boyle, New Scientist