Mars is the planet of illusion and deception. For generations, planetologists have routinely misinterpreted observations of Mars, and they continue to do so, and no doubt will do so for generations to come.

Recently, the THEMIS project released an example of what may be one of the more interesting misinterpretations of Martian surface features: A Tale of Two Craters.

In the upper part of the image we see an impact crater of the "splosh" variety, showing all the classic signs of an impact event. Next to it is a circular ring formation, like thousands of similar formations on Mars, a low ring-shaped mound, with a small opening on one side, and with a hill inside the ring. There are no signs of an impact origin for this ring formation, nor is there any sign of impact origin for any of the other ring formations on Mars, yet they are all interpreted as impact craters, generally referred to as "partly exposed" or "heavily degraded."

Perhaps that is the correct interpretation, but could there be other means to cause ring formations such as this to appear on the surface of Mars? For example, are there internal processes which could create these rings on the surface?

And is there a detailed process by which impact craters such as the one on the left of the image, can become ring formations such as the one on the right?

Cheers, BFelix