Amid miles of perfectly flat lava flows in the Athabasca region of Mars, this enormous mound appears out of nowhere, looking for all the world like a titanic cookie — and scientists are unable to account for it. Athabasca is characterized by some of the youngest lava on the planet, forming a smooth surface yet to be marred by stress cracks and meteor impacts. The 1.2-mile-wide cookie is one of several such formations in the area, but how they came to exist is still a mystery. It's possible that lava pushed up from beneath to make the mound, and the troughs suggest ice too may have been present — but why here and not elsewhere? Geologists and astronomers are poring over imagery from Athabasca taken by NASA's Mars Reconnaissance Orbiter, and hope to find some reason for this striking formation's appearance.
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