ESA's Mars Express finds possible supervolcano remnant
April 13 (UPI) -- ESA's Mars Express has photographed a unique and mysterious geologic structure on the Martian surface.Astronomers aren't sure of the crater's origins. The crater, dubbed Ismenia Patera, may have been created by a meteorite impact. It's also possible the imprint was left behind by an ancient supervolcano.The layout and structural patterns seen in and around Ismenia Patera are different and more complex than the typical impact crater. Uneven lumps of rock are found scattered around the outer edge of the crater.Scientists believe the rocky deposits are debris ejected by neighboring impacts. These miniature impacts have created their own system of gullies inside Ismenia Patera.The crater's floor is dynamic, too, showing signs of movement. The floor is likely composed of a roc...