Hieroglyphic-like Features Point to Past Subsurface Water on Mars
Nancy Atkinson
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These unusual shapes on Mars surface are actually cones and inflated lava flows, Credit: NASA/JPL/University of Arizona.
Although these strange features on Mars look a bit like hieroglyphics or geoglyphs such as the mysterious Nazca lines on Earth, they are completely natural features, ones that are found on Earth too.
This is one of the latest images from the HiRISE camera on the Mars Reconnaissance Orbiter.
Called ‘rootless cones,’ they form on lava flows that interact with subsurface water or ice. Their formation comes from an explosive interaction of lava with ground ice or water contained within the regolith beneath the flow. Vaporization of the water or ice when the hot lava comes in contact causes an explosive expansion of the water vapor, causing the lava to shoot upward, creating a rootless cone.
Dr. Alfred McEwen, HiRISE Principal Investigator, described the ancient lava flow as ‘inflated.’ “Lava inflation is a process where liquid is injected beneath the solid (thickening) crust and raises the whole surface, often raising it higher than the topography that controlled the initial lava emplacement,” he wrote on the HiRISE website.
The scene above is located in Amazonis Planitia on Mars, a vast region covered by flood lava. McEwen said if this image were in color, we’e see the surface is coated by a thin layer of reddish dust, which avalanches down steep slopes to make dark streaks.
Similar features are found in Iceland, where flowing lava encountered water-saturated substrates.