Thousands of mysterious mounds on Mars were formed by ancient water

Sign up for CNN’s Wonder Theory science newsletter. The mounds appeared similar to one another from a distance, but the high-resolution imagery captured by the orbiters allowed McNeil to zoom in, revealing “incredible variety in their structure.” While Monument Valley’s buttes and mesas can reach up to 1,000 feet above the valley floor and cover an area of 145 square miles, the Martian mounds reach 1,800 feet and sprawl across an area 2,000 times larger, McNeil said. But McNeil’s analysis shows that the Martian mounds are likely the last remnants of ancient highlands that were washed away and worn down, formed in much the same way as Monument Valley’s features through erosion. “Most of the evidence has been eroded away, and what’s left — the mounds — are so old that they’ve also had an additional 3.8 billion years of wind erosion on top of whatever made them mounds in the first place,” McNeil said. ESA/ATG medialab Getting up close with the mounds McNeil began investigating the mounds of the Chryse Planitia region near the dichotomy as part of his doctoral program while at the Open University in England because he believes they are “a prime location for future Mars missions.” Areas close to the mounds, such as Oxia Planum and Mawrth Vallis, are of interest to scientists because they may preserve past signs of life on Mars.