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Mystery mounds reveal the history of water on Mars: study discovers erosion the size of the UK

Posted on Science, maths, computing and technology

A team led by a researcher at London’s Natural History Museum and The Open University (OU), Dr Joe McNeil, have published a study into the history of water on Mars’ surface, how the surface evolved, and its potential to support life.

The experts used high-resolution images and compositional data captured by orbiters to understand the geology of mounds and hills on Mars’ barren northern plains, discovering they are made of rocks rich in clay minerals. This provides evidence that they were once soaked in liquid water.

The team discovered that the mounds, which are up to half a kilometre tall, are the remnants of ancient highlands which retreated by hundreds of kilometres after erosion wore away a landscape that covered an area the size of the UK billions of years ago. These actions played a key role in shaping the Martian dichotomy, which divides the planet’s low-lying northern hemisphere from its higher southern hemisphere.

The mounds are made of layered deposits containing clay minerals, formed through water interacting with rock over millions of years. These clay layers are sandwiched between older, non-clay layers below and younger, non-clay layers above, marking distinct geological events in Mars’ history.

Dr. McNeil said:

These mounds are incredibly exciting because they preserve the complete history of water in this region within accessible, continuous rocky outcrops. They are a prime location for future missions aimed at uncovering whether Mars ever had an ocean and whether life could have existed there.

The study also reveals that the mounds are geologically linked to the nearby plains of Oxia Planum, which the European Space Agency’s Rosalind Franklin rover is set to launch to in 2028 looking for signs of past and present life. By piecing together Mars’ ancient past, scientists are uncovering the story of a planet that may have once been capable of supporting life.

Mars is a model for what the early Earth might have looked like, as its lack of plate tectonics means that much of its ancient geology is still in place,” Joe continues. “As more missions visit the red planet, the more we’ll be able to dig into our own planet’s history to work out how life began.”

This study has been funded by the UK Space Agency. It is published today in Nature Geoscience.

Header image credit: ESA/ DLR/ FU Berlin