Mars: Was Olympus Mons once a giant volcanic island?

Imagine a volcanic island about the size of France and over 20,000 metres high. Such a landscape may once have existed on the planet Mars. Published in Earth and Planetary Science Letters on July 24, recent work led by a CNRS researcher1 shows that the giant Olympus Mons volcano on Mars shares morphological similarities with many active volcanic islands on Earth. Scientists believe they are the result of contact between liquid water and lava from the volcano. Similar features on the northern flank of the Alba Mons volcano, located more than 1,500 km from Olympus Mons, also support the idea that a vast ocean of liquid water once occupied the Red Planet's northern lowlands. Precise dating of these volcanic rocks could provide a considerable amount of information about the climatic evolution of Mars.

• 1At the Laboratoire Géosciences Paris-Saclay (CNRS/Université Paris-Saclay)