Around the frigid north pole of Mars, frozen layers of dust and ice have formed, deposited over millions of years as the planet’s climate has waxed and waned in response to Mars’ axial tilt. Now, in new observations beamed back to Earth by the High-Resolution Imaging Science Experiment (HiRISE) camera on board NASA’s Mars Reconnaissance Orbiter (MRO), some of these layers have been spotted that have fragmented and fallen down a slope as a “block fall.”

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Studying block falls are important to scientists trying to understand Mars’ climatic changes and dynamic geological processes. Overhanging layers can become fractured as the atmosphere warms, causing ices to sublimate, fracturing the material. They could even become dislodged by nearby meteorite impacts. Whatever the cause, as shown in this orbital image, huge chunks can collapse and fall down sloping landscapes.

HiRISE scientists were alerted to this dynamic process after comparing two observations from different dates, providing a clue as to when the rock fall occurred. They are continuously surveying the north polar layer deposits and watching for more rock falls to understand how it is changing.