The smooth topped, rounded flows seen extending from the base of the crater wall are ‘debris aprons’: remnants of rock-covered glaciers that likely formed when the martian climate allowed ice to accumulate at the mid-latitudes of Mars. Over time, the debris-covered glaciers slowly crept downslope to form the gently sloping bulges seen today.
The erosive action of ice and water has resulted in the considerable widening of the crater of up to twice its original size.
A particularly dramatic example is seen at the right edge of this image, where a wide channel has been gouged out. It is reminiscent of the U-shaped valleys carved by glaciers on Earth. Here, it may have started out in a V-shape due to flowing water – or water draining out from beneath and causing collapse – and later widened during a period of glaciation.
The oblique perspective view was generated from the digital terrain model, the nadir and colour channels of the High Resolution Stereo Camera on ESA’s Mars Express from data collected 25 October 2024.
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[Image description: A sweeping view along the crater rim of Deuteronilus Cavus, which transects the image from bottom right to centre-top, focuses on the smooth debris flows that have slid towards the centre of the crater. At the right, a large chunk of the crater wall is missing, forming a U-shaped valley with a grooved floor. Towards the centre of the crater – the far top left of the image – a patch of dark volcanic dust covers the surface. Jumbled blocks are seen in the centre, contrasting the smoother flows around the inner walls.]