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This is the Archimedes crater, on the moon, near the Apollo 15 landing site.

Archimedes crater (JAXA)

It is located in Mare Imbrium, a plain filled with lava.

The strange thing is that the interior of the crater looks flat, as if it had been also filled with lava, but there is no passage for lava to come inside the crater. All the walls appear to be intact.

So how could lava have possibly entered the crater?

Could it have had such low viscosity that it infiltrated as seepage?

The interior of the walls appears to be broken as if they suffered a landslide.

(The image source is this video, apparently a Lunar Reconnaissance Orbiter image)

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Great question! The mare lava bubbled up through fractures in the floor of the crater, burying its ring system and central peak.

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  • $\begingroup$ Great answer. I didn't even suspected that the crater had his own papers. $\endgroup$ – tutizeri Aug 23 at 16:42
  • $\begingroup$ Sorry, Archimedes is not a peak-ring crater. It was a central peak before it was filled. The abstract to which you link was not actually presented at the PCC meeting last year, it was print-only, and their interpretation of a ring in the gravity data is extremely dubious (it looks like noise). Based on craters that are not filled with lava on the moon, the transition from central peak to peak ring takes place at several hundred kilometers in diameter, while Archimedes is about 81 km (comparable to Tycho and Copernicus, both with very well formed central peaks and no hint of a ring). $\endgroup$ – Stuart Robbins Aug 26 at 6:51

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