Archimedes, 50 miles or 82 kilometers in diameter, is one of the most picturesque craters on the Moon. It consists of a flat floored ring of mountains, and lacks the central peak typical of craters of this size because the interior has been flooded with lava flows.
Archimedes is a nice example of dating events by superposition. It lies within the Imbrium Basin, a huge impact basin formed during the final bombardment of the Moon about 4 billion years ago. We can be confident that no craters would have survived the Imbrium impact. On the other hand, the crater is flooded with the lava that filled the Imbrium Basin about 3.1 billion years ago. So its age is between 4.0 and 3.1 billion years.
The hilly terrain on the near side of the crater is called Montes Archimedes, or the Archimedes Mountains. As lunar mountains go, it's a fairly nondescript and low massif, and probably represents an exposed part of the Imbrium Basin floor that wasn't buried by lava.
Created 17 December 2007, Last Update 25 May 2011
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