Schröter's Law suggests that the ground level inside a crater is lower than that outside it. Wargentin (upper left) defies this rule, as the lava which has welled up into it has raised the floor some 1000' above the surrounding landscape, level with the rim for most of its circumference.

The crater at the centre of the image is Nasmyth, and below it is Phocylides.

Photo: António Cidadão. His Home Page of Astrophotography includes stereograms, animations, and "Seven Craters a Week" from his forthcoming photographic lunar atlas.

Inconstant Moon