It is no secret that Mercury's surface is scarred by abundant tectonic deformation, the vast majority of which is due to the planet's history of cooling and contraction through time. Yet Mercury is also heavily cratered, and hosts widespread volcanic plains. So it's perhaps unsurprising that these three types of landform often intersect-literally-as shown in this scene. Here, an unnamed crater, about 7.5 km (4.7 mi.) in diameter was covered, and almost fully buried, by lava. At some point after, compression of the surface formed scarps and ridges in the area that, when they reached the buried crater, came to describe its curved outline. Many arcuate ridges on Mercury formed this way. In this high-resolution view, we can also see the younger, later population of smaller craters that pock-mark the surface.
http://photojournal.jpl.nasa.gov/catalog/PIA19263