Doppelmayer Surprises

Doppelmayer Surprises

Craters we don't look at carefully sometimes hold secrets! Here is an excellent image of the floor-fractured crater Doppelmayer on the southern shore of Mare Humorum. Like Gassendi, this 64 km crater was tilted by the subsidence of Mare Humorum, in this case so much that the northeastern rim was submerged under mare lavas. Doppelmayer has a single massive peak that looks like it may rise higher than the remaining rim crests. A crater pit occurs near of the summit of the peak - presumably a chance impact. The most interesting feature inside the crater is it broad wreath of hilly ridges that are concentric with the crater rim. This wreath is also flooded by Humorum lavas, demonstrating that the floor uplift that modified Doppelmayer occurred before the last stage of mare flooding. A surprising find is an apparent lunar dome immediately south of Doppelmayer's rim, just west of the crater Lee. Mike's low Sun image shows a bright east side and a delicate shading on the west side of the putative dome. On the summit is a large and elongated central pit, and two smaller craterlets occur on the sides. This feature does not appear on the GLR Dome Map. Finally, note that the wreath and crater floor between Doppelmayer'sentral peak and Mare Humorum is dark - dark pyroclastic deposits have been mapped to the north of the crater, but this may be another new surprise.