April 17, 2013
A Submerged Terrain
image by Raf Lena, Rome, Italy
The western edge of Mare Fecunditatis is a submerged terrain where lavas have covered and embayed pre-existing craters and mountains. There are few large features younger than the mare lavas (Taruntius is the biggest), so crater walls are broken and submerged, and Goclenius, Columbo and Cook all have flooded interiors, like Plato and Archimedes, showing that magma came up fractures associated with basin edge fractures. Fecunditatis lavas are not thought to be very thick - perhaps a few hundred meters at most - so it is surprising that so many craters are completely submerged by lavas. I count 7 or 8 ghost rings, typically about 20 km wide. The fact that the ghosts are roughly the same size is strange, perhaps they were all secondaries from the formation of the Crisium or Nectaris basins.
April 14 2013 (18:31 UT). Mak-Cassegrain 18 cm lumenera LU075M. Mosaic of 10 images; processed with Registax 6 and Photoshop.
Rükl plate 48
21st Century Atlas chart 3.
Yesterday's LPOD: Milk for the Moon
Tomorrow's LPOD: A Prinzly Origin