April 18, 2018
In the Moat
Originally published December 9, 2008
image by Carmelo Mel Zannelli, Palermo - Italy. North to the left.
Here are three of the Moon's 1519 named craters that are rarely imaged. They are on the "uninteresting" side of the Nectaris Basin, opposite from the Altai Scarp and the Theophilus threesome. More geologically, the craters shown here are in the swampy space between two of Nectaris' basin rings. As is common in moats between rings, thin sheets of lava leaked to the surface surrounding older craters (hence the swampy nature). We can easily determine a stratigraphy related to the time of mare lava emplacement. Santbeck, the 64 km wide crater near the center, has been surrounded by lavas, as has the smaller crater at the 9 pm position whose rim was breached by the lavas. Santbeck is also floored by mare lava that must have risen from the lunar mantle up crater and basin ring fractures. To the upper left is Monge, whose ejecta covers the nearby mare which thus must be older. At the upper right is Borda whose age is less certain. The crater is perhaps too far from the lava to expect to see ejecta, but the rim is more battered than that of Monge and Borda is probably older.
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Rükl plate 59
Yesterday's LPOD: Not a Valley
Tomorrow's LPOD: The Famous Moscow Sea