by Matt Tarlach
The small, flooded crater Baily (Rukl chart 6) is bracketed by some patches of dark material. The patch E of Baily is on a flat area of mare lava and surrounds an odd, elongated, rimless crater. The patch to the W of Baily appears to be draped over a lumpy deposit of basin ejecta. The area shows up fairly well on this Orbiter image:
http://www.lpi.usra.edu/resources/lunar_orbiter/images/aimg/iv_091_h3.jpg
In the telescope 2 nights ago the contrast was actually better, the dark areas easier to see (though the Orbiter image of course shows more fine detail). In the image I see that the irregular crater is actually an opening in a short rille. I wonder if it is a collapse pit. The juxtaposed features remind me a little of Hyginus and its accompanying rille.
South of Eudoxus, a wrinkle ridge across Serenitatis extends into the large field of ejecta splashed across the northern portion of that Sea, crossing the "shore" of Serenity at about longitude 20.5E (Rukl 13). I spent a long time trying to figure the progression of events here....it seems the mare lava must have come before the ridge, and the ridge before the ejecta deposit. Yet the lava appears to embay the edge of the ejecta field. Chuck Wood's "Modern Moon" explains that the Serenitatis basin was filled with lava in a series of flows spread over 7 or 800 million years. Perhaps the ridge and the ejecta deposit both came to be while the filling process was underway? Or perhaps the ejecta deposit came last, but is thin enough for the ridge to be seen beneath it?
Does anyone know of a smallish crater filled to the brim with lava, like a little Wargentin, in the highlands around longitude 20E? I thought I saw such a thing while scanning near the terminator 2 nights ago, but my session was cut short and I didn't get the chance to go back to it. Can't find anything like what (I thought) I saw in Rukl.
Posted on shallow-sky Apr 17, 2005 18:04:15 PT
Converted by report.pm 1.2 Apr 23, 2005 21:21:38 PT
