The first hole in the 'gash' theory came when larger apertures were able to image the "river" in the valley. (there is a "riverbed" that runs all the way through). It was kinda hard to figure out how a gash could cause that.
Current ideas involve actual water movement when there may still have been some (highly questionable) and more popularly the idea that it was some kind of lava tube (or flow) between the maria. This is supported by the small "collapse craterlets" that formed along the "riverbed" or interior valley.
By the way, I've peeked the "river" with the eight inch, and got a pretty good look at parts of it with the twelve; I really don't know what the minimal aperture might be to see it.
Still, the way it cuts through the Alps is simply amazing. I'm not sure there's a similar valley anywhere on earth, though to me it seems more consistent with rift geology.
It's my understanding that it's a real bear to image, which makes sense to me as I find it a real bear to see... but I noted some time back that it looks like Thierry Legault nailed the easiest part of it (in the "pond" nearest Mare Imbrium) with his 225mm SCT.
The rille is "collateral damage" in that Plato was apparently the target (for extra credit, count the craterlets and check out the clean split on the fine "double crater."
Those Tak SCTs are amazing! Well, so is Theirry...
There is also a curious eastish to westish line starting beyond Rima Archytus (that includes it) running along the northern edge of the Alpine talus that breaks suddenly at the end of the valley, subsequently trending more southerly. There is a tentative hint of this in Rukl's drawing, and equally vague but notable indications of same in the Times atlas. I suspect this to be a large but obscured feature related to Imbrium in some fashion.
Bratislav <epabcc _at_ broady.ericsson.se> commented on sci.astro.amateur:
> Good indication of seeing are craterlets > at the floor of nearby Plato. If you don't see at least 4 or 5, don't > bother with the Rille.
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