January 11, 2013

Battered Rings

image by Claude Navarro, Toulouse, France

Do you see three basin rings? The shadow-casting Altai Scarp is the topographic equivalent to the Apennines at Imbrium
and the Cordillera surrounding Orientale. At the bottom right corner more shadows are cast by Fracastorius and Beaumont,
and between them are hints of a basin ring made by hills. Between the Altai and this inner ring is a broad arc of elevated
and hilly terrain that is the intermediate ring. These two inner rings are not the narrow, ideal rings that we might suppose
exist under Imbrium lavas that are marked by mare ridges and isolated peaks. They are more like the wide Inner and Outer
Rook Mountains of Orientale, but eroded by many more later impacts and their ejecta. The moats between the Nectaris
rings are less rough than the ring areas, and while the outer moat fronting the Altai is about flat, according to the Path tool
of LRO QuickMap, the inner moat tilts down 1200 m towards the basin center. In fact, there has been little study of the
variations in morphology of inner basin rings so we don't know how to explain wide versus narrow rings.

Chuck Wood

Technical Details
Oct/05/2012. C14 + Basler 1300 + IR Pass 742 filter. Processing with Registax 6 (250 Images on 2000).

Related Links
Rükl plate 57
21st Century Atlas chart 6.

Yesterday's LPOD: Full Moon Last Quarter

Tomorrow's LPOD: Building the 21st Century Lunar Map

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