February 7, 2004

Crumpled Sheets of Lava

Image Credit: K.C. Pau

Crumpled Sheets of Lava Crumpled sheets on a bed result from movement of a thin surface layer (the sheet) due to underlying motion (the restless sleeper). KC Pau's low sun view of eastern Mare Nubium looks like a messy lava sheet where most of the movement may have been vertical. Mare ridges - or the more descriptive term, wrinkle ridges - clearly trace out a buried rim of the impact crater (Ancient Thebit) cut by the Straight Wall. Shadows from these draped ridges clearly reveal that the surface inside the buried rim is lower than Mare Nubium itself. The other Nubium ridges are harder to understand. A few small arcs seem to likewise mark a crater engulfed by lavas, but most ridges here do not parallel the nearly indistinct rim of the Nubium impact basin. Nubium's rilles are more like those of Mare Fecunditatis - unrelated to anything we understand. But look closely at KC's photo for two other linear mare features. (1) Do you see the apparent crease in the surface running from north to south, west of the Birt rille? I have seen this on other images, but this one shows that the surface texture immediately east of the crease is rougher than that to the west. (2) Another subtle linear feature runs from the top center of the image diagonally to the right. This is possibly an earlier delicate, nearly lava-buried rille. It is not shown in Rukl's wonderful Lunar Atlas but is hinted at in the Related Link Lunar Orbiter IV image below. Has KC discovered another rille? And what happens to it to the north? Technical Details: 10" reflector with 2.5x barlow and Philips Toucam. Related Links: Lunar Orbiter IV View Geology of Mare Nubium KC Pau Yesterday's LPOD: New and Old All Together Tomorrow's LPOD: Crazy Quilt Imbrium

Author & Editor: Charles A. Wood

 

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