image from Clementine via Map-A-Planet
While collecting images for the-Moon wiki I came upon a feature that I had never noticed before. Chances are most of you haven’t either, and - like me - wouldn’t recognize the area without the name overlay. Swabe is an uninteresting older crater about 25 km wde. It formed long ago on some subdued hilly terrain, perhaps ejecta from the Humboldtianum Basin. Schwabe’s floor was later covered with some smooth material, perhaps a mare basalt or fluidized basin ejecta. The interesting feature is the gash that runs from just south of the crater, eastward about 80 km. Although this is a linear trough it is not a rille, rather it looks like a chain of closely overlapping craters. Near simultaneous formation would result in the destruction of walls between adjacent craters. Is this a miniature Snellius Valley? If so, this gash is a secondary crater chain from the formation of an impact basin. At first I thought that the Schwabe Valley was radial to Imbrium and that basin was the parent crater. But it looks like a great circle extrapolation would pass just north of Imbrium. A more promising source lies in exactly the opposite direction. The valley points back to the northern half of the Humboldtianum Basin, which is perhaps a second basin, roughly centered on the Hayn-Belkovich area. This basin - if real - is old, as is the gash. But is this the source? I am not sure!
Rükl chart 6
Yesterday's LPOD: Get Out Your Red-Blue Glasses Again
Tomorrow's LPOD: A Nomenclatural Screwup