May 27, 2015
Originally published May 26, 2004
Image Credit: Tom Leech
Most rilles fall into one of three categories: sinuous, linear or arcuate. But the rilles near Triesnecker don't. As this high resolution view by Tom Leech demonstrates they are mostly narrow and straightish with some tight curves. The NW-SE trending rille segments are approximately radial to Imbrium, but the N-S and E-W segments aren't. The rilles are not associated with overtly volcanic features such as domes or Cobra Head-like collapse pits. These are unusual, maybe unique rilles. Ejecta from Triesnecker appear to cover the rilles, which must thus be older than that crater. Because some of the rilles cut across other ones there must be an age progression; in general the thinner rilles seem to be older than the wider, more pronounced ones. If these razor thin rilles, like larger linear ones, are surface expressions of igneous dikes, they would have had to be very close to the surface. This is the place in an LPOD writeup where I often provide an explanation, but I don't know why these rilles are here!
Yesterday's LPOD: A Grand New Lunar Atlas
Tomorrow's LPOD: The Jura and a Missing Rim
Author & Editor:
Charles A. Wood