Still moving south, the unusually colored crater Zach lay east of
Clavius. There is an odd region of dark material in the NE corner. I
am fairly certain this was not a shadow, but I expect to look at it
again Sunday night. This dark feature, of which there's no hint at
all in Rukl, abutted the NE interior wall. In the SE area of the
crater, there was another, smaller, lighter colored dark spot, which
was oval in shape, and stood out from the wall.
This caught my attention because the terrain in this area seems to be
fairly uniformed light colored highland material. The presence of
dark material made a strong contrast with the rest of the terrain.