From: http://www.habitablezone.com/space/messages/33253.html

The Solar longitude is 339.13 for this picture. Southern Summer (Where this picture was taken) begins at 270° and ends at 0°. So this picture was taken in the summer time.

Ok. Late summer at 38 deg south, my mistake.

That doesn't change the information for the sun's position, I transcribed that directly from the image header information.

Anyway, whatever it is doesn't wan't to flow from high to low, it likes to hide up where it has high slopes on the sides.

Maybe it knows exposure to sunlight will kill it.....

I give up.

Your right, it's a mystery dark material residing in that gully. I wonder if it's related to the unenlightened material residing within your cranium.