Thanks for the critique
I was not aware that they had been observed and discussed for so long.
The lack of erosive traits is interesting.
I hope we will get cameras there that can show gradations in a higher degree of accuracy in the future.
It sounds like the "blackness" is a figment of the limitation of the technology.
Or is there a way to extrapolate out more data points from the dark streaks themselves?
Good luck in Europe,
Ed