Where is that dark outcropping that has been seen from orbit?
It's supposed to be on the southside of the Columbian Hills.
And there have been posts here in month's past [at HZ] of a possible 'cave' near the dark outcropping.
Of other interest.....
Husband Hill is about 650 feet above the basalt plains.
Mars has a diameter 5/8ths that of Earth.
How far the horizon in miles?
A crude equation:
Distance = ([650ft/6ft]^1/2) x 3 miles x (5/8) = 32 miles x [5/8] = 20 miles.