Vallis Alpes

The valley is narrow at both ends and widens to a maximum width of about 10 km along the middle stretch.

[1] The valley floor is a flat, lava-flooded surface that is bisected by a slender, broken, cleft-like rille.

The center rille is a challenging target for telescope observation from the Earth and described as, "notoriously hard to spot.

The more rugged edges of the valley lie at the narrow west-southwest end that cuts through the mountain range.

[4] However, the valley could have been formed by stress fractures due to expansion of the mantle or contraction after solidification of regolith.

Vallis Alpes area
Selenochromatic image(Si) of Vallis Alpes area with some selenochromatic landmarks
Lunar Orbiter 4 image of Vallis Alpes
Oblique view of Vallis Alpes from Lunar Orbiter 5 . Mare Imbrium is in the background.
Closeup of Vallis Alpes from Lunar Reconnaissance Orbiter data. The center rille is clearly visible.