Crossword Clue:

a valley on the moons surface

Answer	Crossword Clue
RILLE	Trench on the moon's surface.
RILLE	Cleft on the moon's surface.
RILLE	Valley on the surface of the moon.

SCUM	Film on the surface of a liquid
RHUMB	Curve on the surface of a sphere
ETCH	Put on the surface, in a way
WATERWAVER	Quiver on the surface of a pool?
DAP	Skip, as a stone on the surface of water.
ADSORBS	Gathers on the surface, as a layer of molecules