(1):

(n.) A ripple in a stream or current of water; also, a place where the water ripples, as on a shallow rapid.

(2):

(n.) A trough or sluice having cleats, grooves, or steps across the bottom for holding quicksilver and catching particles of gold when auriferous earth is washed; also, one of the cleats, grooves, or steps in such a trough. Also called ripple.