dalle [< Cdn F "trough, flume" < F "flagstone"]
1 n. Obs. a smooth flume or artificial slide for floating logs.
2 n. a fast-moving stretch of water over a relatively smooth bed.
See also: flat rapid riffle ((n.)) (def. 1c)
3 n. a narrow stretch of river between high rock walls, characterized by whirlpools, rapids, and treacherous currents.