DCHP-2

riffle ((n.)) † [origin obscure; cf. ruffle, ripple] DCHP-1 (pre-1967)

• 1a n.

  an obstruction in a watercourse, as a shallows, rapids, or sandbar.

  See also: ripple (def. 1)  shoot ((n.)) (def. 1)  rift  

  • 1859  (1964)  Some of the boats at that season came up from York in 18 days with forty pieces so that it could not have been so low as the year the rif[f]les came up. . . .
  • 1938  The river became swifter and shallower, and, at low water stages, riffles and scattered boulders broke its course.
  • 1954  Just west of that riffle a log bridge crossed the brook. . . .
  • 1956  Above one of the riffles, a good-sized trout--a rainbow--rose to a small blue dragonfly

• 1b n.

  a stretch of ruffled water caused by such an obstruction; the place where such an obstruction is.

  See also: ripple (def. 2)  rip ((n.))  

  • 1869  The citizens of Quesnelmouth had subscribed $450 for the widow of the late unfortunate Frank Roberts, who was drowned at Spanish Riffle.
  • 1894  But the moment they [the logs] drifted into the riffles, and plunged into the foaming rapids, they began to act in the most scandalous manner.
  • 1963  It was at a riffle called the Figure Eight . . . that we almost came to grief.

• 1c n. — Northwest

  a fast-moving stretch of water over a relatively smooth bed. See 1955 quote.

  See also: chute (def. 2)  dalle (def. 2)  flat rapid  run ((n.)) (def. 1)  slide (def. 1b)  

  • 1908  Presently . . . we entered a succession of the sweetest little rapids and riffles imaginable. . . .
  • 1952  There were so many memories--the sudden rush of white water in the riffles . . . the swirl and struggle of the arctic grayling and those gigantic Dolly Vardens of the Flat River.
  • 1954  riffle--a chute or slide of water in a river, usually in shingle or broken rock and not in solid rock.
  • 1963  One could slide down a riffle [in a canoe]--which is a chute through or around a shingle bar. . .

• 2 n. — Placer Mining

  the transverse barriers placed across the bottom of a sluice-box to arrest the particles of gold.

  • 1900  . . . there would come a time when those dumps would pass through his sluice-boxes, depositing in the riffles, in the course of half a dozen days, several hundred thousand dollars.
  • 1927  The gold, being heavier than the sand and small stones, settled to the bottom to be caught by cleats or riffles, while the lighter material was carried away. . . .
  • 1965  Riffles are cross pieces of wood, two inches square and set about two inches apart with nails left projecting so the riffles can easily be removed.