\Dalles\ (d[a^]lz), n. pl. [F. dalle a tube, gutter,
trough.]
A rapid, esp. one where the channel is narrowed between rock
walls. [Northwestern U. S. & Canada]
      The place below, where the compressed river wound like
      a silver thread among the flat black rocks, was the
      far-famed Dalles of the Columbia.        --F. H. Balch.