DALLE, a rapid falling over flat smooth rock surfaces in a river bed, especially in rivers flowing between basaltic rocks (Fr. for a flag-stone or flat tile). The name is common in North Amer ica, and came into use through the French employes of the Hud son's Bay Company. Well-known "dalles" are on the St. Louis, St. Croix and Wisconsin rivers. The "dalles" of the Columbia river are very beautiful, and have given its name to The Dalles (q.v.), county-seat of Wasco county, Oregon.