beaver dam

A dam built by a beaver acro a stream likely to run off in summer. It is generally formed of drift-wood, green willows, birch, poplars, and similar materials. The simple method by which a beaver makes a tree fall in a particular direction acro a stream, is by nibbling it round, not horizontally, but so as to slope or dip in the direction in which it intends the tree to fall. "The author expre ed his belief that the deposits indicated, at places, the effects of beaver-works, tracts of forest having been, to all appearance, submerged and destroyed by the action of beaver - dams ." - Н . Woodward, in Brit . A oc. Rep . for 1869, pt. ii., p. 104.