Timber Rafting on the Ottawa
The rafting of square timber down the Ottawa River, begun in 1806, reached its peak during 1861-91 and ended in 1909. Pine "sticks" from .1 to .2 square metres and 12 to 15 metres long were floated down tributary rivers such as the Petawawa, Madawaska, Bonnechere and Mississippi to rafting points on the Ottawa. There "cribs" were made up, containing 20 to 40 pieces of timber, and as many as 200 cribs, were in turn assembled into a raft. These rafts could be taken apart for passage down rapids or the timber slides which by-passed them. Arriving at Quebec City as much as two months later, they were dismantled and the timber loaded for shipment overseas.
Plaque via Alan L. Brown's site Ontario Plaques. Full page here.