Grenville

Small town in south Québec, Canada; population (1991) 1,400. It is situated on the Ottawa River, opposite Hawkesbury, Ontario, 83 km/52 mi west-northwest of Montréal and 19 km/12 mi west of Lachute. A canal built here in 1819–34 was part of a plan, centred on the Rideau Canal, to provide an all-Canadian alternative to the Great Lakes as a route west from Montréal into the interior. Grenville has a mining history and is today a recreational centre.

The town gives its name to the Grenville Province, a band of Precambrian rocks that constitute the newest and southeasternmost part of the Canadian Shield; they extend northeast–southwest from Labrador through the southeast US and into Mexico. Roughly underlying the Appalachian system, Grenville rocks, which for the most part are now found far below the surface, also extend west beyond Lake Erie; the Grenville Front, extending northeast from Lake Huron's northeast shore to Labrador, represents the boundary between them and older Shield rocks. The Grenville Province is thought to represent a collision of continental plates over 1 billion years ago. The high mountains raised by that event have long since been eroded away; various low hills throughout the Appalachian region represent their mere roots.