Ontarians are sometimes not aware that the province has three distinct geographic zones:

The well known, fertile, post-glaciation farmlands to the south, the equally well known Canadian Shield, of which Algonquin Park or the Temagami wilderness area are the best examples, and a third, the roadless but geographically important Hudson Bay lowlands, taking up almost a third of the area of the province, which drain into James Bay & Hudson Bay. Although there is plenty of water in Ontario, these lowlands are the only sea coasts we have, and really are not part of the Ontario consciousness because of the remoteness and lack of road access. Interestingly, the oldest port in Ontario—and indeed one of the oldest in Canada—is not on the Great Lakes, but is Moosonee, where the ships of the Hudson Bay company sailed from.

The three zones are marked as much by their vegetation as they are by their geology—the south has mixed deciduous trees with plenty of beech, oak, maple and birch, while the shield is largely Boreal forest composed of firs and pine. The lowlands have few trees and are mainly scrub. 

There are also two important—and interesting—exceptions in the southern farmlands: notably, the Niagara Escarpment, but also the area west of London. This area of unbroken flatness is considered part of the mid-west prairie, part of the same area that extends to Iowa and the Dakotas and up into Manitoba and Saskatchewan, and accounts for the absence of hilly terrain west of London, up to Windsor. West Lorne, where our family first settled in 1962, sits in the middle of this flatland. East of London, the farmland is quite different, and much more rolling. 

see also

ONTARIO—A Place To Stand:
a detailed geographic perspective