The Town of Stouffville is located within the Great Lakes - St. Lawrence Lowland area of Canada. The Great Lakes - St. Lawrence Lowland is a well-defined region, densely populated, and in many ways, the most prosperous region of the country. It is home to Toronto and Montreal, the two largest cities in Canada where much of the country’s economic life is controlled.

The identity of the Stouffville area within the Lowland is controlled mainly by its physical characteristics. Its geological foundation is of sedimentary rock strata of Palaeozoic age, distinctly different from the Canadian Shield lying to the north. The bedrock is almost perfectly horizontal.

The entire Stouffville area, as with the rest of southern Ontario, was subjected to successive glaciations during the last Pleistocene epoch, which left profound affects. In most areas throughout Stouffville, the glacial overburden is many meters thick. As a result, agricultural soils of good to excellent quality cover much the land. Glacial deposition and erosion has also created a hilly topography that is extremely variable.

Stouffville is traversed, largely west to east, by the Oak Ridges Moraine, an interlobate kame moraine deposited during the recession of two glacial lobes at the end of the last ice age, approximately 10,000 years ago. The moraine, one of the province’s largest spanning from Caledon in the west to east of Cobourg, sports highly variable sediment clasts ranging from sand to boulder sized rock. As a result, numerous gravel pits dot the surface taking advantage of the economic benefits sand and gravel bring.

In Stouffville, the surface of the moraine also sports numerous kettle lakes – lakes that do not have drainage. These variable sized lakes were created as large portions of the melting ice from the ice sheets broke off and melted in place, creating large sinkholes that ultimately filled with water. Three of the largest kettle lakes in Stouffville – Musselman’s Lake, Island Lake and Preston Lake – are home to small communities of residents and offer many year-round recreational activities.

What drainage does occur on the Oak Ridges Moraine either flows south to Lake Ontario or north to Lake Simcoe.  The watershed boundary is slightly north of the current Bloomington Road.  Two conservation authorizes (Lake Simcoe Region C.A. and Toronto and Region C.A.) govern the watersheds.

In addition to the deposition of various sediments, the recession of the two ice lobes also eroded the landscape around Stouffville, most notably by widening and deepening river valleys. As the largest example is the scouring of the Great Lakes, many smaller river valleys in the Stouffville area lead to Lake Ontario and ultimately to the St. Lawrence River and the Atlantic Ocean. Two of the prime examples are the Rouge River basin and the Duffins Creek basin. In geologic terms, the watersheds leading from the Stouffville area are young and weak. Consequently, the drainage systems of Southern Ontario are not yet well developed.

The climate of the Stouffville area, as with the rest of the Great Lakes - St. Lawrence Lowland, is continental, with great variation from season to season. Because of the influence of the Great Lakes, the Stouffville area experiences temperatures less extreme than other parts of Canada (cooler in the summer, warmer in the winter). Precipitation (rain in the summer and snow in the winter) is most commonly the result of frontal activity between polar continental and maritime tropical air masses. Frontal systems typically move eastwards across the region at an average of once a week. At any time of year, warm and humid days alternate with surprisingly abrupt, cool, clear and crisp days.

The growing season and the number of frost-free days are longer than in most other parts of Canada. The mean date of the first occurrence of 0^oC in the Stouffville area is typically between September 30 and October 5 each year. This combination of conditions allows growth of a natural mixed forest in which deciduous species (maple, oak, beech and others) and coniferous species (chiefly white pine and white cedar) co-exist, with a rich variety of cultivated crops where the forest has been cleared.

Vast stretches of Stouffville, particularly to the north, are covered by the York Regional Forest. The pine trees that populate the Forest were planted between 1920 and 1960 by provincial and county governments to help restore cleared, eroded and sandy farmlands into healthy soil and shaded areas welcoming to native trees and plants. Today, the Forest is welcome to numerous recreational, educational and tourist activities.

Although Stouffville is located completely within the Great Lakes – St. Lawrence Lowlands, the Canadian Shield is less than an hour drive to the north. The geologic boundary between the two Regions is not abrupt, with the Trent-Severn Waterway forming a convenient zone of demarcation between the two areas. The southern Canadian Shield area of Ontario is vastly different from the Stouffville area, in geologic, climatological, geomorphological and biological terms.