Origin of The Oak Ridges Moraine - Regional Physiography

Regional Physiography

The Oak Ridges Moraine consists of four elevated, wedge-shaped structures; from west to east, they are:

• The Albion Hills wedge,
• the Uxbridge wedge,
• the Pontypool wedge, and
• the Rice Lake wedge.

These wedges are separated by narrow east to west ridges, and formed via sedimentation. The hummocky terrain, small elevated plains and narrow ridges suggest that its formation is of glacial origin.

The moraine is nearly bisected in the east; the Rice Lake wedge is isolated from the three western wedges since the moraine is absent directly south of Rice Lake.

Four primary geophysical structures are intimately tied to the formative processes of the Oak Ridges Moraine:

• the Niagara Escarpment to the west
• drumlinized uplands in the north, with extensions south of the Oak Ridges Moraine
• wide, flat-floored valleys, primarily in the north
• low-relief plains in the south.