The Niagara Escarpment (1) forms a north to northwest trending feature demarcated by the purple colour band. In the vicinity of the escarpment, bedrock predominately subcrops beneath a thin cover of surficial sediments. Isolated outcrops along the escarpment face are restricted to 5-10 m exposures of Silurian dolostones and at lower levels Ordovician siltstones. To the east, dissected terrain (2) occurs at the western end of the Oak Ridges Moraine (ORM), a predominately sand and gravel ridge that extends 150 km to the east. In this scene glacial meltwater pathways wrap around the escarpment to both the north (3) and the south (4). The undulating terrain atop the Escarpment is the Singhampton Moraine (5), a linear northwest-trending belt of hummocky terrain representing an ice front position during deglaciation.

The Humber River (6) occurs in the lower left corner and is present in a narrow fluvial valley. This valley has graded to lowering Lake Ontario base levels during the past 10, 000 years. The low relief terrain to the west of the Humber, is the Halton lacustrine - till plain (7).

Further Reading

Chapman, L.J. and Putnam, D.F. 1966: The Physiography of Southern Ontario, 2nd edition; University of Toronto Press, 386 p.

Straw, A. 1968: Late Pleistocene glacial erosion along the Niagara Escarpment of Southern Ontario; Geological Society of America Bulletin, 79, 889-910.

Tinkler, R.J. and Stenson, R.E. 1992: Sculpted bedrock forms along the Niagara Escarpment, Niagara Peninsula, Ontario; Geographique physique et Quaternaire, 46, 195-207.

White, O.L. 1975: Quaternary Geology of the Bolton area, southern Ontario; Ontario Division of Mines Geological Report 117, 119