During the Silurian Period, rising seas flooded much of the continent. At that time the GTA was south of the equator and the warm shallow seas were inhabited by an abundance of marine invertebrates as depicted in the reconstruction below. Remains of these organisms are preserved as fossils in the rocks that form the Niagara Escarpment.

Since the tropical seas disappeared millions of years ago, exposure to the elements has caused weathering and removal of the softer underlying shale, leaving a steep dolostone cap. This weathering process, called sapping, continues today.

Grey cliffs of the escarpment are exposed within a forested strip. Below the cliffs, a golf course shows one of the recreational uses of this area. Above the cliffs, dolostone is being extracted for construction.