Neotectonic jointing control on Lake Ontario shoreline orientation at Scarborough, Ontario

Many parts of the coastline of Lake Ontario and other Great Lakes consist of long linear sections, commonly made up of tall cliffs cut into Pleistocene-aged glacial sediments. Scarborough Bluffs on Lake Ontario east of Toronto is such a shoreline. Study of the orientation of subaerial and subaqueous joints in both Pleistocene-aged sediments and Ordovician-aged bedrock in the Scarborough Bluffs area indicates that joint orientation in the Pleistocene sediments compares closely with that of the Ordovician bedrock. This observation supports the conclusion that it is neotectonic jointing in Pleistocene sediments that controls the orientation of the cliffed shoreline and the associated creeks in the Scarborough Bluffs area.