A smaller Onondaga Escarpment which runs east to west is located along the northern shoreline of Lake Erie. Consisting of Onondaga limestone cap rock, this escarpment runs through Buffalo, New York and Fort Erie, Ontario. This escarpment is most noticeable east of Buffalo, however it rarely rises more than 10 meters.
Substantial breaks in the Onondaga Escarpment allowed Lake Erie waters to flow into the low lands of the Wainfleet Marsh. This first occurred 10,500 – 11,000 years ago and then again 4,000 – 5,000 years ago during periods of time when the water level in the Erie Basin was much higher due to the influx of waters from glacial Lake Agassiz. Other physical breaks in this escarpment can be found at Lowbanks and Highway #58 in Port Colborne.
Between the Niagara Escarpment and the Onondaga Escarpment is the relatively flat and poorly drained lowland called the Tonawanda Plain.