Portage Escarpment

The Portage Escarpment is a major landform in the U.S. states of Ohio, Pennsylvania, and New York which marks the boundary between the Till Plains to the north and west and the Appalachian Plateau to the east and south. The escarpment is the defining geological feature of New York's Finger Lakes region. Its proximity to Lake Erie creates a narrow but easily traveled route between upstate New York and the Midwest. Extensive industrial and residential development occurred along this route.

The Portage Escarpment forms the northern and western boundary between the Appalachian Plateau and the Till Plains of the Central Lowland physiographic section of the United States.

The escarpment begins in eastern New York. Nevin Fenneman placed its starting point between Cayuga Lake and Seneca Lake, where the Onandaga Escarpment transitions to the sandstone of the Portage Escarpment. But New York state officials concluded that it began east of Auburn, New York. As it approaches Buffalo, New York, it turns to the southwest and hugs the shore of Lake Erie. The escarpment moves across northwest Pennsylvania, continuing lose to the shoreline.

In Ohio, the escarpment gradually moves further away from shore. At Cleveland, Ohio, it turns sharply southward. It proceeds in an undulating south-southwest direction across Ohio, Kentucky, and Tennessee. In these latter two states it is known as the Highland Rim.

The landform's name is derived from attempts by the French to establish a portage over the escarpment in the 1750s which would link their Great Lakes forts with their fort at Pittsburgh.

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