Complex sentence: 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.
Split into simpler sentences: The Portage Escarpment is a major geological landform in the U.S. states of Ohio, Pennsylvania, and New York. It marks the boundary between the Till Plains to the north and west and the Appalachian Plateau to the east and south.