The Frankstown Branch Juniata River runs north along the west foot of the ridge before turning east along U.S. Route 22 at Water Street, the river, road, and rail (the abandoned Petersburg Branch) crossing the ridge line through a water gap.
Northward along the west side of the ridge, the Frankstown Branch Juniata River flows until it reaches U.S. Route 22 at Water Street. There, it also crosses the abandoned Petersburg Branch railway and a natural water gap created by the ridge.