The county terrain is formed by the folded Appalachian Mountain ridges which run from southwest to northeast across the county. The terrain slopes to the northeast, with its highest point (Broad Mtn) 1.25 mile (2 km) ENE from the county's NW corner, just south of the county's border with Centre County. It measures 2,339' (713m) ASL. The Juniata River flows northeast through the lower part of the county, exiting northeastward into Juniata County near Hawstone. The county has a total area of , of which is land and (0.9%) is water.