The terrain of northern Putnam County is mostly flat; rolling hills become more evident in the center and southwest portions. At the time of settlement, the county was completely tree-covered (poplar, oak, walnut, maple, beech, and hickory), but presently the flat portions have been cleared and used for agriculture; the drainage areas are still wooded. Walnut Creek drains the east central part of the county, flowing south-southwestward into Owen County. Big Walnut Creek drains the upper part of the county, flowing southwestward into Parke County, where it is captured in the Cecil M Harden Lake. The highest point in the county (980 feet/299 meters ASL) is a gradual rise two miles (3.2 km) SW of Bainbridge.