The Arbuckle Mountains are the defining geographical entity in this region, with peaks (once taller than the Rockies) eroded down to their current elevation of 200-300' above the surrounding terrain. Many lakes are also located throughout the region, often shaped by the irregular topography of the underlying Arbuckle range. Larger manmade lakes include Lake Texoma, with over , and Lake Murray, a lake impounded about south of Ardmore.