 The county contains parts of several physiographic regions, including the Arbuckle Mountains, the Coastal Plains, the Red Bed plains and the Cross Timbers.The northern part of the county drains to the Washita River, while several creeks drain the southern part directly to the Red River.The Healdton Field, encompassing Healdton and located in the western portion of Carter County, produces from the Pennsylvanian Healdton sands of the Hoxbar Group and the Ordovician massive carbonate Arbuckle Group.