The county is located in the Ozarks region, with steep hills and deep valleys, caves, springs, and sinkholes characteristic of karst areas. The underlying rock is typically carbonate, including limestone and dolomite. Mining activity in the county included ores of lead, copper, zinc, and deposits of refractory clay. The soils in most of the county tend to be thin, rocky red clay, and are poor for most agriculture, while the soil near the Missouri River is dark, rich, and thick, and used primarily for row crops such as corn, wheat, and soybeans. Much of the county is covered with thick forests, reestablished since the 1920s.