Tennessee is divided into three parts by the Tennessee River. It begins above Knoxville, flows southwest into Alabama and then returns some 230 km west to cross the state a second time. The tree parts are:

  1. The Appalachian Highlands
    East Tennessee has a lot of limestone, which is karstified. Most caves of Tennessee are in this area, along the Eastern Continental Divide. This divide, the border between two huge catchment areas, runs north to south, along the Appalachian Mountains. The Tennessee side drains to the Gulf of México while the North Carolina side drains to the Atlantic Ocean.
  2. Interior Lowlands
    are not really low, they are only lower than the Appalachian Highlands. There are the Eastern Highland Rim and the Western Highland Rim with limestone and caves.
  3. Gulf Coastal Plain
    This area between Tennessee River and Mississippi River is flat and is covered by sediment washed down from both the Rocky Mountains and the Appalachians, some areas are covered by loess, a fertile aeolian sediment. However, there is no subterranean drainage, so there are no caves.

Tennessee is definitely a cave State, today some 10,000 caves are known. There are 11 show caves [2021], and other caves are used for cave trekking tours. It also has numerous Natural Bridges, sometimes called arches.