Fort Donelson lies within the Western Highland Rim Subsection, Highland Rim Section, of the Interior Low Plateaus Physiographic Province (Fenneman 1938). This subsection consists of a maturely dissected plateau with narrow ridges, steep slopes, and stream valleys; karst features and caves are not uncommon in the section but none occur in Fort Donelson. Elevations above sea level range from 360 feet along the river to 550 on the ridge crests (USDI 1950). Topographic conditions vary from nearly flat bottomlands and terraces to upland slopes of 50 percent and perpendicular bluffs along the river. Major battlefield roads, historic attractions, and the National Cemetery are on level to rolling but relatively narrow ridges. The battlefield is underlain by Warsar Limestone of Mississippian age. This yellowish-gray, medium to very coarse-grained limestone in some places is at least 200 feet thick and is often cherty near the surface (Marcher 1962). Outcrops occur along the river and in some steep-sloped ravies. The limestone bedrock has weathered into rocky soils which are shallow and nutrient deficient except in the limited acreage covered by alluvial and colluvial bottomlands and terraces. At least 25 soil types and phases are found in Fort Donelson.