II.

Physical Geography

Tennessee ranks 36th in size among the states of the Union, with an area of 109,150 sq km (42,143 sq mi), including 2,398 sq km (926 sq mi) of inland water. The state has a maximum extent, from east to west, of 790 km (491 mi), a maximum north-south distance of 185 km (115 mi), and a mean elevation of 300 m (900 ft).

A.

Natural Regions

Tennessee’s seven natural regions lie between the Blue Ridge Mountains on the east, and the Mississippi River on the west. The Tennessee portion of the Blue Ridge Mountains is known as the Unaka Range, a sparsely populated and mostly forested region along the Tennessee-North Carolina border. Within the Unaka Chain is a large portion of the Great Smoky Mountains National Park, including Clingmans Dome, which rises to 2,025 m (6,643 ft) above sea level and is the highest point in Tennessee.

The Ridge and Valley Province, containing the Great Valley of Tennessee, stretches westward from the Blue Ridge for 90 km (55 mi). It consists of a succession of relatively fertile and generally cultivated valleys that are separated by forested ridges. The ridges and valleys trend northeast-southwest, and rise to elevations between 600 and 750 m (2,000 and 2,500 ft).

From the Ridge and Valley Province the land rises abruptly over an escarpment to form the Tennessee portion of the Cumberland Plateau, which ranges northward into Kentucky. About 80 km (50 mi) wide, the once relatively flat plateau surface has been heavily dissected by streams, which have carved deep V-shaped valleys. Parts of the plateau are extremely rugged and difficult to access, and the usually flat-topped hills reach more than 600 m (2,000 ft) above sea level. The upturned eastern edges of the plateau, identified from south to north as Walden Ridge, the Crab Orchard Mountains, and Cumberland Mountain, in places rise to more than 1,060 m (3,600 ft) in altitude.

Elevations drop sharply from the Cumberland Plateau on the west to the Highland Rim, an upland plain of low-to-moderate fertility that surrounds the Nashville Basin. The eastern portion of the Rim (Eastern Highland Rim) averages 300 m (1,000 ft) above sea level, but elevations decline somewhat toward the south and west.

Nestled within the Highland Rim is the Nashville Basin, a somewhat oval-shaped region extending 80 km (50 mi) east-west and 130 km (80 mi) south-north. Most of the basin is flat, with elevations ranging from 150 to 210 m (500 to 700 ft). Although some parts of the basin contain deep soils that support prosperous agriculture, other portions have thin soils that are limited primarily to grazing activities. The Nashville Basin is similar in geologic origin, composition, and structure, to the Blue Grass Basin of Kentucky, and both regions are known for raising fine horses.

The north-flowing Tennessee River marks the western boundary between the Highland Rim and the Gulf of Mexico portion of the Coastal Plain, which is characterized by gently rolling to flat surfaces. The rougher and higher parts lie closest to the Tennessee River. Overall, this region contains the state’s largest and most productive farms. Its east-west extent is about 160 km (about 100 mi).

The westernmost natural region in Tennessee is a narrow strip of land along the Mississippi River known as the Mississippi Alluvial Plain. Also known as the Mississippi Bottoms, this is the smallest of Tennessee’s natural regions. Its low-lying swampy surface contains the lowest elevations in the state (54 m/178 ft). On the east it is bounded by steep bluffs.

B.

Rivers and Lakes

All the major rivers of Tennessee lie within the vast Mississippi river system. The principal rivers are the Mississippi River, along the state’s western border, and the Tennessee and Cumberland rivers. The Tennessee River is formed just east of Knoxville by the junction of the Holston and French Broad rivers. Flowing southwestward, it leaves the state at Chattanooga, curves through northern Alabama, and then flows northward across Tennessee to join the Ohio River in Kentucky. Its major tributaries in Tennessee include the Little Tennessee, Clinch, Big Sandy, Hiwassee, Elk, and Duck rivers. The Cumberland River, also a tributary of the Ohio, rises in Kentucky and meanders through northern Tennessee before reentering Kentucky to join the Ohio. Its principal tributaries in Tennessee are the Stone, Harpeth, Caney Fork, and Obey rivers. In western Tennessee several rivers flow directly into the Mississippi.

The largest natural lake is Reelfoot Lake, formed by the New Madrid earthquakes in 1811 and 1812. However, the largest bodies of water are reservoirs that lie behind dams on the Tennessee and Cumberland river systems.

C.

Climate

The climate of Tennessee is characterized by hot summers, mild winters, and abundant rainfall.

C.1.

Temperature

Average July temperatures range from less than 21° C (70° F) in the Blue Ridge region to 27° C (80° F) at Nashville and Memphis. Maximum daytime temperatures in summer often rise above 35° C (95° F) in central and western Tennessee. Daytime temperatures in the mountains rarely rise above 32° C (90° F). Summer nights tend to be warm and muggy in central and western Tennessee, but temperatures often are cooler in the east.

Average January temperatures range from less than 1° C (34° F) in the eastern mountains to more than 6° C (42° F) in southwestern Tennessee. In west-central Tennessee, even in midwinter, daytime temperatures often rise to a pleasant 10° C (50° F). Short periods of freezing temperatures occur in lowlands, but temperatures below -18° C (0° F) normally occur only in the mountain areas.

C.2.

Precipitation

Average precipitation (rainfall and snowfall) ranges from more than 1,500 mm (60 in) in some of the higher mountain areas to less than 1,100 mm (45 in) in the more protected sections of the Ridge and Valley province. In western and central areas most precipitation falls during winter and early spring in the form of rain. Snowfall is light in the center and west, but it is often heavy in the eastern mountains. Thunderstorms occur frequently during spring and summer.

C.3.

Growing Season

The growing season ranges from less than 150 days in northeastern Tennessee to more than 230 days in the southwest. The last killing spring frost usually occurs in the third week of March in western Tennessee and about 10 days later in the east. The first killing fall frost usually occurs in early November.

D.

Soils

The principal soils in Tennessee are the red and yellow podzols, which occupy most of the lowland areas of the Ridge and Valley province and the western and central areas of the state. Light brown in color, these soils erode easily, require especially careful management, and are characteristically poor in organic matter and nutrients. The most productive podzols occur in the Nashville Basin, where the underlying rock, a phosphatic limestone, contributes unusually high amounts of phosphorus to the soil. Somewhat less productive are the podzols developed on the Highland Rim and the Gulf Coastal Plain.

Lithosols, or thin mountain soils, cover most of the Cumberland Plateau and the ridges and mountains of eastern Tennessee. Highly acidic, these soils support meager crops and pastures. Much of the land is forested. Alluvial soils, which are productive when properly drained and cultivated, predominate in the Mississippi bottomlands and in other river valleys. Near the Mississippi River is a band of loess, a very fine-textured, wind-deposited, soil that is highly productive.

E.

Plant Life

In the 18th century most of Tennessee was covered by great hardwood forests. Today forests cover 55 percent of the state’s land area. Private landowners control most of the forest land.

Many species of oaks and hickories are found throughout Tennessee. Among the other forest trees of Tennessee are the tulip poplar, or tulip tree, which is the state tree, and the red maple, American sycamore, American elm, shortleaf pine, table-mountain pine, pitch pine, and white pine. Flowering trees and shrubs include the flame azalea, mountain laurel, vaccinium, and species of dogwoods and rhododendrons. Common wild flowers include the creeping phlox, fumitory, Dutchman’s-breeches, and Oswego tea.

The upland forests of eastern Tennessee are dominated by red spruces and Fraser firs. Forests of northern hardwoods also occur in the mountains and include such trees as the yellow birch, sugar maple, white ash, beech, and black cherry. Among the wild flowers in the high mountain forests of Tennessee are the wood sorrel, trout-lily, spring beauty, and phacelia. There are more varieties of plant life in the Great Smoky Mountains National Park than in all of Europe.

In the Nashville Basin there are open stands of red cedars together with post oaks, chinquapin oaks, shagbark hickories, winged elms, redbuds, and southern buckthorns. In the red cedar woods the spring wild flowers include the sandwort, sedum, phlox, verbena, and evening primrose. The iris, which is the state flower, is cultivated extensively in central Tennessee.

The bald cypress is common in the low swampy bottomlands of western Tennessee, along with black willows, cottonwoods, silver maples, sweet gums, and river birches. Some oaks and hickories are found on higher ground.

F.

Animal Life

The bison, wolves, and elk (wapiti) that once roamed Tennessee have now disappeared from the state, and the only large mammals remaining are the black bear, the white-tailed deer, and the cougar. Red wolves were recently reintroduced into the Great Smoky Mountains National Park. Among the small mammals now found are the red fox, beaver, mink, raccoon, striped skunk, long-tailed weasel, and opossum. Other small mammals also found in Tennessee include the muskrat, woodchuck, cottontail, swamp rabbit, gray fox, and southern flying squirrel.

Western Tennessee lies in the Mississippi Flyway, and each spring and fall thousands of migratory birds pass through the state. Thousands of ducks spend the winter in the state. Among the other game birds of Tennessee are the bobwhite, ruffed grouse, mourning dove, and turkey.

The year-round bird residents of Tennessee include the robin, eastern bluebird, cardinal, meadowlark, Carolina chickadee, and the mockingbird, the state bird. Also found are the yellow-shafted flicker, whippoorwill, Carolina wren, sparrow hawk, and several species of woodpeckers. The summer bird residents include the brown thrasher, scarlet tanager, indigo bunting, rose-breasted grosbeak, and species of warblers, sparrows, thrushes, flycatchers, hawks, and swallows.

There are many varieties of turtles, lizards, and snakes in Tennessee. The three poisonous snakes found there are the copperhead, cottonmouth, and timber rattlesnake. Among the nonpoisonous snakes are the black rat snake, black racer, garter snake, king snake, water snake, and pine snake. Fish found in the waters of Tennessee include black bass, carp, perch, catfish, and crappie.

G.

Conservation

Among federal agencies the TVA has played a very important role in conservation efforts, because the greater part of the state lies within the Tennessee river basin. The principal state agency responsible for conservation is the Tennessee department of conservation. Soil erosion, floods, and mismanagement of forests are the chief conservation problems. Erosion is widespread, because land too steep for cultivation has been plowed for centuries. Precious top soil has not only been washed away by the rivers but has silted up reservoirs, thereby creating further problems. Many critically eroded areas have been reforested with seedling trees, and other conservation techniques, such as contour plowing, have been introduced. The dams, reservoirs, and other control works on the Tennessee and Cumberland rivers and their tributaries help to prevent flooding.

The Tennessee pollution control board seeks to prevent pollution of the water and air. The Surface Mining Act of 1972 placed surface mining operations under strict control.

In 2006 the state had 13 hazardous waste sites on a national priority list for cleanup due to their severity or proximity to people. Some progress was being made in efforts to reduce pollution; in the period 1995–2000 the amount of toxic chemicals discharged into the environment was reduced by 19 percent. Still, this reduction was less than that recorded by many other states.