Physical Geography

Arkansas lies in two of the principal physiographic regions of the United States: the Central Uplands in the north and west, the Gulf Coastal Plain in the south and east.

The Central Uplands, shared with Missouri and Oklahoma, divide in Arkansas into two sections: the Ozark Plateau and the Ouachita Mountains. Separating these two sections is the broad valley of the Arkansas River.

The Ozarks are made up of geologically old rock formations, in which erosion has formed many ravines and deep valleys. The terrain is generally rough, especially along the plateau's southern edge in the Boston Mountains. Here, hard rocks have resisted the effects of weathering, and elevations are higher than elsewhere on the plateau, reaching a maximum of nearly 2,600 feet (790 m) above sea level.

South of the broad valley of the Arkansas River are the Ouachita Mountains. Steeply folded ranges here resemble some of the ridges and valleys of the Appalachians. Magazine Mountain, rising 2,753 feet (839 m) above sea level, is an outlier of the Ouachitas, the highest point in the state.

The Gulf Coastal Plain area of Arkansas is low and flat, ranging from 55 feet (17 m), the lowest elevation in the state, to about 350 feet (107 m) above sea level. It is one of the most northerly parts of the Coastal Plain—at the state's northern boundary the Gulf coast is 500 miles (800 km) to the south. The only break in the seemingly flat land is Crowley's Ridge, a low but distinct landform in the northeast. Rich alluvial soils occur along the Mississippi and some of its tributaries, providing the most fertile and productive land in the state.

Arkansas lies in the drainage basin of the Mississippi River. With few exceptions, the entire eastern boundary of Arkansas is formed by the Mississippi. Within the state, the largest river is the Arkansas, running from Fort Smith to the Mississippi in the southeast. Other tributaries of the Mississippi include the White and St. Francis rivers, both of which originate in the Ozarks. In the south, the Saline and Ouachi- ta rivers rise in the Ouachitas and flow southeastward, roughly paralleling the course of the Arkansas. The Red River runs through the southwestern corner of the state.

Natural lakes are few. The largest are crescent-shaped oxbow lakes formed by the shifting of the Mississippi River.

Mineral springs are numerous, particularly in the Ozarks and Ouachitas. The largest and best-known are those in Hot Springs National Park, at Hot Springs.

Many large artificial lakes and reservoirs have been created by damming the rivers. They include Lake Ouachita on the Ouachita River, Lake Dardanelle on the Arkansas River, and Greers Ferry Lake on the Little Red River. Bull Shoals Lake, Norfork Lake, and Beaver Lake are on or near the White River.

Arkansas has a humid climate with hot summers and mild to cold winters. Temperatures average about 80° F. (27° C.) nearly everywhere in July and from 36° F. (2° C.) in the northwest to 44° F. (7° C.) in the south during January. Summer highs of more than 90° F. (32° C.) occur throughout the state. Temperatures often dip well below freezing during winter.

Precipitation is fairly abundant, ranging from 45 inches (1,140 mm) annually in the north to 52 inches (1,320 mm) in the south. Snowfall is scant throughout the state.

Roughly 55 per cent of Arkansas is wooded; timber is one of the state's chief resources. Almost all the forests are of commercial quality. Loblolly and shortleaf pines predominate in the south, but give way to hardwoods elsewhere in the state. Oaks, hickories, maples, and hawthorns are among the many hardwoods found in the state.