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Alabama Natural
Regions
From plateaus and uplands in the northeastern
section of the state, the land slopes gradually southward across forested
ridges, rolling prairie, and fertile valleys to the delta of the Mobile
River on an arm of the Gulf of Mexico.
Alabama can be divided into five natural regions: the Appalachian
Plateaus, the Ridge and Valley province, the Piedmont, the Interior Low
Plateau, and the Gulf Coastal Plain. The Appalachian Plateaus, the Ridge
and Valley province, and the Piedmont together make up part of the vast
Appalachian Region, or Appalachian Highland.
The Appalachian Region, in Alabama, extends
across much of the northern half of the state in a northeast-southwest
direction. The northwestern part of the region is the Cumberland Plateau,
which is one of the Appalachian Plateaus (see
Cumberland Plateau and Cumberland Mountains).
It is an almost level sandstone upland that averages about 1300 ft above sea level and is drained by the Tennessee and Black Warrior
rivers. The Ridge and Valley province is made up of sandstone ridges paralleled by fertile limestone valleys. The ridges impose a distinctive
northeast-southwest trend on the local pattern of rivers, railroads, and highways. The meandering Coosa River is the main stream of the Ridge and
Valley province. Southeast of the Coosa lie the rugged Talladega
Mountains, which rise to 733 m (2405 ft) above sea level at Cheaha
Mountain, Alabama’s highest point. Between the Talladega Mountains and the
Georgia state line on the east is the
Piedmont Plateau, a large area with
numerous low hills and ridges.
The Interior Low Plateau extends southward into
northern Alabama from Tennessee. It is a limestone region that is made up
of low uplands and broad valleys. The region is drained by the Tennessee
River.
The Gulf of Mexico portion
of the Coastal Plain
covers the remainder of the state. Sedimentary rocks, much younger than
those of the Appalachian Region, underlie the Gulf Coastal Plain. The
plain is by no means flat. Parallel bands of low, generally forested hills
and ridges stretch across the plain from east to west. The ridges usually
have a steep northern slope and a more gentle southern slope. They are
separated by broad level lowlands, including the well-known
Black Belt,
which is a gently rolling prairie, 40 to 80 km (25 to 50 mi) wide, that
extends across the state into Mississippi. The Black Belt, named for its
fertile dark-colored soils, is one of the major agricultural regions of
Alabama. In the extreme southwest, near the Gulf of Mexico, the plain
becomes very flat and swampy. The southeastern part of the plain is a flat
area, dotted with pine forests. Extensive areas of these forests have been
cleared to provide excellent farming lands.
Climate
Alabama has a humid subtropical climate, with short, relatively mild
winters and long warm summers. Temperature differences between the coastal
and inland areas, however, are small. January averages range from about
57° F at Mobile to about 44° F at Birmingham. July averages are in the
upper 80°s F at Mobile and at Birmingham. Very low or very high
temperatures are unusual. The growing season, the period between the last
killing frost of spring and the first killing frost of fall, ranges from
about 200 days in the north to more than 300 days in the southwest. During
the summer, daytime temperatures are frequently in the mid-80°s F or
higher and afternoon thundershowers are common. In winter, mild humid air
masses from the gulf alternate with cold air masses from the north. Snow
occasionally falls in the north. Rainfall is plentiful,
ranging annually from about about 53 inches in the north to more than 68
inches in the southwest. Most rainfall occurs in winter and early spring,
but a second wet season occurs in July, owing primarily to thunderstorms.
Tropical cyclones and, in some years, severe hurricanes are a threat to
the coastal areas in summer. Winds, floods, and high tides accompanying
the storms can cause considerable damage to crops and property. |
