Land use: Most of this area consists of small and medium-size farms. A large part in Indiana is in the Hoosier National Forest; some large tracts belong to coal mining companies. About 40 percent of the area is cropland, but the acreage varies widely from county to county, depending largely on the topography. Corn, soybeans, and wheat are the major crops, but tobacco is important in some parts. About 40 percent of the area is in forests of mixed hardwoods, but forest products are important in only a few parts of the area. About 17 percent is pasture used mostly for beef cattle. Urban development is minor. Stabilizing strip mine spoil is a major concern of management.
Elevation and topography: Elevation ranges from 100 m on the Ohio River flood plain to about 200 m on the higher ridges. Local relief generally is 50 to 100 m between ridgetops and the flood plains of local streams. The area is mostly hilly with broad undulating ridgetops on major divides. The flood plains and terraces of the Ohio River and its tributaries are nearly level to sloping.
Climate: Average annual precipitation-1,175 mm. About 525 mm falls during the growing season. The variable snowfall averages 25 cm. Average annual temperature-14 C. Average freeze-free period-185 days.
Water: Water is abundant in most of the area. In most years precipitation is adequate for crops. In some years, however, droughts reduce yields, and in others, too much rainfall delays planting or interferes with harvesting operations. The large streams and constructed lakes supply most of the urban water, and waterlines supply much of the water to nearby rural communities. Large quantities of ground water are available in the valley of the Ohio River and its major tributaries, but only small quantities are locally available throughout the rest of the area.
Soils: Most of the soils are Udalfs. They are medium textured and moderately fine textured. These soils have a mesic temperature regime, an udic moisture regime, and mixed mineralogy. They formed in loess and in residuum from sandstone, shale, and siltstone. Fragiudalfs (Grenada and Zanesville series), which have a fragipan, and Hapludalfs (Wellston and Frondorf series) are the dominant soils on ridgetops and side slopes. Fragiudults (Tilsit series) and Hapludults (Gilpin series) are in the northern part of the area. Hapludolls (Huntinton series), Eutrochrepts (Nolin series), and Fluvaquents (Melvin series) are loamy soils on flood plains of major streams. Haplaquepts (Karnak series) are clayey soils in slack water areas. Dystrochrepts (Cuba series), Udifluvents (Haymond series), and Fluvaquents (Stendal and Wakeland series) are loamy soils on flood plains of local origin. Hapludalfs (Wheeling series) and Fragiudalfs (Otwell series) are loamy soils on terraces of the major streams.
Potential natural vegetation: This area supports oak-hickory forest
vegetation on the rolling plateau. Coves and cooler slopes support mixed
hardwood vegetation of beech, supar maple, yellow-poplar, white ash, and
red and white oak. Eastern redcedar often grows on the shallower limestone
soils. Such bottom land hardwoods as cottonwood, cherrybark oak, pin oak,
Shumard oak, sweetgum, and swamp white oak are on flood plains.
(From "Land Resource Regions and Major Land Resource Areas of the United
States". United States Department of Agriculture Soil Conservation Service
Handbook 296. Dec. 1981. page 87.)