Ohio

Relief

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Ohio straddles two major subregions of the Interior Lowlands physiographic region of the United States: the Appalachian Plateau on the east and the Central Lowland on the west. These two subregions divide the state almost in half. The Appalachian Plateau, reaching westward from Pennsylvania and West Virginia, stretches along Ohio’s eastern border, roughly from Lake Erie in the north to the Ohio River in the south. The northeast is only partially glaciated, while the southeast is unglaciated terrain. Throughout the plateau the land is dissected by rivers winding among steep hills, and many areas reach elevations of some 1,300 feet (395 meters).

The Central Lowland reaches westward from the Appalachian Plateau. The Lake Plains section of the lowland extends along Lake Erie and across the northwestern segment of the state to the Michigan border, before stretching irregularly to the south. It then levels to become slightly rolling terrain that was once under water; the swampiness of the northwest, around Toledo, posed obstacles to settlement before drainage made the land more arable. The Central (or Till) Plains, which extend westward toward the Mississippi River, include parts of western and southwestern Ohio and provide a deep soil. That region contains the state’s highest and lowest points: Campbell Hill, the highest point, at 1,549 feet (472 meters), is located near Bellefontaine; the lowest point, at 433 feet (132 meters), lies at the confluence of the Miami and Ohio rivers, near Cincinnati.

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Drainage

The principal water sources are rain-fed streams, lakes, and reservoirs. Floods, once prevalent, have generally been brought under control by state and federal dams and other conservation measures. Groundwater is used widely for public supplies, though the industrial and population centers have limited access to these resources. Huge stores of these waters are buried in preglacial valleys in central and south-central Ohio.

Lake Erie, with an average depth of only 62 feet (19 meters), is the shallowest of the Great Lakes. It is also the most tempestuous, with frontal storms often roaring across it from Canada, and the most liable to shoreline erosion, harbor silting, and filling of its bed. Its shallowness, coupled with the concentration of population, farms, and industrial plants in its watersheds, led to severe pollution by the mid-20th century. Subsequent attempts to abate pollution in Lake Erie have shown signs of success, however. Fish returned to previously uninhabitable waters, a revival of sport fishing and recreational activity stimulated economic growth along the shoreline, and urban water supplies were protected.

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A low watershed separates the roughly one-fifth of Ohio drained by the Maumee, Cuyahoga, and other rivers emptying into Lake Erie from the rest of the state, which is drained by the Miami, Scioto, Muskingum, and others flowing into the combined system of the Ohio and Mississippi rivers. The Ohio, only a tiny part of which is under state jurisdiction, is canalized and channeled for its entire length, as is the Muskingum River from Zanesville to Marietta. More than 100 lakes and reservoirs supply recreational and industrial water.

How big is Ohio?

Soils

Most of Ohio’s soils are well suited to agriculture. The naturally fertile Central Plains soils contain glacial limestone, and they also are rich in phosphates—one of the principal ingredients in fertilizer. Lake Plains soils also are highly productive. The sandstone-based soils of central and northeastern Ohio are best adapted to pasturelands, while the thin-soiled and heavily eroded hilly areas of the southeast support little productive farming except in river bottomlands.