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Physiographic Regions

ohio map showing various colored regions

After nearly two million years, the last great Ice Age ended about 11,700 years ago. Two-thirds of Ohio had been buried under glaciers, which scoured and shaped the landscape and then covered it with thick layers of glacial till, comprised of sands, gravel, and clay.

In contrast, a third of the state — where the ice didn't reach — remained a rugged, wrinkled land, providing an entirely different home for plant and animal life. Humans have impacted these landscapes as well — clearing, draining, and reshaping the land to make way for farms, industries, and homes.

Today, the Ohio landscape features five physiographic regions, each with its own geological profile and distinct communities of plants and animals.

blue boxHuron-Erie Lake Plains

  • Once the bottom of a much larger ancient lake known as Lake Maumee, this region is an extremely flat plain.
  • A narrow strip of land along the Lake Erie coast in northeastern Ohio, it broadens significantly west of Cleveland.
  • As water levels rose and fell, sandy beach ridges and dunes formed along the shore.
  • The northwestern area of the region was called the Great Black Swamp - marked by rich, black soils and poor drainage.

tan boxGlaciated Allegheny Plateaus

  • Carved by glaciers and ancient streams, this region is less hilly and lacks the rugged quality of the unglaciated landscape.
  • Following glaciation, many streams reversed their flow, cutting new paths throughout the region.
  • Evidence of the region's glacial past includes bogs, kettle lakes, and a landscape marked by small hills of sand and gravel called "kames".
  • Today, the area is marked by smaller tracts of forests, ranging from a few acres to hundreds of acres.

green boxTill Plains

  • This fertile region located south of the Lake Plains is not as flat and is characterized by gently rolling hills.
  • Most hills are a series of moraines, which are glacier-created mounds of rock and soil that are up to 100 feet high and 6 miles wide.
  • A hilly belt of bedrock in Bellefontaine rises 1,549 feet above sea level - the highest point in the state, called Campbell's Hill.
  • Glaciers created terraces along valley sides and new drainage patterns including today's Ohio River.

red boxAllegheny Plateaus

  • Untouched by glaciers, this southeastern Ohio region features deep valleys, high hills and winding streams.
  • Sandstone, resistant to erosion and common in the region, supports a variety of cliffs, gorges, natural bridges and waterfalls.
  • Although the region has thousands of forested acres, the topography is rough and much of the soil is infertile.
  • A long belt of high hills on the eastern edge, running from Monroe to Columbiana County, divides eastward and westward flowing streams.

yellow boxBluegrass

  • A small, triangular region that reaches up into southern Ohio's Adams County from Kentucky.
  • Flat-topped hills and uplands rimmed by cliffs define the area.
  • Limestone, dolomite and shale bedrock are characteristic of the region and its landscape moves from gentle slopes to steep slopes, depending on erosion.
  • Some uplands are marked by sink holes or depressions that formed in rocks composed mainly of chalk.