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Ohio's Land

Ohio's land is largely the result of glaciers that pushed down and scoured the land from Canada during previous ice ages, with the last one ended about 10,000 years ago after covering 2/3s of Ohio for about 2 million years with a sheet of ice that was estimated to be about 1 mile thick.

As the climate began to dramatically warm the glaciers, including those that covered much of Ohio, began melting and have been melting for the last 10,000 years. That is, up to a few years ago, when they suddenly stopped melting and for the first time in 10,000 years, they once again began growing. But that's another story.

As the ice melted it caused numerous striking features to be formed that we recognize today. As the ice moved from the north, it scraped against the exposed rock and removed tiny particles of sand, gravel and in some cases, small boulders were pushed down from Canada. As the ice melted, it left these particles in areas across the land. Some of the particles were carried further south by the rushing water of the melting ice with such force that it carved out the twists and turns we see today in the Hocking Hills. In fact, the entire southeastern quarter of the state was not covered by ice and except for the Hocking Hills area, it remains much the same as it did 2 million ago, a rugged area of dense forest.

Once the ice left the state, Ohio's landscape was comprised of 5 distinct physical regions, each with its own geological profile as well as the plants and animals that live in those areas.

Ohio's 5 Physiographic Regions

LAKE PLAINS (yellow area on above map)

  • 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

GLACIATED APPALACHIAN PLATEAU (light green area on above map)

  • 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

TILL PLAINS (orange area on above map)

  • 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

UNGLACIATED APPALACHIAN PLATEAU (darker green area on above map)

  • 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

BLUEGRASS (pink area on above map)

  • 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