During the past two million years, glaciers have shaped and reshaped the surface of Ohio several times. These continental masses of ice affected as much as two-thirds of the state. Moving from the north and northwest, glaciers have scraped and flattened the landscape. Often more than a mile thick, they smoothed existing hills and filled valleys with enormous amounts of rocks, gravel, and smaller particles. Through these actions, glaciers have had a very important impact on the agriculture of Ohio. Their activity has been felt in two noticeable ways: shaping the ground upon which people work and build, and forming the soils that cover that ground.
