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Know Ohio: Rock Out With Ohio's Greatest Geology Hits

Many types of rocks are found in Ohio--sedimentary, flint (Ohio's state gem), shale, sandstone, coal, and limestone. Learn about their formation, place in Ohio's history, and other cool facts including fossils and landforms.

Class Discussion Questions:

1) Using the fossil evidence Mary describes, describe what early Ohio was like.

2) What is your favorite rock formation in Ohio? Explain why.

Read the Script:

Get ready to rock out – because I’m about to tell you about some of Ohio’s coolest rocks. Here in the Buckeye State, some of our rocks are important in making everything from peanut butter to iPads, and that give us clues about the history of this land of ours.

Most of the rocks here are sedimentary. Sedimentary rocks are formed by mud, sand and the remains of plants that harden together over time — usually this happens at the bottom of a lake or sea. Some of these rocks that you might have heard of are sandstone, limestone, and coal.

They are all over the state. Now, you might be thinking: wait if they come from the bottom of the sea how did they get so far away from the ocean? Well, Ohio used to be covered in water. It was less of a buckeye state and more of a sea state, with all sorts of underwater animals. This was a quite a while ago -- some scientists say over 500 million years ago.

Evidence of this watery time is captured in the Limestone and dolomite of Western Ohio. Limestone is mined for lots of uses. Construction workers build landscaping walls with it, side houses with it and even pour cement paths made of it. Limestone is also an ingredient in everything from toothpaste to hair mousse to medicine.

Limestone and dolomite in Ohio also preserved plenty of fossils from animals that used to roam the shallow sea here, including these guys: trilobites. Trilobites are marine arthropods. Arthropods are animals without spines that have segmented bodies, arms or legs with joints and usually shells that cover their bodies. Spiders and crabs are also considered arthropods.

If we head East, you can find our state gemstone in central Ohio. Flint is a hard, durable mineral with plenty of uses. Flint is used for starting fires — when it is hit by steel it makes sparks. Native Americans used it to make weapons like sharp arrow heads or knives. Ohio flint was valued for its colors of red, gray, yellow and pink. Native Americans would trade the beautiful stones with others as a form of currency. Most of these pretty stones come from Flint Ridge in Licking and Muskingum Counties. In 1965, Flint was named the state’s official gemstone.

Southeastern Ohio is rich with shale, sandstone and coal. At Hocking Hills there are some particularly amazing blackhand sandstone formations. Check out Rock House. It was formed by the erosion of soft spots in the sandstone. With openings like windows that let light into the tall cave, it was the perfect place for Native Americans to take shelter.

Not too far away is Old Man’s Cave, a huge recess cave that was formed by erosion of layers of soft sandstone. I bet you can guess how it got its name… Legend says that Richard Rowe moved into the cave in 1796. He had intended to begin a trading post, but was known more as a hermit. With a house like this though who could blame him!

Instructional Links

Website: Ohio Division of Natural Resources Geological Survey


Reference Book: Occupational Outlook Handbook, Geoscientists


Website Article: Ohio State University, Orton Geological Museum, Ohio Geology


Website Article: Mineralogy4kids, The Rock Cycle, Sedimentary Rocks


Images: Geology.com, Pictures of Sedimentary Rocks


Interactive Website: PBS LearningMedia, The Rock Cycle


Website Article: OneGeology Kids, Rocks and Minerals