Answer:
Ohio has had many different geologic periods ranging from the Precambrian Period to the Permian Period. In the 245 million years following the Permian Period rocks were formed in what is now Ohio but were erased by natural forces, this is called the geologic gap. Around a million years ago the Ice Age caused glaciers to move across Ohio which covered around 2/3 of the state, which scraped much of Ohio's surface. After all the glaciers melted around 10,000 years ago the Earth entered the recent period of geologic history. Now new igneous rocks are being formed.
