Welcome to the Glacial Grooves State Memorial. This memorial, containing of three and one-half acres on Kelleys Island, has been administered by the Ohio Historical Society since 1932.
Impressive is size and shape, these glacial grooves are of great geologic significance as well. Approximately 35,000 years ago, when the climate was much cooler and wetter, a great continental glacier flowed from Canada into northern Ohio. After the climate warmed and the ice melted (about 10,000 years ago), this island retained a spectacular reminder of the glacier's presence here — these huge glacial grooves, which had been carved in the limestone bedrock by the action of the advancing glacier.
Due to their size and ease of accessibility, these are the most famous glacial grooves in the world. Since this formation was discovered over a century ago, it has been an object of fascination to students, vacationers, and scientists alike. Geologists have studied these grooves for many years in an effort to determine exactly how they were carved by the glacier. Several theories have been proposed, but there is still no entirely satisfactory explanation.