Glacial Grooves State Memorial

Ohio's Origins

The glacial grooves on Kelleys Island showcase Ohio’s geographic evolution that began thousands of years ago. Within the last fifty years, the area has been preserved, and made into a visitable attraction.

Over one million years ago, the earth’s warm climate began to cool, and this change ushered in the Pleistocene Ice Age. During the Pleistocene Epoch, large continental glaciations formed in the northern hemisphere. Two-thirds of Ohio was once covered by glaciations known today as Pre-Illinoian (beginning more than 300,000 years ago), Illinoian (beginning 300,000 years ago), and Wisconsinan (beginning 24,000 years ago). These large sheets of ice, which may have been one mile thick in some areas, completely transformed Ohio’s landscape, and have affected every facet of its history. The last glaciation to shape Ohio’s geography was the Wisconsinan, and its most visible impact can be seen in the Great Lakes. The Wisconsinan glaciation retreat began 18,000 years ago and lasted for about 4,000 years. During that time, the large sheet of ice did not steadily retreat; depending on climate patterns, it would advance and retreat sporadically, creating ridges and river valleys that evolved to become the state’s landscape as we view it today. As the ice moved northward out of the Ohio region it began to melt and created large basins filled with melted glacial ice and sediments. Over time, climate patterns and erosion transformed these large glacial deposits into the Great Lakes. In Ohio’s northern region, the rock sediments trapped inside the slow-retreating glaciers would scratch the area’s native limestone, leaving carved grooves along its path. The largest visible example of this is at Glacial Grooves State Memorial on Kelleys Island. Kelleys Island was formed as the Wisconsinan glaciation retreated over a large block of limestone where Lake Erie sits today. During the nineteenth century, groups excavated grooves and quarried the limestone – an industry propelled by the easy access to national markets that followed the construction of Ohio’s canals. In 1892, a small portion of glacial grooves on the northern side of the island was saved by the Kelleys Island Lime & Transport Company. In 1972, excavation of the remaining glacial grooves by the Ohio Historical Society began. Today, Ohio History Connection – formally OHS -- continues to interpret and manage the site.

Notes for Travelers

Kelleys Island’s nature preserves, beaches, and historic sites, showcase how the island came to be and tell of the story of those who lived there. The small portion of remaining glacial grooves, now located in Kelleys Island State Park, represent an era of Ohio’s ancient past that was at one time close to being completely destroyed by booming industry. Because of the efforts of those who have preserved this landscape by exposing the remaining limestone, a rare alvar ecosystem was given the appropriate environment to form and thrive and is now protected as part of the North Shore Alvar Preserve. The Glacial Grooves Geological Preserve is the largest site of its kind offering visitors a unique understanding of how Ohio’s current landscape was created thousands of years ago.

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