Approximately 11,700 years ago, at the end of the Pleistocene epoch, the glaciers that covered North America began to retreat. As this occurred, one large block of ice broke from a glacier, carving out a deep depression in the area now known as Conneaut Lake. Sediment accumulated around this block of ice and when the ice melted, the melt water filled the depression resulting in Conneaut Lake, a kettle lake that continues to be fed by springs