<Li> Historic High Water . The lake fluctuates from month to month with the highest lake levels in June and July . In the summer of 1986, Lake Erie reached its highest level at 5.08 feet (1.55 m) above datum . The high water records were set from 1986 (April) through January 1987 . Levels ranged from 4.33 to 5.08 feet (1.32--1.55 m) above Chart Datum . </Li> <Li> Historic Low Water . Lake Erie experiences its lowest levels in the winter . In the winter of 1934, Lake Erie reached its lowest level at 1.5 feet (0.46 m) below datum . Monthly low water records were set from July 1934 through June 1935 . During this twelve - month period water levels ranged from 1.5 feet (0.46 m) to the Chart Datum . </Li> <P> Lake Erie was carved out by glacier ice, and in its current form is less than 4,000 years old, which is a short span in geological terms . Before this, the land on which the lake now sits went through several complex stages . A large lowland basin formed over two million years ago as a result of an eastern flowing river that existed well before the Pleistocene ice ages . This ancient drainage system was destroyed by the first major glacier in the area, while it deepened and enlarged the lowland areas, allowing water to settle and form a lake . The glaciers were able to carve away more land on the eastern side of the lowland because the bedrock is made of shale which is softer than the carbonate rocks of dolomite and limestone on the western side . Thus, the eastern and central basins of the modern lake are much deeper than the western basin, which averages only 25 feet (7.6 m) deep and is rich in nutrients and fish . Lake Erie is the shallowest of the Great Lakes because the ice was relatively thin and lacked erosion power when it reached that far south, according to one view . </P> <P> As many as three glaciers advanced and retreated over the land causing temporary lakes to form in the time periods in between each of them . Because each lake had a different volume of water their shorelines rested at differing elevations . The last of these lakes to form, Lake Warren, existed between about 13,000 and 12,000 years ago . It was deeper than the current Lake Erie, so its shoreline existed about eight miles (13 km) inland from the modern one . The shorelines of these lakes left behind high ground sand ridges that cut through swamps and were used as trails for Indians and later, pioneers . These trails became primitive roads which were eventually paved . U.S. Route 30 west of Delphos and U.S. Route 20 west of Norwalk and east of Cleveland were formed in this manner . One can still see some of these ancient sand dunes that formed in the Oak Openings Region in Northwestern Ohio . There, the sandy dry lake bed soil was not enough to support large trees with the exception of a few species of oaks, forming a rare oak savanna . </P>

Where is the deepest part of lake erie located