Several parks comprise the Lake Erie Island group.The islands were formed during the glacial period when massive ice sheets entered Ohio. Glaciers gouged and scoured the bedrock; their tremendous weight left deep depressions which filled with meltwater, forming the Great Lakes.Lake Erie is the shallowest of the Great Lakes -allowing for violent storms with high waves.The lake is divided into three basins.The western basin has an average depth of 25 to 30 feet; the central basin averages 61 feet; and the eastern basin shows an average depth of 120 feet.
Lake Erie has high nutrient levels and warm temperatures which produce greater numbers and varieties of fish than any other Great Lake.Annual catches nearly equal the combined catch of all other Great Lakes. Yellow perch, smallmouth bass, white bass, channel catfish and walleye are dominant species.The islands are composed of limestone bedrock.Small scratches in the rock surface known as glacial striations are common while major grooves such as those found at Kelleys Island are rare but awesome.Vast stands of red cedar and the presence of underground caverns, both associated with limestone are found here. The islands and shoreline support a variety of reptiles including the state's highest concentration of the harmless fox snake.The timber rattlesnake was at one time quite prevalent on the islands but is now gone from the area.Rattlesnake Island was so named due to the presence of this reptile years ago.Migrating songbirds rest here before winging across the lake.Hundreds of different species have been identified, making this one of the best birdwatching areas in the country.Several nesting pairs of the magnificent bald eagle are located in the area.