The Great Lakes Rock
From the round surf-polished rocks of Lake Superior’s shore to the sand dunes of Lake Michigan, I have roamed and picked up stones: agates, pudding stones and some bearing copper or fossils. And I hiked the alvars on the Door Peninsula and Ontario’s Bruce with their layered limestone shores bearing fossils of ancient salt seas. Lake Huron’s green waters pour into Lake St. Clair and its silty marshes and then to Lake Erie teeming with birds and fish. The waters pick up speed in the Niagara River to take a tremendous plunge over Niagara Falls. The rock underlying the falls will wear away in time I am told, but not in my life time. Lake Ontario’s flat shores have good soil for vineyards and farm lands. Sailors and sports fishers enjoy Lake Ontario’s riches and the lake flows out through the St. Lawrence River with a myriad rocky islands.
pictured are layers of limestone on Wisconsin's Door Peninsula. This formation is called an alvar.