Chicago's Ancient Shoreline
Near Chicago Lake Michigan, Illinois
The ridge you're near right now is not a human-made feature. It is an ancient beach, a shoreline of Lake Chicago, the glacial ancestor of Lake Michigan, from many thousands of years ago, when the water stood well above today's level. As glacial ice melted and drainage patterns shifted, the lake level dropped in stages, each time leaving behind a ridge of sand and gravel where the water had lapped.
Clark Street runs north along the top of this old beach line. The shallow ponds in the park between the ridges trace the same ancient geography, sitting in the low troughs between successive shorelines. This whole stretch of the North Side is built on the layered memory of a much larger lake, one that would have swallowed everything you see today.
Chicago is, in a very real sense, a city growing on the floor of a vanished sea.
