My Backyard Sand

About 12,000 years ago, pro-glacial Lake Iroquois occupied all of the current Lake Ontario and extended significantly south and east into New York.  The glacial ice was retreating but had not yet melted far enough north to expose the St. Lawrence Seaway, forcing the significantly larger Lake Iroquois to drain east through the Mohawk Valley and then south along the Hudson River.  All of Rochester, NY was beneath this lake.

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