At One time Saint Anthony Falls was not the biggest or the only falls on the river. 11,700 years ago, the “River Warren Falls” believed by geologists to be the biggest waterfall ever seen in America, took up most of what became downtown St. Paul. Back then the falls may have been 200 feet high and over a half-mile wide and kept going by a enormous flow of meltwater from Lake Agassiz that came barreling down the Minnesota River valley.
The falls eventually withdrew upstream as the layer of sandstone under the limestone caprock was eroded away. By 10,000 years ago the falls were past Mendota and the new falls we know as St. Anthony were carving a gorge on their way to its downtown Minneapolis. St. Anthony Falls is the only waterfall on the Mississippi River, and the now flooded gorge below is the river’s only gorge.
