The Mississippi River Gorge, stretching from Saint Anthony Falls to Fort Snelling and opening into a broad floodplain near downtown Saint Paul, is a distinctive geological landscape whose 100-foot limestone bluffs, natural springs, waterfalls, and forests were shaped by ancient inland seas, continental glaciers, and the cutting power of Glacial River Warren. Layers of shale, Platteville Limestone, and Saint Peter Sandstone were deposited more than 500 million years ago, while glacial ice later left behind drift of pebbles, rocks, and sand that underlies Saint Paul. About 13,000 years ago, Glacial River Warren excavated through this glacial drift below Trout Brook, and a waterfall formed where the river met hard limestone above softer sandstone; as the sandstone eroded, the limestone collapsed in large blocks that still line the valley. Geologists have long traced the ancient waterfall’s retreat from the river bend in downtown Saint Paul upriver to Fort Snelling and the future meeting of the Minnesota and Mississippi rivers, where the falls once stood 200 feet high and nearly a mile wide before splitting in two, with one branch moving up the Minnesota River Valley until it vanished into a buried channel and the other continuing as present-day Saint Anthony Falls, which moved about eight miles upstream over the next 10,000 years. When Father Hennepin visited and named the falls in 1680, they were about 3,000 feet south of their current position in Minneapolis. Early explorers recorded the gorge’s wooded bluffs, and in 1817 Colonel Stephen Long praised their rich variety of trees, shrubs, berries, and vines. In 1883, landscape designer H.W.S. Cleveland made the gorge central to his vision of linked boulevards and parklands for Saint Paul and Minneapolis, admiring the river banks for their magnificent natural growth and picturesque forms.
