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Minneapolis in Hennepin County, Minnesota — The American Midwest (Upper Plains)
 

Changing the Shape of the Falls

 

—Saint Anthony Falls Heritage Trail —

 
Changing the Shape of the Falls Marker image. Click for full size.
By Keith L, August 20, 2007
1. Changing the Shape of the Falls Marker
Inscription. When Europeans first saw the falls, the crest was well below Hennepin Island. Natural erosion caused the line of the falls to move steadily upriver at about four feet a year. By the 1850s, the cataract was approaching the upper limit of the limestone ledge that sustained it. In the course of time, without human intervention, the falls would soon have become a rapids.

The pace of erosion increased after lumbering and milling began. Logs floating downriver crashed against the limestone and broke off great chunks. Excavating for dams and tailraces ate away at the stone, and a disastrous tunnel project nearly destroyed the falls in the 1860s. To prevent further damage, the US Army Corps of Engineers built a concrete dike under the river and placed a wooden apron over the ledge, protecting and hiding the face of the falls. The apron was later replaced with a concrete spillway which is still in place.

In the 1930s Congress authorized a massive project to improve navigation on the Upper Mississippi. Completion of the Upper Lock at St. Anthonay Falls in 1963 allowed shipping to use the river above Minneapolis. Construction of the Upper Lock altered the entire west side of the falls, eliminating Upton Island and the mill pond and cutting off access to waterpower. Two sections of the Stone Arch Bridge were replaced by a steel
Upper Lock and the Falls image. Click for full size.
By Keith L, August 20, 2007
2. Upper Lock and the Falls
Main Channel; photo taken from the Stone Arch Bridge.
truss. A rocky islet known as Spirit Island was also destroyed. This landmark was the nesting ground of eagles that fed on fish below the falls and was significant in Dakota traditions. What remains of Spirit Island lies beneath the breakwater leading into the lock.

marker photo captions:
This wooden apron, finished in 1880, concluded a million-dollar government project to save the waterpower so vital to Minneapolis business. A concrete spillway later replaced the wooden apron.

Huge blocks of limestone, broken from the face of the falls, can be seen in this photo taken in 1850.

This is a diagram of the rock formations beneath the falls. Water wore away the soft sandstone beneath the limestone, and the limestone ledge periodically broke off. This continuous process of erosion caused the falls to move upriver over many years.

Spirit Island, in the foreground, as it looked in 1855. Several sawmills can be seen behind Spirit Island, built out on platforms over the falls.

Construction of the Upper Lock went forward in the late 1950s.
 
Erected by the St. Anthony Falls Heritage Board.
 
Location. 44° 58.829′ N, 93° 15.322′ W. Marker is in Minneapolis, Minnesota, in Hennepin County. Marker can be
Breakwater below the Falls image. Click for full size.
By Keith L, August 20, 2007
3. Breakwater below the Falls
reached from West River Parkway west of Portland Avenue South. Click for map. Marker is attached to the north railing of the Stone Arch Bridge. Marker is at or near this postal address: 1 Portland Avenue, Minneapolis MN 55401, United States of America.
 
Other nearby markers. At least 8 other markers are within walking distance of this marker. The West Side Milling District (within shouting distance of this marker); Beneath the Surface (within shouting distance of this marker); Stone Arch Bridge (approx. 0.2 miles away); Historic Milling District (approx. 0.2 miles away); New Uses for Old Mills (approx. 0.2 miles away); a different marker also named The Stone Arch Bridge (approx. 0.2 miles away); Father Hennepin Bluffs (approx. ¼ mile away); Pettingill's Wonderful Water (approx. ¼ mile away). Click for a list of all markers in Minneapolis.
 
Also see . . .  Saint Anthony Falls. Wikipedia entry. (Submitted on February 27, 2010.) 
 
Categories. Man-Made FeaturesWaterways & Vessels
 
<i>Bird's-eye View of St. Anthony Falls, Minneapolis, Minn.</i> image. Click for full size.
By The Acmegraph Co., circa 1910
4. Bird's-eye View of St. Anthony Falls, Minneapolis, Minn.
The Stone Arch Bridge is in the foreground. Note the absence of the lock, which was completed about 50 years after this photo was taken.
 
 
Credits. This page originally submitted on , by Keith L of Wisconsin Rapids, Wisconsin. This page has been viewed 1,004 times since then and 25 times this year. Photos:   1, 2, 3. submitted on , by Keith L of Wisconsin Rapids, Wisconsin.   4. submitted on . • Craig Swain was the editor who published this page. This page was last revised on June 16, 2016.
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