Wow. These photos are absolutely incredible. Between June and November 1969, the American Falls (the smaller of the two waterfalls making up the Niagara Falls) were suddenly ‘shut off’. The massive engineering endeavor was intended to combat erosion of the river bed. The ‘Dry Falls’, as they became known, attracted millions of visitors over the six-month period.
‘Knick point erosion’, as the process is called, naturally wears away waterfalls on a timescale of thousands of year, causing them to retreat and eventually form a series of smaller ‘steps’. In the American Falls, water pours over the edge and falls more than 150 feet, cutting away at the soft limestone below. This destabilizes the rock face, causing large chunks of shale from the upper layers to crumble. In 1969, after several large rock slides, the US Army Corps of Engineers built a partial dam across the Niagara River, using nearly 28,000 tons of rock. After intensive study, several drainage holes were drilled to reduce water pressure and steel rods and cables installed to secure the rock face.
And just like that, six months later, the tap was turned on and the Falls roared back to like. The massive engineering effort, along with later diversions and erosion reduction operations, has reduced their retreat from nearly 5 feet per year to only 3-4 inches per decade at present. For me, this serves as another vivid reminder of how much power humans truly have over nature.
Cover photo courtesy of Wikimedia Commons