Human intervention
Although Niagara Falls was formed by natural means, this doesn’t mean it doesn’t need human intervention to keep it flowing normally. In the 1960s, scientists were shocked to learn that the natural waterfall formation was actually destroying its own rocks.
Over the course of thousands of years, Niagara Falls had pushed countless rocks over the edge. Loose rocks, known as scree or talus, became accumulating at the bottom of the falls. This raised concerns over whether the falls would collapse entirely over the next couple of decades. To begin the waterfall maintenance project, engineers had to come up with extreme ideas.