Existing comment:
Prospect Point From Below:
The rocks of the Niagara Gorge are sedimentary, formed at the bottom of the ancient seas from sank, silt, clay, and prehistoric animal remains. All of these rock layers are exposed at the edge of the Niagara Encampment near Lewiston. Because of the gradual dip of the rocks in this region to the south, only the top layers are exposed at the falls.
Lockport Dolostone, this hard, resistant caprock of the falls, has a network of vertical and horizontal fractures known as joints. Beneath the dolostone is the Rochester Shale, a much softer layer with vertical fractures. As water flows over and through the dolostone into the shale, the shale is weakened and removed by a process called "sapping." The dolostone is left with no support and eventually falls.
The rocks below the American Falls and Bridal Veil Falls are known as talus. They have been breaking off and piling up beneath the falls for the past 900 years. There is not enough water from the falls to erode these rocks away. Secondary, the talus will reach the top, forming steep rapids instead of falls.
On July 28, 1954, the largest single rockfall ever recorded at Niagara Falls took place when 185,000 tons of rock from the edge of the falls and Prospect Point above collapsed into the gorge. A few weeks later, work began to remove a large section of rock overhang left from the rockfall. The falls viewing area above reopened to the public in November 1954. |