Niagara Falls Observation Tower Falls to the River Floor 1698 Sketch T.Cole Sketch by James Hall Trigonometric Survey and Map of Falls by Hall Sir Charles Lyell Map of Falls 1850 Daguerrotype Horseshoe Falls Horseshoe Falls From Prospect Point 1870 photo by Charles bierstadt Alber Bierstadt painting George Barker photo, 1888 George Barker photo, 1883 Fairyland of Ice and Snow Niagara Rock Stratigraphic Section Falls Recession Aerial photo of dry falls
Niagara Falls, New York
Niagara Falls is one of most popular attractions in New York and around the world. The majestic power of immense volumes of water spilling over the falls and plunging to the rocks and river below is an awesome physical and visual experience, which is rarely matched elsewhere.
Niagara is far from the highest waterfall in the world, or even in New York. However, the rush of over 6 million cubic feet of water per minute, approaching the cascade at about 25 miles per hour, and plunging 70 to 190 feet across a distance of about 3000 feet, make it one of the natural wonders of the world. The varied patterns of flow across the wall of the waters' decent easily capture your attention, and hold you almost hypnotized at times. Whether viewing from the side, the river below, or behind the falls, the experience of Niagara Falls is a powerful one, indeed.
The earliest report of Niagara Falls by Europeans (1604) comes from Samuel de Champlain on his first voyage to the New World in 1603. He traveled only as far as modern-day Montreal, but gathered information on features further upriver from Native Americans. On Niagara Falls he wrote "That there is a fall about a league wide, where a very large mass of water falls into said lake..." (translated from French; from Mason, 1921, Anthology and Bibliography of Niagara Falls).
The Geological Story—Basics
Approximately 12,000 years ago water found a single low pathway through the "Niagara Escarpment", and began to carve out a channel—the Niagara River. At that time, however, "Niagara Falls" was about seven miles downstream— Lewiston, NY and Queenston, Ontario. Over the last 12,000 years erosion of the resistant rocks that cap Niagara has allowed the Falls to migrate about 7 miles upstream, and form the high-walled Niagara Gorge along it's former path.
Even today, Niagara Falls is estimated to be migrating upstream, on the order of one foot per year. At current rates of erosion and migration, the falls may reach softer, more easily erodible rocks (including shale and rock salt) upstream in about 15,000 years, leading to the end of a major waterfall along the Niagara River. And by some estimates, the river will erode back to Lake Erie in roughly 50,000 years, and after cutting through a second escarpment of resistant rocks (the Onondaga Limestone), it will erode through soft shales, and begin to very slowly drain Lake Erie.
The rocks that are seen in the falls were deposited in a shallow sea that covered much of the eastern U.S. and adjacent Canada between about 440 and 425 million years ago (middle part of the Silurian geologic period). Slightly older rocks, visible downstream through the Niagara Gorge, were deposited along a coastal area, sometimes below sea level, and sometimes on land. These sedimentary rocks, such as limestone, shale, sandstone and dolostone, are seen as distinct layers in the falls and along the gorge. Some of the rock layers, such as the soft, easily eroded Rochester Shale below the cap of Niagara Falls, contain a great diversity of marine fossils, such as brachiopods, trilobites, corals and crinoids.
The Geological Story—In Greater Depth
The rocks visible at Niagara Falls were deposited in a shallow seaway that covered much of the eastern U.S. during the Silurian Period. Older Silurian rocks below the river level were variously deposited in shallow seas to lowlands. At the bottom of the river channel, even older red shales and sandstones of the Ordovician Period (Queenston Formation) were deposited on land, during a major fall in global sea level. An erosion surface, with a few million years of time missing, occurs at the contact of the Ordovician and Silurian rocks.
The erosional retreat of the falls upstream is slower today than in the past, largely due to withdrawal of waters from the Niagara River for hydro-electric power generation. Retreat for the last 500+ years was between three to five feet per year; the rate now is estimated to be about one foot per year. Climate change models predict drier conditions in the Great Lakes watershed in the future, potentially slowing the rate of erosion and retreat of Niagara Falls.
Niagara Falls Facts and Figures, from the Niagara Park Commission, Government of the Province of Ontario, Canada
Niagara Falls geology fieldtrip article, from the 2005 Binghamton Geomorphology Symposium: http://www.geog.buffalo.edu/~rensch/binghamton/BGS%202005%20Field%20Guide%20final.pdf
A more modern perspective on the geology of Niagara Falls is found in Colossal Cataract: The Geologic History of Niagara Falls, by I.H. Tesmer and J.C. Bastedo (1981, State University of New York Press, Albany, 219 p.). A briefer geological overview of the post-glacial and Paleozoic history of Niagara Falls and Niagara Gorge can be found in C.E. Brett and P.E. Calkin (1987, Niagara Falls and Gorge, New York-Ontario. Geological Society of America, Denver, Centennial Field Guide, p. 97-105).