The physical geography of New York is largely the result of glacial erosion during the Ice Ages. Almost all of the state was covered several times with a layer of ice nearly two miles thick. They slowly pushed their way southward out of Canada, ending their assault in present day Long Island. (You can see the evidence for this. There are two ridges running the length of island, called moraines. It is very obvious along the north shore and at Montauk Point).
The ice sheets profoundly changed the landscape. Even the Adirondack Mountains were eroded, giving them a rounder profile. Old river valleys were deepened into U-shaped troughs. The sides of the valleys are steep and the bottoms are flat. They are most common in the Finger Lakes Region of New York, but troughs can be found all over the state. When the glaciers finally receded, their meltwaters caused massive flooding. One pathway was down the Mohawk Valley. You can see the results of this flooding on Moss Island in Little Falls, NY. Another flood went down the Hudson River, and it blasted a channel between Staten Island and Brooklyn, the Verrazano Narrows.
When the ice had finally departed into northern Canada, giant basins carved by the glaciers filled with water, the Great Lakes. Since Lake Erie is around 300 feet higher than Lake Ontario, a waterfall emerged at Lewiston, the mighty cataract of Niagara. (It has since migrated upstream seven miles to its present day location). River systems re-established themselves now that the ice was gone. Some rivers followed their old courses, but others were diverted. When that happened they needed to carve out new valleys, resulting in deep gorges and waterfalls. The Genesee River is a good example. It has "new" gorges in both Rochester and in Letchworth State Park. Both locations have three falls.
Most of the troughs mentioned above point roughly north-south, since that was the direction of the glaciers movement. Small tributary streams flowing into the troughs from either the east or the west were left "hanging." They tumbled down the sides of the trough, created the gorges so common around the Finger Lakes. These hanging valley waterfalls are some of the most scenic places in the state.
Waterfalls are also important to human geography as well. As settlers moved into New York, they tended the form communities around the cascading waters. They captured the hydropower to grind flour and to saw lumber. For example, many villages in western New York can be found along the Onondaga Escarpment - Batavia, Caledonia, LeRoy, Honeoye Falls, just to name a few. At each location, there is a stream that tumbles over the escarpment face. Even though they are no longer mill towns, the falls are still focal points in the villages. The waterfalls of New York are still sources of power. Niagara Falls made Buffalo the first electrified city. Hydropower is captured all over the state - Cohoes, Rochester, Glens Falls, etc. The electric grid is vital for the health of the state's economy.
Of course, people are always drawn to waterfalls, both large and small. There is something hypnotic and comforting about water falling over a cliff. There are an amazing variety of waterfalls in most sections of the state. Some examples include the Ausable Chasm in the Adirondacks, Watkins Glen in the Finger Lakes, Cohoes Falls on the Mohawk River, and the "Grand Canyon of the East" in Letchworth State Park. Pictured here are some other waterfalls. We encourage you to get out an enjoy them during all seasons of the year. This is just another reason why we are u-NY-que!
Here is a small sample of scenic waterfalls in New York: Top row - Lucifer Falls near Ithaca, the High Falls of the Genesee in Rochester, Bronx River Falls in New York City. Middle row - Lower Falls in Letchworth State Park, Cohoes Falls on the Mohawk River, Niagara Falls (as seen from the bottom). Bottom row - Rexford Falls near Sherburne, NY, the Upper Gorge of Robert Treman State Park, Kaaterskill Falls in the Catskills, and the High Falls Gorge near Wilmington NY (Adirondacks). "