Extending over 7 miles from Lewiston, NY to Niagara Falls, NY, the Niagara Gorge offers many recreational opportunities to explore nature. You can experience the gorge at Earl W. Brydges Artpark State Park, Devil’s Hole State Park, Whirlpool State Park, and Niagara Falls State Park. While there, stop to see the amazing rocks that make Niagara the wonder that it is today!
Visible downstream at the lowest level of the gorge, is the oldest visible rock layer within the gorge wall. This layer was deposited along a coastal area of a warm shallow sea in the late Ordovician Period, alternating between below and above sea level. The periodic exposure of the iron rich sediments resulted in the coloration visible in the sedimentary rock of the Queenston Shale. As you travel upstream the tilt of this layer causes it to disappear below visible levels.
The rocks seen in the walls of the Niagara Gorge are sedimentary; they are made from sediments deposited in a shallow sea that covered much of the eastern U.S. and adjacent Canada around 440 to 410 million years ago (middle part of the Silurian Period). Rocks, such as limestone, shale, sandstone and dolostone, are seen as distinct layers. Some of these layers, for instance the soft, easily eroded Rochester Shale below the caprock of Niagara Falls, contain a great diversity of marine fossils, such as brachiopods, trilobites, corals and crinoids.
These rocks are layered, from oldest at the bottom to youngest at the top along a long ridge known as the Niagara Escarpment. The Niagara Escarpment is a prominent cliff-forming cuesta that extends from western New York into southern Ontario, northward to the upper peninsula of Michigan, and then bends downward into eastern Wisconsin and Illinois. The escarpment is capped by relatively hard, resistant rocks of the Silurian-age Lockport Group (chiefly dolostones and limestones), which are underlain by less resistant rocks (shales and sandstones, such as the Rochester Shale).
Near the end of the last ice age, around 12,300 years ago, the Niagara River began to flow over the Niagara Escarpment, located at what is now Lewiston, New York. Through the process of erosion the falls have receded to their present location. In the past, the falls receded on average 3-6 feet per year. However, the rate has been greatly reduced due to flow control and diversion for hydropower generation, to a mere 3-6 inches per year. 50,000 years from now, at the present rate of erosion, the remaining 20 miles south to Lake Erie will have been undermined. There won’t be a falls anymore, but rather a series of steep rapids!
While visiting Niagara Falls, or hiking in the Niagara Gorge, take some time to marvel in the events and processes that took place over time. From continental collisions to ice-age glaciers and the present day Great Lakes drainage basin, we are fortunate enough to witness the interactions of nature.
Post and Niagara Gorge photos by Mike Drahm, State Parks, Niagara Region