<P> The Great Falls of the Passaic River is a prominent waterfall, 77 feet (23 m) high, on the Passaic River in the city of Paterson in Passaic County, New Jersey, United States . The falls and surrounding area are protected as part of the Paterson Great Falls National Historical Park, administered by the National Park Service . The Congress authorized its establishment in 2009 . </P> <P> One of the United States' largest waterfalls, it played a significant role in the early industrial development of New Jersey starting in the earliest days of the nation . It is part of the Great Falls of Paterson--Garret Mountain National Natural Landmark . It has also been designated as a National Historic Landmark District since 1976 . The Great Falls' raceway and power systems were designated an Historic Civil Engineering Landmark in 1977 . </P> <P> Geologically, the falls were formed at the end of the last ice age approximately 13,000 years ago . Formerly the Passaic had followed a shorter course through the Watchung Mountains near present - day Summit . As the glacier receded, the river's previous course was blocked by a newly formed moraine . A large lake, called Glacial Lake Passaic, formed behind the Watchungs . As the ice receded, the river found a new circuitous route around the north end of the Watchungs, carving the spectacular falls through the underlying basalt, which was formed approximately 200 million years ago . </P> <P> The falls later became the site of a habitation for Lenape Native Americans, and later for Dutch settlers in the 1690s . </P>

The great falls of paterson flows over what type of rock