The dramatic 215 foot (66 meters)-high Taughannock Falls near Ithaca is one of the highest waterfalls in the United States east of the Rocky Mountains. Tumbling off resistant sandstones, Taughannock Creek has carved a deep gorge through soft Middle to Upper Devonian shales, with walls nearly 400 feet (122 meters) high in places. At the base of the gorge, the creek runs over another resistant rock ledge, formed by the Tully Limestone.
Taughannock Falls forms a classic example of a “hanging valley”, formed after the retreat of the great glacial ice sheet that covered nearly all of New York and lands to the north about 20,000 years ago. Where Taughannock Creek enters Cayuga Lake, a delta, formed of the rocks eroded and carried out of the gorge, projects out into the lake.
Geological Features Include:
The rocks in the gorge were deposited in relatively shallow seas that covered New York in the Middle to Late Devonian, around 385 million years ago. The Tully Limestone, in the base of the gorge, was deposited in clear, shallow water environments. Subsequently, the sea level rose, depositing muds (Geneseo Shale) in deeper water in the Ithaca region. Following the period of high sea level, it began to fall again, and silt and sand were carried to central New York by storms and currents (Sherburne Siltstone and Ithaca Sandstone). These sediments were later cemented together to form limestone, shale, siltstone and sandstone.
All of these ancient rocks remained deeply buried below the Earth’s surface for hundreds of million of years, until erosion began to uncover and expose them. During the recent ice age, the rocks became exposed at the surface. Then the erosive power of the waters of Taughannock Creek, the freezing and thawing of water in cracks, and rocks falls carved out the gorge. Over time, the falls retreated farther and farther back from the shores of Cayuga Lake.
Upstream of the falls, Taughannock Creek flows through a higher valley than in the gorge below. The upper valley is the at the level that the Cayuga Lake valley used to be before glaciation eroded it down more deeply. That lowering resulted in formation of the upper “hanging valley”, the cutting of the gorge downstream and the retreat of Taughannock Falls over time.
Directions to Taughannock Falls: