Letchworth State Park is a New York state park located 35 miles (56 km) southwest of Rochester and 60 miles (95 km) southeast of Buffalo in Livingston (towns of Leicester, Mount Morris, and Portage) and Wyoming (towns of Castile and Genesee Falls) counties. The park is roughly 17 miles (24 km) long,[2] covering 14,350 acres (58 km2) of land along the Genesee River.[2]

Within the park, there are three large waterfalls on the Genesee River and as many as fifty waterfalls found on tributaries that flow into it; the gorge formed by the river, with rock walls rising up to 550 feet (170 m) in places and which narrow to 400 feet (120 m) across above the middle of the three falls, prompted the area’s reputation as the “Grand Canyon of the East”.[3]

The park is named after William Pryor Letchworth (1823-1910), an industrialist who in 1906 bequeathed the 1,000-acre (4 km2) estate that forms the heart of the park to New York State.[2] There are park entrances near the towns of Mount Morris, Perry, Castile and Portageville, New York. A modern, well-maintained two- or three-lane road follows the west side of the gorge, allowing many scenic viewpoints for the geologic features.
The three major waterfalls — called the Upper, Middle, and Lower Falls — are located in Portage Canyon, the southern section of the park. The Seneca called the land around this canyon “Seh-ga-hun-da”, the “Vale of the three falls”;[4] the Middle Falls (“Ska-ga-dee”) was believed to be so wondrous it made the sun stop at midday.[2]

The only trail bridging the Genesee River across Portage Canyon crosses a stone bridge just below the Lower Falls. The Middle Falls is the highest, and the Upper Falls has an active railroad trestle crossing immediately above it, providing an even higher vantage immediately above the falls.
The highest waterfall in New York State is located in the park. It is a spectacular ribbon waterfall that is located on a tributary creek a short distance east of the Inspiration Point Overlook, 0.4 mile (640 m) west of the park visitor center. Known as Inspiration Falls, it has a total drop of 350 feet (107 m). While impressive in its height, it is seasonal and often appears as only a water stain on the cliff. The falls faces to the south-southwest and has a crest that is only one foot (300 mm) wide. (215-foot (66m) Taughannock Falls, 100 miles east of Letchworth in Trumansburg is generally recognized as the highest waterfall in New York as well as in the entire Northeastern United States).

The bedrock that is exposed in the gorge is Devonian in age, mostly shales, with some layers of limestone and sandstone. The rock was laid down in an ancient inland sea, and many marine fossils can be found. The landform of the section of the Genesee River valley represented by the park is geologically very young, caused by a diversion of the river from the old valley by the last continental glacier, forcing the river to cut a new section of valley.

http://nysparks.com/parks/79/details.aspx
http://www.letchworthpark.com/
http://en.wikipedia.org/wiki/Letchworth_State_Park