The Catskill Mountains are not actually mountains, but a deeply eroded ancient plateau

Cultures · Published 29 September 2026 Swipe more like this →

In short: While they define the skyline of southeastern New York, the Catskills are geologically a dissected plateau rather than a traditional mountain range. Formed by the erosion of ancient sediments, this rugged landscape has served as a haven for artists, a training ground for legendary comedians, and a vital water source.

Geologically, the Catskills are the northeastern end of the Allegheny Plateau. Unlike ranges formed by tectonic folding, these mountains are the result of uplifted sedimentary rock that has been carved into sharp relief by watercourses over millions of years. During the Devonian and early Mississippian periods, between 395 and 325 million years ago, sediments from the rising Acadian Mountains flowed westward, creating a massive delta. These deposits eventually hardened into rock, which was later exposed by uplift and further shaped by glaciers and streams.

The region's cultural identity is as layered as its geology. Named by Dutch settlers in the 17th century, the area became a celebrated destination for 19th-century Hudson River School painters and a mid-20th-century vacation hub. The latter era, known as the Borscht Belt, saw about 500 resorts flourish, providing a stage for young Jewish stand-up comedians to refine their craft. Today, the region is defined by the 700,000-acre Catskill Park, a forest preserve where roughly 60% of the land remains in private hands.

The Catskills are also a critical piece of infrastructure. The Ashokan Reservoir, famous for its rainbow trout, is a key component of the New York City water supply system. The landscape remains a popular destination for outdoor recreation, from fly fishing in the Esopus Creek—which flows around the rim of a 375-million-year-old meteor impact crater—to hiking the Devil's Path. While the fire towers that once protected these forests from 1908 to 1950 have been largely decommissioned, eight have been restored as public observation posts, offering panoramic views of the plateau's enduring, rugged beauty.

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