Glacial Erratic – Pleasantville, New York - Atlas Obscura

Glacial Erratic

Pleasantville, New York

This giant rock arrived at this quiet park thousands of years ago on the back of a massive glacier.  


Standing at the base of the 20-foot-high glacial erratic in Rockefeller State Park Preserve, one can’t help to notice the sweeping grey, blue, and brown striations that wind their way around this boulder’s 65-foot circumference; often interrupted by jagged edges and deep gouges.

A glacial erratic is a rock that has been transported by a glacier, and are sometimes used to track glacial movement. This giant piece of gneiss, which is estimated to be more than 600 million-years-old, didn’t always stand among the aged trees of the park. It was dragged down from the peaks of the Hudson Highlands by the southward flow of the Late Wisconsin continental glacier thousands of years ago.

Although the massive rock still weighs in at a hefty eight and a half tons, it was likely much larger before it was ground down and carved into by the pressure of the traveling ice. As the ice melted, the rock settled in its new home which would soon be surrounded by the estates of Gilded Age elites.

The erratic sits among the hardwood forest of Rockefeller State Park Preserve, a bucolic setting pieced together from the former estates of oil magnates, and brothers, John D. and William Rockefeller. The park’s 2,000 acres of woodlands and riverfront property once served as the grounds of the brother’s Pocantico Hills and Rockwood Hall country estates.

Lauded landscape architect and designer of Central Park Frederick Law Olmsted worked on the landscaping of William’s estate. Forty-five miles of crushed stone carriage roads, once traveled by the richest men in America, now serves as a network of meandering paths for park visitors, some of whom still travel on horseback.

Soon after the park’s dedication 1986, a 100-yard path to the erratic was cleared by a local Eagle Scout. He created “a natural amphitheater” with rustic log benches, a space that could be used as an outdoor classroom. New benches were put in place by a group of kids as part of “I Love My Park Day” in 2019.

As visitors saunter through the enveloping woods, the clearing with the giant stone at its head commands attention and draws all in for a closer look. The benches offer a contemplative place to rest, just a 10-minute walk from the parking lot. Long before the Rockefellers’ mansions were built, and long after they were torn down, the Glacial Erratic stands as a witness to the unceasing march of time.

Know Before You Go

The erratic can be found on a short path that branches off Nature’s Way Trail. It's approximately half a mile, around a 10-minute walk, from the preserve entrance and parking lot. It's clearly labeled on Rockefeller State Park maps which are available online and at the Preserve Office.

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