Umpire Rock: Billion-Year-Old Manhattan Schist

Why is it significant?

Climb up the sloping gray crest of Umpire Rock, also known to generations of local climbers as Rat Rock, and place your palm directly against the cool, sparkling stone.

Key Facts

Open the walk

Climb up the sloping gray crest of Umpire Rock, also known to generations of local climbers as Rat Rock, and place your palm directly against the cool, sparkling stone. Look closely at the surface: you are touching Manhattan schist, a metamorphic bedrock formed nearly five hundred million years ago under intense subterranean heat and tectonic pressure.

Run your fingers across those long, straight grooves carved into the stone like knife scratches. Those are glacial striations, scraped into the hard bedrock twenty thousand years ago during the Wisconsin Ice Age, when a colossal glacier two thousand feet thick slowly ground across this landscape, dragging boulders and coarse gravel across the bedrock surface like coarse sandpaper.

Look out over the sprawling green baseball diamonds of Heckscher Ballfields right below. When Olmsted and Vaux surveyed this terrain in eighteen fifty-seven, they deliberately preserved giant outcrops like Umpire Rock to remind hurried city dwellers of nature's primeval, timeless power in the heart of an industrial metropolis.

Today, this giant rock serves as New York's most famous urban bouldering spot, where local rock climbers practice tricky moves before heading to the Adirondacks. Step back down onto the path as we head toward the majestic canopy of The Mall.