The upper end of Ganoga Glen past Oneida and Mohawk falls — how the falls formed: hard Huntley Mountain caprock over soft Catskill shale, the Allegheny Front, and the Ice-Age flood that carved them.
You're near the top of Ganoga Glen now — the last few falls up here are Oneida and Mohawk — and if your legs are burning, well, you've earned the right to know exactly what built this astonishing staircase you just climbed. It's a story written in the rock, and it's millions of years long.
You're climbing the edge of a great tableland called the Allegheny Front — basically a giant step in the landscape, where the high plateau drops away. Now look at the cliffs the water pours over. Up top is a layer of very hard, tough sandstone — the Huntley Mountain rock — and underneath it sits much softer shale. Water is patient and relentless: it eats away the soft shale underneath far faster than it can wear down the hard cap on top. So the hard layer juts out as a lip, the soft rock hollows out beneath it into a plunge pool, and the creek drops off the edge — a waterfall. Stack a whole series of these hard-over-soft layers down the face of the Front, and you get exactly what you just walked up: a staircase of falls, twenty-one of them.
And there was one more ingredient: ice. About twenty thousand years ago, in the last Ice Age, the glaciers rearranged the drainage up on the plateau and shoved a lot more water into this little creek — roughly half again as much country draining through here. All that extra water, with all that extra cutting power, is what carved these glens as deep and dramatic as they are. So you're not just looking at waterfalls; you're looking at the plumbing of the Ice Age, still running. Catch your breath — the hardest climbing is behind you, and the trail's about to level out into the forest on top.
Photo: Doug Kerr · CC BY-SA 2.0
