The rock there is alternating layers of fairly hard sandstone and soft mudstone. The mudstone is all rotten and crumbles underfoot. It's not just the little gravel - the rock itself is unsound. That's what keeps the waterfall so steep. The mudstone is constantly eroding out from under it while the sandstone caprock lasts longer. The rock climbers give the whole Escarpment a wide berth because protection pulls right out of that garbage. The technical ice climbers love Kaaterskill Falls, but only once there's a solid ice column - dry tooling that rotten stone is insane.