A weak spot from a notch? That's just a bad cut, not the method.

Actually, the vitamin C thing was more about oxidation, not pH. But yeah, mixing separate acid peels is still a terrible idea for the exact reasons you said.

Honestly I used to be the worst at overpacking. Like I'd bring three jackets for a weekend because what if the weather changed. Now I just wear my bulkiest shoes on the plane and roll everything else. Last trip I even had room in my backpack for a book.

That's wild, @sullivan.nina. I've seen smaller undercuts in sandstone, but a gap that goes on for miles is hard to picture. Do you know what kind of rock the missing layer was, like was it a softer sandstone that just turned to sand and washed out?

Moms always know the fix.