Resurrecting a Tired Old Figure of Speech

A multi-fingered canyon system is just as interesting to explore at the top as at the bottom.

You can walk out on the peninsulas to the point where two canyon fingers join. But you can get a bit nervous with these mudstone (?) walls:

Don't walk too close to the cliffs when they are made of mudstone or whatever this crap is!

Incipient "colapso" on a canyon wall.

I keep a safe distance between myself and the cliff. But how can I know what that distance is?

One day I looked across the canyon and saw a crumbling isthmus on the adjacent peninsula. (The peninsula widened out again as you passed over the isthmus.) I became obsessed with knowing whether the isthmus was continuous and walkable. But I am always developing these little obsessions.

Coffee Girl checks out the tenuous isthmus in mesa caprock. I have to be doing something right to become obsessed about things like this.

It turned out to be not quite continuous, but still walkable. You are on a narrow finger of mesa cap-rock that separates two separate fingers of the canyon system. So you must step carefully.

Talk about the 'slippery slope' metaphor/cliche made real and fresh! When I walk along places like this I wonder how far off the high spot you could step before you slide on crumbling mudstone. And once that happens, you stumble onto a lower spot where it collapses easier than the first mis-step. And so on. It would only take a couple mistakes like this before you slide continuously, and then finally go over the side of a vertical or overhanging  cliff.

The cliff is only 20 to 80 feet high. But that would be enough to put you in the hospital or the morgue. Thinking about real situations like this makes the old figure of speech so forceful and powerful again. I wonder who first used it?