Zion National Park got a reminder on Monday that the canyon walls aren't decorative. A large rockfall came down inside the park and cut off access to one of the busiest areas in the whole place, according to Fox 13 Now.

If you've stood at the bottom of Zion Canyon, you know the feeling. The walls go up and up and up, two thousand feet of Navajo sandstone, and you feel very small and very temporary. The thing is, that rock is still moving. It's been moving for millions of years. Rockfall is how the canyon got its shape in the first place, and the park closes trails after a big one for exactly this reason: loose rock above a fall often means more of it is ready to go.

Park crews will assess the stability of the slope before reopening anything, and I'd urge you to actually respect whatever closures stay in place. Every year someone ducks a barrier for a photo, and every year search and rescue folks have to go get them. The rock doesn't care about your itinerary.

Quick practical stuff if you're headed to Zion soon: check the park's official site or stop at the visitor center before you commit to a plan, because closure status can change day to day, sometimes hour to hour. Have a backup hike. Zion has plenty, and some of the less famous ones are less crowded for reasons that have nothing to do with quality. The Watchman area, Pa'rus Trail, lower Emerald Pools. All solid consolation prizes.

And if you're in the canyon when you hear a crack or a boom from the walls, don't stand there filming it. Move away from the base of the cliff, especially near the shuttle stops and the river trail where the walls are steepest. I've been on trails where rock came down a few hundred yards away, and the sound arrives before you've processed anything. You don't get a warning bell.

The timing stings, too. Late August in Zion means the tour buses are thick and the Riverside Walk and Narrows corridor is one of the busiest stretches in any national park in the country. Losing access there reroutes a lot of people onto trails already carrying heavy foot traffic. Be patient with the rangers. They're not the ones who dropped the rock.

I'll keep an eye on the reopening announcement, because when the trail comes back I'd expect it to look a little different. Rockfall reshapes things. The landscape you loved last spring might have a new scar, and in five years that scar will just be part of the view, the way all the other scars are.

When was the last time a place you love got rearranged on you? It happens slower than a rockfall, usually. But the canyon's not done yet.