Here's the reason you see those "falling rock" signs in the mountains.

Somebody filmed a pretty serious rockslide that came down right in front of his car and covered a large section of the road.

This past November, a slide was caught hear Palisade, as well.

And, the year before that, one closed I-70.

Here's hoping these videos are the only way you and I see these in action - Or, we're as lucky as the people who made the ones above.