Stay off of rock slides - I almost stepped on one a few years ago, thanks to the rattle warning I jumped my way off back to the grass - it was a smaller slide, only about 20 feet across. Same thing happend to my friend the next year on a small rock slide. He jumped away also but wiped out & bruised himself a bit - got away from the snake anyway.
This was in an area a few miles up off the Columbia River on the Oregon side,