For a geologist, the 8-mile hiking trail to the Grand Canyon's floor is an irresistible lesson in Earth's history.
My husband has some friends who live in Arizona, about two hours from the Grand Canyon. One year a friend of theirs, a geologist named Dave, came to visit, and they proudly drove him to see the national park. Many people feel overwhelmed the first time they glimpse the Grand Canyon, but for geologists, visiting it is like finally beholding the Holy Grail. Earth hides most of her history, burying it underneath mountains or sinking it below oceans. The Grand Canyon is one of the few spots where the planet's past is laid bare for anyone to see.
Dave needed to leave in an hour, so he couldn't hike the eight-mile trail that winds down to the canyon floor – but he wanted to walk the first quarter mile, just to get a taste. His friends sat down on a park bench, and Dave trotted off in his sneakers, carrying a small water bottle. An hour later, they were worried. Two hours later, they started down after him. It was 95 degrees F. that day, and a hiker needs a gallon of water just to make it to the bottom – a 17-mile journey that drops nearly a full vertical mile from the rim to the Colorado River. It's the sort of jaunt the Park Services strongly advise against.