The Grand Question

摘要

No adults forget their first experience of walking from the relatively flat, forested plateaus of the Coconino or the Kaibab to the Grand Canyon's rim. Suddenly, they are confronted by a vast space of quiet wind and successions of gray, white, and red cliffs and benches that drop thousands of feet beneath them. Somewhere at the bottom of the canyon, an inner gorge holds a river they cannot see. The Grand Canyon is Earth's greatest celebration of geology. Whether tourist or earth scientist, at some point, we ask, "How did this happen?"