Nick Barnes said he found the GC disappointing after Utah. So did I the first time I saw it, in ~1978, so I'd warned James that it wasn't really up to much. Naturally with such low expectations, he was delighted and thought it was thoroughly grand. I enjoyed it more this time too, as I made the effort to appreciate the geology. The Colorado plateau rose up, and the Colorado river cut down (although quite how it did it on such a grand scale is not at all clear). In only 6 million years the river cut through layers of rock going back half the age of the earth. Wow! And here are all the layers. What a lot of different colours! The tilted red rocks near the river are special - they are the Grand Canyon Supergroup, and are not visible in very many places.