I'll swear I saw an episode of The Flintstones which showed the Grand Canyon as a tiny crack under Fred's feet with just a trickle of water in it. A man who I disliked intensely once came with us to Malham Tarn, a natural lake formed on the Mid-Craven Fault in the Yorkshire Dales which inspired The Water Babies by Charles Kingsley (a work marred by a bit of of-its-day bigotry, unfortunately). He swore blind that it was a man-made lake and got quite nasty when I gently explained to him its geological origins. Nature and time can sometimes soften human handiwork, but the Grand Canyon and Malham Tarn are both beyond reproach!