Two hundred and forty million years ago, waves left ripples in soft sands and silts. [S]ediments swept in and buried the ripples whole. They lay there under their blanket for hundreds of millions of years, as ages passed, an orogeny lifted the plateau, time turned ancient muds to rock, and erosion wore the blanket away. Now here we are, in the middle of a desert, looking at the echo of wetter days.
Dana Hunter, “Permanent Impermanence: or, How the Fudge Did That Fossilize?” Scientific American, June 27, 2017