Stanley William Lohman, The Geologic Story of Canyonlands National Park
“ The Earth is very old—four and a half billion years or more according to recent estimates. Most of the evidence for an ancient Earth is contained in the rocks that form the Earth’s crust. The rock layers themselves—like pages in a long and complicated History—record the surface-shaping events of the past, and buried within them are traces of life—the plants and animals that evolved from organic structures that existed perhaps three billion years ago. ”
