BIOSTRATIGRAPHY OF THE GRAND CANYON

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"The Grand Canyon contains a marvelous record of geologic and paleontologic events spanning most of the last two billion years, nearly one half of the life span of this planet. Although it is neither the deepest nor the longest canyon in the world, it is one of the fewest places where so many chapters of earth history are clearly displayed."

Stanley A. Beus & Michael Morales
Grand Canyon Geology