Grand Canyon Is "Frankenstein" of Geologic Formations

sciencehabit writes "It's a debate that has vexed scientists for decades: Is the Grand Canyon young or old, geologically speaking? Both, a new study declares. A group of scientists reports that the famed formation is a hybrid of five different gorges of various ages--two of three middle segments formed between 70 million and 50 million years ago and between 25 million and 15 million years ago, but the two end segments were carved in the past 5 million to 6 million years--and the Colorado River only tied them into a single continuous canyon 5 million or 6 million years ago."