LOS ANGELES -- The Grand Canyon was probably carved about 70 million years ago, much earlier than thought, a provocative new study suggests -- so early that dinosaurs might have roamed nearby.
Using a new dating tool, scientists came up with a different age for the gorge's western section, challenging conventional wisdom that much of the canyon was scoured by the Colorado River in the past 5 million to 6 million years.
Critics contend that the study ignores evidence pointing to a geologically young landscape, and they have doubts about the technique used to date it.
The researchers crushed rocks from the canyon bottom to analyze a mineral called apatite. It contains radioactive elements used to calculate the time since the canyon eroded. -- AP