It was sort of a last minute thing, but we just spent a few days in the Grand Canyon from which we’re now back. A magnificent site. Besides the size, of course, one gets the impression of age. This is an ancient place. The Colorado river has worn away rock over millions of years to open up this expanse. The exposed rocks and formations are themselves ancient. We have near the bottom a group of layers called the Tonto group which consists of Tapeats sandstone (beach sand deposited around 550 million years ago), Bright Angel shale (calm water sediment from 540 million years ago), and Mauv limestone (sea sediment from 530 million years ago). Fossils from these layers include jellyfish, trilobites (some of which we saw in some of the exhibits, unfortunately the memory card on the camera was full), and others. Near the top is the Kaibab formation, which are old sea sediments from around 250 million years ago. Fossils here include trilobites, sponges, brachiopods, etc. In between there are deposits from swamps, flood plains, ancient rivers, etc. A snapshot of earth’s ancient history.
The corroborative techniques of radiometric dating, fossil layers, and other techniques all point to the same answers for the ancient ages. What about the canyon itself? How old is it?
As late as last year, a report pointed to a strong possibility that the canyon may have formed, or at least started forming, 55 million years ago. From the article:
The team believes an ancestral Grand Canyon developed in its eastern section about 55 million years ago, later linking with other segments that had evolved separately. “It’s a complicated picture because different segments of the canyon appear to have evolved at different times and subsequently were integrated,” Flowers said.
The ancient sandstone in the canyon walls contains grains of a phosphate mineral known as apatite — hosting trace amounts of the radioactive elements uranium and thorium — which expel helium atoms as they decay, she said. An abundance of the three elements, paired with temperature information from Earth’s interior, provided the team a clock of sorts to calculate when the apatite grains were embedded in rock a mile deep — the approximate depth of the canyon today — and when they cooled as they neared Earth’s surface as a result of erosion.
Apatite samples from the bottom of the Upper Granite Gorge region of the Grand Canyon yield similar dates as samples collected on the nearby plateau, said Caltech’s Wernicke. “Because both canyon and plateau samples resided at nearly the same depth beneath the Earth’s surface 55 million years ago, a canyon of about the same dimensions of today may have existed at least that far back, and possibly as far back as the time of dinosaurs at the end of the Cretaceous period 65 million years ago.”
Of course, some literal fundamentalist Creationists would like people to accept their hypothesis, if it could be called that, that the canyon was formed during Noah’s flood where it rained 40 days and more water that exists on our entire planet covered it for a period of time. So that instead of 55 million years towards which the evidence points, they would like to advance the idea that the canyon was formed in about a year, I guess. So here’s what I suggest to Creationists to test their ideas. Since the time scale suggested is so short, this should be easy. Scale model. Get some limestone (We’ll only deal with the top Kaibab layer here, to give a starting point) of some thickness, and perhaps combined with shale as well. Put on top of it the appropriately scaled volume of water. Allow it to drain for an appropriately scaled amount of time. This will probably 2 weeks to a month, depending on how much limestone you have and I’m too lazy to work out the numbers. It will be up to you to convince scientists that the appropriate amounts of rock, water, and time were chosen. See if you make a small canyon. I eagerly await your results.