When Was Grand Canyon Carved and How Do We Know?

Grand Canyon is a gigantic formation located in Arizona that was carved by the Colorado River. It is almost 450 kilometers long, almost 30 kilometers wide and if you happened to drop something off the edge of the canyon, it will travel close to 2 kilometers before it hits the ground in the deepest section around 20 seconds later. Science has shown that this impressive geological structure is between 5 and 6 million years old. But how do we know? The answer is because of the massive amount of independently converging scientific evidence.

Young earth creationists wrongly think the Grand Canyon is only a few thousand years. This is because they start with their pseudoscientific ideology and then they have to rationalize and explain away all the scientific realities that challenge their beliefs. However, scientific evidence cannot be disproved by mere ideology. We know the Grand Canyon is very old due to a multitude of different sources of evidence, from fission tracks and helium amounts in apatite crystals, cosmogenic radionuclide dating (CRN) and dating using optically stimulated luminescence (OSL) of river terraces and differential incision rates. Most young earth creationists either do not accept or even known of these forms of evidence.

Apatite crystals are fascinating. This is because they accumulate fission tracks after they have cooled, and the more fission tracks, the older the rock is. Cooling also traps helium, so the amount of helium inside the rock is proportional to the age. River terraces can be dated with CRN by the fact that exposed rocks exposed to cosmic rays cause nuclear reactions and the daughter products and be measured. The longer the rocks have been exposed, the more amount of daughter products will be found with a mass spectrometer.

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Another inventive method (OSL) is measuring the dosage of ionizing radiation from radioactive decay that occurs in the rock over time. Although these methods use different techniques and have different strengths and weaknesses, they give comparable ages when they are applied to the same area or object. Even if creationists were able to underline the credibility of one of these methods, they would still have much difficulty with explaining why these different and independent methods give comparable results. This is only possible if the Grand Canyon was very old, and of course, it is.

Lorence G. Collins is an American petrologist who is perhaps most well-known for his research on the chemical changes that occur in rocks when they are exposed to hot water or other liquids. In 2015, he wrote a highly readable paper on the history of the Grand Canyon and the evidence for its ancient age in the Reports of the National Center for Science Education, which is the official journal of National Center for Science Education. This organization has defended the teaching of evolution in public schools for decades and expanded to cover climate science a few years ago.

They have reached immense achievements and decisive legal victories against those who want to undermine the teaching of good science and replace it with fundamentalist religious ideology. Collins’s paper is entitled “When Was Grand Canyon Carved: Millions of Years Ago or Thousands of Years Ago? How Do We Know?” and is available here. Access to the PDF version of the can be found here if you want to download the paper and a cache of the paper can be found here.

The paper explains just enough of the different dating methods so that a layperson can understand the methods and results, but not too much detail that could otherwise confuse the reader. Crucial references are listed at the end of the article so that interested readers can find more knowledge about these methods.

Despite being a popular science paper, it combines sufficient detail to grasp the methods being discussed with the pedagogic logic of testing hypotheses about the world with scientific evidence. It is a crucial paper for anyone who wants to learn about the age of the Grand Canyon and more specifically how we know what science claims to know in this area. One does not have to have any particular scientific background to understand the material in the article, because it is presented in a pedagogic and clear way. It is also an excellent reference for science advocacy efforts online.