Few can fail to be impressed by the Grand Canyon, which is approximately one mile deep. Hiking from the North to the South Rim involves a distance of 21 miles, a vertical descent and spectacular scenery. However, the Grand Canyon is also of great interest for its historical value. According to the National Park Service, human artefacts of 12,000 years old, dating to the Paleo-Indian period, have been discovered and there have been plenty of other archaeological findings from other digs. The exact age that the Canyon was forged, largely believed to be by water erosion, can only be approximate, but has long been believed to be approximately 6 million years old. Now a new, and controversial study, suggests that it could be a lot older than that.
The study, published in the academic journal called Science, was led by University of Colorado geologist Rebecca Flowers, who has spent a great deal of time and energy studying rock formations at the Grand Canyon. She claims to have found evidence that there was a canyon in existence about 70 million years ago, which would take it back to the time of the dinosaurs, and was incised by two rivers that are no longer in existence. According to the researchers, the Colorado River, rather than being the river that was responsible for the Grand Canyon, simply took advantage of the natural path that had already been forged.
According to the University of Colorado website, Flowers et al analysed mineral grains from the bottom of the Western side of the Canyon using a dating method that “exploits the radioactive decay of uranium and thorium atoms to helium atoms in a phosphate mineral known as apatite.” After looking at temperatures and thermal history, the team were then able to “infer how much time had passed since there was significant natural excavation of the Grand Canyon.”
Despite these findings, the claims have been rejected by other expert geologists. Karl Karlstrom, from the University of New Mexico at Albuquerque, has dismissed it as ‘ludicrous’ and Richard Young, a geologist at SUNY Geneseo claims that there is little fact behind the claims. Even one man who has applauded the new study, Joel Pederson, an Associate Professor at Utah State University, still argues that the current Grand Canyon is just 6 million years old. The argument against the study, according to the Washington Post, comes down to a case of semantics – the University of Colorado findings are based on a canyon that existed before and which the Colorado River then used to forge the current Grand Canyon just 6 million years ago.
The controversy may not be of much interest to lay people, but the difference of 64 million years between the two arguments is enormous and is obviously of great importance to the geologists involved. Flowers is due to give a speech at the American Geophysical Union, after which she will be followed by at least one of her critics. Whether they will be able to come to a compromise about the approximate history of the Grand Canyon remains to be seen.
