The huge hole that cuts through the Arizona region has long been the subject of debate among the scientific community. Until now, estimates of the age of this natural giant, mostly based on the dating of the sediments that form it, variedbetween 5 and 17 million years. However, new research analyzing the distribution of helium atoms in rocks indicates that the Grand Canyon began to form much earlier, no less than 70 million years ago.
The method proposed by the researchers, from the California Institute of Technology (USA), analyzes the concentration of the noble gas helium in calcium phosphate minerals, calledapatitas, found in the canyon rocks. When apatites are found deep inside the earth, due to temperatures above 70 ° C that are reached, helium can ‘escape’ from the minerals by diffusion. But, when minerals rise to the surface, or when erosion carves a canyon around them,rocks cool and trap helium inside apatites, in which it begins to accumulate. Therefore, the concentration of this gas in them helps scientists estimate when the rocks cooled.
The dating done by the researchers, which is published in the journal Science, indicates that the rocks of the western portion of the Grand Canyon were already carved some time ago.70 million years, and that erosion has not increased excessively in recent times. The result is surprising, since it is very far from the 5 million years of age suggested by some research, and is four times the oldest estimated by other works, which place it at about 17 million years.
The debate is not closed, since it is a single study against the abundant evidence that the relative ‘youth’ of the natural monument. Rebecca Flowers, one of the authors, defends her work: “If the history of the Grand Canyon of the Colorado were that simple, the origins of the canyon would not continue to be a subject of debate.” Further research will be needed to corroborate the clues offered by the helium buried in its rocks.
