The Grand Canyon in the United States is actually 65 million years older than previously thought, a new study suggests.
Researchers said that the Grand Canyon was carved some 70 million years ago, at a time when dinosaurs still roamed the Earth.
Most previous estimates have put its age at five to six million years, based on the age of gravel washed downstream by the ancestral Colorado River.
But now a team from the University of Colorado Boulder, who used radioactive decay and thermal dating to make their estimate, said that it is much, much older.
According to the Daily Mail, Professor Rebecca Flowers explained how the study exploited the radioactive decay of uranium and thorium atoms into helium atoms in a phosphate mineral known as apatite.
She said in Journal Science that the helium atoms were locked in apatite grains as they cooled and moved closer to the surface during the carving of the Grand Canyon.
The hotter the apatite was the fewer helium atoms remained within it, allowing scientists to get a thermal history of the area, the report said.
Because temperature variations at shallow levels beneath the Earth's surface are influenced by topography this allowed the team to infer how much time had passed since there was significant natural excavation of the Grand Canyon, the report added.
Prof Flowers also suggested that it was carved by an ancestor of the Colorado, which flowed in the opposite direction, it added. (ANI)