Natural history books may now need some revision.
For years scientists believed the Grand Canyon was formed 5-6 million years ago by the Colorado River. However, a new study published in Science suggests the Grand Canyon is much, much older and was carved by a different river entirely.
"Our research implies that the Grand Canyon was directly carved, to within a few hundred meters of its modern depth, by about 70 million years ago,” CU assistant professor Rebecca Flowers told treehugger.
To gauge the age of the canyon in the past, scientists dated the gravel washed downstream by the Colorado River. However, when researchers dated mineral deposits in caves lining the canyon walls, they came up with a number close to 17 million. And when they looked into the radioactive decay of uranium and thorium atoms in the phosphate mineral apatite, the number popped up to 70 million.
Furthermore, the researchers believe the river that carved out the canyon actually flowed in the opposite direction, a theory that would explain some of the oddities in the canyon walls.
If the number is correct, it would mean that the tyrannosaurus could have walked the rim and stalked the ravines before dinosaurs’ extinction 65.5 million years ago.