Grand Canyon Older than Previously Thought; Creationists Cry.
Posted on March 7th, 2008 by blue collar scientistIn today’s issue of Science, researchers report that the Grand Canyon is 16 to 17 million years old.
The oldest rocks exposed in the Grand Canyon are roughly two billion years old. But the age of the Canyon itself is a different matter. The researchers rely upon mammillaries, cave formations resulting from calcium carbonate precipitating out of water and onto existing rock at the level of the water table. Mammillaries in the western Grand Canyon are much higher than the present-day water level, so radioactive dating of the mammillaries reveals when the water level was at that level, beginning to erode the Canyon into being. The researchers dated the mammillaries using a uranium to lead isotope ratio method.
Studies on the age of gravel washed down the Canyon have suggested the Canyon formed about 5-6 million years ago. This result isn’t discredited; scientists have thought for some time that the western Canyon was a different age than the eastern, and this research supports that view. So the result isn’t a huge surprise to geologists, but it is still an advance on what we knew before.
Reaction from creationists has been muted, on account of they are still crying after finding out that yet another piece of evidence shows that Earth formed more than 4,000 years ago.
Tags: dating, geology, Grand Canyon, gravel, isotope dating, lead, mammillaries, uranium
