The Grand Canyon is 277 miles long, up to 18 miles wide and attains a depth of over a mile. It is huge but how old is it? How long did it take to be created? For over 150 years, geologists have debated how and when one of the most dramatic features on our planet—the Grand Canyon—was formed. New data unearthed by researchers at the California Institute of Technology (Caltech) builds support for the idea that conventional models, which say the enormous ravine is 5 to 6 million years old, are way off. It might well be 70 million years old.