entists have debated the actual age of the Grand Canyon for 140 years, but thanks to geochemical techniques, we now have the answer. Scientists looked at the temperature history of rocks by using the mineral, apatite, found in the canyon. As erosion occurs, the rock moves closer to the surface and cools down. In their research they found the Grand Canyon is made of different segments of different ages and histories. The eastern part is 15 to 25 million years old. An older expanse down river is 50 to 70 million years old. But they discovered two other segments that were eroded far more recently than they originally thought. They didn’t join to form the Grand Canyon as we know it until about 5-6 million years ago.