No, the oldest rocks on Earth are not in the Grand Canyon. While the Grand Canyon does contain rocks that are billions of years old, there are even older rocks found elsewhere on Earth.

Here's why:

* The Grand Canyon's oldest rocks are about 2 billion years old. This is impressive, but not the oldest.

* The oldest known rocks on Earth are found in the Nuvvuagittuq Greenstone Belt in Canada. These rocks are estimated to be around 4.28 billion years old.

* Other very ancient rocks are found in the Jack Hills region of Western Australia. Some of these zircon crystals are dated at 4.4 billion years old.

So, while the Grand Canyon is a magnificent geological wonder with rocks dating back billions of years, it doesn't contain the oldest rocks on Earth.