History of the Grand Canyon "It's all about the layers!" TThe Grand Canyon showcases 20 layers of visible rock in a canyon that is one mile deep, which is nearly the length of 15 football fields! Remarkably, the oldest rock in the Grand Canyon is known as Vishnu schist and dates back 1.8 billion years, which is millions of years before dinosaurs existed. The lower layers are composed of Igneous rocks, formed from cooled liquid magma, and Metamorphic rocks, created by heat a