3Explore the Grand Canyon's layers from the nearly 2-billion-year-old rocks of the Pre-Cambrian Era to the few formations of the Mesozoic Era. Learn about the different kinds of rock that make up the canyon and how the Colorado River carved them into the majesty of the Grand Canyon today. Additional features include a diagram labeling each of the layers, Fast Facts, a phonetic glossary, an index, an introduction to the author, and further sources for learning.