The massive White Cliffs in Zion National Park are composed of Navajo sandstone which is Triassic in age. The Gray Cliffs exposed on Cedar Mountain above Cedar City are composed of the Straight Cliffs and Wahweap sandstones which are Cretaceous in age. Examine the Geologic Time Scale on page 205. You already looked briefly at this in Chapter 1. Mnemonic devices are often used to assist in remembering lists, including the divisions of the Geologic Time Scale.
M ake P eople P uke.