How Did the Layers of the Grand Canyon Form?
ES2906  Ages of Rock Layers

This diagram represents the sequence of rock units exposed in the Grand Canyon. Using geologic dating principles and fossils preserved in the layers, the ages of each layer have been established. The letters to the left of each layer in the diagram show abbreviations for the geologic time periods when the rocks formed.

  !   Move your cursor over the rock layers for the name and timing of each period. Use the information to answer the two questions below.

Adapted from National Park Service

2. When did the rock layers exposed in the canyon form?

3. Are there any major gaps in the rock record? If so, when?

 Step:   1   2   3   4   5   6   7   8   9   10   11   12