Let's practice some more....
We are now ready to solve the diagram that looked so complicated when we first started- the geologic history of the Grand Canyon area (Please note that the patterns representing the Unkar and Chuar Groups simply represent that these groups contain multiple formations. The number and rock types of the actual formations are not accurately represented).
Sequence the rock layers and geologic events that must have taken place to produce the cross section at left. For each event, list the principle that you used to determine it's place in the sequence. Then click ahead to see how you did.