With all of the rules you have learned so far you should be able to interpret the sequence of events of some geologic sections. We will go through one together and then you can practice on your own. I'll start you off with a fairly difficult one so if you follow that you'll be able to do any of the other ones. Study the following diagram and follow my interpretation below.

• The law of superposition tells us that the rocks on the bottom are going to be the oldest, so we always start our interpretation at the bottom. At the bottom we see three things: fault K, rocks P and F. The law of inclusions tells us that F must be older than P. Fault K cuts across all of the units so it must be younger. So we know that our order so far is F, P and sometime later K.
• Just above P is an unconformity illustrated by the wavy line so it must be next. (current order: F, P, unconformity).
• Layers B, R, H, and A with intrusion M are next because they lie on top of the unconformity. We know that M must come after B,R,H,A because of cross-cutting relations. We also know that the folding that caused B-A did not fold M because it is still straight so we can add to our sequence after B-A (current order: F, P, unconformity, B, R, H, A, folding, M).
• above these layers is another unconformity and layers E, X, D, Keep in mind that K is still offsetting these units so it must come later (law of cross-cutting relations). (current order: F, P, unconformity, B,R,H,A, folding, M, unconformity, E,X,D)
• notice how E,X,D are no longer horizontal? This is when they were tilted. (current order: F, P, unconformity, B,R,H,A, folding, M, unconformity, E,X,D, tilting)
• above D is another unconformity, but notice how it cuts across fault K. That means that fault K is younger than the unconformity. (current order: F, P, unconformity, B, R, H, A, folding, M, unconformity, E,X,D,K, unconformity)
• The last two units are S and J. Because S cuts into J it must be the youngest. So our final order is: F, P, unconformity, B, R, H, A, folding, M, unconformity, E,X,D,K, unconformity J,S

Practice:

Block diagram 1

Block diagram 2

Block diagram 3
(Hint: Note the shaded region in Unit B right at the contact between B and D.  That is contact metamorphism which occurred as Unit D, which was a magma, was emplaced into Unit B and "cooked" the rocks of Unit B right next to the contact.  Also note how this contact metamorphism is not present in Unit A just above Unit D.)

Block diagram 4
(Hint: Note the thin shaded region surrounding Unit A in the rocks adjacent to Unit A.  That is contact metamorphism which occurred in the surrounding rocks as Unit A, which was a magma, was emplaced into the surrounding rocks (just like in Block diagram 3.  Again, note how this contact metamorphism is missing where A is in contact with Unit N.)