# Puzzle using relative dating principles

This isn't directly looking at a real life ecological example kind of thing, but it requires knowledge of relative dating, so I thought I would come here. Here is what was told:

-"Worms" (curved lines) tunnelled through a block of material that used to be rectangular. (C,D,F,J,H)

-faintly-circled letters represent "cracks" (discontinuities such as faults, I guess) (A,B,E,G,I)

-D is "broken" by B. (hard to tell in picture)

-Although there are ten letters, only 8 of them can be placed for certain. But we have to place the letters in order, say the two letters we cannot place for certain, and show all the possible locations where the other letters may be placed.

Here is what I have so far:

I looked at the cracks first.

E crack goes through A crack.

B crack goes through A crack.

B crack goes through I crack.

B crack goes through G crack.

I crack goes through G crack.

G crack goes through A crack.

Using principle of cross-cutting relationships, order from oldest to newest here is A, G, I, ((E,B) or (B,E))

Then I looked at the worms to the earthquakes.

A --> F goes through A, but J is broken by A.

B --> breaks C, H, F, J, and D

E --> C goes through E, but J, D, F, and H are older.

G --> C goes through G, but D is broken by G

I --> F goes through I, but H is broken by I.

Since B breaks all of the "worms" but E only breaks through four of the five "worms," we can place the cracks as, from oldest to youngest

A, G, I, E, B

Then I started to place the "worms" between the cracks using principle of cross-cutting relationships. I got in the end (oldest to youngest):

J, A, G, I, F, E, C, B - D and H cannot be placed for certain.

That's all I have for now and it seems a bit off to me, but I can't place where? Am I doing this right?

• If anyone close votes, please do explain your reasoning. (I believe) I remember doing similar exercises back in Intro to Geology myself... so it does seem related to the science. You gave some explanation of your thinking, and it's certainly an earth sciences related problem. So really not sure why some might think it'd merit closing. throwaway0555585 it's not a bad first question, and I hope you'll get a good answer :-) Only hope you'll decide to stick around the Stack Exchange communities more than your username may indicate :-D – JeopardyTempest Jan 31 '18 at 7:12