You need to have collected at least 49 of the "Ancient Relics" throughout the game. The 50th relic is only available after the credits roll and you're able to explore Iraq freely again. Finding all 50 relics will give you the Shadows out of Time achievement.

You need to have all 50 relics in your inventory to get the "Shadows out of Time" achievement, since you can solve this with 49 out of the 50 relics make sure you have all of them in your inventory before solving the vault. When this puzzle is solved it will remove the relics used and you'll be blocked from getting the achievement, so if you're going to solve it with 49 relics, make sure to pick up all 50 first if you want the achievement.

The four wall sections each need to have the ancient artifacts put in the correct spot and rotated to the correct orientation. Here's the solution I used (there may be others). Note that each artifact can be either rotated to the right (activating all the spaces orthogonally) or to the left (activating all spaces surrounding it).

Once this is complete, you'll receive the final journal note and (if you collected the other notes in the game) get the "Archivist" achievement.

Interestingly, if you're diligent and get all 49 relics before reaching the vault, you can unlock the it without needing to progress further. This makes the cutscene you see not make any sense chronologically ( why is the ark in Antarctica when Voss hasn't yet installed all the stones? Whose footprints are leading away from the Ark if Locus is still here?) and you can actually see the end credits before beating the last area.


11 Relics


11 Relics


13 Relics


15 Relics

14 Relics (See note about only using 49 relics)