You access the pedestal again; the platinum discs suddenly appear once more in your backpack. With the knowledge of the stone watcher learned and the discs returned to your possession, the time has come to return to Ironforge and inform the Explorers' League of your discovery.
Welcome back <name>. Were you able to use the discs to your advantage, or did it end up being a wild goose chase?
You were missing some discs? Interestingly enough, it seems that the discs of Norgannon are only parts of the complete set - like keys on a key ring, if you will. If we can find the Plates of Uldum, then we could actually access the Uldum complex itself! Imagine actually exploring the place where the Creators worked without having to bring a huge shovel! Not that there's anything wrong with shovels... or digging...