User blog comment:Ralok/forerunners/@comment-halo/@comment-72.207.209.157-20100407003431

"However, the Terminals show that that the "Librarian" was on Earth, discovering early modern humans 100,000 years ago, indexed them, and built a portal to the Ark to send them there."

That's a pretty big plot hole, if it's mentioned in two places (legends and in-game terminals)