Silent Interference

"Amy, this isn't any old asteroid. It's the Delerium Archive, final resting

place of the headless monks, the biggest museum ever"

The headless monks are mentioned in The Time of the Angels. The museum where

River's message was.  The monks work for the Silence.  The Silence was using Riverto kill the Doctor.  Is it possible that they were working behind the scenes, trying to kill the Doctor in different ways?  If so, sending him to a cave filled with

Weeping Angels would be a pretty good way to do it.  And a good disguise.

Use River without her knowing.  That box wasn't there by coincidence.  The

Silence placed it there to kill the Doctor. They failed