The story arc in series five is that cracks are appearing and are splinters in the skin of the world. The pattern of the cracks is always the same.

The Eleventh Hour

In young Ameila’s bedroom there is a crack on her wall.

Prisoner Zero says that the Pandorica will open and silence will fall.

Another crack pops up on the monitor in the Tardis.

The Beast Below

A crack appears on the Starship UK.

Victory of the Daleks

After the Tardis dematerialises when the Doctor and Amy leave London in World War II, a crack is seen on the wall. The Doctor notices that Amy forgets previous events from The Stolen Earth/Journeys End.

The Time of Angels/Flesh and Stone

The Crack opens on the Byzantium ship. It removed Christian, Marco, Pedro, and Phillip from existence and then the Weeping Angels which close it as the crack needed to consume a complicated space-time event which the Weeping Angels are. The Doctor traced the origin of the temporal explosion behind the crack to the day of Amy's wedding.