At first...nothing appeared. Magic was peculiar in that regard. In fact, the spell itself produced no visible tracks of any kind - which should be a hint itself to the Unspeakables.
Of course, level 9 itself had its own personality.
Should the duo take a few more steps forward and shine a light towards the ground, however, tracks would easily be found in the remnants of prophecy sphere glass and dust.
The tracks do in fact lead further back into the Hall of Prophecy...where yet another loud CRASH can be heard. This time accompanied by a low rumble.