Bet all those BIG chunks of ice at the bottom of the ice fall didn't start there... Look at that HUGE one in the middle. Now imagine it crashing and bouncing into place from the upper seracs.
Pucker factor = 10.
We didn't see (or hear, for that matter) anything coming down, but that huge one falling would have been a sight to behold!
The rocky scars on the face are further testament that big parts of the glacier occasionally drop off.