pretty sure thats the ice slab giving way... there wasn't a tree within hundreds of yards.
I think it was crazy how he looked back, saw the slab, and just gassed it. You can hear the other guy saying "pin it!!"
and then he gets like 50 more feet hits a rock/pillow/bump or something and just bails. He was going fucking fast. That was still probably the best possible response though. Still GNAR.