Littlefoot leaned forward, feeling his body weight shifting into the sodden log. All around him, he heard the concerted straining grunts of his friends as they all pulled, pushed, and dug at the log to try to pry it loose. He could feel some wiggle in the log, for sure, but no real budge.
'This silt's holding out pretty well,' he thought to himself, wiggling his toes over the gooey slime. 'Maybe if I just...'
He reared back a little onto his hind legs, and then brought his front legs crashing down onto the log. There was a satisfying forward lurch as Littlefoot felt his momentum uproot the log and carry on forward.
A victorious smile lit up his face as he reared his forelegs back up again.
Then the silted cliff he was standing on broke.
There was no warning, no delay, no instant where he realized what was happening and no sensation other than a stomach-churning drop. He just plunged in--soundlessly--like a heavy rock. The world of air and light turned into freezing water so laden with silt that it blocked out the light of the setting bright circle. As every muscle in his body clenched defensively, there was just enough time for him to consciously realize that he had fallen into the river before the sensation of water rushing down his throat caused it to lock up.
Animalistic semi-consciousness kicked in. He thrashed wildly and without thought. There was no light; no indication of which way the surface was. He couldn't think. He couldn't see or hear anything. All he felt was a black, screaming fear as he quickly started drowning.