Brie Mattson's character falls, her leg getting pinned under a boulder roughly three feet in diameter, or at most approximately 4,000 pounds regardless of type of rock. The ratchet style car jack used to attempt to dislodge the rock should have easily lifted it without the struggle the two boys displayed, ending with the rock re-pinning her. This should have especially been the case if they opted to use a tire iron or the lever supplied with the jack instead of a piece of wood.