Teen wolf mountain ash myth

Like a lot of the mystical elements of this show, the details about how mountain ash works are purposely left vague (that way, the writers have freedom to fudge things as needed).

However, the point about the mountain ash is not that it physically prevents a werewolf from crossing over it, but rather, there's is a magical barrier to werewolves passing over it. We see, near the end of Season 1, Scott's special status allows him to break through a mountain ash barrier with extreme effort, but it creates a visible energy barrier that goes all the way to the ceiling.

The idea seems to be that a werewolf cannot do anything that would allow them to break or cross a mountain ash barrier. Any act that the werewolf would take that might disrupt that barrier is magically prevented from working. The mountain ash itself would somehow resist any such attempt to break the circle.

There's also another minor bit of supporting evidence in favor of this theory. If you look closely, you'll notice that mountain ash, when laid down by a druid, always seems to fall in a straight line or perfect circle. In other words, the mountain ash seems to "know" it's being used to create a barrier and forms itself up in the appropriate shape to do so. That would imply that whatever magic is driving the mountain ash to work is capable of "fixing" any attempts to break the barrier.