The trails at the Giant City State Park close at dusk. The reason seems obvious: You could get lost, fall off a cliff, and die.
The truth is more sinister. After sunset, the innocent looking gnomes go into hiding, and from the rocks the true owners of the place emerge.
These two above still have humanoid features, but you start wondering whether there are other nameless horrors here. Death by falling off a cliff might have been a merciful alternative.
I am sure Howard Phillips Lovecraft would have found inspiration here.