I've never seen a whole-log fence anywhere here in Virginia that I'm aware of, wwh. However, split-rail fences are common in the mountains all up into Appalachia. I saw them when I drove through the Cumberland Gap back about, oh, 15 years ago. The zigzag fence constructed of whole logs of which you write would be more difficult to construct, however, because of the sheer weight and instability of the logs stacked vertically. Interesting concept to imagine, but I'd like to see a photograph of such a fence if you come across one today! I'm off to school--the ice has melted and I'll miss being here today--boohoo!