<font color="beige"><b>I suppose the worm fence is an American manifestation, as mentioned earlier there was an abundance of wood when clearing fields, old Abe Lincoln was said to be a rail splitter in his younger years.
Although it may seem like a wasteful practice what the worm fence uses in wood is more than made up for in the strength (small opennings between rails and gravity holds it up), longevity (limited ground contact)and ease of construction (no holes to dig in the ground, to bore in the posts or nails used), all you needed was an axe and a strong back.
The bottom rail is set on a rock so only the cross ties (if used) at each intersection touch the ground...these can slowly rot where they touch the ground with out effecting the fence structure, repairs and replacement of rails is easy.
I have a small version (only four sections) at my driveway entrance which I built 9 years ago with spit white oak, there's some rot in the sap wood of the rails but they are still in serviceable shape. Here in the mid-Atlantic a white oak post set in the ground might last 10 years, sitting on a rock up off the ground it could last 20+ years.
The Gettysburg area had a lot of hybrid type fences using a fieldstone bottom half with cross rails ever 10 feet or so topped with a rail, the wood gave the stone fence another foot or so of height.</b></font id="beige">
<center> <font color="beige"><b>General R.A.'Bob'Weir
</b></font id="beige"><font color="green"><b><font size="4">CSA Eastern Theater Commander</b></font id="size4"></font id="green">
<b>ACWGC Cabinet Member</b> </center>