These can be very effective as screens and physical barriers. Drystone construction is traditional in many rural landscapes, while mortared stone is appropriate in more urban settings or near buildings or other structures. Local stone which weathers usually fits the setting admirably.
Post-and-rail or other traditional constructions can also be used. They may not prevent determined people from breaking through them, nor are they so visually useful. They are best in rural settings where such forms are appropriate and robustness is not required.
Hedges used as a barrier. Their structure is important: (a) A tapered section is easier to maintain and keep dense at the bottom. (b) Square shapes are difficult to trim properly at the top. (c) Poorly trimmed hedges lose their lower branches to become thin and transparent. (d) A hedge on an earth mound is both physically and visually more effective.
A drystone wall makes an effective barrier in areas where they are traditional.
They are easily repaired, and will last a long time if left undisturbed.
Vertical board-on-board fencing provides a visual screen where this is needed.
It will usually be appropriate to use a range of these barrier types on many sites. The sight of one type of barrier used extensively can be overpowering. Rocks in mounds, mounds with posts in between, barriers alternating with posts and so on all give variety. Also, the choice should reflect the setting. Mounds and rocks are more appropriate to wilder, more open settings; posts to forests; and log barriers, walls or fences to rural or urban situations.