<P> Dry stone construction is best known in the context of stone walls, traditionally used for the boundaries of fields and churchyards, or as retaining walls for terracing, but dry stone sculptures, buildings, bridges, and other structures also exist . </P> <P> Some dry - stone wall constructions in north - west Europe have been dated back to the Neolithic Age . Some Cornish hedges are believed by the Guild of Cornish Hedgers to date from 5000 BC, although there appears to be little dating evidence . In County Mayo, Ireland, an entire field system made from dry - stone walls, since covered in peat, have been carbon - dated to 3800 BC . The cyclopean walls of the acropolis of Mycenae have been dated to 1350 BC and those of Tiryns slightly earlier . In Belize, the Mayan ruins at Lubaantun illustrate use of dry stone construction in architecture of the 8th and 9th centuries AD . </P> <P> Terminology varies regionally . When used as field boundaries, dry stone structures often are known as dykes, particularly in Scotland . Dry stone walls are characteristic of upland areas of Britain and Ireland where rock outcrops naturally or large stones exist in quantity in the soil . They are especially abundant in the West of Ireland, particularly Connemara . They may also be found throughout the Mediterranean, including retaining walls used for terracing . Such constructions are common where large stones are plentiful (for example, in The Burren) or conditions are too harsh for hedges capable of retaining livestock to be grown as reliable field boundaries . Many thousands of miles of such walls exist, most of them centuries old . </P> <P> In the United States they are common in areas with rocky soils, such as New England, New York, New Jersey, and Pennsylvania and are a notable characteristic of the bluegrass region of central Kentucky as well as Virginia, where they are usually referred to as rock fences or stone fences, and the Napa Valley in north central California . The technique of construction was brought to America primarily by English and Scots - Irish immigrants . The technique was also taken to Australia (principally western Victoria and some parts of Tasmania and New South Wales) and New Zealand (especially Otago). </P>

Why are there so many rock walls in ireland
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