ones ▁comple tes ▁the ▁top ▁of ▁a ▁wall , ▁with ▁the ▁long ▁rect angular ▁side ▁of ▁each ▁cap stone ▁per pend icular ▁to ▁the ▁wall ▁alignment . ▁ ▁Gall ow ay ▁dy kes ▁consist ▁of ▁a ▁base ▁of ▁double - wall ▁construction ▁or ▁larger ▁b ould ers ▁with ▁single - wall ▁construction ▁above . ▁They ▁appear ▁to ▁be ▁r ick ety , ▁with ▁many ▁holes , ▁which ▁det ers ▁liv est ock ▁( and ▁people ) ▁from ▁attempting ▁to ▁cross ▁them . ▁These ▁dy kes ▁are ▁princip ally ▁found ▁in ▁locations ▁with ▁exception ally ▁high ▁wind s , ▁where ▁a ▁solid ▁wall ▁might ▁be ▁at ▁risk ▁of ▁being ▁un sett led ▁by ▁the ▁buff eting . ▁The ▁por ous ▁nature ▁of ▁the ▁wall ▁significantly ▁reduces ▁wind ▁force ▁but ▁takes ▁greater ▁skill ▁to ▁construct . ▁They ▁are ▁also ▁found ▁in ▁gra zing ▁areas ▁where ▁they ▁are ▁used ▁to ▁maxim ize ▁the ▁utility ▁of ▁the ▁available ▁stones ▁( where ▁pl ough ing ▁was ▁not ▁turning ▁up ▁ever ▁more ▁stones ). ▁ ▁Another ▁variation ▁is ▁the ▁Corn ish ▁h edge ▁or ▁Wel sh ▁cla w dd , ▁which ▁is ▁a ▁stone - cl ad ▁earth ▁bank ▁to pped ▁by ▁tur f , ▁scr ub , ▁or ▁trees ▁and ▁character ised ▁by ▁a ▁strict ▁in ward - cur ved ▁batter ▁( the ▁slope ▁of ▁the ▁" h edge "). ▁As ▁with ▁many ▁other ▁vari eties ▁of ▁wall , ▁the ▁height ▁is ▁the ▁same ▁as ▁the ▁width ▁of ▁the ▁base , ▁and ▁the ▁top ▁is ▁half ▁the ▁base