yardangyear to year pressure differenceyear to year temperature differenceyelatire humidityyieldyield depression curveyoung riveryoung valleyyouthful valleyzeolitezero layerzero point of chargezero tillage = no tillagezeta potentoal electrokinetic potentialzigzag lightningzingg bench terrace conservation bench terracezonalzonal flowzone of aerationzone of rock fracturezone of saturationzone of weatheringzone tillage
