surface or structural changescurlingchippingcrumblingcorrosionweatheringerosionblisteringcrackingpeelingpittingwrinklingbucklingwarpingcocklingcreasingtentingcrumplingtearingliftingthrow upliveringpoppingbloatingsofteningpatinationbioturbationpowderingopacificationteasingisomerizationchalkingwetting-drying cycledentingcase hardeningcondition changingchanges, surface or structural changesurface or structural change