unconformity      
noun [ C ]  geology specialized uk/ˌʌn.kənˈfɔː.mə.ti/ us/ˌʌn.kənˈfɔːr.mə.t̬i/
 (地表岩层的)不整合
an interruption in the series of the earth's rock layers, resulting from either erosion (= gradual loss by the effect of weather) or the failure of layers to be created