earthwork (n.)youdaoicibaDictYouDict[earthwork 词源字典]
"mounds of earth thrown up for some purpose, especially as a military fortification," 1630s, from earth + work (n.). In this sense Old English had eorðbyrig "mound, embankment;" Old English eorðweorc meant "work on the land."[earthwork etymology, earthwork origin, 英语词源]