Any feature, such as a bank, ditch, dyke, or cursus, which is built from the natural surface materials, rather than one which is constructed by artificially modifying (such as carving) the materials See Aerial Photography, Glacis rampart, Henge, Linear earthwork, Shadow-marks
Earthworks are large structures of earth that have been built for defence, especially ones which were built a very long time ago. a large long pile of earth, used in the past to stop attacks