earthwork

barricade citadel fortress reinforcement

barrier bastion battlement block blockhouse breastwork buffer bulwark castle consolidation defense entrenchment fastness fort garrison keep outpost parapet preparation presidio protection stockade strengthening stronghold support wall

embattlement

opening

dam

bank breakwater mound

barricade

barrier bastion breastwork bulwark defense elevation embankment fence fort guard hill mound parapet protection ridge security support wall

vallation

depression ditch

dike foxhole gorge gully moat pit trough waterway

arroyo canal cut depression drain drill dugout entrenchment excavation fosse furrow gulch gutter hollow main rut sink tube