Retaining walls: common practice and successful on small slopes and cut faces, but not on larger slopes.
Large unstable slopes are not easily retained; it is difficult and usually uneconomic to build and found massive retaining walls at the toe of major natural landslides or large unstable slopes.
Concrete walls: need sound footing; prevent from rotation by buttresses, or by combination of heels, toes and shear keys at base; or rock anchors from near top and/or base, or deep foundations; weep holes permit drainage; masonry facing improves appearance.
Dental masonry: hack out weak zone of rock and refill with cemented masonry or concrete with stone facing; may dowel into rock.
Gabion walls: cheap to install, can retain soil slopes and act as toe weight.
Sprayed concrete (shotcrete): may be used with rockbolts (section 38); spray over bolted reinforcing mesh, or use fibrecrete containing 50 mm lengths of steel wire within the sprayed mix to give tensile strength.