When water saturated soils freeze, they expand, pushing rocks and boulders on the surface upward perpendicular to the slope.
(water saturated soils; freeze; ) (they; expand; T:When water saturated soils freeze) (they; pushing upward perpendicular; rocks and boulders; on the surface)
water saturated soils they they
freeze expand pushing upward perpendicular
T:When water saturated soils freeze
rocks and boulders on the surface