Once rock has been broken up by weathering, the small pieces can be moved by the action of water, ice, wind, or gravity on these rock pieces.
(rock; has been broken up; ) (the small pieces; can be moved; by the action of water, ice, wind, or gravity on these rock pieces; T:Once rock has been broken up by weathering)
rock the small pieces
has been broken up can be moved
by the action of water, ice, wind, or gravity on these rock pieces T:Once rock has been broken up by weathering