Boulders have broken off from high above to form rock shelters.
(Boulders; have broken off; to form rock shelters) Context(Boulders have broken off,List([0, 24))):(Boulders; have broken off to form; rock shelters)
Boulders have broken off,List([0, 24))
Boulders Boulders
have broken off have broken off to form
to form rock shelters
rock shelters