The huge delta of the two rivers was made up of mucky stuff that was formed by river-borne sediment and dead grass and reeds.
(The huge delta of the two rivers; was made up; ) (mucky stuff; was formed; by river-borne sediment and dead grass and reeds)
The huge delta of the two rivers mucky stuff
was made up was formed
by river-borne sediment and dead grass and reeds