( ( ( ( ( The ( denser plate ) ) , ) ( made ( of ( oceanic crust ) ) ) ) , ) ( ( is ( subducted ( underneath ( ( ( the ( less ( dense plate ) ) ) , ) ( which ( can ( be ( either ( ( ( continental or ) oceanic ) crust ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN denser) (NN plate)) (, ,) (VP (VBN made) (PP (IN of) (NP (JJ oceanic) (NN crust)))) (, ,)) (VP (VBZ is) (VP (VBN subducted) (PP (IN underneath) (NP (NP (DT the) (JJR less) (JJ dense) (NN plate)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (MD can) (VP (VB be) (NP (DT either) (ADJP (JJ continental) (CC or) (JJ oceanic)) (NN crust)))))))))) (. .)))
The denser plate, made of oceanic crust, is subducted underneath the less dense plate, which can be either continental or oceanic crust.
(ROOT (S (NP (NNP Gabbro)) (VP (VBZ is) (NP (NP (DT a) (JJ dark) (JJ dense) (NN rock)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (VP (VB be) (VP (VBN found) (PP (IN in) (NP (DT the) (JJ oceanic) (NN crust)))))))))) (. .)))
Gabbro is a dark dense rock that can be found in the oceanic crust.