( ( Oceanic crust ) ( ( is ( the ( rock type ) ) ) . ) )
(ROOT (S (NP (NNP Oceanic) (NNP crust)) (VP (VBZ is) (NP (DT the) (NN rock) (NN type))) (. .)))
Oceanic crust is the rock type .
(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.