( ( Both ( ( ( the ( continental crust ) ) and ) ( the ( oceanic crust ) ) ) ) ( ( are ( less ( dense ( than ( the mantle ) ) ) ) ) . ) )
(ROOT (S (NP (DT Both) (NP (DT the) (JJ continental) (NN crust)) (CC and) (NP (DT the) (JJ oceanic) (NN crust))) (VP (VBP are) (ADJP (RBR less) (JJ dense) (PP (IN than) (NP (DT the) (NN mantle))))) (. .)))
Both the continental crust and the oceanic crust are less dense than the mantle.
(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.