( rocks ( ( ( are ( ( ( ( ( lighter , ) ( less dense ) ) , ) and ) ( generally ( more resistant ) ) ) ) ( to ( weathering ( than ( ocean ( crust iii ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS rocks)) (VP (VBP are) (ADJP (ADJP (JJR lighter)) (, ,) (ADJP (RBR less) (JJ dense)) (, ,) (CC and) (ADJP (RB generally) (RBR more) (JJ resistant))) (PP (TO to) (S (VP (VBG weathering) (PP (IN than) (NP (NN ocean) (NN crust) (NN iii))))))) (. .)))
rocks are lighter, less dense, and generally more resistant to weathering than ocean crust iii.
(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.