( ( Continental crust ) ( ( ( is larglely ) ( composed ( of ( ( granite , ) ( which ( ( is ( less ( dense ( than ( ( ( oceanic crust ) , ) ( which ( is ( largley basalt ) ) ) ) ) ) ) ) ( -LRB- ( ( ( ( ( both ( continental granite ) ) and ) ( oceanic basalt ) ) ( ( are generally ) ( ( overlain ( by ( sediments ( and ( sedimentary rocks ) ) ) ) ) ( at ( the surface ) ) ) ) ) -RRB- ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Continental) (NNP crust)) (VP (VBZ is) (ADVP (RB larglely)) (VP (VBN composed) (PP (IN of) (NP (NP (NN granite)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADJP (RBR less) (JJ dense) (PP (IN than) (NP (NP (JJ oceanic) (NN crust)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADJP (RB largley) (JJ basalt)))))))) (PRN (-LRB- -LRB-) (S (NP (NP (DT both) (JJ continental) (NN granite)) (CC and) (NP (JJ oceanic) (NN basalt))) (VP (VBP are) (ADVP (RB generally)) (VP (VBN overlain) (PP (IN by) (NP (NNS sediments) (CC and) (NN sedimentary) (NNS rocks))) (PP (IN at) (NP (DT the) (NN surface)))))) (-RRB- -RRB-))))))))) (. .)))
Continental crust is larglely composed of granite, which is less dense than oceanic crust, which is largley basalt (both continental granite and oceanic basalt are generally overlain by sediments and sedimentary rocks at the surface).
(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.