( ( Oceanic crust ) ( ( ( consists ( almost entirely ) ) ( of ( ( ( ( ( the ( mafic ( rocks basalt ) ) ) ( -LRB- ( ( on top ) -RRB- ) ) ) and ) gabbro ) ( -LRB- ( ( on bottom ) -RRB- ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Oceanic) (NNP crust)) (VP (VBZ consists) (ADVP (RB almost) (RB entirely)) (PP (IN of) (NP (NP (DT the) (JJ mafic) (NNS rocks) (NN basalt)) (PRN (-LRB- -LRB-) (PP (IN on) (NP (NN top))) (-RRB- -RRB-)) (CC and) (NP (NN gabbro)) (PRN (-LRB- -LRB-) (PP (IN on) (NP (NN bottom))) (-RRB- -RRB-))))) (. .)))
Oceanic crust consists almost entirely of the mafic rocks basalt (on top) and gabbro (on bottom).
(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.