( Geologists ( ( study ( ( the layers ) ( of ( rock ( of ( ( the ( earth 's ) ) crust ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Geologists)) (VP (VBP study) (NP (NP (DT the) (NNS layers)) (PP (IN of) (NP (NP (NN rock)) (PP (IN of) (NP (NP (DT the) (NN earth) (POS 's)) (NN crust))))))) (. .)))
Geologists study the layers of rock of the earth's crust.
(ROOT (S (NP (NP (DT The) (NN earth) (POS 's)) (NN crust)) (VP (VBZ is) (VP (VBN composed) (PP (IN of) (NP (JJ igneuos) (NN rock))))) (. .)))