( ( ( Plates Pieces ) ( of ( ( ( crust and ) brittle ) ( uppermost mantle ) ) ) ) ( , ( perhaps ( ( ( ( ( 100 kilometers ) thick ) and ) ( ( ( hundreds or ) thousands ) ( of ( kilometers wide ) ) ) ) ( , ( that ( ( cover ( ( the ( Earth 's ) ) surface ) ) . ) ) ) ) ) ) )
(ROOT (S (NP (NP (NNP Plates) (NNP Pieces)) (PP (IN of) (NP (ADJP (JJ crust) (CC and) (JJ brittle)) (NN uppermost) (NN mantle)))) (, ,) (ADVP (RB perhaps)) (UCP (ADJP (NP (CD 100) (NNS kilometers)) (JJ thick)) (CC and) (NP (NP (NNS hundreds) (CC or) (NNS thousands)) (PP (IN of) (NP (NP (NNS kilometers)) (ADVP (JJ wide)))))) (, ,) (NP (DT that)) (VP (VBP cover) (NP (NP (DT the) (NN Earth) (POS 's)) (NN surface))) (. .)))
Plates Pieces of crust and brittle uppermost mantle, perhaps 100 kilometers thick and hundreds or thousands of kilometers wide, that cover the Earth's surface.
(ROOT (S (NP (NP (NP (DT The) (NN earth) (POS 's)) (JJ continental) (NN crust)) (, ,) (PP (IN on) (NP (NN average))) (, ,)) (VP (VBZ is) (ADJP (NP (CD 35) (NNS kilometers)) (JJ thick))) (. .)))