( ( ( FUSION CRUST ) ( When ( ( a meteorite ) ( ( falls ( through ( the ( ( ( ( Earth 's ) atmosphere ) , ) ( a ( ( very thin ) layer ) ) ) ) ) ) ( on ( ( the ( outer surface ) ) ( of ( the rock ) ) ) ) ) ) ) ) ( melts . ) )
(ROOT (S (NP (NP (NNP FUSION) (NNP CRUST)) (SBAR (WHADVP (WRB When)) (S (NP (DT a) (NN meteorite)) (VP (VBZ falls) (PP (IN through) (NP (DT the) (NP (NP (NNP Earth) (POS 's)) (NN atmosphere)) (, ,) (NP (DT a) (ADJP (RB very) (JJ thin)) (NN layer)))) (PP (IN on) (NP (NP (DT the) (JJ outer) (NN surface)) (PP (IN of) (NP (DT the) (NN rock))))))))) (VP (VBZ melts)) (. .)))
FUSION CRUST When a meteorite falls through the Earth's atmosphere, a very thin layer on the outer surface of the rock melts.
(ROOT (S (NP (NP (DT The) (JJ outer) (NN core)) (PP (IN of) (NP (DT the) (NN earth)))) (VP (VBZ is) (ADJP (JJ molten))) (. .)))