( ( ( The mantle ) ( of ( the Earth ) ) ) ( ( is ( ( a ( 1,800-mile-thick layer ) ) ( that ( surrounds ( the ( outer core ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN mantle)) (PP (IN of) (NP (DT the) (NN Earth)))) (VP (VBZ is) (NP (NP (DT a) (JJ 1,800-mile-thick) (NN layer)) (SBAR (WHNP (WDT that)) (S (VP (VBZ surrounds) (NP (DT the) (JJ outer) (NN core))))))) (. .)))
The mantle of the Earth is a 1,800-mile-thick layer that surrounds the outer core.
(ROOT (S (NP (NP (DT The) (JJ outer) (NN core)) (PP (IN of) (NP (DT the) (NN earth)))) (VP (VBZ is) (ADJP (JJ molten))) (. .)))