( ( ( ( continental material ) ( is ( too ( light ( , ( too ( ( buoyant , ) ( to ( sink ( into ( the mantle ) ) ) ) ) ) ) ) ) ) ) ( -LRB- ( ( ( ( ( see '' ) ( ( Buoyancy and ) ( Floating Continents ) ) ) '' ) ( in ( the ( next lesson ) ) ) ) -RRB- ) ) ) . )
(ROOT (S (S (NP (JJ continental) (NN material)) (VP (VBZ is) (ADJP (RB too) (JJ light) (, ,) (RB too) (JJ buoyant) (, ,) (SBAR (S (VP (TO to) (VP (VB sink) (PP (IN into) (NP (DT the) (NN mantle)))))))))) (PRN (-LRB- -LRB-) (VP (VB see) ('' '') (NP (NP (NNP Buoyancy)) (CC and) (NP (JJ Floating) (NNS Continents))) ('' '') (PP (IN in) (NP (DT the) (JJ next) (NN lesson)))) (-RRB- -RRB-)) (. .)))
continental material is too light, too buoyant, to sink into the mantle (see &quot; Buoyancy and Floating Continents &quot; in the next lesson).
(ROOT (S (NP (NNS Continents)) (VP (VBP are) (ADJP (JJ unable) (S (VP (TO to) (VP (VB be) (VP (VBN pushed) (PRT (RP down)) (PP (IN into) (NP (DT the) (NN mantle))) (PP (IN by) (NP (NP (NN plate) (NNS boundaries)) (PP (RB because) (IN of) (NP (NN buoyancy))))))))))) (. .)))