( ( The islands ) ( ( are ( ( the peaks ) ( of ( ( a ( mountain range ) ) ( ( raised ( from ( ( the ( ocean bed ) ) ( by ( ( a series ) ( of ( volcanic eruptions ) ) ) ) ) ) ) ( ( ( some ( 25 million ) ) years ) ago ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNS islands)) (VP (VBP are) (NP (NP (DT the) (NNS peaks)) (PP (IN of) (NP (NP (DT a) (NN mountain) (NN range)) (VP (VBN raised) (PP (IN from) (NP (NP (DT the) (NN ocean) (NN bed)) (PP (IN by) (NP (NP (DT a) (NN series)) (PP (IN of) (NP (JJ volcanic) (NNS eruptions))))))) (ADVP (NP (QP (DT some) (CD 25) (CD million)) (NNS years)) (RB ago))))))) (. .)))
The islands are the peaks of a mountain range raised from the ocean bed by a series of volcanic eruptions some 25 million years ago.
(ROOT (S (NP (NNS Scientists)) (VP (VBP know) (SBAR (IN that) (S (NP (DT some) (NNS mountains)) (VP (VBD were) (ADVP (RB once)) (PP (IN at) (NP (NP (DT the) (NN bottom)) (PP (IN of) (NP (DT an) (NN ocean))))) (SBAR (IN because) (S (NP (JJ marine) (NNS fossils)) (VP (VBP have) (VP (VBN been) (VP (VBN found) (PP (IN on) (NP (NP (DT the) (NNS peaks)) (PP (IN of) (NP (DT some) (NNS mountains)))))))))))))) (. .)))