the mystery of four decades back the springboard for a more immediate mystery in the present 
(ROOT (S (NP (NP (DT the) (NN mystery)) (PP (IN of) (NP (CD four) (NNS decades)))) (ADVP (RB back)) (NP (NP (DT the) (NN springboard)) (PP (IN for) (NP (NP (DT a) (ADJP (RBR more) (JJ immediate)) (NN mystery)) (PP (IN in) (NP (DT the) (NN present))))))))
(ROOT (S (NP (NP (DT ) (NN )) (PP (IN ) (NP (CD ) (NNS )))) (ADVP (RB )) (NP (NP (DT ) (NN )) (PP (IN ) (NP (NP (DT ) (ADJP (RBR ) (JJ )) (NN )) (PP (IN ) (NP (DT ) (NN ))))))))