Then they left, they left for the mountain, they went on up.
( ( Then ( they ( ( left , ) ( they ( left ( for ( the mountain ) ) ) ) ) ) ) ( , ( they ( ( went ( on up ) ) . ) ) ) )
(ROOT (S (S (ADVP (RB Then)) (NP (PRP they)) (VP (VBD left) (, ,) (S (NP (PRP they)) (VP (VBN left) (PP (IN for) (NP (DT the) (NN mountain))))))) (, ,) (NP (PRP they)) (VP (VBD went) (ADVP (RB on) (RB up))) (. .)))
They left to go on up the mountain.
( They ( ( left ( to ( ( go on ) ( up ( the mountain ) ) ) ) ) . ) )
(ROOT (S (NP (PRP They)) (VP (VBD left) (S (VP (TO to) (VP (VB go) (PRT (RP on)) (ADVP (RB up) (NP (DT the) (NN mountain))))))) (. .)))