He sat for a moment in silence.
( He ( ( ( sat ( for ( a moment ) ) ) ( in silence ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD sat) (PP (IN for) (NP (DT a) (NN moment))) (PP (IN in) (NP (NN silence)))) (. .)))
Seated, he let silence surround him. 
( Seated ( , ( he ( ( let ( silence ( surround him ) ) ) . ) ) ) )
(ROOT (S (S (VP (VBN Seated))) (, ,) (NP (PRP he)) (VP (VBD let) (SBAR (S (NP (NN silence)) (VP (VBP surround) (NP (PRP him)))))) (. .)))