( ( This acid ) ( ( ( ( ( weathers rocks ) , ) ultimately ) ( producing ( calcium carbonate ) ) ) . ) )
(ROOT (S (NP (DT This) (NN acid)) (VP (VBZ weathers) (NP (NNS rocks)) (, ,) (ADVP (RB ultimately)) (S (VP (VBG producing) (NP (NN calcium) (NN carbonate))))) (. .)))
This acid weathers rocks, ultimately producing calcium carbonate.
(ROOT (S (NP (NNP Carbon) (NN dioxide)) (ADVP (RB chemically)) (VP (VBP weather) (NP (NNS rocks)) (PP (IN by) (S (VP (VBG creating) (NP (NNS acids)))))) (. .)))