( ( ( The composition ) ( of ( the atmosphere ) ) ) ( ( has ( changed ( through ( geologic history ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN composition)) (PP (IN of) (NP (DT the) (NN atmosphere)))) (VP (VBZ has) (VP (VBN changed) (PP (IN through) (NP (JJ geologic) (NN history))))) (. .)))
The composition of the atmosphere has changed through geologic history.
(ROOT (S (SBAR (WHADVP (WRB How)) (S (NP (NN ice) (NNS cores)) (VP (VBP are) (ADJP (JJ important) (PP (TO to) (NP (NP (DT the) (NN study)) (PP (IN of) (NP (JJ geologic) (NN history))))))))) (VP (VBZ is) (ADVP (RBS best)) (VP (VBN described) (SBAR (IN as) (S (NP (PRP they)) (VP (VBP contain) (NP (NN evidence) (NN showing) (NNS changes)) (PP (IN in) (NP (NP (DT the) (JJ atmospheric) (NN composition)) (PP (IN over) (NP (NN time)))))))))) (. .)))