( ( ( The Law ) ( of Superposition ) ) ( ( states ( that ( ( ( ( for ( ( a set ) ( of ( ( undisturbed rock ) layers ) ) ) ) ( , ( ( the ( oldest layers ) ) ( are ( on ( the bottom ) ) ) ) ) ) and ) ( ( the youngest ) ( are ( on ( the top ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN Law)) (PP (IN of) (NP (NNP Superposition)))) (VP (VBZ states) (SBAR (IN that) (S (S (PP (IN for) (NP (NP (DT a) (NN set)) (PP (IN of) (NP (ADJP (JJ undisturbed) (NN rock)) (NNS layers))))) (, ,) (NP (DT the) (JJS oldest) (NNS layers)) (VP (VBP are) (PP (IN on) (NP (DT the) (NN bottom))))) (CC and) (S (NP (DT the) (JJS youngest)) (VP (VBP are) (PP (IN on) (NP (DT the) (NN top)))))))) (. .)))
The Law of Superposition states that for a set of undisturbed rock layers, the oldest layers are on the bottom and the youngest are on the top.
(ROOT (S (S (NP (NP (DT The) (NN law)) (PP (IN of) (NP (NN superposition)))) (VP (VBZ is) (VP (RBS best) (VBN described) (PP (IN by))))) (: :) (S (PP (IN in) (NP (NP (JJ undisturbed) (NNS layers)) (PP (IN of) (NP (JJ sedimentary) (NN rock))))) (, ,) (NP (DT the) (JJS lowest) (NNS layers)) (VP (VBP contain) (NP (DT the) (JJR older) (NNS rocks)))) (. .)))
The law of superposition is best described by: in undisturbed layers of sedimentary rock, the lowest layers contain the older rocks.