( ( ( Stromatolites Several ) ( of ( ( the ( sedimentary ( rock layers ) ) ) ( described ( above ( contain fossils ) ) ) ) ) ) ( ( called stromatolites ) . ) )
(ROOT (S (NP (NP (NNS Stromatolites) (JJ Several)) (PP (IN of) (NP (NP (DT the) (JJ sedimentary) (NN rock) (NNS layers)) (VP (VBN described) (PP (IN above) (NP (JJ contain) (NNS fossils))))))) (VP (VBD called) (NP (NNS stromatolites))) (. .)))
Stromatolites Several of the sedimentary rock layers described above contain fossils called stromatolites.
(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.