( ( ( ( ( ( Rock layers ) ( ( are also ) ( called ( strata ( -LRB- ( ( ( the ( plural form ) ) ( of ( the ( Latin ( word stratum ) ) ) ) ) -RRB- ) ) ) ) ) ) , ) and ) ( stratigraphy ( is ( ( the science ) ( of strata ) ) ) ) ) . )
(ROOT (S (S (NP (NNP Rock) (NNS layers)) (VP (VBP are) (ADVP (RB also)) (VP (VBN called) (NP (NP (NN strata)) (PRN (-LRB- -LRB-) (NP (NP (DT the) (NN plural) (NN form)) (PP (IN of) (NP (DT the) (JJ Latin) (NN word) (NN stratum)))) (-RRB- -RRB-)))))) (, ,) (CC and) (S (NP (NN stratigraphy)) (VP (VBZ is) (NP (NP (DT the) (NN science)) (PP (IN of) (NP (NN strata)))))) (. .)))
Rock layers are also called strata (the plural form of the Latin word stratum ), and stratigraphy is the science of strata.
(ROOT (S (NP (PRP We)) (VP (VBP call) (NP (NP (DT the) (NN study)) (PP (IN of) (NP (NN rock) (NNS layers)))) (ADVP (RB stratigraphy))) (. .)))