( ( In ( ( the identification ) ( of ( soil horizons ) ) ) ) ( , ( ( an ( uppercase letter ) ) ( ( represents ( the ( major horizons ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NP (DT the) (NN identification)) (PP (IN of) (NP (NN soil) (NNS horizons))))) (, ,) (NP (DT an) (JJ uppercase) (NN letter)) (VP (VBZ represents) (NP (DT the) (JJ major) (NNS horizons))) (. .)))
In the identification of soil horizons, an uppercase letter represents the major horizons.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (VP (VBD represented) (PP (IN by) (NP (DT a) (JJ single) (NN letter)))))) (, ,) (NP (JJ dominant) (NNS alleles)) (VP (VBP are) (VP (VBN represented) (PP (IN by) (NP (JJ uppercase) (NNS letters))))) (. .)))