( ( Longshore drift ) ( ( ( carries ( particles ( of ( ( sand and ) rock ) ) ) ) ( down ( a coastline ) ) ) . ) )
(ROOT (S (NP (NNP Longshore) (NNP drift)) (VP (VBZ carries) (NP (NP (NNS particles)) (PP (IN of) (NP (NN sand) (CC and) (NN rock)))) (ADVP (RB down) (NP (DT a) (NN coastline)))) (. .)))
Longshore drift carries particles of sand and rock down a coastline.
(ROOT (S (NP (NP (NNS Particles)) (PP (IN of) (NP (NN sand) (CC and) (NN rock)))) (VP (VBP are) (VP (VBN carried) (PP (IN by) (NP (JJ longshore) (NN drift))))) (. .)))