( ( Gravity causes ) ( ( ( ( stress ( for ( ( slope materials ) ( such ( as ( ( rocks and ) soil ) ) ) ) ) ) , ) ( because ( it ( ( is constantly ) ( acting ( to ( try ( to ( pull ( the ( materials downslope ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Gravity) (NNS causes)) (VP (VBP stress) (PP (IN for) (NP (NP (NN slope) (NNS materials)) (PP (JJ such) (IN as) (NP (NNS rocks) (CC and) (NN soil))))) (, ,) (SBAR (IN because) (S (NP (PRP it)) (VP (VBZ is) (ADVP (RB constantly)) (VP (VBG acting) (S (VP (TO to) (VP (VB try) (S (VP (TO to) (VP (VB pull) (NP (DT the) (NNS materials) (NN downslope))))))))))))) (. .)))
Gravity causes stress for slope materials such as rocks and soil, because it is constantly acting to try to pull the materials downslope.
(ROOT (S (NP (NNP Gravity)) (VP (VBZ makes) (SBAR (S (NP (NN soil) (CC and) (NN rock) (NNS particles)) (VP (VBP move) (ADVP (RB gradually)) (ADVP (RB down) (NP (DT the) (NN slope)) (PP (IN during) (NP (DT each) (NN thaw)))))))) (. .)))