( ( Under ( ( laboratory conditions ) ( with ( particles ( larger ( than ( a micron ) ) ) ) ) ) ) ( , ( gravity ( ( ( ( causes ( sedimentation ( of ( the particles ) ) ) ) , ) ( ( forming ( a ( thin ( horizontal layer ) ) ) ) ( at ( ( the bottom ) ( of ( the plasma ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Under) (NP (NP (NN laboratory) (NNS conditions)) (PP (IN with) (NP (NP (NNS particles)) (ADJP (JJR larger) (PP (IN than) (NP (DT a) (NN micron)))))))) (, ,) (NP (NN gravity)) (VP (VBZ causes) (NP (NP (NN sedimentation)) (PP (IN of) (NP (DT the) (NNS particles)))) (, ,) (S (VP (VBG forming) (NP (DT a) (JJ thin) (JJ horizontal) (NN layer)) (PP (IN at) (NP (NP (DT the) (NN bottom)) (PP (IN of) (NP (DT the) (NN plasma)))))))) (. .)))
Under laboratory conditions with particles larger than a micron, gravity causes sedimentation of the particles, forming a thin horizontal layer at the bottom of the plasma.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NNS sediments)) (VP (VB settle) (PRT (RP out)) (PP (IN of) (NP (NN water)))))) (, ,) (NP (PRP they)) (VP (VBP form) (NP (JJ horizontal) (NNS layers))) (. .)))
When sediments settle out of water, they form horizontal layers.