( ( Watch ( ( ( which ( settles first ) ) and ) ( how ( ( layers ( of sediment ) ) form ) ) ) ) . )
(ROOT (S (VP (VB Watch) (SBAR (SBAR (WHNP (WDT which)) (S (VP (VBZ settles) (ADVP (RB first))))) (CC and) (SBAR (WHADVP (WRB how)) (S (NP (NP (NNS layers)) (PP (IN of) (NP (NN sediment)))) (VP (VBP form)))))) (. .)))
Watch which settles first and how layers of sediment form.
(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.