( ( The lake ) ( ( is ( ( ( a ( crater lake ) ) , ) ( ( a basin ) ( formed ( on ( ( an ( old ( volcanic cone ) ) ) ( that ( ( was later ) ( filled ( with water ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN lake)) (VP (VBZ is) (NP (NP (DT a) (NN crater) (NN lake)) (, ,) (NP (NP (DT a) (NN basin)) (VP (VBN formed) (PP (IN on) (NP (NP (DT an) (JJ old) (JJ volcanic) (NN cone)) (SBAR (WHNP (WDT that)) (S (VP (VBD was) (ADVP (RB later)) (VP (VBN filled) (PP (IN with) (NP (NN water))))))))))))) (. .)))
The lake is a crater lake, a basin formed on an old volcanic cone that was later filled with water.
(ROOT (S (NP (NNS Craters) (CC and) (NNS rifts)) (VP (VBP become) (NP (NNS lakes)) (SBAR (WHADVP (WRB when)) (S (NP (PRP they)) (VP (VBP fill) (PP (IN with) (NP (NN water))))))) (. .)))