( ( ( ( Esker ( A ( ( long ( , ( narrow ( , ( often curving ) ) ) ) ) ridge ) ) ) or ) ( mound ( of ( sand ( , ( ( gravel and ) boulders ) ) ) ) ) ) ( ( ( ( deposited ( by ( ( a stream ) ( flowing on ) ) ) ) , ) ( ( ( within or ) beneath ) ( a ( stagnant glacier ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (NNP Esker)) (NP (DT A) (ADJP (JJ long) (, ,) (JJ narrow) (, ,) (RB often) (JJ curving)) (NN ridge))) (CC or) (NP (NP (NN mound)) (PP (IN of) (NP (NN sand) (, ,) (NN gravel) (CC and) (NNS boulders))))) (VP (VBD deposited) (PP (IN by) (NP (NP (DT a) (NN stream)) (VP (VBG flowing) (PRT (RP on))))) (, ,) (PP (IN within) (CC or) (IN beneath) (NP (DT a) (JJ stagnant) (NN glacier)))) (. .)))
Esker A long, narrow, often curving ridge or mound of sand, gravel and boulders deposited by a stream flowing on, within or beneath a stagnant glacier.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN esker)) (VP (VBZ is) (NP (NP (DT a) (JJ winding) (NN ridge)) (PP (IN of) (NP (NN sand))) (SBAR (S (VP (VBD deposited) (PP (IN by) (NP (NP (DT a) (NN stream)) (PP (IN of) (NP (NP (NN meltwater)) (VP (VBN called))))))))))) (. .)))