( ( An esker ) ( ( is ( ( ( a ( ( long ( , ( low ( , ( typically sinuous ) ) ) ) ) ridge ) ) ( of ( sand ( and ( gravel deposited ) ) ) ) ) ( along ( ( the course ) ( of ( ( a stream ) ( that ( tunneled ( through ( a ( wasting ( ice sheet ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (NN esker)) (VP (VBZ is) (NP (NP (DT a) (ADJP (JJ long) (, ,) (JJ low) (, ,) (RB typically) (JJ sinuous)) (NN ridge)) (PP (IN of) (NP (NN sand) (CC and) (NN gravel) (NNS deposited))) (PP (IN along) (NP (NP (DT the) (NN course)) (PP (IN of) (NP (NP (DT a) (NN stream)) (SBAR (WHNP (WDT that)) (S (VP (VBN tunneled) (PP (IN through) (NP (DT a) (NN wasting) (NN ice) (NN sheet)))))))))))) (. .)))
An esker is a long, low, typically sinuous ridge of sand and gravel deposited along the course of a stream that tunneled through a wasting ice sheet.
(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))))))))))) (. .)))