( There ( ( is ( ( ( a ( submerged rock ) ) , ) ( ( known ( as ( Groin Baa ) ) ) ( to ( the north ) ) ) ) ) . ) )
(ROOT (S (NP (EX There)) (VP (VBZ is) (NP (NP (DT a) (JJ submerged) (NN rock)) (, ,) (VP (VBN known) (PP (IN as) (NP (NNP Groin) (NNP Baa))) (PP (TO to) (NP (DT the) (NN north)))))) (. .)))
There is a submerged rock, known as Groin Baa to the north.
(ROOT (S (NP (NP (DT A) (NN wall)) (PP (IN of) (NP (NP (NNS rocks)) (CC or) (NP (JJ concrete) (DT a))))) (VP (VBD called) (NP (DT a) (NN groin))) (. .)))