( ( ( ( ( Iceland sits ) ( astride ( the ( volcanic ( Mid-Atlantic Ridge ) ) ) ) ) , ) ( ( its back ) ( against ( the ( Arctic Circle ) ) ) ) ) . )
(ROOT (NP (NP (NNP Iceland) (NNP sits)) (PP (IN astride) (NP (DT the) (JJ volcanic) (NNP Mid-Atlantic) (NNP Ridge))) (, ,) (NP (NP (PRP$ its) (NN back)) (PP (IN against) (NP (DT the) (NNP Arctic) (NNP Circle)))) (. .)))
Iceland sits astride the volcanic Mid-Atlantic Ridge, its back against the Arctic Circle.
(ROOT (S (NP (NNP Iceland)) (VP (VBZ sits) (PP (IN on) (NP (DT the) (JJ mid-atlantic) (NN ridge)))) (. .)))