( it ( ( provides ( ( evidence ( ( ( ( for ( ( the ( long lifespan ) ) ( of ( proto-Pacific ( ocean basins ) ) ) ) ) , ) and ) ( therefore ( of ( ( ( potentially immense ) areas ) ( of ( oceanic crust ) ) ) ) ) ) ) ( that ( must ( have ( ( disappeared ( by subduction ) ) ( beneath ( ( the ( North ( American continent ) ) ) ( in ( Paleozoic ( and ( Mesozoic times ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP it)) (VP (VBZ provides) (NP (NP (NN evidence)) (PP (PP (IN for) (NP (NP (DT the) (JJ long) (NN lifespan)) (PP (IN of) (NP (JJ proto-Pacific) (NN ocean) (NNS basins))))) (, ,) (CC and) (PP (ADVP (RB therefore)) (IN of) (NP (NP (ADJP (RB potentially) (JJ immense)) (NNS areas)) (PP (IN of) (NP (JJ oceanic) (NN crust)))))) (SBAR (WHNP (WDT that)) (S (VP (MD must) (VP (VB have) (VP (VBN disappeared) (PP (IN by) (NP (NN subduction))) (PP (IN beneath) (NP (NP (DT the) (NNP North) (NNP American) (NN continent)) (PP (IN in) (NP (JJ Paleozoic) (CC and) (JJ Mesozoic) (NNS times)))))))))))) (. .)))
it provides evidence for the long lifespan of proto-Pacific ocean basins, and therefore of potentially immense areas of oceanic crust that must have disappeared by subduction beneath the North American continent in Paleozoic and Mesozoic times.
(ROOT (S (S (NP (DT This) (NN process)) (ADVP (RB usually)) (VP (VBZ takes) (NP (NP (DT the) (JJS longest) (NN amount)) (PP (IN of) (NP (NN time)))))) (: :) (S (NP (DT an) (NN ocean) (NN basin)) (VP (VBZ forms) (PP (IN between) (NP (CD two) (NNS continents))))) (. .)))
This process usually takes the longest amount of time: an ocean basin forms between two continents.