( It ( ( follows ( that ( ( ( the areas ) ( of ( the ( two ( shaded portions ) ) ) ) ) ( are ( ( proportional ( to ( ( the bulk ) ( of ( the ( ( continents and ) oceans ) ) ) ) ) ) respectively ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ follows) (SBAR (IN that) (S (NP (NP (DT the) (NNS areas)) (PP (IN of) (NP (DT the) (CD two) (JJ shaded) (NNS portions)))) (VP (VBP are) (VP (VBG proportional) (PP (TO to) (NP (NP (DT the) (NN bulk)) (PP (IN of) (NP (DT the) (NNS continents) (CC and) (NNS oceans))))) (ADVP (RB respectively))))))) (. .)))
It follows that the areas of the two shaded portions are proportional to the bulk of the continents and oceans respectively.
(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.