Acrack in the crust near iceland is what is thought to have started the breakup of pangaea. as this crack grew larger, the ocean grew, and the ocean shrank

Atlantic and the pacific.

Explanation:

The Pacific plate is known as the shrinking plate and is moving at a speed of about 7-11 cm in a year,  in the northwestwards due to the spreading or the opening up of the Atlantic plates due to the mid-oceanic ridge and in the S-shaped patterns of the ocean between western Europe and eastern America.

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