Volcanic islands rarely appear where two plates meet; they appear in the middle of them. A h column o rock ri from de inside t mantle a burns thr the cr above i. The pl keeps moving, but the column stays put, so the volcano is carried away and a new one grows behind it. The result is a chain of islands whose ages increase steadily along its length, with an active peak at one end and worn, sinking remnants at the other.

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