Scientists believe that the Hawaiian island chain as it currently exists was formed as sea-floor spreading caused the Earth's crust to slowly move over a stationary point of volcanic activity in the mantle of the Earth.
While above the area of activity, volcanic eruptions formed the islands, and as sea-floor spreading moved the newly formed island off the area of activity, other new islands formed leading to the seven islands that now exist. The largest island in the chain is the only one that is currently volcanically active, suggesting that it is still above the active region on the mantel.
If this is true, which of the following should be observed?