How does plate tectonics help explain the development of Pacific coral atolls?

Plate-tectonic theory provides a geological mechanism for the development of Pacific coral atolls by explaining the subsidence of the ocean floor. As the ocean floor spreads outward from oceanic ridges, it cools and gradually subsides.1

This process supports the subsidence theory of Charles Darwin, which posits that atolls form as coral reefs grow upward to keep pace with a sinking volcanic island. Initially, a reef fringes a volcanic island; as the island subsides due to the movement and cooling of the underlying oceanic crust, the reef continues to grow upward, eventually becoming a barrier reef separated from the island by a lagoon. Once the volcanic cone is completely submerged, only the ring-shaped coral reef remains at the surface, forming an atoll. The Hawaiian Islands serve as a classic example of this progression, where reefs transition from barrier stages in the southeast to atolls in the northwest as the seafloor moves away from the volcanic source.12