Pearl and Hermes Reef, consisting of many small islets, can be seen in this beautiful, near-vertical-looking photograph. A lagoon is visible near the center of the photograph. This reef, like all of the Hawaiian Island chain, is volcanic in origin, having been born nearly 70 million years ago as the Pacific crustal plate gradually drifted northwest over a hot spot-a source of magma in the Earth's crust. As the volcanic island gradually moved away from the hot spot, erosion of the island began. The greatest portion of the original volcanic island that made up Pearl and Hermes Reef has long since eroded away. Today, the reef is a bird sanctuary.