Why is Rose Atoll different from the volcanic islands of American Samoa?

Rose Atoll is fundamentally different from the other islands of American Samoa because of its geological composition and formation. While the primary islands of the territory are rocky and formed by volcanic activity, Rose Atoll is a coral atoll.123

Volcanic islands in the region are characterized by high elevations, such as mountains formed by past eruptions, and are often ringed by reefs. In contrast, an atoll represents a different stage of development. According to the subsidence theory, an atoll forms as a coral reef grows upward around a sinking, extinct volcanic island. Eventually, the original volcanic cone becomes completely submerged, leaving behind a low-lying ring of coral that encloses a lagoon.245

Consequently, Rose Atoll is extremely low-lying, with its constituent islands rising no more than 10 feet (3 meters) above sea level, lacking the mountainous terrain found on the volcanic islands of the archipelago.1