Bermuda: A seamount in the Atlantic

Image: One of our researchers standing atop Bermuda's prehistoric limestone formations


Walking around Bermuda, you will see many houses constructed from white limestone brick and amazing weathered limestone pillars edging the white sandy bays. Some visitors may not realize that the island is actually standing on an extinct black, basalt rock volcano.

Bermuda's earliest beginnings

Bermuda originated 110 million years ago when intense geological activity along the junction of the European and American tectonic plates formed a massive basalt rock volcano (seamount) in the mid-Atlantic Ocean. Over time, the submerged seamount, which was in shallow, warm water with plenty of light, attracted reef-building corals that settled on the extinct volcano and thrived.

As sea levels rose, and the seamount eroded, reef-building corals grew on top of one another to be close to the light. As more coral grew, the crushed coral skeletons ground down into sand, which was compacted under pressure and gradually become solid limestone rock in a process called lithificaiton. This process is ongoing, with limestone rock from this ‘old reef’ forming the island of Bermuda and the base of its fringing reef, which we have been surveying for the last week.

The value of coral reefs to Bermuda

Coral reefs in Bermuda provide vital protection for the coastline, a food source for residents and jobs in the tourism and fishing industries. The coral reefs of Bermuda have played a central role in creating the island ‘atoll’ and even in bringing the first people to the area!