Are coral cays and coral atolls just volcanic islands?

Question

Are coral cays and coral atolls just a different type of volcanic island? When I hear: "volcanic island" I think at places like Moorea or Hawaii, but ultimately, coral cays and coral atolls lay their foundation on the residuals of a volcano, right?

Answer 1

You are mostly correct! Coral atolls aren't referred to as 'volcanic islands' because they are submerged underwater, but they do form on the remnants of once active volcanoes and seamounts. Coral cays are more a result of sedimentation and lithification on top of a pre-existing coral reef and are 'islands' because they are not submerged underwater!