What is the first step of the Darwin-Dana theory of coral atoll formation?

The first step of the Darwin-Dana theory of coral atoll formation is that an oceanic volcano rises and forms an island. This process begins with a submarine volcano that erupts and builds up to create an island above the ocean surface. Once this volcanic island is formed, coral polyps can begin to establish themselves in the surrounding waters. As the coral grows, it forms a fringing reef around the island. Over time, geological processes such as subsidence can cause the island to sink or erode, leading to the development of a barrier reef and eventually an atoll formation if the conditions are right. This sequential understanding highlights the importance of volcanic activity as the initial catalyst for atoll development in marine environments.