Geologically, what is the best way to explain the thousands of metres of coral limestone beneath most atolls?
A) Sea level has fallen thousands of metres since the reef began to grow.
B) The volcano never reached the surface, but built a very thick cap of coral limestones from its deep submarine hot springs emissions.
C) The eroded volcano slowly sank as sea level remained steady or rose gradually.
D) An eroded volcanic seamount rose thousands of metres after the limestone formed.

Question

Quizplus · Accepted Answer

The correct explanation is that the volcanic base of an atoll tends to sink over geological time due to the weight of the accumulating coral limestone and the natural subsidence of the oceanic crust. As the volcanic island erodes and sinks, coral growth continues upwards towards the sunlight, resulting in the thick deposits of coral limestone seen today. Sea levels may also rise gradually, but the primary factor is the sinking of the volcanic base beneath the growing coral reef.

Geologically, What Is the Best Way to Explain the Thousands