Lilly Sallinger’s Reviews > Coral Reefs > Status Update

Fringing-reefs are thus converted into barrier-reefs; and barrier-reefs, when encircling islands, are thus converted into atolls, the instant the last pinnacle of land sinks beneath the surface of the ocean (p. 147).

The significance of coral reefs is that there is so much that Darwin is telling the readers about reefs and so many different facts that no one knew to try and inform the audience and give them better knowledge on coral reefs. Obviously I think coral reefs would be looked at a different way if the rhetorical situation was the purpose. The subject and purpose of this book are completely different.