Conversations with Professor Prestwich #8
CHARLES DARWIN AND ATOLLS

Dear Geoneophytes,

Many of you will have read of Charles Darwin’s error in Glen Roy: the misinterpretation of the famous Parallel Roads as marine shorelines when they were in fact the shorelines of a temporary lake dammed by ice. What can you, as students of scientific methodology, learn from this case? Simply that error is an essential part of the process of scientific investigation. In this particular case, Darwin’s arguments could not be sustained against the new paradigm of Ice Ages that began with Agassiz’s dramatic statement in Edinburgh; “Ice has done this.”

While in scientific error in Glen Roy, Darwin has proposed other ideas that seem much more promising. Natural Selection is a strong hypothesis, although many of my fellow citizens are very wary of the confrontational interface that they perceive with their religious faith. Equally strong (and much less controversial) are Darwin’s ideas on the formation of coral atolls.

During the voyage of the Beagle, Darwin visited many islands in the Pacific and Indian Oceans that were to one extent or another surrounded by coral reefs; he recognized a sequence that starts with reefs that are attached to volcanic islands, proceeds through volcanic islands with a circumferential lagoon and barrier reef and ends with an atoll - the enigmatic circular reef surrounding a deep lagoon but with no island in the middle. He ascribes this sequence, in my opinion quite correctly, to the gradual sinking of the volcano as it becomes extinct and sinks beneath the waves: the corals continue to grow upwards, maintaining themselves at sea level. I only wish I could think of an explanation for the fact that the islands in the Pacific occur in linear array. Ah well, I can’t solve everything: maybe you can help.

Fondly,

Joseph Prestwich