Charles Darwin – Coral Reefs

As Europeans plied the seas in search (and ultimately management) of colonies and conquests, they learned the practical geology they needed to find their way and avoid wrecks. Everyone knows that Charles Darwin’s opportunity to spend several years on the Beagle ultimately rested on the British Admiralty’s need to improve navigation maps, especially along the South American coasts. The near shore conditions change, some of the existing maps were not adequate, and the size of ships was increasing so once-safe passages no longer necessarily were. The Beagle’s Captain Fitzroy had a reputation was for tenacious accuracy in map making and navigation, and the fact that a one or two year voyage (as planned) more than doubled in its time is a testament to this.

Repost from gregladen.com

One of the features critical to navigation is the coral reef. Reefs provided an excellent way to wreck your ship in a storm as well as one of the best ways to harbor a ship. By the time of Darwin’s voyage, the world’s preeminent geologist, Charles Lyell (1797 – 1875), has advanced the previously extant notion that reefs were formed on old volcanoes. The Beagle launched in December 1831, and in 1832 Lyell published Volume II of “Principles of Geology” with a chapter on the reefs, in which he gave the volcanic explanation his refinement and his blessing.

When I read about Darwin, and when I read what he wrote, I am convinced that he stepped onto the Beagle as a geologist. Geologizing (as they called it back then) was what really turned him on, and it is what captured much of his attention in anticipation of visiting many of the Beagle’s destinations, and it is what brought him to some of his more adventurous inland journeys.

Be that as it may, the situation was this in 1831/2: The standing belief among geologizers of the time was that coral reefs were organic colonies grown up on volcanic rims. Coral reefs that did not look like they were build on volcanic rims were explained as being, well, complicated and difficult to interpret.

When Darwin went off on the voyage, he was young and unsure of his place among the well established natural historians (the geologizers and biologizers) of the time. He was a student and very willing to learn, and may have had less self confidence than, to make a rough comparison, the average second or third year graduate student of today. In short, he was in awe of his elders, and unsure he would ever meet their lofty standards.

This was probably no more true than in the case of Charles Lyell, one of the leading scientists of the day. There is a story in Stone’s fictionalized biography of Darwin that I do not know the veracity of. It concerns Darwin’s first visit to Lyell’s home. Mrs. Lyell has excused herself to the kitchen to make tea. Darwin and Lyell are engaged in a conversation in which Darwin makes some clever point or asks a sticky question. Lyell walks to a dining room chair and turns it to face himself. He then bends at the waist, placing his forehead on the chair’s seat. Lyell remained thus, silently bent over onto the chair, with his head pressed to it, for a few minutes. Darwin, unsure of what to do waits silently for … who knows what? Eventually, Mrs. Lyell returned from the kitchen. Seeing Darwin visibly mortified and unsure of what to do, she explains “Oh, this is How Charles thinks. He’ll be done in a minute…”

Whatever.

The point is that Lyell was a big man in his field. The biggest man in Geology. A big, somewhat strange man, indeed. So when Darwin went off on the voyage, with Lyell’s Principles of Geology Volume I in hand and Volume II to catch up with him later, he essentially followed in Lyell’s footsteps, working out new geological sequences and descriptions, refining older descriptions, and so on.

But not long into the Voyage Darwin began to re-conceptualize what a coral reef was, how it formed, and in fact, to develop ideas of reef dynamics and classification that were light years ahead of the prevailing thinking at the time. He wrote letters home that ended up (to Darwin’s chagrin) being read and disseminated among the Royal Society members explaining Lyell’s conception was wrong. On returning from the Voyage, he was faced with the grave task of meeting Lyell again and providing his evidence that the coral reefs were formed in a very different way than Lyell had laid out in the last chapter of Principles Volume II.

Darwin ended up writing an extensive monograph on the coral reefs, and I want to give you a flavor of it here. He begins by reclassifying the reefs and describing several classic cases. He provides intensive discussion rich in description of the process of reef formation and erosion. Throughout the text he continuously tests the idea of growth of coral on extant geological formations against the idea of reefs growing, essentially, to keep up with the light zone near the sea’s surface as the ocean subsides. (It was not until much later that general ocean subsidence observed in all seas was realized to be eustatic sea level rise due to melting glaciers … duh… but Darwin can be forgiven that bit of misgeologizing. Nobody got that at the time, apparently.)

One gets the sense that Darwin does not want to get anything wrong. He wants to make his case as strongly as possible, he wants to fit all of the observations he can into the monograph to support his case and as a matter of duty.

A contemporary of Darwin’s, one Colonel Jackson, provides a long winded but in my view dead-on-the-money description of what Darwin accomplished in a review of his coral reef monograph. I wonder if I can get the Colonel’s sense across without bludgeoning you with too much of his Victorian prose.

“…we have too frequently [seen] theories … raised upon the insufficient foundation of a few isolated facts; …[and] … we have often occasion to regret that an immense number of valuable observations on the most interesting and important subjects remain dispersed, and therefore almost useless, long after there is more than enough from which to deduce some satisfactory conclusion. Ever prone to extremes, we either begin to build without sufficient materials, or go on collecting long after we have an abundant supply to complete the structure. … the former of these errors … springs from vanity, and ends in disappointment: … the latter, … is … attributed to ignorance,…of what has been done, and [failure] to make a proper use of what is already [known].
… what an immense addition to our knowledge of the laws of nature [could be gleaned from many sources]…and judiciously arranged!… and new truths… added to the mass of human knowledge. A better testimony to the justice of this remark can hardly be afforded than in the work before us–Mr. Darwin’s ‘Structure and Distribution of Coral Reefs.’ To … a perfect acquaintance with what has been observed and written by others on coral reefs–Mr. Darwin has added his own personal examination of a great many of those interesting structures; and, from the manner in which he has grouped the facts, and then reasoned upon them, the mind remains satisfied that he [totally figured them out].”

[Jackson, 1842. [review of] The Structure and Distribution of Coral Reefs: Being the First Part of the Geology of the Voyage of the ‘Beagle,’ under the Command of Capt. Fitzroy, R. N., during the Years 1832 to 1836. Journal of the Royal Geographical Society of London 12: 115-120.]

It seems that Darwin never missed an opportunity to conduct an experiment or test a hypothesis, preferably by doing something yucky, as he describes here:

On the outside of the reef much sediment must be formed by the action of the surf on the rolled fragments of coral; but, in the calm waters of the lagoon, this can take place only in a small degree. There are, however, other and unexpected agents at work here: large [schools] of two species of Scarus, one inhabiting the surf outside the reef and the other the lagoon, subsist entirely… by browsing on the living polypifers. I opened several of these fish, which are very numerous and of considerable size, and I found their intestines distended by small pieces of coral, and finely ground calcareous matter. This must daily pass from them as the finest sediment;

[Darwin, C. R. 1842. The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the Beagle, under the command of Capt. Fitzroy, R.N. during the years 1832 to 1836. London: Smith Elder and Co. Page 14.]

It appears that Lyell had little trouble having his model coral reefs overturned. Perhaps that is partly because it was not really his idea, but rather what has been stewing for some time, formalized and advanced by him. Perhaps it was because Lyell was a nice guy. All that could be true, but it is also undoubtedly true that any geologizer of the day regardless of their temperament or sense of academic territoriality would have had difficulty disregarding Darwin’s 200+ page detailed and carefully researched and documented monograph. In no one place was there more attention to details. No other chapter or volume advanced such a cogent argument. Darwin nailed the science of the reefs and one couldn’t really disagree.

This approach, of comprehensive, extensive, intensive and integrated demonstration and synthesis would characterize all of Darwin’s monographs including, of course, the Origin of Species (a little book he put out during his Biologizing Phase…). In some ways I think of this approach as having been required by subsequent researchers because of the quality and influence of Darwin’s monographs. I have not read enough pre 1842 material to be sure of this, but I would be interested to see if Darwin’s style represented a turning point in how science operated. If so, then Darwin needs to be accredited with something other than The Origin of Species as his most important work. If it is true that Darwin hatched, or was mainly responsible for the advancement of, this method of scientific “monographizing,” then he is really the father of Modern Science. Armed with this new approach to science, Darwin’s Five Theories of Evolution would have emerged without The Origin but nonetheless because of his influence.

This is part of the following series of posts on gregladen.com:

Charles Darwin Bicentennial
Charles Darwin Bicentennial – A Tangled Bank
Charles Darwin Bicentennial- Beagle and The Voyage
Charles Darwin Bicentennial – Coral Reefs
Charles Darwin Bicentennial – Finches
Charles Darwin Bicentennial – Gauchos
Charles Darwin Bicentennial – Iguanas, a “most disgusting, clumsy lizard…
Charles Darwin Bicentennial – Notebooks

Comments

  1. #1 Adrian Thysse
    February 13, 2008

    Nice article Greg, and a a great series for the Bicentennial. Coincidentally today I touched on coral reefs on my final (and short) ‘Darwin’s Birthday on the Beagle’ entry, when he is in Hobart prior to departing for the reef research at the Keeling Islands.

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