September 4, 2011

Geology Word of the Week: N is for Nummulite

Posted by Evelyn Mervine

Nummulite fossils. The small ones were collected near Notre Dame, France. Photo courtesy of Callan Bentley.

Nummulite fossils. The small ones were collected near Notre Dame, France. Photo courtesy of Callan Bentley.

def. Nummulite:
1. A fossil or living foraminiferan of the Nummulites genus (or a related genus) that has a disc-like, spiral, calcareous skeleton. Fossil nummulites range up to several inches in size, making them quite impressive protozoa (single-celled, eukaryotic organisms). Nummulite fossils are common in Tertiary rocks, particularly in the Mediterranean area. The term nummulite originates from the Latin word “nummulus,” which means coin.
2. The unwitting star of a very strange and scientifically bunk, yet somehow delightful, book titled “The Nummulosphere: An Account of the Organic Origin of So-called Igneous Rocks and Abyssal Red Clays” by Randolph Kirkpatrick.

Nummulites are beautiful and very distinctive fossils that are relatively easy to recognize in the field– they look like little coins set into the rocks. Because nummulites have calcium carbonate skeletons, they are generally found in limestone rocks. Nummulite fossils are even found in some of the limestone blocks used to construct Egyptian pyramids!

Ian Stimpson of the blog Hypo-theses sent me this beautiful photograph of nummulite fossils in limestone:

This Nummulitic limestone is from the Tertiary of the Spanish Pyrenees. The nummulites are up to 1cm across in this sample. Photo courtesy of Ian Stimpson.

Nummulites can be very small (microfossils) but can also range up to several inches (or centimeters, to use the more-scientific metric system) in size, such as the ~2 cm example in the top image. What is impressive about the size of these macro-nummulites is that all nummulites are protozoa, which means that they are single-celled organisms. I’m not much of a biologist, but those large nummulite fossils look like pretty big cells to me!

Lorraine Casazza of the University of California Museum of Paleontology does know a thing or two (or many things!) about biology and also about nummulites, which she studies. I highly recommend reading Casazza’s  description of her research on Egyptian nummulites. Casazza has some great discussion on how and why single-celled nummulites became so large. One reason that nummulites may have become so large is because of an interesting symbiosis with algae. Again, I’m not much of a biologist, but according to this abstract (thanks to Lockwood DeWitt for finding it), all modern nummulites house symbiotic algae.

Kirkpatrick's 1912 "Nummulosphere" book. Image taken from Wikipedia. The book is now in the public domain.

Nummulites are fascinating and important foraminifera, but they aren’t quite as important as indicated by Randolph Kirkpatrick in his self-published 1912 book “The Nummulosphere: An Account of the Organic Origin of So-called Igneous Rocks and Abyssal Red Clays.” In this book, Kirkpatrick claims that all rocks– including the “so-called igneous rocks”– actually formed through the accumulation of foraminifera such as nummulites. The book has a catchy and clever title, but alas the book is mostly pseudoscience and, fortunately, was not taken seriously by many scientists when it was published. In fact, Kirkpatrick’s crazy ideas about “The Nummulosphere” tarnished his scientific reputation. Kirkpatrick actually was a good scientist when it came to certain aspects of his work. Kirkpatrick had kooky– and very wrong– ideas about how rocks formed, but he was very good at studying the biology of sponges. However, much of his good scientific work on sponges was probably overlooked by his contemporaries because of his crazy ideas about how rocks formed. Not until a decade or so after his death was his work on sponges truly recognized.

Kirkpatrick is an intriguing example of a smart and capable scientist who fell victim to pseudoscience. Many scientists– myself included at times– fall victim to pseudoscience. Just because scientists are smart and educated doesn’t mean that they can’t fool themselves, even in their own research. For example, Linus Pauling won not one but two Nobel prizes but had some very strange (and now largely discredited) ideas about how taking large quantities of vitamins could make you live longer. Physicists Russell Targ and Harold Putoff convinced themselves that Uri Geller has “genuine” paranormal powers, even though it has been demonstrated repeatedly that Geller is likely using simple magic tricks. In my own family there is an excellent example of a very smart person believing in pseudoscience. Upton Sinclair (I was named after Upton’s cousin, my great-grandmother Evelyn Sinclair) wasn’t a scientist, but he was a brilliant writer, journalist, and political activist. However, my Uncle Upton (as I like to call him) also wrote a book called “Mental Radio” in which he described his belief that his second wife had telepathic abilities. I’m sorry, Uncle Upton, but your psychic experiments were not carried out in a proper scientific environment and, really, most long-married husband-wife pairs develop non-verbal communication that may seem telepathic at times. In my own scientific encounters, I’ve met many a scientist who is mostly rational and reasonable but who also believes in one or more flavors of pseudoscience: homeopathic medicine, talking to the dead, chiropractics, and so on.

I guess the main point I want to make is that scientists are smart, but they aren’t smart about everything. Just because someone is a smart and accomplished scientist does not mean that that person is always right. PhD or not, Nobel Prize or not, scientists are not always right. The great thing about science, though, is that (eventually) data and evidence always trump scientific reputation. For example, just because Linus Pauling had a PhD and two Nobel Prizes didn’t mean other scientists weren’t critical of views on vitamins. Perhaps his scientific prestige helped him push the vitamin idea at first, but eventually concrete data largely dismissed his pseudoscientific idea. Similarly, just because a scientist has one crazy or scientifically wrong idea does not mean that the scientist’s entire body of work should be dismissed. For example, Kirkpatrick’s work on sponges should not have been dismissed just because he didn’t understand rocks very well. Kirkpatrick is an extreme example. However, too often a scientist publishes a paper with an idea that is later dismissed, and then this scientist receives a “bad reputation,” and other scientists become critical of all of this scientist’s ideas. The whole point of science is putting ideas– hypotheses– out there. Just because one of a scientist’s hypotheses turns out to be wrong does not mean that all of this scientist’s hypotheses will be incorrect. We must remember that science is a process, not a popularity contest. Reputations should not matter where evidence and good (or bad) data abound. Of course, I do simplify. Some scientists have good (or bad) reputations for good reasons. Regardless, we must never let prestige or reputation blind our science– we scientists must strive to be as neutral as possible.

A final thought: be cautious when listening to a scientist talk about something that is clearly outside of that scientist’s field. For instance, I’m a geologist with specialties in marine geology, geochronology, and isotope geology. When I’m talking about one of those three specialties, you can probably trust what I say. However, if I’m talking about something else, you better make sure I’ve done my homework and actually know what I’m talking about. When I step outside of my scientific specialties, it is very important for me to talk to other scientists and develop collaborations. As I mentioned above, I don’t know very much about biology. So, if I were to take on a research project involving some biology (for example, a study of biological influences on rock weathering), it would be important for me to work with some biologists. Kirkpatrick was a biologist, not a geologist. Perhaps if he had worked with some geologists and had better understood geology, he would never have written his Nummulosphere book. That would have been a shame, though. Nummulosphere is such a wonderful-yet-terrible little volume.


“nummulite, n.” The Oxford English Dictionary. 2nd ed. 1989. OED Online. Oxford University Press. 4 September 2011.


***Thanks to Etienne Médard for suggesting this week’s word. Thanks to Callan Bentley and Ian Stimpson for providing pictures. Thanks to Lockwood DeWitt and Callan Bentley for some information and interesting discussion of nummulites on twitter.***