An exhibit called The Art of Science will be at indi go art co-op between March 31st and April 2nd. An opening reception is on the 31st from 6:00–8:30 p.m. The exhibit features various images that were taken using the ultra high-tech equipment at the Institute for Genomic Biology at the University of Illinois. While the images were all originally taken for scientific reasons, they were selected for the exhibit based on their aesthetic qualities.
As a preview, Melissa McKillip, Director of Development for the institute, showed me one of the images (pictured below) that will be in the exhibit — an image taken using a high resolution digital camera of a sample of limestone (called travertine) collected from an ancient aqueduct southeast of Rome in Romavecchia. The travertine was deposited from water flowing along the aqueduct channel.
McKillip also put me in touch with Professor Bruce Fouke, Professor in Geology, Microbiology, and the Institute for Genomic Biology at the UI, who is the scientist who originally collected the sample in Rome and brought it back to Illinois for analysis. I spoke with Fouke recently about this particular image and the work associated with it.
One thing leads to another
Fouke, who is trained as a geologist, told me that he didn’t set out to study ancient Roman aqueducts; he was in Italy as a geologist looking at travertine as it is deposited naturally in hot springs, and one thing led to another:
I was studying travertine that forms in natural hot springs that occur throughout the Apennine Mountains. In the process, I met archaeologists from Italy as well as at Illinois. Much is known of when the aqueducts were built. However, knowledge of the use of aqueducts during and after the fall of Rome is poorly known because the written record is minimal. One of the benchmarks that comes out in the written record is the date of 537 AD when the Ostrogoths breached the walls of Rome.
From there, Fouke and his colleagues came up with an historical question, and decided to look at it scientifically.
The idea was that the Ostrogoths were thought to have broken down the infrastructure of the Roman Empire and that’s when the aqueducts supposedly stopped flowing. I’d been in Rome enough to be fascinated — like we all are — by these monuments. When I hear a number like 537 AD, as a scientist, I think ‘That’s very specific. How do you know? What’s your evidence?’ As it turned out, after I did some digging around, the evidence is pretty much one paragraph in a hard-to-access library that supported aqueduct disuse at 537 AD.
That’s when I proposed that we take the scientific analysis of the travertine that was formed in the aqueduct, analyze the layers optically and chemically, and come up with our own independent evaluation of the date of last flow of aqueduct water.
Obstacles and some help from digital technology
Fouke and his colleagues needed samples of the travertine that had chemically precipitated as calcium carbonate mineral deposits from flow aqueduct water near Rome. However, it was a long time before his team was able to get the required sample permits, due to the (understandable) reluctance of the modern Italian government to let people collect small pieces of their cultural treasures.
Fouke had been studying the aqueducts for nearly five years when, in June of 2010, the permits suddenly came through from the Italian government to collect samples from the Anio Novus Aqueduct. Along with a student and an Australian colleague, he took three small samples. The 20 cm thick samples were taken using a hammer and chisel, then cut on a diamond saw back in Illinois and photographed using a digital camera at the Institute for Genomic Biology.
According to Fouke, recent developments in digital technology have advanced science tremendously in recent years, and allowed him to look at his travertine samples in a manner not previously possible:
What I call the ‘imaging revolution’ has been phenomenal; it has fundamentally changed everything we can do in the geosciences, as well as the life sciences. The new imaging capabilities now let us look at materials with transmitted light — in other words the kind of light you have in a room… white visible light. We can shine that light through very thin slices of material, be it metal, rocks, tissues, or anything. And we can use this new imaging technology to do analyses at scales that are generally 100 to 1,000 times smaller than what we could do even ten years ago. That’s fundamentally opened up a new regime of scientific possibility.
The area of research that’s combining geology and the life sciences with things like archaeology is called Geobiology. With the new imaging technology, we can now conduct geological analyses at and below the same spatial scale as the size of a single bacterial cell. This has allowed us to make revolutionary breakthroughs in Geobiology.
Reaching some conclusions
Fouke elaborated on his analysis of the travertine taken from the aqueduct and commented on the layering of the travertine clearly visible in the above image in this article:
Travertine is a well known and common building stone, having been used to construct major portions — or all — of some of the most famous buildings in the world, including the Colosseum, the Vatican, the Baths of Caracalla, as well as many cathedrals throughout the world. The fine dark-light layering that is characteristic of travertine is strikingly beautiful. With the new imaging techniques, each layer can be scrutinized to determine what forces may have caused them. Various examples are the dark-light layers caused by ancient climate change, changes in water flow, changes in water chemistry, or perhaps even changes in the types of bacteria that lived within the aqueduct.
As a geologist, you can look at those layers now and reconstruct time in a manner similar to that of tree rings.
From his analyses of the travertine from the aqueduct — and also from analyses of samples taken from the Baths of Caracalla, Fouke and his colleagues reached the conclusion that the aqueducts had actually been flowing for centuries after the date of 537 AD: “We have good evidence now that the flow continued for at least 400 years longer than what was previously recorded. We have a lot of dates now that go back to 950 AD. As geologists, we deal in scales of millions of years, but for an archaeologist, 400 years where the aqueducts are still flowing is a big deal.”
Basically, Fouke reached the conclusion that while the Roman Empire collapsed after the Ostrogoths invaded Rome, the invaders kept the aqueducts flowing — for a few centuries at least: “The Ostrogoths were smart people. When they took over Rome, instead of destroying all of the infrastructure, they said, ‘Hey Romans, keep doing what you’re doing on some level, give us the profits and the water, and keep the aqueducts running.'”
Fouke and his colleagues then did some traditional historical research to back up his findings: “Once we got those dates, we went back to libraries around Rome, as well as at Illinois, and we did find some evidence in the written record about massive amounts of water flowing to the area of St. Peter’s Piazza at the Vatican. Indigent people were apparently required to bathe prior to being given food.”
In any era, keeping up the aqueducts was no small endeavor:
It took armies of slaves to remove the rapidly forming travertine deposits and thus keep the aqueducts flowing. The aqueducts contained a series of manholes for maintenance. The slaves were sent in with acetic acid and a trowel to scrap off the travertine deposits. The job of these slaves, for their whole lives, was to crawl through these dark, dank, wet aqueduct channels and clean out the travertine.
Fouke explained that while the Ostrogoths and others kept the aqueducts flowing, the maintenance during that period wasn’t as good as it should have been, and eventually the accumulated deposits of travertine nearly sealed the aqueducts and the flow of water stopped: “The aqueducts eventually kept flowing until they nearly self-sealed, with more than a meter of travertine in many locations.”
The aqueduct travertine itself, however, proved useful to future generations, and because of its aesthetic qualities was favored over naturally deposited travertine for special building projects:
Later when the aqueducts were broken down for various reasons, some of the most valued travertine for use in church altars came from aqueducts. Aesthetically, people building these altar pieces preferred the travertine from aqueducts from the travertine that grows in the natural hot springs. This is presumably due to the enhanced high-contrast nature of the dark-light layering of the aqueduct travertine.
“Strikingly beautiful”
Aqueduct travertine is still prized for its beauty, which is one of the reasons why Fouke decided to use this particular image for presentation alongside his academic work, and why it was eventually selected for The Art of Science exhibit. He explained his criteria, in general, when selecting an image to take public alongside his academic work:
The number one thing, of course, is for an image to capture the fundamental scientific aspects. When selecting images for public presentations, the optimal is to have an image that is strikingly beautiful that also carries the required scientific content. I was delighted with the image of that sample we collected from the Anio Novus aqueduct. You never really know what you’re going to get until you prepare any given sample and see the final image.
Cross-disciplinary
Fouke was highly enthusiastic when he talked about how various academic disciplines came together in the case of his work with the Anio Novus aqueduct, and credits advancing technology for this kind of research being possible:
The primary goal of this project was to be able to reconstruct the age of the last flow of water in the aqueduct — because this is poorly known. A complementary incentive was to reconstruct the chemical integrity of the aqueduct water during that time period. Therefore, the project evolved naturally from geological to an unexpected interdisciplinary geo-archaeology project.
That’s just how this work evolved. That’s the beauty of bringing science, and the humanities, and literature together. You can cross-pollinate, so to speak, and answer compelling questions in multiple fields.