Friday Rocks: K/T Boundary

My Friday Rocks photo shows the K/T boundary, aka the Cretaceous/Tertiary Boundary. I took this photograph in August 2011, when I was out in the field with the Dig School, a wonderful education program co-founded by Burke Museum paleontologists Greg Wilson and Lauren DeBey. We were about 16 miles north of Jordan, Montana. The site is known to paleontologists as Lerbekmo Hill, after geologist Jack Lerbekmo. One of the highlights of the spot is that I could place my hand on the iridium anomaly layer, the famous bed of material that helped geologists understand what happened to the dinosaurs, and many others, at the end of the Cretaceous. In addition, about ten miles away is the location where Barnum Brown found the first specimen of Tyrannosaurus rex. It’s certainly one of the niftiest spots for any geogeek to visit.

Here is another view of the location showing the different layers.

K/T Boundary

The Duomo and the Dinosaur: Not?

Finally we have a nice uniting of science and religion and boy has it titillated the Internet. Apparently for the past 350 years or so the fine parishioners of the Cathedral of St. Ambrose (aka Sant’Ambrogio) in Vigevano, Italy, have been praying and genuflecting with a dinosaur fossil in their midst, or so says paleontologist Andrea Tintori. The fossil has been right in their sight, in fact just to the left of the center of their altar, though there are a few skeptics who doubt Tintori’s observations. (read further)

Photo from Discovery News, courtesy of Andrea Tintori

University of Milan paleontologist Tintori has determined that the early Jurassic age (~190mya)-stone slab contains the cross section of a dinosaur skull with visible nasal cavities and numerous teeth. Total length is about 12 inches. Tintori also found a second part of the skull in another slab. He hopes to get the first slab removed to do additional work.

Photo from Discovery News, courtesy of Andrea Tintori

Built between about 1532 and 1660, the cathedral, or duomo in Italian, contains a wide array of stone. The fossil-rich slab comes from quarries in Arzo, Switzerland, about 40 miles due north of Vigevano. They were first opened in the thirteenth century but didn’t become widely used till the seventeenth and eighteenth centuries, when the stone was used primarily for altars. It is a purple-red, grey-veined limestone with skeletal grains of crinoids and goes by various names but broccatello (brocaded) is the most common. (I wonder why builders wanted this stone for altars. Is there something about its color and pattern that conveys a message suitable to getting closer to God?)

The broccatello became popular as a replacement for the legendary Portasanta stone of Rome, the rock used for the Holy Door (Porta santa) of St. Peter’s Basilica in Rome. Builders often combined the Arzo stone with red and grey limestone from Bergamo, black limestone from Lake Como, and white marble from the Apuan Alps. You can see the broccatello throughout Italy and Switzerland. No other dinosaur fossils have been reported.

In regard to Tintori’s dinosaur, one person I corresponded with wrote back. “ALERT: this seems to be a cross-section of an ammonite!”

After my initial posting, I received one more note about the fossil.Ammonites are well known from the Broccatello Formation, which is entirely marine and devoid of terrigenous sediment derived from the continent. The Broccatello preserves a rich fauna of marine fossils, sponges, sea lilies, brachiopods, bryozoans, solitary corals and the like and has been deposited in waters near the base of the photic zone [down to 600 feet]. The preservation looks also typical for an ammonite. The test [or shell], originally composed of the mineral aragonite, an unstable form of calcium carbonate would have been dissolved and the void filled by calcite, the stable mineral form of calcium carbonate. The photograph is not good enough to see the crystal fabric of the calcite, but I have no doubt about my diagnosis. If this is the head of a dinosaur, I’ll give up geology and eat my rock hammer.” Perhaps the sexiness of finding a dinosaur in a church made Tintori see more than meets the eye.

If you read the comments on various sites reporting this story, you will see that many note the irony of a catholic church having a fossil in it. Hundreds of church buildings are fossil rich so this isn’t really a new irony to report in regard to religion and evolution. I can only hope though it will get more people to take notice of the stone in their religious institutions, which seems to me to be one of the best reasons I can think of for visiting a church, synagogue, or mosque.