In the week between Christmas and New Years, my girlfriend Casey and I took a trip to Northern Ireland. We stayed with her friends Jodie and Rory in Portadown, and on our first full day, Jodie took us out to Armagh (pronounced "Ar-maa"), where she teaches at a primary school. Saint Patrick apparently decided that Armagh was going to be the seat of Irish faith, and he decreed that the Archbishop of Armagh would have preeminence over the rest of Ireland. Of course, Northern Ireland is a land still strongly divided along religious lines. Though it's no longer violent, there is still strong "us and them" sentiment among the Northern Irish people I spoke to. Jodie took us to visit Armagh's two cathedrals: one Catholic, one Protestant. They occupy the two highest hills in town (of course!).







Flatscreen television monitors inside the Catholic cathedral, so that worshippers can see what's going on behind those massive columns.










I was delighted to note a bunch of geological details in the two buildings. This image is of the limestone that makes up the exterior of the Catholic cathedral. It's full of fossils. Here's some spiral-shelled creature. Not sure what exactly. Width of fossil is about 1 inch.












Fossil coral colony on the exterior of the Catholic cathedral. Pound coin for scale.











The Protestant cathedral (Church of Ireland) is made of a greater variety of stones. Most of it is sandstone, and the sandstone hosts deposits of iron oxide (hematite) in precipitated horizons called Liesegang banding. Though it looks strongly layered, the Liesegang banding is not sedimentary bedding. In this block, bedding is horizontal, and the Liesegang banding was deposited by groundwater at an angle to the bedding. Pound coin for scale.


The lower part of the Protestant cathedral is made of conglomerate/breccia. The large clasts are fairly angular, indicating that they did not travel far from their source area before they were deposited. This makes it more a breccia than a conglomerate. Unlike a lot of true breccias, however, this rock is pretty well stratified (layered), indicating that it was deposited by moving water: a characteristic of conglomerates. Pound coin for scale.



Here's one particular clast from the conglomeratic lower part of the Protestant cathedral is made of conglomerate/breccia. In it you can see fossil fragments, apparently of the same coral visible in the Catholic cathedral's stone. Pound coin for scale.






Of greatest interest to me was the fact that James Ussher was the head of the Church of Ireland (the full title is "Primate of All Ireland") from 1625 until 1656. As I mentioned earlier, this means that he was the Archbishop of Armagh. Ussher has a reputation as the most scholarly of the historial archbishops, and he is particularly known to geologists because he attempted to calculate the age of the Earth using the Bible. By estimating generational times and tracking geneaological lineages in Scripture, Ussher proposed that moment of the Earth's creation was the evening immediately before Sunday, October 23, 4004, B.C. It is from his work that the specific notion of a young Earth arose. According to Ussher and his subsequent legions of young Earth creationists, our planet is only 6000 years old (well, 6011 years, to be precise.) Of course, this caused some tension with geologists of the time like James Hutton, who realized that if the uniformitarian concept is correct, the Earth must be vastly older than 6000 years (or, to be precise, 5750 years old at the time Hutton himself was mulling it all over in the mid-1700s). Later discoveries by the many geologists inspired by Hutton, in particular that of radioactive decay, provide quantitative evidence that the Earth is in fact much older than 6000 years. Three different lead isotope systems, for instance, provide ratios of radiogenic lead to non-radiogenic lead that suggest the Earth is about 4.5 billion years old. That's approximately 6 million times older than Ussher calculated -- a vast, vast difference. In spite of the overwhelming physical evidence for an ancient Earth, I still find that many students enter my classes with a perception that the Earth is less than 10,000 years old. I have James Ussher to thank for that. It was a pleasant moment for me to visit his cathedral and ponder his lasting effects.

Labels: armagh, fossils, geology, northern ireland, ussher