11 October 2022

Newborough fossil forams

Since forever, the essence of what I had been doing during our annual field trip was make the students compare modern foraminifera assemblages from known environments to assemblages from several stratigraphic levels in a fossil core. The idea is that they can then figure out what sort of environment these various levels represent.

The fossil assemblages had been established before my time; the modern assemblages were originally established by the students during the field trip, but as the trip had to become shorter and shorter for financial reasons, there was less and less time for that, and in the end I had to just make them work with data from previous years.

Then we went to a new field area, and we were working with a blank slate. In the first year, we did get modern assemblages, but the sediment core was so dull I didn't even bother to sample it. And I didn't entirely trust the modern assemblages; I wanted to go through the slides and check, as there were some identifications I was very skeptical about. I try to check them all there and then, but it seemed like that hadn't quite been successful. But the technical staff hadn't kept the samples, so I couldn't verify anything. In a way, this year, the second year we were doing this field trip on Anglesey, we therefore had yet again a clean slate.

This time I decided to only take and process the samples during the field trip, and do the assemblage analysis during the semester. Everything is ready for that. But we did the coring on the last field day of the fieldwork; I did not want to drag the students into the lab to process these samples too. So I sieved them myself on the day the students were putting the final touches to the field notebooks, and put them in the oven. A few days later I got around to sieving them again; if you dry your samples like that, they become a clump, and you have to disaggregate them to be able to do foraminifera analysis. And when that was done, only the big job of actually picking and identifying the forams had to be done.

I picked some strategic horizon; I don't have time to do them all. I took 23 samples! And I started with a rather small sample, only covering 1 cm. 

Not a good picture, but believe me; these are good-looking forams!

When we cored up these sediments, we developed hypotheses about what sort of environments they represented. Some of it may be dune sand, and that won’t have forams in them at all! This horizon surely did. The work has started!

It is actually quite nice to do a bit of foram analysis. I borrowed a microscope from the lab and put it in my office, so I'm doing this in private, with the radio on. Quite nice! And I will be the first one to know whether our interpretations were correct…

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