Heather Upton's UNIQ+ graduate access project working in our Tephrochronology Laboratory, July 2023

Heather joined the School’s tephrochronology team this July for a UNIQ+ Research Internship overseen by Prof. Victoria Smith. These internships are aimed at talented undergraduates from under-represented groups, who would find continuing into postgraduate study a challenge for reasons other than their academic ability.

In the autumn, Heather will be starting the third year of her four-year degree in Geology and Geography at the University of East Anglia. She is passionate about studying volcanos and palaeontology and has just spent two weeks on fieldwork with her degree cohort in mainland Greece and Santorini.

“I looked at a lot of internship opportunities before I found this one. What stood out for me about UNIQ + and this project was the opportunity to focus on a distinct research question, which I get to take from start to reporting completion. Other internships I saw were more about working on general lab tasks or shadowing members of staff. I really feel like this is my project.”

My day starts when I enter the tephrochronology laboratory and complete any time-sensitive tasks which were left processing overnight. For this project I need to analyse about 130 continuous samples extracted from a marine sediment core collected in the Atlantic (offshore of North-West Africa). I’m trying to identify cryptotephra (non-visible volcanic ash) layers in the core with the aim of eventually correlating these to cryptotephra layers also found in the stratigraphy of archaeological sites in Morocco. The cryptotephra layers can be used as marker horizons in the marine and archaeological sites, allowing us to precisely compare the palaeoclimate record and any Palaeolithic changes. My project will contribute to the Leverhulme Funded ‘CAVES Africa Project’, https://caves.web.ox.ac.uk .

Sample magnified 20x under the microscope

‘Cryptotephra’ are defined as discrete horizons of tephra (usually glass shards, in the size range 25–125 μm) that are not visible to the naked eye. So, I spend the morning sieving samples to separate the glass from other unwanted particles (e.g., foraminifera). I use mesh sieves of 80 and then 25 µm. Each sample takes around 20 minutes to sieve so I can process between 5-10 samples in a morning. After lunch, I may continue sieving, or, once I have a batch of about 25 samples prepared, I begin the next stage in the process. This involves using Sodium Polytungstate (SPT), which when dissolved in water, produces a low-viscosity, transparent solution with a specific density. By varying the density of the solution, we can further extract and concentrate the glass shards in the sieved sample. Once the samples are extracted, I will then mount the tephra fraction onto microscope slides and analyse each under the microscope at 20 - 40x magnification. So far, I have found generally low concentrations of cryptotephra in most samples, with some sharp peaks in tephra concentrations which may represent primary ash fall events. Shards from these peaks will be prepared in resin mounts to be chemically analysed and photographed in the microprobe – the chemical analyses can then be compared to data for known eruptions to create a chronology for the sediment core.

I hope to go on to study at postgraduate level within the next year or two, and for me, the experiences I have been able to cultivate during my UNIQ+ project have been really valuable for getting a taste of what a research project may be like. I have picked up so many new transferable skills and really built my confidence in the lab setting. Something I wasn’t expecting when I first came to Oxford is just how welcoming everyone has been – it has been such a great experience talking to the staff and current DPhil students about their experiences here.