Paisley Caves – a view from the microscope


Working on the microscope

So this is my second year taking part in the Day of Archaeology. It’s great to look back at my post from last year, when I was working as a research associate on the Feeding Stonehenge project – lots of new things have happened since then, including a new position for me as a research fellow at the University of Edinburgh. Since joining Edinburgh I’ve been working on a lot of new and exciting projects, which you can read more about in my blog, Castles and Coprolites. This week I’ve mostly been sat in front of a microscope, analysing thin section samples from the site of Paisley Caves, Oregon USA, directed by Dr Dennis Jenkins. Paisley provides evidence for the earliest dated human occupation in North America, famously in the form of ancient human DNA recovered from coprolites, aka fossilised faeces. The samples I am working on are known as thin section micromorphology samples – perhaps not as well known as animal bones and charred plant remains, thin section samples investigate the actual sediments in which archaeological materials are found.

The way in which sediments are deposited can actually tell us a great deal about the environment and human activity in the past, and are also useful in helping interpret the artefacts that are found within the sediment. For example looking at soils and sediments under the microscope, we can tell whether they were deposited by wind or water action, or whether they were trampled by humans or animals. With the Paisley samples we are looking at the formation processes in the cave environment, to see whether this can help understand the activities that were occuring in the cave.

Paisley 3

Thin section slide of sediments from Paisley caves. Photo by Julie Boreham,

Thin section micromorphology is quite a specialised technique, and requires laboratory processing. We cut out blocks of sediment from profiles during excavation, wrap them very carefully to avoid any disturbance, then take them to the lab where they are set in resin and cut into slides for viewing under the microscope. I have been working with Earthslides to process the Paisley samples, and we will be presenting a poster exhibiton of the thin sections at the European Association of Archaeologists conference this September.