Friday, 6 November 2015

Pollen for Archaeologists

The past few weeks have been pollen themed. Teaching pollen for Environmental Archaeology, and a new paper out on pollen analysis (and geoarchaeology) at Radzyń Chełminski in Poland. The latter is from my time working on the Ecology of Crusading project, and is a nice case study in using multi-proxy approaches, including historical documentary sources, to investigate landscape change. Pollen analysis is not my area of research expertise, but I have spent a long time working with pollen data. As a geography undergraduate I had several pollen classes for modules in Quaternary Environments and Biogeography, and it also featured heavily in my MSc Geoarchaeology. Pollen analysis does what it says on the tin - we extract pollen grains from sequential layers in sediment cores, and count them to see how vegetation has changed over time. If we have a sediment layer dated to 1000 years ago that is full of oak pollen for example, we can reasonably assume that there was an oak woodland somewhere in the region 1000 years ago, even if the landscape today looks quite different. Of course interpretation is complicated by a variety of factors, including differential production and dispersal of pollen in different species. Pollen analysis is sometimes referred to as palynology, from the Greek paluno (sprinkle) and logy 'study', but technically this refers to more than just pollen, and includes a wide variety of palynomorphs such as spores, dinoflagellates and algae. Palynology  doesn't however include my own favorite microfossils, the phytoliths, which are biological 'casts' of plant tissues.

Pollen is one of those techniques that I feel is under appreciated - all archaeologists should be aware of how pollen analysis works, as it forms the basis of vast majority of environmental reconstructions, which are central to our understanding of questions such as the development of agriculture, patterns of migration, to anthropogenic landscape change. It is for these reasons that pollen analysis is one of the key 'practical' techniques that I focus on in my Environmental Archaeology teaching. In the past I have focused largely on working with reference material, being able to identify key genera/species, and how pollen keys work. However whilst designing a new module at Newcastle, specifically for students without a background in sciences, I wanted to go beyond this and focus on the experience of working with archaeological samples, which I think is a better way of demonstrating some of the problems and limitations of the technique. But what to do without a good set of 'easy' archaeological slides to work with? I came across a great solution developed by Prof Christopher Hill at Boise State University, Idaho - create your own 'virtual' pollen slides! It's a pretty simple idea - using pictures of pollen grains you can create an 'assemblage' on a PowerPoint slide, provide a reference key for expected species, and students can go through the process of counting, data interpretation and presentation. It worked really well, and can easily be scaled for larger class sizes. I'm hoping to develop a similar exercise for phytoliths!

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