Friday, March 1, 2013

Plans and Profiles: Meghan Burchell Researching Shells, Seasonality, and Settlement in Coastal British Columbia

Meghan Burchell sampling the temperature 
and salinity of water on the central coast
 of British Columbia.  These instrumental data
 are used to help understand how shellfish
 incorporate local water into their shell matrix.  
(Photo credit B. MacDonald).
Meghan Burchell is on the cusp of completing a PhD in the Department of Archaeology at McMaster University.  She's also the Operations Manager for Sustainable Archaeology at McMaster Innovation Park, which is a massive and much needed undertaking in Ontario to centralize archaeological collections and make them more accessible to researchers.  For her PhD, she's been developing some really amazing laboratory techniques for analyzing the growth rings on shellfish shells.  I saw her speak in St. John's recently and the level of resolution that she's been able to recognize is incredible; the shell growth is influenced by tides, so she can actually spot individual days and tidal cycles recorded in the shells.

Read on to learn more about her boundary pushing research in the field of sclerochronology...

Plans and Profiles #12. Meghan Burchell, Shells, Seasonality, Settlement and Subsistence in Coastal British Columbia.

1) Tell me a little bit about your project.

My current project focuses on understanding patterns of seasonality, settlement and subsistence at shell midden sites on the coast of British Columbia, in the traditional territories of the Heiltsuk on the central coast, and the Coast Tsimshian on the northern coast. More specifically, I employ high-resolution sclerochronology and stable oxygen isotope analysis to understand patterns of shellfish harvest and by proxy, the timing of site occupation.

Alignment of biological growth markers with stable
 isotope data from a live-collected shell.
Sclerochronology is analogous to dendrochronology were the ‘rings’ that form on the shells can be counted – except these ‘rings’ aren’t just annual lines. They represent annual, sub-annual, daily and tidal lines. There are also disturbance lines caused by predation, spawning and changes in the environment. Using geochemical profiling, specifically stable oxygen isotopes, we can understand what these lines mean and better interpret past climatic conditions, sea surface temperature and site seasonality.

In many interpretations of hunter-gatherer settlement systems, archaeologists have assumed implicitly or explicitly that a pattern of mobility based on seasonally-scheduled movements between different site locations was practiced. This pattern of mobility is often characterized as a seasonal round, where different locations are used during specific times of the year for different purposes. An implication of this pattern of mobility is that short-term occupation sites are visited annually, approximately at the same time each year and longer term residential sites can span multiple seasons. The Pacific Northwest Coast provides an ideal landscape to examine seasonality since many of the staple resources, particularly salmon, were available on a seasonal basis. Contrary to long standing assumptions of regular seasonal movement between sites, the analysis of shell samples from multiple archaeological sites from distinct regions in British Columbia show complex patterns of multi-seasonal occupation at smaller campsites and specific seasonal or multi-seasonal emphasis in occupation and/or shellfish harvest at longer-term residential sites.

In addition to my research in British Columbia, I am also the Operations Manager for Sustainable Archaeology at McMaster Innovation Park. Sustainable Archaeology is a collaborative initiative between Western University and McMaster University in southern Ontario, Canada, funded by the Canadian Foundation for Innovation (CFI) and the Ontario Research Fund (ORF). These state-of-the art research facilities will bring together thousands of previously inaccessible archaeological collections generated from across the Province of Ontario as a result of research and cultural resource management excavations.

2) How did you become interested in this particular problem?

When I was in my third year of undergraduate studies at McMaster University, I saw a picture of the site of Namu on the central coast of British Columbia. Namu is one of the longest continually occupied sites on the British Columbia coast, and just from looking at the pictures, seeing people doing innovative field work using coring and augering techniques, I knew I had found the place I wanted to go - and I knew I had found the kind of field archaeology I wanted to employ. I was extremely fortunate to be able to go there in 2010 to collect materials (water samples and live shellfish) for my dissertation.

I became interested in this specific project because I am fascinated in the application of stable isotope analysis in archaeology and micro-analytical techniques. I think it’s amazing that we can investigate large-scale regional histories of archaeological sites with an extremely powerful microscope that allows you to zoom into at the micron level, and a mass spectrometer that measures the isotope ratios of only micro-grams of shell carbonate powder. More importantly, I wanted to learn more about long-term histories of seasonal settlement patterns and resource acquisition. I’ve always been interested in shell midden sites in British Columbia; each one is different, not only in the stratigraphy and composition of the site, but the function and nature of the site as well. I am motivated by learning more about the environmental and historical variability along the coast and the variability within a region; especially how people used short- and long-term camps and villages to create networks of interaction on the coastal landscape. 

Shell sampling techniques using a micro-mill and a micro-mill in preparation for stable oxygen isotope analysis via mass spectrometry.

3) Has your project changed since you originally began working on it? How?

My project has completely changed since I first started working on it. I began using low-resolution stable isotope methods, and the method simply wasn’t working, but it took two years of research and experimentation to learn what I was doing wrong. I also had too much faith in new analytical techniques for the analysis of shells, and these techniques had not been fully understood from a geochemical perspective – what seemed simple and straightforward was not. Once I learned that, the goals of my dissertation changed. I believe they changed for the better, since one of the outcomes of my dissertation has been developing advances for the archaeological analysis of shell for seasonality and paleoclimate reconstruction. I also developed a healthy skepticism of new analytical techniques. When someone says ‘you can just zap it’, (i.e. XRF), I know now that it takes much more than that. It takes an understanding of the biology of the organism being studied, it’s geochemical properties and the limits of the analysis.

Aside from the methodological changes, my ideas around seasonality have changed a lot. While seasonality is important for understanding patterns of resource acquisition, site occupation and sedentism, I’m thinking about this problem more critically now – seasonality isn’t as simple as four seasons. Now I’m interested in tackling the theoretical component of understanding the role and importance of seasonality interpretations in archaeological narratives.

4) If you could ask the people/person who lived at your site(s) one question what would it be?

There are so many questions I’d like to ask, but if I could know one thing, I would want to know something that we can’t see archaeologically. I’d want to know what the sites smelled and sounded like when people were gathering and processing shellfish. 

5) Has your research taught you anything about yourself? What?

The process of working through this project has taught me many things. Probably the most important is that you can’t do archaeology, stable isotope analysis and sclerochronology by yourself – working in a team is important. I also learned that I really enjoy working with people from other disciplines, such as paleontology, biology and geochemistry. I think engaging with people from different disciplines allowed me to broaden my own expertise while gaining a much deeper appreciation for the work that is accomplished in other scientific fields – especially when it can be applied to archaeology. 

6) I can’t imagine doing this research without…

Lecturing at the University of Mainz, Germany at the annual
Geocycles Symposium (Photo credit Uni. Mainz)
… the support of my thesis committee at McMaster University, my colleagues at the INCREMENTS research group at the university of Mainz in Germany, and Elroy White from Bella Bella, British Columbia who has shared so much insight into local histories of shellfish harvesting

7) How do you unwind when you need to get away from your research?

I unwind in a ballet studio. I’ve been taking ballet since I was three years old, and I can’t imagine my life without it. When I’m not in the ballet studio, I’m in the woods on my mountain bike. But if I really need to relax, I usually have a nap with my two cats.

8) Have you ever found anything in the field or in the lab that you wish you hadn’t?

One time I found a frog stuck at the bottom of a 3m deep excavation unit. My good friend and I spent a long time trying to find a way to get the little guy out, we tried our best but we couldn’t help him. Excavation units should always be carefully backfilled not only to protect the rest of the site, but also to protect the precious animals that may stumble into them.

9) What books or websites would you recommend if people want to learn more about your area of interest in general? Or your project in particular?

Definitely check out the world of sclerochronology. This technique is rarely applied in archaeological contexts, but it’s definitely something archaeologists should look into before engaging in the analysis of shells or any other hard tissue that grows on a regular basis (i.e. teeth and bone, especially otoliths).

Analytical Chemistry for Archaeology by Cambridge University Press is also a great book to introduce people to archaeological sciences.

I also really like Human Impacts on Ancient Environments by Charles Redman, and Human Impacts on Ancient Marine Environments edited by Torben C. Rick and Jon M. Erlandson. Tim Ingold’s writing about landscape has also been very influential for my work, but one of my all time favourite papers is ‘Sacred Power and Seasonal Settlement on the Central Northwest Coast’, by Aubrey Cannon from the book Beyond Forging and Collecting: Evolutionary Change in Hunter-Gatherer Settlement Systems (2002).

Shell midden stratigraphy at the Pender Island site in 
southern British Columbia. (Photo credit R. Klenkler)
For my current area of research, here are some of the publications I’ve co-authored with colleagues at McMaster and the University of Mainz:

2013 Burchell, M., Cannon, A., Hallmann, N. Schwarcz, HP., Schöne, BR. Refining estimates for the season of shellfish collection on the Pacific Northwest Coast: Applying high-resolution stable oxygen isotope analysis and sclerochronology. Archaeometry. 55: 258-276.

2013 Burchell, M., Cannon, A., Hallmann, N. Schwarcz, HP., Schöne, BR. Inter-site variability in the season of shellfish collection on the central coast of British Columbia. Journal of Archaeological Science. 40:626-636.

2011 Hallmann, N., Schöne, BR, Irvine, GV., Burchell, M., Cockelet, D., Hilton, M.
An improved understanding of the Alaska Coastal Current: The application of a bivalve growth-temperature model to reconstruct freshwater-influenced paleoenvironments. Palaios. 26: 346-363.

2010 Risk, M., Burchell, M., de Roo, K., Nairn, R., Turbett, M. Trace elements in bivalve shells from the Rio Cruces, Chile, trace the evolution of an earthquake-impacted watershed. Aquatic Biology. 10: 85-97.

2009 Hallman, N., Burchell, M., Schöne, BR., Irvine, G., Maxwell, D. High-resolution sclerochronological analysis of the bivalve mollusk Saxidomus gigantea from Alaska and British Columbia: techniques for revealing environmental archives and archaeological seasonality. Journal of Archaeological Science. 36: 2353-2364.


The INCREMENTS research group at the University of Mainz:

And our Sustainable Archaeology Facebook Page – we upload our research images on a regular basis. Right now we’re doing a lot of experimentation learning how to use our new equipment, and we regularly upload some pretty amazing pictures that are taken by staff using different types of microscopes.


Do you know of any interesting archaeological research projects or researchers who should have their work profiled here?  Maybe its you?  Drop me a note with your suggestions:

Photo Credits: 
As indicated in the captions.
Plans and Profiles Banner, Tim Rast based on a linocut by Lori White


  1. There are a lot of variables to work through that influence the shell growth, but once you understand the seasonal changes in salinity and water temperature for a specific area, the potential rewards from this technique (palaeoclimate reconstruction, past water temps, site seasonality) are pretty impressive. Those daily and tidal variations are kind of amazing.

    1. It is amazing what you can learn from the micro-structure of a shell - in some areas, you can identify the time to day the shell was collected and it's position on the tidal shelf!

  2. We find marine shells in village sites on the lakes miles from the coast here on Kodiak Island, and I have always wanted to use the shells to prove that the sites were occupied in the winter. Or at least that the shells were harvested in winter. But it's often hard to say exactly where the clams were collected and I gather pin-pointed the spot (for water salinity etc) is rather important. This spring we even found sea urchin - now that has to be collected in the spring - right? Patrick

    1. That's funny - Chelsee Arbour, who is working in Labrador is dealing with some very interior sea urchin shells and spines right now, as well. I'll have to ask her about seasonality.

      From what I recall from hearing Meghan talk about her research, yes, I think you need a pretty good idea of the specific area where the shells came from. From my imperfect memory, I believe she needed to establish some sort of salinity and water temperature baselines at each site/island that she was studying. Freshwater run off was the big factor and could change significantly over relatively short distances (ie, tens of kilometres).


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