Oyster shells from archaeological sites: a brief illustrated guide to basic processing

An ancient Saxon period oyster shell (Ostrea edulis Linnaeus) the spat of which originally settled on the shell of a Sting Winkle, Ocenebra erinacea (Linnaeus), which survives attached to the heel of the mature oyster.

An ancient Saxon period oyster shell (Ostrea edulis Linnaeus) the spat of which originally settled on the shell of a Sting Winkle, Ocenebra erinacea (Linnaeus), which survives attached to the heel of the mature oyster.

Oyster shells from archaeological sites: a brief illustrated guide to basic processing

Important notes

This manual (which can be downloaded via the links below) describes a simple way of recording details of the macroscopic appearance in oyster shells recovered from archaeological excavations, with a view to quantifying their natural and man-made characteristics, to understand about their exploitation, and enable comparisons to be made between oyster shell samples within the various contexts of a single site, or between samples from different sites, and different periods. It describes a recording method which was devised in 1975, and finally written up and published informally on-line in 2011.

The method was designed to be easily learnt and used by non-specialists. This means that it is also easy to miss-apply. Originally, the technique was taught side-by-side with the expert in a training session so that checks were possible while recording was in progress, and the accuracy of the trainee’s independently-obtained results could be determined by carrying out statistical tests for comparability between the results of the expert and the trainee for selected samples. This ensured consistency of results.

I would like therefore to urge caution in the use of the manual at the present time on four fronts:

  1. Before commencing full recording of the archaeological oyster shells, question whether the samples are valid for further study. Do the samples comply with the standards and requirements outlined in Campbell (2015, 2017)?
  2. In recognition of the development of other approaches to studying archaeological oyster shells during the 45 years since this methodology was first devised, and in particular the advancement in technological methods of analysis, is this recording technique the most appropriate to use?
  3. Given the importance of comparability between samples both spatially on an intra-site and inter-site basis, and temporally between historical periods, what quality control measures are in place to ensure accuracy and consistency of the recording? Can the results be trusted in comparisons between samples recorded by different individuals?
  4. Finally, an editorial correction regarding the names of the dimensions being measured. The measurement from the umbo to the ventral margin which is termed maximum width in the manual is more correctly called the maximum height. This was corrected in Winder (2017).

About the handbook

  • Oyster shells from archaeological sites: a brief illustrated guide to basic processing is included in this post as a free downloadable PDF file. See below.
  • It is a starter’s guide to handling oyster shells (British Native Oyster, European Flat Oyster, Ostrea edulis Linnaeus) from archaeological excavations.
  • This handbook can be used in conjunction with other postings both on Oysters etc. and Jessica’s Nature Blog that provide more information about various characteristics of oyster shells, and surviving evidence of their infestation and encrustation by marine invertebrate epibiont organisms.
  • The guide provides useful information for recognising observable macroscopic details. It suggests some simple methods for processing archaeological oyster shells that may be useful for collecting and collating data,  in both a qualitative and quantitative way, prior to further statistical analyses and interpretation.
  • Thirty Figures with 63 colour photographs illustrate the topics discussed.
  • Sources of information are provided in a bibliography; and relevant textbooks are recommended.

Click here for PDF file Oyster shells from archaeological excavations: a brief illustrated guide to basic processing.24MB

OYSTFORM3

N.B. The large file size means that it may take quite a while to download – depending on the speed of your internet connection. You may need to be patient.

If you have a problem with downloading the document, please contact me via winderjssc@aol.com, and I will try to send the file to you by e-mail or other means.

REFERENCES

Campbell, G. (2008) Beyond means to meaning: Using distributions of shell shapes to reconstruct past collecting strategies, Environmental Archaeology, Vol. 13 No.2, 111-121.

Campbell, G. (2010) Oysters ancient and modern: potential shape variation with habitat in flat oysters (Ostrea edulis L.) and its possible use in archaeology, MUNIBE Supplemento-Gehigarria, No. 31, Donostia-San Sebastian, D.L. SS-1055-2010, 176-187.

Campbell, G. (2015) “What do I do with all these shells?” Basic guidance for the recovery, processing and retention of archaeological marine shells, in Quaternary International 2015, http://dx.doi.org/10.1016/j.quaint.205.09.013, 1-8

Campbell, G. (2017) Chapter 16 The collection, processing and curation of archaeological marine shells, in Molluscs in Archaeology: methods, approaches and applications, ed M. J. Allen, Studying Scientific Archaeology No. 3, Oxbow, Oxford and Philadelphia, 273-288

Somerville E., Light, J., and Allen M. J. (2017) Marine molluscs from archaeological contexts: how they can inform interpretations of former economies and environments, in Allen, M. J. (ed.) Molluscs in Archaeology: Methods, approaches and applications. Studying Scientific Archaeology 3. Chapter13, 214-237.

Winder, J. M. & Gerber-Parfitt, S. 2003. The oyster shells. In Malcolm, G. & Bowsher, D. with Cowie, R. (eds.), Middle Saxon London – Excavations at the Royal Opera House 1989–99, 325–332. London: Museum of London Archaeology Service Monograph 15

Winder, J. M. (2011) Oyster shells from archaeological sites: a brief illustrated guide to basic processing https://oystersetcetera.wordpress.com/2011/03/29/oyster-shells-from-archaeological-sites-a-brief-illustrated-guide-to-basic-processing/

Winder, J. M. 2017 Oysters in Archaeology. In Allen, M. J. (ed.) Molluscs in Archaeology: Methods, approaches and applications. Studying Scientific Archaeology 3. Chapter 14, 238-258, Oxford, Oxbow Books

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Oysters in Archaeology (Chapter Offprint Download))

Molluscs in Archaeology – methods, approaches and applications edited by Michael J. Allen, part of the Studying Scientific Archaeology Series (3) was published by Oxbow Books in June 2017. I contributed a chapter on Oysters in Archaeology to this book, summarising my past research and suggesting new ways forward using latest technologies. I am authorised to publish this chapter on-line at the present time because three years has now passed since the date of publication in print.

CHAPTER OFFPRINT DOWNLOAD

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Wild Oysters on the Queensland Coast Part 2

The oysters that I found on the rocks at the northern end of Three Mile Beach in Port Douglas were so different from the ones I had seen at Cape Tribulation that I wondered if they were oysters at all.
The identification of Rock Oysters of the Saccostrea Group in the Indo-West Pacific is a fairly hot topic and some very interesting work was completed a few years ago to try and sort out what is what. See the work of Katherine Lam and Brian Morton.
On the basis of shell morphology, I think the oysters illustrated in this post are Saccostrea mordax which are distinct from the other Saccostrea species in having regularly-spaced grooves radiating from the umbone to the ventral margin of the right valve, the triangular shell shape, and finely plicated valve margin (with regular m-shapes). The left valve is completely attached as in the other species of Saccostrea such as cucullata, glomerata, and kegaki which are all morphologically similar to each other with an oval, deeply cupped left valve and a smaller, relatively flat right valve with slightly plicate, raised margins.
The molecular study by Lam and Morton (2006), based on samples obtained from along the whole of the Australian coastline, clarifies what is known about rock oyster biogeography. The identification of the oysters shown here from Port Douglas tallies with the distribution of Saccostrea mordax that is now thought to have a range from the tropical eastern coast of Australia, along the northern coast and throughout Western Australia. S. glomerata only occurs on the south-eastern coast of Australia on temperate shores from southern Queensland to New South Wales while S. cucullata shares the geographical range of S. mordax. One exception, based on someone’s personal observation – and not as a result of inclusion in the mitochondrial DNA work – is that putative S. mordax also occurs, but in much lower numbers, on shores dominated by S. glomerata around Moreton Island and Sydney.

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Wild Oysters on the Queensland Coast Part 1

I have written a lot about the natural variations in oyster shells belonging to the British Native, Flat, or European Oyster, Ostrea edulis Linnaeus. However variable these shells may be, it is always possible to identify the shells as belonging to that species, and to distinguish them from other species.
In Australia and the Far East, the oysters that grow wild and naturally on the tropical shores include several species of Saccostrea which can be difficult to differentiate from one another because of the diversity of their outward appearance. The morphologies of Saccostrea glomerata, Saccostrea cucullata, Saccostrea kegaki, and Saccostrea mordax, are so variable and overlapping that is not always possible to tell them apart by eye. As with so many other groups of organism currently being investigated (marine algae for example), it is only by use of mitochondrial-DNA analysis that true identities and relationships can be established (Lam and Morton 2006).
Which brings me to a discussion of the Rock Oysters that I photographed in several locations on the Queensland Coast. The images shown in this Posting were taken at Cape Tribulation in tropical Far North Queensland. Just going by the external characteristics, I suggest that they may be Saccostrea glomerata – also called the Sydney Rock Oyster. However, the differentiation of that species from Saccostrea cucullata is so problematic at times even for experts that oysters like this are frequently given both names, S. glomerata cucculata.
In following Posts I’ll show oysters growing in Port Douglas for comparison with these from Cape Tribulation. The shells from the rocks at the northern end of Three Mile Bay at Port Douglas look very different from the others and I think that they may be Saccostrea mordax. I’ll also refer in more detail to the Lam and Morton paper:
Lam, K. and Morton B. (2006) Morphological and mitochondrial-DNA analysis of Indo-West Pacific Rock Oysters (Ostreidae: Saccostrea species), Journal of Molluscan Studies (2006) 72: 235 -245, Oxford University Press on behalf of The Malacological Society of London.

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Ligament Scars in Flat Oyster Shells – Image Gallery 02

Ligament Scars in Flat Oyster Shells – Image Gallery 02 – photographs of variations in ligament scars showing growth lines in right and left valves of modern/recent Ostrea edulis oyster shells found washed up on the beach in Gower, South Wales. Click any image to enlarge and view in the gallery. Photographs of the whole shells from which these close-up shots were taken, from a variety of perspectives, are available upon request should anyone be interested in this topic.

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Ligament Scars in Flat Oyster Shells – Image Gallery 01

Ligament Scars in Flat Oyster Shells – Image Gallery 01 – photographs of variations in ligament scars showing growth lines in right and left valves of modern/recent Ostrea edulis oyster shells found washed up on the beach in Gower, South Wales. Click any image to enlarge and view in the gallery. Photographs of the whole shells from which these close-up shots were taken, from a variety of perspectives, are available upon request should anyone be interested in this topic.

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Ligament scar variations in right valves of Ostrea edulis oyster shells 004

Ostrea edulis right valve ligament scar Ostrea edulis right valve ligament scar Ostrea edulis right valve ligament scar

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Ligament scar variations in right valves of Ostrea edulis oyster shells 003

Ostrea edulis right valve ligament scar Ostrea edulis right valve ligament scar Ostrea edulis right valve ligament scar

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Ligament scar variations in left valves of Ostrea edulis oyster shells 002

Ostrea edulis left valve ligament scar Ostrea edulis left valve ligament scar Ostrea edulis left valve ligament scar

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Ligament scar variations in left valves of Ostrea edulis oyster shells 001

Ostrea edulis left valve ligament scar Ostrea edulis left valve ligament scar Ostrea edulis left valve ligament scar

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Oysters and Other Marine Shells from Excavations at the Old Methodist Chapel and Greyhound Yard, Dorchester

Please click on the link below to download a copy of the oyster and other marine mollusc shells report for excavations at Greyhound Yard in Dorchester, England.

Winder, J. M. (1993) Oyster and other marine mollusc shells, in Excavations at the Old Methodist Church and Greyhound Yard Dorchester, 1982-1984, (eds. P. J. Woodward, S. M. Davies and A. Graham), Dorset Natural History and Archaeological Society Monograph Series Number 12, Series Editor J. Draper, pp 347 -348.

Permission to use this published report has kindly been granted by Dorset County Museum where it is possible to purchase copies of the full publication.

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