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Beachcombing for bioarchaeology

February 10, 2015

On Saturday I took a walk along the beach from Preston to Weymouth in Dorset, looking for shells and other invertebrate remains to identify and add to my reference collection. Building a collection of modern material is important, as it is much better to have physical examples for comparison than pictures online or in books. Looking at my collection, I had last visited these beaches in 2008, when I found numerous slipper limpets (Crepidula fornicata). These aren’t particularly useful for British archaeology, as they are an accidental introduction from North America which arrived during the nineteenth century when a new species of oyster was imported from the United States to be grown in British waters. They are significant in the ecosystem however. They eat plankton either in suspension in the water or in deposits, and can out-compete many native molluscs including our native oyster Ostrea edulis. They are often found stacked on top of one another – the oldest animals at the base of the stack are females, the youngest at the top males. When females die, the males nearest the bottom become female.

Chain of Crepidula fornicata on Weymouth beach.

Chain of Crepidula fornicata on Weymouth beach.

Despite the dominance of slipper limpets, a few other species were to be found, especially on Weymouth beach. Mollusc shells included the queen scallop Aequipecten opercularis, the dog cockle Glycymeris glycymeris, the great top shell Gibbula magus, the common otter shell Lutraria lutraria, and the common whelk Buccinum undatum.

Great top shell (Gibbula magus) from Preston beach

Great top shell (Gibbula magus) from Preston beach

As well as mollusc shells, I was looking for bryozoans. These are colony-forming invertebrates that are quite often found on marine shells from archaeological sites, and occasionally in sediments on coastal sites too. Identifying the species on shells may help identify the region or environment from which the shell was harvested. Back in 2013, I published a (now happily open access) paper reviewing bryozoans in archaeology, and I was keen to build up my reference collection.

On a frond of Fucus seaweed, I found a colony of Electra pilosa, a relatively common lower shore species found on all British coasts.

Electra pilosa on a Fucus frond

The zooids (individual animals) of this particular colony had especially pronounced medial proximal spines looking rather like bristles:

Electra pilosa zooids

Electra pilosa zooids.

The inner surface of the otter shell I found was also home to two species of bryozoa – Plagioecia patina, which forms disc-shaped colonies and is found in shallow water on all British coasts, and Tubulipora plumosa, which is also found on all British coasts. Along with these were long tubes secreted by the worm Pomatoceros triqueter. In his 1978 report on the shells from the Graveney boat, Ken Thomas noted that the presence of organisms on the inner surface of a shell from an archaeological context suggests that it was already an empty shell at the time it was collected from the shore, meaning it is not food waste, so may have arrived at a site as a curio or for some other reason.

Common otter shell (Lutraria lutraria) showing bryozoans and worm tubes

Common otter shell (Lutraria lutraria) showing bryozoans and worm tubes

Colony of Tubulipora plumosa

Colony of Tubulipora plumosa


Colony of Plagioecia patina

Penmyarth Fish Stone/ Llangorse/ Crug Hywel

May 24, 2014

This will be the fourth year that I have worked at the Green Man Festival for what has become Guerilla Archaeology. The festival, which takes place in August, is held at Glanusk Park on the banks of the River Usk near Crickhowell. It is a rich archaeological landscape, and Alan Lane and I have written a brief guide to the archaeology of the Park and its environs, which is available as an information board during the festival. The major prehistoric monument of the Park, the Fish Stone, is not accessible to the public, however, nor is it accessible during the festival. Having never seen it, I wrote to the Park’s estates office and asked to visit. A number of other Guerilla Archaeologists were able to come. Alan Lane kindly agreed to extend the trip with a guided visit to the crannog at Llangorse, and Jacqui Mulville suggested we climb to the hillfort on Table Mountain,Crug Hywel.


Standing at just over 4.2 metres tall, the Fish Stone is an Old Red Sandstone orthostat which looks somewhat like a fish. It is sited in a quiet glade on the banks of the Usk. The worn face in the photo above faces east towards Crickhowell – as Ian Dennis noted, at sunrise and sunset the stone must cast a long shadow of a fish on the ground, while at noon a thin shadow will point due north. It is believed to be Bronze Age, and to form part of a possible group of route markers. There is another standing stone in Glanusk Park – this one is thought to have been early medieval, although it has been moved to a new location in Penmyarth churchyard and engraved with an epitaph to Joseph Henry Russell, the 2nd Baron Glanusk, in 1928.


ImageStanding stone in Penmyarth churchyard

After Glanusk Park, we headed off to Llangorse lake, site of the only crannog in Wales. A visitor centre tells the story of the archaeology – with the pallisaded settlement being built in the late 9th century AD, and periodically extended, until being destroyed in 916 by an army led by Aethelflaed, Queen of Mercia (and King Alfred’s daughter). The reconstructed roundhouse that houses the visitor centre is based on an iron age crannog house from Scotland or Ireland, rather than any of the Llangorse structures. Chained outside the visitor centre is a reconstruction from the 1990s by Time Team of a log boat discovered in the lake. To reach the crannog itself, we hired rowing boats. The site is protected by a stone bund, and there is little to see of the archaeology, although we could make out some planks in the shallow water to the south east of the crannog


The south east of the crannog at Llangorse

After lunch in Crickhowell, we climbed up to Crug Hywel hillfort on Table Mountain, a spur of Pen Cerrig Calch. Walkers are damaging the site by taking stones from the banks to build shelters – two of these were extant when we visited. The hillfort encloses an area of 162 x 59 metres, and has frankly stunning views . A small number of rounded hollows are visible which may be hut sites.


The entrance to Crug Hywel, at the east of the hillfort, and just a little taste of the fabulous views.


So we started a journal…

April 29, 2014

At the time that I started this blog, I wasn’t attached to any university at all, which made keeping up with research – too often locked away in expensive to access journals – a pain. Things have improved, more and more researchers are self-archiving their work online for example through services like, but I made it my mission back to try to help make research more widely available. Late last year, I published a paper on bryozoans in archaeology, and when I was looking for  venue to submit it, I realised that Quaternary science and environmental archaeology are quite poorly served for so-called open access journals. I eventually published in Internet Archaeology, which is paywalled but has very liberal policies about how I can disseminate the paper. At the time I (semi-jokingly) wrote on Twitter that I was this close to starting a new journal. Happily, Suzanne Pilaar Birch and Victoria Herridge saw the potential in the idea, and so yesterday, after about six months of planning, and with the involvement of Ubiquity Press and an excellent and supportive editorial board, Open Quaternary opened its call for papers. I’m incredibly excited for the coming months – we’re planning the first issue for September. Watch this space!

On Then Dig: Sanctifying Our Sites (Ceri Houlbrook) and open peer review…

November 20, 2013

Ceri Houlbrook’s contribution to Colleen Morgan’s Zeitgeist theme on Then Dig was posted this week. It’s called Sanctifying Our Sites:  Self-reflection on an archaeological dig, and discusses the archaeology of folklore and how investigating a site archaeologically can change the way it is perceived. The post was subject to open peer review, and Colleen very kindly invited me to be one of the reviewers, alongside Sara Gonzales from University of Washington, and you can read our comments at the end. It’s excellent reading. Take a look!

Call for Posts on Then Dig: Green

November 10, 2013

Then Dig is a collaborative archaeology blog hosted by UC Berkeley, and originally set up by Colleen Morgan and Alun Salt. I’m hosting the theme for November/ December, which is called “Green”, and is about how archaeology and palaeoecology can inform sustainability and conservation biology. Posts are welcome – please read the call below:

“Our theme for November is inspired by one of the earliest posts on this blog, DIY, Green Burials, and Mortuary Archaeology by Colleen Morgan. Archaeology and green issues are intrinsically linked, often explicitly in conservation legislature and in the designation of UNESCO World Heritage Sites, as well as in the public imagination (at times wrongly, as evidenced by an English politician’s characterisation last year of archaeologists as ‘bunny huggers’ – to see just how wrong this can be, read this extract of a recent paper on Hebridean archaeology by Mike Parker Pearson, Jacqui Mulville, Niall Sharples and Helen Smith).

As Martin Bell has noted:

 ‘Green concerns are about current and future trends. However understanding them requires knowledge of what has happened in the past’

(Bell 2004, p. 509). In this context, archaeological studies have been informative in issues such as the reintroduction of locally extinct animals, the development of sustainable farming and livestock management processes, the mitigation of agricultural soil erosion, and the prediction of potential outcomes of climate change.

Green concerns may also be more humanistic, and draw on archaeological imagery to suggest a utopian past where humans lived in sustainable coexistence with nature. Environmental archaeology has shown that such an idealised image of the past may not reflect reality, however – perhaps most dramatically in the famous case of Rapa Nui, which may have become unproductive after overzealous deforestation and poor land management (Bahn and Flenley 1992; Mann et al. 2008) (archaeological evidence does not necessarily support the idea of ‘ecocide’ however – Hunt 2007).

Additionally, indigenous knowledge traditions may be informative for environmental policy makers and planners (Johannes 1993, 33). Such knowledge can be drawn either directly from modern ethnographic studies (e.g. Costa-Neto 2000, 90, Blurton Jones and Konner 1989, 21), or inferred from archaeological and palaeoecological data (e.g. Jackson 2001; Mannino and Thomas 2002).

This theme welcomes posts which explore any interaction between archaeology and green concerns, including the topics discussed above, the environmental sustainability of archaeological practice, or personal reflections on how archaeology has made you think about green issues. If you’re interested in contributing a submission of 750 words or less, please e-mail me (LawMJ [at] with the title of your contribution as the subject line, or drop us a message on the facebook page or on twitter (@ThenDig). Posts will be published throughout November and December and are due by November 20th. Submissions in the form of images, music, video, and other multimedia are, as ever, also welcome. Your submission will be subjected to open peer review before being posted on Then Dig (our open peer review guidelines are here)


Bahn, P.G.,and J.R. Flenley, 1992. Easter Island, Earth Island. London: Thames and Hudson.

Bell, M., 2004. Archaeology and green issues. In J. Bintliff. Ed. A Companion to Archaeology Oxford: Blackwell. pp. 509-531.

Blurton Jones, N. and M.J. Konner, 1989. !Kung knowledge of animal behaviour. In R.E.Johannes Ed. Traditional Ecological Knowledge: A Collection of Essays Gland: IUCN. pp. 21-29.

Costa-Neto, E.M., 2000, Sustainable development and traditional knowledge: a case study in a Brazilian artisanal fisherman’s community. Sustainable Development 8, pp. 89-95. doi:10.1002/(SICI)1099-1719(200005)8:2<89::AID-SD130>3.0.CO;2-S.

Hunt, T.L., 2007. Rethinking Easter Island’s ecological catastrophe, Journal of Archaeological Science 34, pp. 485–502. doi:10.1016/j.jas.2006.10.003.

Jackson, J.B.C., et al., 2001. Historical overfishing and the recent collapse of coastal ecosystems. Science 293, pp. 629-638. doi: 10.1126/science.1059199.

Johannes, R.E., 1993. Integrating Traditional Ecological Knowledge and management with Environmental Impact Assessment. In J.T.Inglis, Ed. Traditional Ecological Knowledge: concepts and cases. pp. 33-39 .

Mann, D., et al., 2008. Drought, vegetation change, and human history on Rapa Nui (Isla de Pascua, Easter Island). Quaternary Research 69 (1), pp. 16–28. doi:10.1016/j.yqres.2007.10.009.

Mannino, M.A., and K.D.Thomas, 2002. Depletion of a resource? the impact of prehistoric human foraging on intertidal mollusc communities and its significance for human settlement, mobility and dispersal, World Archaeology 33 (3), pp. 452-474.”

An open bibliography for sustainability from archaeology and palaeoecology

October 17, 2013

I thought I would try using WikiArc to host crowd-sourced bibliographies, with the idea that they anybody can contribute to them, and that open access materials will be searchable using a Google custom search engine. I’ve started off with papers and books related to how archaeology and human palaeoecology can be used to inform sustainability and conservation biology, and you can read (and contribute to!) the bibliography here.

I’m unsure whether this idea has any mileage, but I’m eager to try. I’d like to have more open bibliographies on the site. Use the comments area below to suggest topics to cover.

An underground snail

September 21, 2013

A couple of weeks ago, I wrote about my modern mollusc survey at the archaeological site I have been working on, and mentioned that I had also seen Cecilioides acicula, a snail which lives underground, while excavating. I managed to take a picture of a live animal on my phone:

Live Cecilioides acicula

Cecilioides acicula – not a great photo, but you may just be able to see the white body of the snail protruding from the shell

As a subterranean species, C. acicula is problematic for archaeologists. It can occur in quite large numbers in samples, but is usually regarded as intrusive. I took a level of the spot I found this snail, and found it was living 90 cms under the former ground surface. In the seminal Land Snails in Archaeology (1972, 186), the late Professor John G. Evans reports that they have been seen 2 metres below the ground surface.

The shells are typically translucent, becoming opaque some time after the snail has died. Here are two very translucent (and quite pretty!) shells from a prehistoric sample elsewhere in Somerset – they are clearly a recent intrusion.

Translucent Cecilioides acicula shells

Translucent Cecilioides acicula shells

They are usually described as a medieval introduction to Britain from Europe (eg. Davies 2010, 170). I have only ever seen them in sediments with a good deal of sand or silt in the mix, and Evans (1972, 186) notes that they “are common in areas which have been cultivated recently but often absent from longstanding grassland which would appear to provide suitable habitats”. I’m interested to know more precisely when they arrived, and how they have come to be spread. In post-industrial Britain, it is not hard to envisage them being spread in soil with potted plants, but if they are truly a medieval introduction, was soil being moved around, or did they spread by some other means? Suggestions very welcome!


Davies, P., 2010. Land and freshwater molluscs. In T. O’Connor and N.Sykes, eds. Extinctions and Invasions: a social history of the British fauna. Oxford: Windgather Press. pp.175-180.

Evans, J.G., 1972. Land Snails in Archaeology. London: Seminar Press


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