A resident alien snail from Sawston, Cambridgeshire

In this post I talked briefly about finding the mid-twentieth century introduction Hygromia cinctella Draparnaud 1801 in Yeovil in Somerset. Back in May I was digging in Cambridgeshire, when I came across these (modern) shells of another introduction, Cernuella virgata Da Costa 1778:

Cernuella virgata Da Costa 1778

C. virgata is a somewhat older resident than H. cinctella, it’s probably a Romano-British introduction (Davies 2008: 178). It is a calciphile, which means it only lives where lime is abundant, and can be found on moderately dry and open sites such as grassland, dunes, and sometimes hedgerows (Davies 2008: 13, Kerney and Cameron 1979: 178).

The impact of Roman occupation on our flora and fauna is worth a mention. As well as a number of other snails, species introduced during the Romano-British period include the brown hare (also found on the site at Sawston), peacocks, and pheasants. It’s possible that the black rat was a Roman introduction (Davis 1987: 193), and in the past some have claimed that the fallow deer was also introduced at this time, although evidence that a breeding population was established in Roman times is lacking (Sykes 2004: 79).

I noticed recently that there is a forthcoming book called ‘Introductions and Extinctions in the British Isles’, edited by Dr Naomi Sykes (who has studied fallow deer extensively) and Professor Terry O’ Connor, and which will also include a chapter on land and freshwater Mollusca by Professor Paul Davies, who wrote the textbook Snails: Archaeology and Landscape Change (Oxbow, 2008), which I reference rather a lot on this blog. I’m not entirely sure when it will be published, but I’m looking forward to reading it.

References

DAVIES, P., 2008: Snails: Archaeology and Landscape Change (Oxford: Oxbow)

DAVIS, S.J.M, 1987: The Archaeology of Animals (London: Routledge)

KERNEY, M.P., and CAMERON, R.A.D, 1979: A Field Guide to the Land Snails of Britain and North-west Europe (London: Collins)

SYKES, N., 2004: The Introduction of Fallow Deer to Britain: A Zooarchaeological Perspective. Environmental Archaeology 9 (1), 75-84

Shell Architecture Up Close

In my opinion, molluscs are quite impressive looking things, and that is no less true of the smaller snails as it is octopi and giant clams. Vertigo pygmaea Draparnaud 1801 is a holarctic land snail often found in dry calcareous grassland and on dunes, but never in wooded areas. Inside the mouth of the shell are a number of folds known as ‘teeth’. which are very useful for identifying the species. V. pygmaea can have between four and seven of these teeth, but only one on the upper (’parietal’) margin of the mouth.

Unfortunately I didn’t include a scale with this photo, but the background is my fingertip. V. pygmaea are seldom more than 2.3 mm high.

Shell of Vertigo pygmaea

A gift from the garden

Left valve of oyster from the garden

You may recall in this post I wrote about finding animal bones and an oyster shell in my parents’ garden when I was young. I still have the bones, but alas the oyster shell is lost. Well, visiting my parents’ garden this weekend, I noticed the shell pictured above in one of their flowerbeds.

The shell is part of the left valve of an oyster (Ostrea edulis L.). Although it is somewhat broken and abraded, I can tell it is a left valve because of the way it curves, right valves are generally flat.  The hole in the shell may have been formed by another animal boring through the shell during the oyster’s lifetime, for example the aptly-named oyster drill Ocenebra erinacea L., a gastropod which preys on oysters and other shellfish.

I like these chance encounters with the past. As Grant (2002: 19) notes, although now considered a luxury commodity, oysters were once an inexpensive and common foodstuff even among relatively poor people. Oyster consumption became incredibly widespread in the UK during the eighteenth and nineteenth centuries, especially as the development of the railway network enabled fresh stock to be carried around the country quickly (Yonge 1966: 156, Stott 2004: 64), however oyster stocks declined steadily towards the end of the nineteenth century(Yonge 1966: 157-8).

It could be that this is the same oyster shell I recovered from that garden wall construction cut all those years ago, unfortunately I have no way of knowing.

References:

Grant, A., 2002, Food, Status and Social Hierarchy, in Milner, N., and Miracle, P., (Eds), Consuming Passions and Patterns of Consumption. Cambridge: McDonald Institute for Archaeological Research

Stott, R., 2004, Oyster. London: Reaktion

Yonge, C.M., 1966. Oysters. Second Edition. London: Collins

Open Access Archaeology Repository (or a start at least…)

Last month, I posted a call for links to open access archaeology journals, books and conference proceedings on the web for a new repository at WikiArc. Thanks to those of you who answered, we now have links to a fair number of resources, although I’m sure the list is very far from definitive so please do keep the submissions coming, either by comment on this blog or by e-mail to the address on the WikiArc links page.

In an attempt to make this resource more useful, I spent this morning playing with Google’s Custom Search Beta, and have created a small custom search widget which searches the resources linked from WikiArc. The search box is near the top of the page on WikiArc. You can also search from the link below:

WikiArc Open Access Archaeology Search

Please do let me know if you encounter any issues searching. I hope you find it in some way useful

Community engagement in California

Entering California from Oregon on I-5

I recently spent a few weeks in northern California, and while I was there encountered an example of an attempt at communicating the past that I thought deserved some note.

I’ve idly musing for a while now on how the historical activity on a development site can be communicated to the site’s future users (be they workers in an office, shoppers at a mall, or residents of an apartment block), so I was quite interested by what I saw at Bay Street, Emeryville. Bay Street is a mixed-purpose retail/ residential/ entertainment development, built close to the site of the Emeryville Shellmound, a massive midden deposit created over the course of 2,500 years, and which contained numerous inhumations. The shellmound, which was said to be up to 40 ft high,  was levelled in 1924 (information from this site). The modern Bay Street development features a number of nods to the Shellmound, from the more figurative -such as a 50ft high metal arch that is supposed to represent the shellmound , to the more literal, such as a display of replica artefacts from the excavations on the site outside the restrooms. It was nice to see an attempt to represent the past use of the site, and even better to see (from my point of view at least) the replica artefacts, which although less architecurally impressive than the other elements, at least present evidence of the past without any interpretative distortion. Outside the restroom was an inpired choice of location too, as I’m sure we’ve all spent some time waiting around outside in those usually bare corridors while somebody uses the facilities. I dream of a day when permanent exhibitions of the site history are part of the planning conditions in the UK (and the USA or anywhere else for that matter).

Call for links

WikiArc is looking to build a directory of links to open access journals, books and conference proceedings of possible interest to archaeologists. Please e-mail links [AT] wikiarc [DOT] org if you have any suggestions. The list so far can be found here.

Fauna in field drains

Being an archaeologist is a handy thing if, like me, you’re fascinated by nature, as we tend to spend a lot of our time in very close proximity to the ground and so get to see some very specific ecosystems. Recently, I have been excavating a large cut feature on a very wet, poorly drained, clay site. The site’s archaeology as a whole is one of occupation and attempts at drainage, with drainage somewhat dominating, from  the Iron Age ditches, each with phases of recuts and subsequent fills, to the somewhat more modern fired ceramic field drains. The field drains are perhaps from the late nineteenth/ early twentieth century, and one of them cut my feature, which also happened to be deeper than the water table. As I removed the pipes in my feature, I noticed that the field drain was about seven centimetres in internal diameter, and still carries water, although is fairly thick with sediment and plant material. The field drains also support their own ecosystem, and I was intrigued at how this now-archaeological feature had become a distinct environment which supports life.

The first thing I noticed was a small crustacean which was carried out of the drain in the flow of water, and began happily crawling around at the (underwater) bottom of my cut. This was a water slater (Asellus sp., probably Asellus aquaticus L.),  an isopod very similar to a woodlouse, but which lives in freshwater, usually in still or slow moving waters, and feeds on dead plant and animal material. Over the next two days, I noticed perhaps four more of these make their way out of the drain.

The other invertebrate large enough for me to spot was a leech of Erpobdella sp., which I rehomed using a small Ziploc-style bag. The leech attached itself to the bag using both ends of its body, and was quite difficult to remove. Leeches like this tend to eat other invertebrates, which might suggest there’s a whole lot more living in those field drains, although perhaps the Asellus are the prey. I think that of British leeches, only the rare medicinal leech (Hirudo medicinalis L.), will suck human blood, but I didn’t fancy using myself to experiment.

Unfortunately, I couldn’t get a clear picture of any of the isopods, but here are two pictures of my leech prior to release:

BAJR Guide 22 Website Building for Archaeology Projects

The first in a whole new series of free practical archaeology guides BAJR have planned was released yesterday. Guide 22 introduces a few things to consider when building a website for an archaeology project, as well as giving pointers to help you get started, and highlighting a few successful examples. The guide is co-written by me (!) with Guy Hunt of L-P: Archaeology (the company behind the Prescot Street and Thames Discovery Programme websites, as well as the amazing online archaeological database application ARK), and David Connolly, webmaster of BAJR.

The guide can be downloaded as a pdf here, and was uploaded to Scribd by David here.

The text is also viewable (and editable!) on WikiArc here

Alien snails

This week non-native species of land snail have been on my mind a lot, as I was analysing an archaeological asssemblage which contained some Cornu aspersum Müller 1774, a species usually described as having been introduced back in Roman times.  Walking in Yeovil this morning, I spotted a shell I had not seen locally before. It was from the snail Hygromia cinctella Draparnaud 1801, another introduced species. The sources I consulted (Kerney and Cameron 1979, Davies 2008*) both agree that it first appeared in Devon around 1950, and Kerney and Cameron describe its distribution as “SE France, extending up the Rhône valley into Switzerland (Geneva basin); also near the Atlantic in SW France” (Kerney and Cameron 1979: 190-191)

Hygromia cinctella

Snails are, you will of course realise, rather slow movers, so how do these species come to be present in the UK, and spread once they get here? Passive dispersal is the most likely answer. In the case of H. cinctella, and the much older introduction C. aspersum, the snails have probably been unintentionally moved by humans, perhaps in soil or produce. Davies (2008: 16-17) lists a number of introductions to the British Isles since the Bronze Age.

Here are some more pictures of Yeovil’s alien snail. I shall be keeping a good eye out for more specimens.

Hygromia cinctella

H. cinctella has a sharply keeled shell, with a thin white band

References:
Davies, P., 2008: Snails: Archaeology and Landscape Change (Oxford: Oxbow)

Kerney, M.P., and Cameron, R.A.D., 1979: A Field Guide to the Land Snails of Britain and North-West Europe. (London: Collins)

*this asterisk doesn’t refer to any special meaning, it’s just there to stop WordPress rendering 2008close parenthesis as 2008) !

Google Toys: Time Travel in Google Earth 5

Yesterday the beta version of Google Earth 5 was launched, packed with exciting features like Google Mars and Google Oceans.  One feature I was particularly interested in, however, was the historical imagery option, which not only allows you to check out each image update since the start of Keyhole Earth/ Google Earth, but in some cases also imagery courtesy of NASA and the US Navy, reportedly back as far as 1940.

As a nod to my last post, here are the most recent image of the area of Yeovil where my parents live, and an older image from 2001.

Yeovil in Google Earth, 2009

Yeovil in Google Earth, 2001

The historical images for the US generally go back a little farther. Below, you can see the downtown development of my wife’s hometown, Clayton CA, from 1993 to 2009

Downtown Clayton, CA, in 2009

Downtown Clayton, CA., in 1993

The oldest images I found during my brief exploration of Google Earth this morning were in San Francisco, where images for parts of the city are available from 1946. Here is the area where the Bay Bridge meets the city, looking roughly south east. I left the street names in the modern image to help with orientation.

San Francisco in 2009

San Francisco in 1946