molluscs and earthworm granules from sample 182

7/28/2019 Molluscs and Earthworm Granules From Sample 182

1/7

MOLLUSCS AND EARTHWORM GRANULES FROM SAMPLE ,

CONTEXT (9052), WALPOLE LANDFILL SITE (PWE11)

Matt Law

For C & N Hollinrake Ltd., June 2013.

Introduction and Methods

A small land snail assemblage was reported during assessment of 200ml of the

lowest fill (9052) of a large (?)grain storage pit from Walpole Landfill Site

(Simmons 2013). The processed sample was rapidly scanned under a low power

microscope at x40 magnification, and faunal remains extracted. Identifications

were determined by reference to the authors own collection. Notes on the

ecology of Mollusca were taken from Evans (1972), Kerney and Cameron (1979)

and Davies (2008) Nomenclature for Mollusca follows Anderson 2008.

Results

Minimum number of individuals (MNI) values for land snails are given in Table 1,

as well as counts of earthworm granules and other non-insect faunal remains.

The assemblage has also been photographed (Appendix 1). Discus rotundatus

was represented by two broken apices and two broken segments of body whorls,

which could all be accounted for by two individuals.Aegopinella pura was

represented by an intact juvenile shell. A fragment of body whorl of another

large snail was judged to be one of the Clausiliidae. An internal plate of a juvenile

slug (Limacidae sp.) was also recovered. One of the earthworm granules was of

the banana-shaped form described by Canti (2006, 113) as typical ofLumbricusrubellus.

Discussion

Snails

Molluscs from pits pose interpretative problems, as they may represent animals

which enjoyed the shady micro-habitat of the pit itself or may be eroded from

soils through which the pit has been cut (Allen 1989, 135). They may also have

been accidentally introduced via human agency with vegetable matter. The

fauna reflects a shaded environment Discus rotundatus andAegopinella puraare both species of damp, shaded places, possibly woodland but at the very least

tall herbage. As a family, the Limacidae are favoured by damp conditions and

shade, althoughAgriolimax reticulatus can live in open country. The Clausiliidae

are rupestral species which generally live on walls, rocks and trees, although

they can also occur in dead leaves. Generally, they prefer shaded habitats.

Although the land snail assemblage is small, it has a reasonable diversity, which

is likely to suggest relatively stable conditions in the local environment. It is

plausible that all of the snails recovered lived within the pit, however they are

also likely to reflect damp, shaded conditions in the wider environment.


2/7

Earthworms

Earthworm granules are small aggregations of calcite crystals which are secreted

by living worms. Therefore the number of earthworm granules found in a deposit

cannot be correlated to a number of individual earthworms. The burrowing

nature of earthworms means that granules are unlikely to have been deposited

at the same time as the sediment in which they are found. Their presence at

Walpole may, however, be subject to some chronological constraint as this

deposit is sealed by several metres of estuarine alluvium which has not thus far

yielded earthworm granules. Lumbricus rubellus prefers rotting leaf litter (Canti

2006, 115).

Conclusions and Statement of Potential

Although the assemblage is too small to carry any real interpretative value, itappears to represent a damp, well shaded environment, certainly within the pit,

and most likely within the local environment. Further molluscan analysis is likely

to be productive, and is recommended for remaining samples from the pit.

References

Allen, M.J., 1989. Land snails, in Fasham, P.J., Farwell, D.E., and Whinney, R.J.B,

eds. The Archaeological Site at Easton Lane, Winchester. Salisbury: The

Trust for Wessex Archaeology, pp. 134-140.

Anderson, R., 2008.Annotated list of the non-marine Mollusca of Britain and

Ireland. London: Conchological Society of Great Britain and Ireland.

Available at:

http://www.conchsoc.org/sites/default/files/MolluscWorld/Anderson-

2008.pdf [Accessed June 14th, 2013].

Canti, M.G., 2006. Deposition and taphonomy of earthworm granules in relation

to their interpretative potential in Quaternary stratigraphy.Journal of

Quaternary Science, 22 (2), pp. 111-118.

Davies, P., 2008. Snails: archaeology and landscape change. Oxbow: Oxford.

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

Kerney, M.P., and Cameron, R.A.D. 1979.A Field Guide to the Land Snails of

Britain and Ireland. Collins: London.

Simmons, E., 2013. Assessment of waterlogged plant macrofossils from Walpole

Landfill Site, Pawlett Somerset (PWE11). Unpublished report for C & N

Hollinrake Ltd.


3/7

TABLE 1: MNI Values of Faunal Remains from Sample 182

Context 9052

Sample 182

Interpretation

Bottom fillof pit

Volume(ml) 200

MOLLUSCA: GASTROPODADiscusrotundatus(Mller, 1774) 2

Aegopinella

pura (Alder,1830) 1

Clausiliidae sp.indet. 1Limacidae sp.indet. 1

ANNELIDA: CLITELLATA

Earthwormgranules indet. 4cf. Lumbricusrubellus

Hoffmeister1843 1

CHORDATA: MAMMALIA

Rodent tooth 1


4/7

APPENDIX: Faunal Assemblage Gallery

Figure 1: Discus rotundatus

Figure 2: Aegopinella pura


5/7

Figure 3: Limacidae sp. plate


6/7

Figure 4. Clausiliidae sp. fragment (right) with modern specimen ofClausilia

bidentata. Note the similar striations on the shell surface.


7/7

Figure 5: Earthworm granules. The possible Lumbricus rubellus granule is on the

right.

Figure 6: Rodent tooth.

molluscs and earthworm granules from sample 182

Documents