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'GBA' SAMPLES FROM EVALUATION TRENCHES AT DIMMER, CASTLE CARY,

SOMERSET (CCD10)

Internal Report for C & N Hollinrake

Matt Law, May 2010

Introduction

Three 'GBA' (General Biological Analysis,sensu Dobney et al. 1992) samples were taken from

Trench 7 at Dimmer, near Castle Cary, Somerset for assessment of the environmental material

contained within them.

Methods

The samples were air dried and then a standard weight of 1 kg was extracted from each and

processed following standard procedures (Kenward et al. 1980) using a 500 m mesh, and rapidly

scanned under a microscope for biological evidence.

Mollusca were identified as closely as possible by comparison with a reference collection. Principle

sources consulted for ecological information are Kerney and Cameron (1979), Kerney (1999), and

Davies (2008). Nomenclature follows Anderson (2008).

Results

The samples were very low in inclusions in general, yielding only very little residue, however a fewshells and shell fragments were recovered from sample 1, context 703; and sample 2, context 701.

MNI (minimum number of individuals) values for recorded taxa are listed below.

SAMPLE SAMPLE SAMPLE

Context (703) Context (701) Context (702)

MOLLUSCA Ecological notes

Cornu aspersum

(Mller, 1774)

fragmentary

Terrestrial, ubiquitous 1 0 0

Helicid sp.

fragmentary

Terrestrial, ubiquitous 1 1 0

Planorbis cf.

Planorbis (L.)

Freshwater, especially

pools and ditches,

tolerant of seasonal

dryness

4 0 0

Anisus leucostoma(Millet, 1813)

Freshwater, especiallypools and ditches,

tolerant of seasonal

dryness

3 0 0

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Discussion

In general, the number of shells recovered is far too low to carry any interpretative value. Cornu

aspersum and an unidentifiable Helicid snail were recovered as small shell fragments only. C.

aspersum, while tolerant of a wide range of habitats, is notable as it is an introduced species in the

British Isles, arriving in the Romano-British period.Planorbis planorbis andAnisus leucostoma are

both common lowland species found in a variety of aquatic habitats, but especially well-vegetatedpools and ditches which dry out seasonally. The low biodiversity and low number of shells from

these samples is likely to be due to poor conditions for survival.

Statement of Potential and Recommendations.

The assemblage is to small to warrant further work.

References

ANDERSON,R.,2008, Annotated List of the Non-Marine Mollusca of Britain and Ireland (London:

Conchological Society of Great Britain and Ireland)

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

DOBNEY,K.,HALL,A.,KENWARD,H., AND MILLES,A.,1992, A Working Classification of Sample

Types for Environmental Archaeology, Circaea 9 (1), 24-6

KENWARD,H.K.,HALL,A.R., AND JONES,A.K.G.,1980, A Tested Set of Techniques for the

Extraction of Plant and Animal Macrofossils from Archaeological Deposits, Science and

Archaeology, 22, 3-15

KERNEY,M.P., 1999,Atlas of the Land and Freshwater Molluscs of Britain and Ireland(GreatHorkesley: Harley Books)

KERNEY,M.P., AND CAMERON,R.A.D., 1979,A Field Guide to the Land Snails of Britain and

North-West Europe (London: Collins)