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50 2006 The Authors. Journal Compilation 2006 The Nautical Archaeology Society
D. ELKIN ET AL.: ARCHAEOLOGICAL RESEARCH ON HMS SWIFT: LOST OFF PATAGONIA, 1770
Figure 20. Detail of the excavation zone showing rope and assorted tableware. Note that some of the latter is inside a wicker
basket. (C. Murray)
the excavation in the stern. The vast majority of very good preservation and integrity of most of
them have the Admiralty broad arrow engraved. the Swift wreck. However, the marine dynamic
Some of them were found stacked, so they must has played a fundamental role in its formation
have been spares. In the excavation four rectangular and evolution. Therefore site-formation processes
lead pieces were found. They are interpreted as constitute the basis for an adequate understanding
counterweights, possibly for sash windows. Their of the changes which took place on the site and
length ranges between 15 and 27 cm, being slightly for a proper interpretation of the archaeological
shorter than the ones found on the Pandora record. They also contribute to guiding aspects
but similar in shape (Campbell and Gesner, 2000: related to conservation, and to developing predictive
73 4). models applicable to other sites in the region
The base, a section of the edge and one handle (Elkin, 1997; Elkin, 2000; Bastida et al., 2004;
of a wicker basket were found in the stern Bastida et al., forthcoming).
excavation, in direct association with other artefacts Bio-deterioration studies have been orientated
such as drinking glasses and porcelain plates and to the identification and evaluation of the action
bowls (Fig. 20). A sample of the wicker was of two principal biological agents: biofouling and
identified as Salix viminalis (Rodrguez, 2002). wood borers. The aim is to understand the diverse
effects these agents have on archaeological artefacts
and structures. Hence, two objectives have been
Biological site-formation processes
proposed. The first is to identify the fouling
The non-traumatic circumstances of the wrecking species present, to understand their mechanisms
and the beneficial environmental conditions allow and cycles of colonisation and growth, and to
2006 The Authors. Journal Compilation 2006 The Nautical Archaeology Society 51
NAUTICAL ARCHAEOLOGY, 36.1
determine their deleterious effects on different
archaeological materials. The second goal is to
determine the presence of wood-borers, identify
the species, and understand their biological cycles
and the extent of their damaging effect on
wooden remains.
The research started by conducting a systematic
observation of the association between the different
biofouling species and the specific archaeological
materials they colonise (taking into account the
raw material, texture and shape). In order to detect
the presence of marine borers, diverse artefacts and
ship structures were first examined macroscopically.
A complementary experimental study conducted
at the same time used acrylic and wood panels of
10 5 cm, fitted to a 30 40 cm acrylic frame and
placed at the bow and stern for studying biofouling
and wood-boring agents respectively (Fig. 21).
Panels were inspected after 6, 12 and 24 months
to monitor colonisation, growth and reproductive
processes of the fouling organisms and to evaluate
the presence of wood-borers. The general tendency
is for biofouling to colonise all structural elements
or artefacts found above the sediment level,
except toxic materials such as copper. The most
characteristic associations observed macroscopically
for diverse materials are illustrated in Table 3.
It has been observed that artefacts as well as
structural components of the wreck show galleries
produced by marine borers of the Teredinidae
family and possibly Pholadidae as well. Some
galleries present a layer of calcium carbonate in
their interior, while others seem to have lost it
Figure 21. Experimental wood panels placed on an acrylic
over time. The sectors of the ship attacked by
base for experimental studies of woodborers. On the reverse
borers include the lower as well as the upper
are other small acrylic panels for biofouling experimental
works (Fig. 22). Differential attack related to
studies. (M. Grosso)
wood-species was not observed, with borer action
recorded on both pine (window-frame and hatch)
and elm (gun-carriage wheel). Galleries or remains gregaria and Cnemidocarpa verrucosa. This con-
of Limnoridae isopods have not so far been stitutes the climax stage of the biofouling process,
found in the analysed wood. after which several detachments take place, which
Study of the experimental panels indicates that leave the original surface free for an immediate
during the first six months of immersion (March new colonisation.
to September 2001, that is, autumn and winter) a The biofouling of the site shows variations
not very intense biofouling process developed. related to water temperature: those panels which
This corresponded to a stage which followed were immersed during the six warm months
the initial biofilm and the beginning of the show a greater biomass and a higher taxonomic
development of pioneer macrocomponents of the diversity. This means that the clean substrates
biofouling (for example incrusting briozoans, which were submerged at the beginning of the
serpulid polychaetes, amphipod crustaceans). In cold season reach their climax within one year,
the panels which were immersed for 12 months while if the initial immersion takes place at the
(March 2001 to March 2002) the community had beginning of the warm season it is possible to
acquired its maximum development and diversity have two climax stages within the same year. All
with a clear dominance of the tunicates Paramolgula of this indicates that Patagonian biofouling is
52 2006 The Authors. Journal Compilation 2006 The Nautical Archaeology Society
D. ELKIN ET AL.: ARCHAEOLOGICAL RESEARCH ON HMS SWIFT: LOST OFF PATAGONIA, 1770
Table 3. Main associations observed macroscopically between fouling species and different archaeological materials
Biodiversity
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