In-situ Preservation of Waterlogged Archaeological Sites 319
A
B
Figure 4The find layers typically found in Nydam. Finds are primarily found in two layers –
the Upper find layer (to the left of A) and the Lower find layer (to the left of B).
The finds in the upper layers are surrounded by peat whereas those in the lower
layers tend to be surrounded by gyttja
The archaeological remains are found primarily in two layers, approxi-
mately 0.80–1.25 m below the surface (Figure 4). The uppermost finds
are lying in peat, whereas the deeper lying finds are in a carbonate-rich
gyttja.
Wood and iron are the most abundant materials, but also artefacts of bone,
leather, amber, glass, bronze, and precious metals are found. Following on
from the period of extensive environmental monitoring at the site between
1996 and the present, it could be seen that the water level has been well above
the find layers and the seasonal fluctuation in water level is modest at approx-
imately40 cm. The meadow is slightly acidic (pH 6–7) and below the root
zone there is very little vertical variation. A good buffer capacity in the peat
and gyttja layers helps to minimise fluctuations. Dissolved oxygen content
is0.1 mg L^1 and the Eh (measured with permanently installed gold elec-
trodes) is stable at200 mV, indicating reducing conditions which is sup-
ported by the levels of reduced chemical species measured in pore water from
the site. Ideal conditions for preservation, but what does all this information
say about the state of preservation and importantly the future state of preser-
vation of artefacts preservedin situ? Research on artefacts themselves has
focused primarily on the deterioration of wooden and iron artefacts. These
form the most abundant groups of material encountered, and, based on the