16 BASICPRINCIPLES – MAKING THEMOST OF THECLUES
- Sites of evidence lost or deposited while using the
water. Shipwrecks are perhaps the most obvious
example. - Sites established on or at the edge of water, which
are partly or wholly submerged. These often relate
to maritime infrastructure such as quays, wharves
or docks. - Sites built in or over water are rarely completely ac-
cessible to investigations based solely on dry-land
methods (e.g. crannogs and pile dwellings). - Sites that were established on land but are now
submerged (e.g. the prehistoric sites in the eastern
Gulf of Mexico or the prehistoric sites which were
submerged when the English Channel flooded). - Sites which have continued to develop during a
rise in water-level. Since the site will progressively
retreat away from its original location, earlier ele-
ments of its development will now only be available
under water.
The second reason for underwater sites being import-
ant is that clues about the past are often so much better
preserved than on land (figure 4.2). However, if artefacts
are left exposed to seawater they will suffer from natural
processes of decay (see chapter 16). Nevertheless individual
objects that do survive are, to some extent, better protected
from recovery or disturbance by the barrier of water
above them (plate 4.1).
Perhaps the most exciting example of potential pre-
servation on underwater sites is a feature sometimes
referred to as the ‘time-capsule effect’. The clues usually
available on land sites, which are often inhabited for long
periods, do not necessarily give an accurate picture of
what was happening at any specific moment; instead
Figure 4.1 Sites have a place in the settlement pattern of their time. Ships, for example, though very mobile, are still
just part of a worldwide system. (Drawing by Graham Scott)