UNDERWATERSURVEY 115
points. The aim of an assessment survey is to get a rough
idea of the extent and layout of a site as quickly and
efficiently as possible. Position accuracy is less important
than speed, as the plan can always be improved at a later
date. As a minimum, the assessment survey should result
in a paper plan, drawn to scale, showing the significant
features on the site, sea-bed type and an outline of the
topography, as well as any information requested in the
project design (figure 14.2).
Recording surveys include pre-disturbance and exca-
vation surveys. These require high position-accuracy so
careful planning, recording and processing are needed
and they take time to do correctly. A common question
regarding pre-disturbance surveys is, ‘how much informa-
tion should be recorded?’ The simple but daunting
answer is, ‘as much as possible without disturbing the site’.
The more information that can be collected through
non-destructive pre-disturbance surveys, the more effect-
ive future work on the site is likely to be. This applies to
both the planning of further work on site and avoiding
unnecessary damage to archaeological material.
A pre-disturbance survey is an essential step in ensur-
ing that a complete record of the site is made. A pre-
disturbance survey is not undertaken for the sake of it;
the work will provide useful information on the condi-
tion of the site at that time. The results can be used as a
benchmark for future monitoring (see chapter 17) if no
further work is to be done, or can be a record of the ori-
ginal condition of the site if it is to be altered or destroyed
by intrusive investigations such as excavation. The in-
formation collected during the pre-disturbance survey
can help to ensure that the appropriate funds, conserva-
tion facilities and expertise are arranged well in advance
of any disturbance to the site.
If intrusive investigation is considered to be the most
appropriate way forward for an archaeological site,
then recording during excavation is an essential contin-
uation from where a pre-disturbance survey left off.
Pre-disturbance survey results are developed during
excavation as more artefacts, structure and stratigraphy
are uncovered.
Monitoring surveys are designed to monitor how
the site changes over time. Using an existing survey, a
monitoring survey compares those parts thought most
likely to indicate change. Typical examples might include
monitoring the position, attitude and remains of aFigure 14.1 Excavation plan of part of the Spanish Armada wreck La Trinidad Valencera(1588), a scattered site on a
flat, sandy sea-bed. The excavation limits are shown within a grid framework, and the locations of prominent objects
shown. The extent of a major deposit of organic material is shown by hatching. (Colin Martin)