On-site observations

© Archivo CAS
Labores de medición y documentación de un pecio del siglo XIX, Camposoto, España.

Primary observations and data are very important. It is good practice in archaeology to keep field-notes and diaries. Systematic field notes in small hardbound notebooks and written in pencil rather than ink, for readability after having been left out in the rain or splash-water, used to be the norm. The entries are both the basis and a check for analysis. As they also contain notes on weather conditions and sea state, headaches, emotions and seasickness, they provide a useful background to assess the accuracy and reliability of the observations made on a particular day. No archaeologist is infallible. Keeping such field notes in the project-archive is not a sign of weakness or doubt concerning one’s final analysis or interpretation. In fact, it is a sign of professional strength.


Example of an artefact record sheet

Offset and trilateration form

Planning frame



Show all / Hide all

fold faq

Primary observations on the site

Methods for taking field notes

The simple method, including notebook and pencil, is still useful today, especially in small operations with small teams, or in operations involving much improvisation. Generally, however, ‘current professional standards of archaeological documentation’ include a formalized system of registering data and observations. Standardized forms have become the norm. There will be a range of these forms in a larger operation. Each form will contain information on a particular aspect. Some are oriented to control the operation, others are meant for description of the drawings, photographs, or measurements that have been collected, still others will be designed for the documentation of specific types of features in a standardized way. 

Meticulous documentation

Documentation can hardly be thorough enough. This is especially true for the documentation of onsite observations. Many archaeological observations, especially those that relate to stratigraphy and spatial relationships in deposits that are unravelled in excavation, are of a one-off nature. It is good practice to have another member of the team corroborate those observations, even if that is not always possible. In low visibility and highly dynamic underwater sites, for instance, every single observation may turn out to be important. This is to say, it can be important for the purposes of the project at hand, but it can also prove important at a much later stage.

Diving documentation

The documentation by the diving supervisor is aimed at safety and management of potentially dangerous situations and accidents. It should always be kept in real-time and hard copy. Individual dive sheets may also contain information that is important for evaluation of safety issues. Archaeologically, however, it is more important that they serve the same purpose as the hardbound notebook referred to above, commenting primary observations as well as remarks on general well-being and the conditions of the dive. Such sheets should also refer to any other documentation that results from that same individual dive, such as drawings, sketches, photos, video or measuring sheets.

Delays of documentation

Due to underwater psychology and the workings of the human mind, it is essential that the delay between the dive and the writing of the individual dive report is as short as possible. Sometimes this implies that they need to be written in hard-copy as well, although the project-director may want them to be entered into a computer at the end of the day. Other forms, such as drawing-sheets, photo-sheets, measuring sheets, feature-sheets, find- and sample-lists, artefact-sheets or timber-sheets, as the case may be, may directly be entered into a computer, for ease of backup and cross-referencing. But that, of course, depends very much on the situation. Backups only work if several computers or a connection to the internet are available on the working platform or at base. Computers do not do well in small boats or with wet fingers, and are even less useful when they fall overboard.


It is not only computers that risk getting wet and washed out. Underwater operations as a whole are particularly prone to all sorts of mishaps and interruptions and to the vagaries of weather and sea state. Documentation should be organized accordingly. An experienced underwater archaeologist is known for his dictum ‘each day one should document as if there is no other day’. It can be very tempting to postpone finishing after a busy shift. However, it is good practice to round off all documentation, including a daily summary before finishing the day, even if that means working late at night.

fold faq

Technological advances


In the diving industry other than recreational diving, there is a tendency to limit the amount of time spent under water to an absolute minimum, whatever the depth. Remotely Operated Vehicles with cameras and documenting equipment, and tracking devices for adequate measuring have replaced divers in many construction jobs, reducing their presence to assessments and complicated operations where their intelligence is needed, or to simple tasks where the diver is nevertheless the more efficient. The technology employed generally calls for extensive investments or high leasing rates. But if a few days of expensive equipment rental can win several months of toiling by inefficient scuba – divers it is still the more efficient option. Miniaturization of offshore technology has the dual effect of reducing rental, shipment and purchase rates with technology becoming more versatile for some of the tasks related to archaeological documentation.

In choosing efficient documentation techniques, one should be prepared to combine different systems. It is quite clear that simple offset measurements and sketches are the most efficient in limited excavation trenches. In setting up a grid for measurements, a Direct Survey Method including computer-processing of simply measured direct distances is to be preferred. There are several simple and readily available computer programmes that can process such data with the help of non-parametric statistics.

In documenting complex structures, long periods of underwater work can be avoided by combining simple triangulation with voice-recording of the measurements and processing in the dry. Direct distances, measured with tape measures, should not as a rule exceed 20 or 30 meters, especially not if visibility is low. Therefore, if measurements need to be taken over larger distances, the tracking devices of the offshore industry might be an efficient answer, especially if their deployment can be focused and concentrated on a few days. For shallow sites, GPS–positioning with the antenna on a long pole may be an answer for the reference grid, and if close to land a traditional surveyor’s Total Station can do the trick. Another step is to integrate the local grid into the land- or sea-bottom-scape, for instance, in a detailed bathymetry image.

fold faq

Consideration for future research


The chosen documentation methodologies and techniques should take into account that future researchers will need to use the data to address problems not recognized at the time that the data was collected. This means that a record of primary observations and raw data should be kept alongside with the processed data. Spatial relationships between different layers and their interfaces can, for instance, profitably be analysed with the help of the so-called Harris-Matrix, but the documentation should allow reconstructing what the interpretations are based on.

It also means that destructive methods of data-gathering should not be applied to portions or elements of the site if non-destructive methods are possible. In those cases, however, where it is known that the site will be destroyed anyway, for example, when industrial construction will follow the investigation, this is not an issue. It may be far more practical and efficient to gather the needed data in the most direct manner, even though this may involve the use of destructive techniques. This is also one of the reasons why destructive archaeological research should preferably target those sites that will meet this kind of fate.

Alongside the primary aims of the documentation programme, it is quite likely that the field operation will collect data that is not fully analysed in the context of the project. Just like the raw data that is actually analysed, this additional data should also be recorded and preserved in a way to facilitate future research.

Similarly, project documentation needs to be recorded in a certain way, and order, and on media that will be equally available and comprehensible for future researchers. Nowadays, digital recording and storage is particularly recommendable, but it has its specific problems and issues. Attention needs to be paid to saving back-up copies in different data formats and places. Also, it should still be contemplated to deposit full paper copies in a safe place elsewhere.

Back to top