Archaeological survey is a means of recording archaeological remains that are physically preserved above and/or below the ground. The types of survey used depend on a whole host of factors such as the type of site, its current condition, its location, and time constraints. Time constraints will often dictate how accurate your recording is, but essentially the aim is to produce measured drawings or digital data of the archaeology to not only preserve remains by record, but also to assist in future research. Here are some types of survey you should become familiar with.
Essential Types of Survey
On-site hand drawing
This is a skill many field archaeologists will have. It is a physical (or perhaps digital, if on a tablet) measured drawing of what has been excavated on a site. “Plan” means it is a “bird’s-eye” view, while a “section” is something 90 degrees to the horizontal plane (typically a “cross section” revealed by digging a slot into a ditch, or by excavating half of a pit, for example). A common way of completing these drawings is with a hard pencil (like a 4H) and permatrace (also called drafting film; a thick, high-quality sheet of film a bit like tracing paper). You will likely either have gridded paper underneath your permatrace or have a grid printed directly onto it. There are many graphic conventions; page 9 of this document details the conventions, and pages 10-13 detail how to complete sections and plans.
You may also be required to survey standing structures, such as historic buildings, by hand. A helpful guide to how to do this is Historic England’s Drawing for Understanding guidance document. For standing historic buildings, instead of drawing sections you will often draw “elevations”; the faces of the building. If you have not completed any measured drawings on an archaeological site, but want to get some experience, you could complete measured drawings of buildings near you, garden features, or anything you have access to. Permatrace is incredibly durable and can survive being rained on, but if you’re just starting out and the weather is good, it can’t hurt to use more ordinary equipment to get a feel for it, since permatrace is quite expensive.
On-site GPS/GNSS and Total Station Theodolite
GPS (which specifically uses just the US Navstar Global Positioning System)/ or more generically GNSS (Global Satellite Navigation System) units use satellites such as US Navstar Satellites, Russian Glonass, and European Galileo, in conjunction with Ordnance Survey (OS) ground stations, to work out where you are on the earth’s surface. The stationary OS ground stations are used to correct any inaccuracies due to effects such as atmospheric conditions and so on to achieve accuracies of roughly + or – 1.5 cm. This can be achieved using a method called post-processing back in the office where OS RINEX data is downloaded and added to your survey data to correct it. Alternatively, your organisation may have signed up to a paid-for subscription service provided by the supplier of your GNSS equipment; a mobile phone or mobile phone module will talk to the OS ground stations to achieve real-time corrections.
Surveyors use GNSS to accurately and precisely locate and record archaeological features at varying scales in the 3D world, building up a picture through many points of data. Meanwhile, Total Station Theodolites (TSTs) measure points relative to each other. These points, often called Station Points, or Temporary Bench Marks (TBMs), can be set up on a local grid or on Ordnance Survey grid points that have already been established, usually via the use of a GNSS. All measurements taken, whether using a local grid or the Ordnance Survey grid, will be in 3 dimensions with height (+) or depth (-) recorded.
Depending on the make and model of a TST, TSTs can measure using a Reflector or Reflectorless; in the latter model the laser beam will bounce back of a surface and is regularly used in the survey of buildings and standing structures. TSTs can also be robotic, whereby the reflector and a controller computer are mounted on a detail pole; the TST will track and follow the surveyor and the reflector.
Each method has different advantages and disadvantages; for example, GPS/GNSS units need to be able to locate satellites in order to work, and are therefore not so useful indoors. A GPS/GNSS will also struggle to record points when directly up against the elevation of a building, and this can be due to the partial blockade of signal strength from the overhead satellites and/or the diameter of the GPS/GNSS antenna preventing the point of the detail pole from being accurately placed as close as possible to the point on the elevation that is being recorded. On the other hand, TSTs need to be in line-of-sight with their targets and reference points, meaning very hilly areas may be difficult to do. However, both methods require the surveyor to carry kit around a site, place it on a point somewhere, and take a reading. It is a bit like a giant dot-to-dot, except you make the dots. See BAJR’s Short Guide to GPS and Historic England’s Traversing the Past: The total station theodolite in archaeological landscape survey. Unfortunately, this can be a difficult skill to gain outside of paid employment, and even some field archaeologists struggle to get an opportunity to gain the experience.
These methods build up datasets that can then be used to create a CAD drawing (see below). This is very common in archaeology, although the data may be imported into GIS instead (see further down). At this point, the data will be processed and may later be edited by an illustrator to make a plan that can go in a report.
CAD (computer-aided design)
This is a tool used in many other industries as well, such as architecture and engineering. CAD programmes visualise your data while retaining information about each point you took, and your drawing exists in a digital 3D space. On-site survey will usually need tidying up in CAD or GIS. AutoCAD is the industry standard, but is very expensive, so some units use free or cheap alternatives, such as DraftSight. If you haven’t already, it would be a good idea to get some experience using this software, either by enrolling on a training course, or downloading a programme and trying it out. You may not have archaeological data to play with at home, but you can draw from scratch in CAD to get used to the way it works.
GIS (Geographic Information Systems)
Most units will use ArcGIS or QGIS. These are powerful tools that allow you to import your own geographical data (such as survey data, if it is georeferenced) and existing data from suppliers such as the Ordnance Survey. This can be useful not only for looking at your site in context, but also for preparing maps and plans for your reports. See BAJR’s QGIS for Archaeologists. GIS is not only useful for processing GNSS and TST data, it can also be used to trace over your hand-drawn survey, import your geophysical survey (see below), overlay different sets of your data, and so on. Luckily, it is easy to try this at home, since both QGIS and some Ordnance Survey data are free.
GIS can also be used to display geophysical datasets, both marine and terrestrial, and LiDAR datasets, although their abilities with regard to displaying and analysing 3D data are more limited. GIS can link to datasets, allowing you to search and visualise information in powerful ways.
Specialist Types of Survey
Geophysics is a specialist type of non-invasive survey that uses a variety of techniques to collect information about underground features. Please see BAJR’s Archaeological Geophysics: A Short Guide.
Geophysics equipment is not exactly easy to get hold of if you are not already working for a unit. However, you can familiarise yourself with the data at the Historic England Geophysical Survey Database, hosted by the Archaeology Data Service. Ultimately, a geophysicist would be expected not only to collect data, but also to interpret it.
Please see BAJR’s Beginners Guide to Aerial Survey and Rectification and Historic England’s page on Aerial Investigation and Mapping.
Aerial survey often involves the use of drones (UAVs), but a lot of archival data are shot from piloted aircraft. As a beginner who is not yet in a relevant role, it can be difficult to get access to drones and high-quality cameras you are willing to risk by flying, let alone the equipment for LiDAR. You can, however, start by using already collected data and processing and/or analysing it. See Britain from Above for a huge collection of aerial photography of the UK. As for LiDAR, try the free government LiDAR data, which you can use in conjunction with GIS software or a programme like FugroViewer.
Photogrammetry and Laser Scanning
Photogrammetry can be used in the field, underwater, or in the office. The idea is to take plenty of photos of something from many angles, then use software to stitch together a 3D model. This may be used for finds once they’ve been cleaned up, things in-situ like burials, or even whole landscapes. The key is high-quality photography, and plenty of it. See Historic England’s Photogrammetric Applications for Cultural Heritage. It may not be utilised much on smaller sites, but it is a useful skill, and you can try it out at home by photographing any object and using software such as Agisoft Metashape (previously known as Photoscan, Metashape is not free, but it does have a free trial period).
Laser scanning, on the other hand, requires specialist laser scanning equipment on-site, which creates a “point cloud” and generates a 3D model from that. It can also texture this model with photographs. See Historic England’s 3D Laser Scanning for Heritage. Unfortunately, this is another skill that is difficult to acquire outside of the workplace, since it requires specialist and expensive equipment. It is, however, used in other industries, and there may be training courses. Otherwise, you could download existing data and see what you can do with it in a 3D programme of your choice, such as Blender (free). Luckily, this is not a skill that is commonly expected of job applicants; that said, it does help to be aware of current technology and the kinds of methods that might be used.
Laser scanners and handheld laser scanners can be rented out along with the processing software; it is also possible to upload your survey data onto the website of the company who supplied your laser scanner equipment who will process your data for a certain charge. Also, some modern TSTs are equipped with the ability to carry out rudimentary laser scanning.
Other forms of 3D data
The use of 3D software to visualise and analyse data is becoming increasingly common, although it is unlikely that you will utilise these packages straight away at the start of your Geomatics career. Your use of such packages will also depend on the nature of work that yourself or your company regularly undertake. For example, 3D software such as Fledermaus will be used to import and analyse 3D data captured by Multi Beam EchoSounder (MBES) bathymetry systems used in underwater archaeology. Other examples are used in terrestrial archaeology such as Golden Software’s Surfer and Voxler programmes.
A surveyor or geophysicist is likely to be collecting data in the field for most of their role, but are also likely to produce some basic figures for reports. Meanwhile, a prime requirement of a Geomatics Technician or Officer will be to both analyse and edit the data from incoming fieldwork and surveys and to produce figures for clients and publications. These figures will be subject to Quality Assurance checks by a colleague to ensure that they are legible, accurate and cartographically correct.
What to expect in the industry
Surveyors are not very commonly recruited as full-time dedicated surveyors, but it does happen, especially within the wider Heritage sector (for example, as Historic Building Recording/HBR surveyors). Survey experience, however, is desirable for field archaeologists, geomatics technicians, and illustrators; this most especially applies to hand-drawn, GNSS and TST survey. Sometimes field archaeologists will grow to specialise in survey within their unit, and there are some survey-related office-based jobs, such as Data Officer. It is recommended to get plenty of commercial field experience for this sort of role, and familiarising yourself with the techniques above will put you in a good position.
Meanwhile, geophysicists are fairly likely to be recruited for dedicated roles, both collecting and processing data. Keep an eye on BAJR for roles that use the keywords geophysics, geophysical and geophysicist.
Surveyors have to be quite independent and resourceful. They will tend to be the first on site with no infrastructure (which has implications for Risk Assessments) and there will be long days; loading vehicles (and doing vehicle checks), heading to site, surveying, driving back, unloading, and at the very least backing up the raw survey data, packing the equipment away, and putting batteries on charge. Project Managers sometimes do not have any understanding of what survey/geomatics need; this can result in short time constraints and not giving information in enough time in advance. Be prepared to have to explain sometimes that the process is a long one, and take the initiative to chase colleagues for the information you need to start.
Surveyors on site have to make decisions about what to map and how to map features; they may have to make decisions that disagree with the pre-conceived notion of what is happening on site. For this reason, there is a necessity for the surveyor to have done fieldwork so that they can interpret the archaeology and therefore map it, especially in case a colleague has marked things incorrectly. You should also watch out to make sure that responsibilities have been clearly defined, as some tasks could naturally sit either with the surveyor, the fieldwork staff, or even the office staff, so be prepared to ensure that you are clear on which tasks are your responsibility.
Specialists in many types of survey often have to figure out new software programmes and how to use them. The instruction booklets (electronic within the programme) are very long, so given the time constraints of commercial archaeological units there can often be a fair bit of experimentation. You can expect to also get into the business of upgrading survey software and application programmes (firmware on survey machines). At some point there will be a software issue that will involve sometimes frustrating phone calls to technical support (sometimes Leica, Trimble, etc., will also struggle to identify the issue). An experienced geomatics team will have identified the common errors and made instructions to deal with them. If you are in an office-based role, you can expect phone calls from people in the field in these instances too, so familiarity is still valuable.
Maintaining/cleaning the equipment and charging/recharging and backing up and processing of data is your responsibility until you hand it over (with confirmation) to a colleague; the next person needs to be able to collect equipment for another survey and go without worrying that it is dirty or uncharged. Also keeping all necessary components of equipment is essential (there is a lot of labelling of individual parts so that people can re-unite cables, etc., with a machine). Not having charged up equipment before turning up can have disastrous consequences, as even if the site has electricity, the time taken to charge will eat significantly into valuable surveying time. Similarly, equipment can fail for no apparent reason, or perhaps the satellite/phone reception is much worse than expected, so always have a backup plan.
Like any speciality, there is a risk of becoming stuck, and you may struggle to get out and into another field; you may have to leave to get a more senior post elsewhere, or even move out of archaeology into some other type of surveying (such as for the Ordnance Survey). This does mean that some of your skills will be transferrable, but archaeology is a small industry, so bear in mind that you will not have the widest choice compared to many other professions. That said, surveying can give you a lot of interesting projects, help you acquire many skills, and be able to see the bigger archaeological picture by virtue of editing the overall map of the site.
Special thanks to Mark Littlewood for the “what to expect” section and assistance with the rest of the text of this page.