Jordan Patsula
Surveying is one the most important parts of the archaeological process. Surveying is used to accurately record the location of artefacts and test units, as well as the elevation across the site.
During this field school, three main instruments were introduced to us: the dumpy level, the theodolite, and the total station. All three of these can spin 360º, and have a powerful scope to narrow in on the target. All three are set up on a tripod and have to be levelled, which takes some practice but we got better over the days we were surveying.
First, the dumpy level was just shown to us, and we did not actually use it. The main difference between this and the other survey instruments is that the dumpy level only can record horizontal angles; the scope does not adjust vertically. A photo of a dumpy level can be seen below, from the Civil Engineering Portal website.
The theodolite is the next step up, and the first instrument that I used. Similar to the dumpy, it takes the horizontal angle, but also the vertical angle, however it does not know where it is, or which way is north. In order to record points, you must find north (whether true north, or a rough determined north) and set the zero to it. As you point the scope to your target, the screen shows the horizontal angle and the vertical angle. Either by using a combination of the vertical angle, the height of the instrument, and some trigonometry, or a measuring tape, the distance of the target can be found. After which, the coordinates can be determined in the lab. For elevation, the vertical angle is set to 90º, and is aimed at a stadia rod (giant meter stick), and the numbers are taken down. The higher the number, the lower the spot is. These elevations are taken at a regular interval. I had used a theodolite on the first site (BcGn-17). During this time, we were given a simulated artefact scatter, where we mapped the location of all the artefacts and set up 10 1×1 metre test units. James also broke down some rough pricing for us, saying that on average, a company would charge $400-$500 per test unit, putting our fairly small scatter at $4000-$5000. This price could be negotiable depending on the company’s need for work or desire for the site.
For my second time surveying, my group used the total station, also at our first site (BcGn-17). This is the most advanced of the three instruments due to its on-board computer. It can take the coordinates of the targets, by inputting the coordinates and zeroing it north. It does this by shooting an infrared beam to a prism, which is a mirror on a stick. It can also take elevation data, with the onboard computer once again doing the math for you, as long as the instrument height is entered. All of these numbers are stored on the instrument, and a USB stick can be plugged into it to transfer the data to a computer later on. My group affectionately named the total station Wilhelm during this round of survey.
My last time surveying, my group exclusively took elevation data for the second site we were on (BcGn-15). We took a scatter of points, and elevations of other groups’ units. Here we ran into a menu error, but we were able to rectify the issue back in the lab, thankfully. Below is a picture of my group in action taking elevation data for BcGn-15.
I am really grateful for the opportunity to survey three times during the field school. It is not only really interesting but also very enjoyable. Looking on towards the future, I feel that I have a good understanding of how these instruments function, and look forward to using them in the future!
Citation for dumpy level photo
Singh, K. 2022. “Dumpy Level.” Civil Engineering Portal – Biggest Civil Engineering Information Sharing Website. https://www.engineeringcivil.com/dumpy-level.html.