Unit Set Up “How-to”

The first week of each of our field sessions began with unit set up. This is a horrid task, so we felt we should share the experience with you all.

Kit2 copy

Some basic tools: line levels (a.k.a. spirit level, bubble level, simple level), plumb bob, tape measure

The technical aspects of setting up an archaeological excavation unit may vary from project to project, but some basic tools remain the same: string, measuring tapes, corner nails/stakes, line levels, compass, plumb bob, a fellow archaeologist [*Editor’s note: or two, or three*], some humility, patience, and no immediate access to sharp objects (see our previous post about an Archaeologist’s Field Kit https://scraparchaeology.com/2016/06/01/what-exactly-is-in-an-archaeologists-field-kit/). If you have ever had the pleasure of setting up a unit before, you know what we are talking about. [*Editor’s note: Shooting in an excavation grid does not count!]  It has been, thus far, the best test of how our crew can work together in a tedious and repetitive process and we can happily report that all crew members are still here and there was no hitch hiking back to camp! So let’s open up a window for you into the specifics of setting up a unit (we will try to keep our stress levels down).

The first thing we feel the need to mention is that the units we are setting up in the Alabama settlement are a little different from “normal” units that many archaeologists in North America are familiar with. Because we are working on mounds, which we believe to be the remains of house platforms, all of our units are set up on slopes. Additionally, we are working in an orange orchard with large trees placed every five feet, so our space to move freely in some instances is limited. However, because we are the best-of-the-best [*Editor’s note: and humble*], our units came out near perfect. Oh the humility! [*Editor’s Note: Oh the humanity!]


Megan holding the tapes and string at top two nails

The first step in unit set up is to determine the dimensions of the unit you desire. During the Phase II Testing program at SCRAP we are using 1 meter by 2 meter areas, although this can vary depending on the size of the mound to be investigated.  Align your 1m x 2m excavation based on the feature you are excavating; measure out one meter on your tape and place two large nails rimmed with bright coloured flagging tape at each end.  Cut two pieces of string each over 2 meters long and attach a line level to both. Ask your fellow crew member to hold one end of each string and the beginning of each measuring tape in each hand, have them stand at the top of your one-meter section with their hands over each nail.  Now ask them to look into your eyes and tell them that you appreciate them and that they are a pleasure to work with because shit is about to get real! [*Editor’s note: Apologies for the foul language, but it really was called for.]


Checking levels

Next, you need to calculate the hypotenuse of your unit. [*Editor’s note: This is where an archaeologist uses pretty much the only math they ever remembered from school…  the Pythagorean Theorem: a2 + b2 = c2.] Since our units are 1m x 2m, the hypotenuse is 2.24 meters. [*Editor’s note: Or, more exactly, 2.236m.] Calculating this measurement will ensure that your unit is perfectly straight and square.  Stand on the bottom left corner of your unit and grab the other ends of each tape and set the one in your left hand to 200cm and the one in your right to 224cm, the strings should also be in each hand as parallel as possible to the tapes.  At this point you want to simultaneously make sure that your tapes/strings are level and line up your 200cm point with your 224cm point.


Matching up points on tapes, and bobbing to place the nail

Using your teeth (or, if you are lucky, a second unsuspecting helper [victim]), use the plumb bob to correctly pin on the ground where the two points meet, placing another large nail with flagging tape into the ground at said point.  Repeat this process for the right side of the unit, reversing the tapes so that your 224cm one is now running diagonally from top left to bottom right, place a nail in the ground and pray to the Gods of Archaeology.  Measure the distances between all nails to ensure they are the correct dimensions.  If they are not, curse the Gods of Archaeology, and start the aforementioned process all over again until your measurements are correct. [*Editor’s note: Alternatively, you could just shoot everything in with a total station. But where would the fun be in that!?!*] Be sure to switch places with your colleague because clearly s/he is the problem and not you.


End product: 2m x 1m back-staked excavation unit with datum

After about an eternity your measurements should eventually be correct, at which point you need to string up and back-stake the corners of your unit.  Back-staking a unit is very important because it allows you to correctly stay within the dimensions of your area while still presenting an opportunity for forgiveness if you happen to lose one of your corner nails while excavating. Outlining your unit with brightly coloured sting that lies directly over your nails will help you with keeping the walls of your excavation area straight, and hopefully prevent you from tripping over the string.  Place two back-stakes behind every nail looping the string around them as tight as you can so that the line doesn’t sag, remove any surface debris/vegetation, and keep your string as low to the ground as possible. Place your datum stake around the middle of the top one-meter section and be sure to measure its height from ground surface and distance from the unit walls, and mark these measurements in your notebook. These are important for tying in all your unit measurements to the larger site mapping program.


Once it is done, kick back and relax with a beer (and beat on a piece of granite just for fun)

Finally, sheepishly look to your crew member, tell them they did good, and offer to buy them a beer because frankly, you guys deserve it.

Until next time,

Megan, Cristina, Kelsey, and Virginia