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As an archaeologist, my personal relationship to soil did not go further than being able to say that excavating in a clay-area is annoying when it rains, excavating in a sandy area makes you get a natural body-scrub when it is windy and excavating where there is tuff makes you look like you have a nice tan (until you take a shower and realize it is just the dusty tuff…). However silly that may sound, it has always been obvious to me that the soils we dig are different. Nevertheless, as many archaeologists, I would focus more on the artefacts and not really pay attention to what secrets the soils may hold. But fear not! There is a solution: the ARCHON Geoarchaeology course at the VU, Amsterdam!

 

Day 1:

Navigating underground, ‘’modern art’’ and dirty dinnerImage and video hosting by TinyPic

The first day of the course began with a short lecture presented by Dr. Sjoerd Kluiving with a review of Quaternary Geology in the Netherlands. This is the geological period we are currently in, but which started more than 2.5 million years ago. The Quaternary period is separated into two epochs: the Pleistocene being the oldest, which is followed by the Holocene. During these times, the Netherlands would be totally unrecognizable: large areas were still covered with water, thick ice caps pushed upon the land and rivers were flowing differently. All of these processes have left traces in the landscape as we know it today, and you do not need to drill a hole in the ground to see some of these.

During the second part of the morning session we were navigating underground by looking over different maps of the Netherlands, which could be seen as a very accessible technique of geoarchaeological research. We studied the soil map and geomorphological map of (the region of) Amersfoort. On first glance, these maps look like a sheet of paper someone spilled many colors of paint over. However, studying them closely gave us some valuable information about what the landscape and soil in that region looks like and by relating the information on the map to each other, you can then go on and interpret why certain soils can be found in a certain location.

No, those are not modern art pieces, though I would not mind having one of these on the wall in my room. They are known as ‘lacquer peel’ and are an imprint of a soil. During this part of the course, we were tasked with describing such a lacquer peel in detail. It starts out by determining which are the different horizons, or layers, the soil is made of. The sediment in each layer is then described by means of elements such as color, texture, structure and the amount of organic material. Armed with that knowledge, you can determine the type of soil, which in this case is called a ‘podzol’.

The day ended with an exercise of describing soil samples that were taken in Scotland. It is a lot about determining colors and textures again (may all else fail, I can maybe think about a career as an interior designer). For describing colors, we used something called a Munsell-scale. Basically, this is a small book with different colored squares in it, which you then compare to the material in front of you. The real challenge starts when describing the texture… It involves a lot of feeling to determine when something is clay, silt or sand, or a combination of those. You want me to let you in on the secret? When you rub sand in your hand you will be able to feel the individual grains. Where silt and clay are involved you wet the material and then rub it in your hand. If the material stick to itself it is clay, and when it sticks to your hand it is silt. Just in case you were wondering: ‘wetting the material’ indeed means that I put it in my mouth…

 

Day 2: Archaeologists gone wild!

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Those who know an archaeologist are probably familiar with the situation: that time archaeologists go wild… Finally, after months of being locked inside, reading dusty books, and working on reports that seem to be endless, it is time for them to go wild and return to their natural habitat: the outside world!

On day 2 of the Geoarchaeology course eight students and two professors enter a tour bus headed for the Wekeromse Zand in the province of Gelderland. There was a general excitement to get outside and apply the techniques we learned during the first day, although there was also some napping while on the bus. Nevertheless, when we arrived at the Wekeromse Zand, everyone was ready to go. I was excited though a bit skeptical about whether I had enough knowledge to do it. However, as with many things, practice makes perfect.

The Wekeromse Zand is located in the High Netherlands (that part of the Netherlands that was formed during the Pleistocene). Here we took three coring samples. The first one was located on a dirt road next to a meadow. Here we found a relatively large horizon of dark brown material with pieces of plants, bricks and charcoal in them. This is called an anthrosol, which is a layer created by human interference. However, underneath this thick horizon, we found a podzol soil which used to be the original surface before the anthrosol was created. The second sample was taken in a more hilly landscape. Here the core sample came back with ‘just sand’ and no distinct layers were visible. Had we cored deeper, it would be very probable that we would have found a podzol soil underneath. This sand on top is drift sand, which has been moved by wind and deposited on the old podzol surface. The third coring was taken in a very open, sandy area. For this coring, there was also nothing but sand and no clear layers were visible in the sample. However, the sand was a different color from the material of the second sample. In fact, this last coring was taken in an area where, by means or erosion, the original podzol had been lost. We were therefore only sampling the Pleistocene sands.

We left the Wekeromse Zand and went on to Amstelveen in the Western Netherlands. As I mentioned before, the Wekeromse Zand was located in the High Netherlands, but Amstelveen is located in the Low Netherlands. This means that it used to be covered by the sea, and this also becomes apparent in the core sample. In total we cored to a depth of 10m below sea level, with which we broke record of 8.10m below sea level from last year’s Geoarchaeology course (try and beat that 2018 participants!). At this depth we mostly found clay with a lot of sea shell fragments in it that indicate sea level was present in the past. With this one coring we went back about 10.000 years in time. As an archaeologist I often tell people I feel like a time-traveler, but I never went back in time to 10.000 years ago!

Day 2 of the Geoarchaeology course allowed me to connect the information taught in the lecture to a ‘real-life’ experience. On a small side not, it turns out that when you are inexperienced and rather small, coring does not go that fast… So, thanks prof. Ian Simpson for helping us speeding up the work!

 

Day 3: Getting closer…

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After an extremely short night (more on that in a bit), the final day of the course started with a coffee and being lost at the VU campus… After wandering around for about 20 minutes we managed to find the correct classroom, where prof. Ian Simpson had already started on a short lecture about ‘thin section’. These are basically extremely thin slices of soil that you can observe under a microscope to get more information about the specific elements that the soil contain. We looked at the thin sections of three different sites in Scotland, each from a different time period: Late Neolithic/Bronze Age, Iron Age and Medieval.

The thin sections were all taken from an anthrosol – a layer in the soil created by human interference. With this exercise we attempted to understand the transition of anthrosols. For my untrained eye it was relatively difficult to determine what the different colors and structures in the thin sections meant. As prof. Ian Simpson said: ‘’Welcome to a new language’’. In the thin sections we were looking for a lot of different elements, such as: the microstructure, the coarse mineral material, the fine mineral material, organic material and possible anthropic inclusions. It is a bit overwhelming, the amount of information that is stored in such a thin slice of earth.  

We saw that the material from the Late Neolithic/Bronze Age site contained kitchen waste material, such as charcoal and bone fragments. In the sample from the Iron Age site we saw some remains of animal manure in addition to the kitchen waste material, which is an indication that the anthrosol changed. The thin section from the medieval period showed a change again, where the kitchen waste material was mostly absent and more animal manure components were visible.

After the microscope practicum all the students of the course gave a short presentation about a geoarchaeological topic. This is why the previous night had been so short for me… I was really struggling to come up with a topic that would fit with my research, but that also fit with geoarchaeology. In my thesis I am working with public archaeology and how archaeology is perceived in contemporary society. This does not really match with soil horizons or thin sections. Nonetheless, with the help of dr. Sjoerd Kluiving and prof. Ian Simpson, I settled on the theme of identity. This is also what I want to look at in my research report: how soil can influence identity of people nowadays and why this is very apparent in some regions, while not in others.

After the student presentations we had a short evaluation of the course and then went for a drink in a nearby restaurant. Before I knew, we had to get back to the car and drive back to Groningen. Overall, I am quite happy I participated in the course, though I would have wished I had known these techniques earlier on in my studies. Now I am towards the end of my studies, it is less likely I can apply the techniques to my own research. Nevertheless, the ARCHON Geoarchaeology course: I am digging it!