As the old saying goes: the field of geoarchaeology is as clear as mud. Literally. After spending some time digging into geoarchaeological research questions and tools during the ‘Geoarchaeology course’ at the VU, it became clear to me that every archaeological project is in need of a solid geological base. Sherds, pots, bones and ruins are – almost – worthless without a proper evaluation of the context in which they were found. And if we did not find any archaeological artefacts, can we actually see how the landscape would have looked like in the past? And how?

Figure 1 – Part of the geo(archaeo)logists’s toolkit

 

Ice ages, field cultivation and manure

If we were to take a trip from Utrecht, the middle of the Netherlands in any direction – west, east, north or south – the landscape would not change very dramatically. However, if we were to dig a bit deeper into the past of the Netherlands, we would find remnants of a past landscape that was very different from what it is today. By looking at the formation of soils, the size of the sand grains, the colour of the different layers in the ground, there is a bulk of information that will tell us about the thick masses of land ice that would occupy the north of the Netherlands for example. Not only would a reconstruction of the landscape in the past be very useful in creating a context in which we can place our flint tools and bell beakers, it also raises more archaeological questions.

One of the main questions which come up when investigating a past landscape is how people have lived in the past? What kind of areas did they prefer? Nowadays, the Dutch live in safely a land that is partially below sea level, because it is protected by dikes, dunes and the delta works. These are all (partially) man-made structures which prevent the Dutch from having wet socks. However, apart from some sand dunes, the rest of these structures were not present in the past. We assume that past populations might wanted to have dry feet and sought a higher place to settle. With geoarchaeology such assumptions can actually be tested.

From macro to micro

The geoarchaeological toolkit comprises of a large range of tools to describe and investigate the soils and sediments. These tools range comprise of large scale investigations of the soil through coring up to 7 meter deep and creating a deep profile of the sedimentation and/or soil formation. By describing the colour, texture, structure and more, the way of deposition and soil type can be determined. These information can lead to e.g. the reconstruction of the past landscape, how much energy was needed to deposit sediments and most importantly to archaeologists: if the landscape was altered by human interference. Analysis also takes place onto a much smaller scale: thin sections of profile sections can be analysed macroscopically. Within these thin sections, inclusions of organic matter, types of grains and organisation structure can tell us about the ways humans modified the soil, type of manure and more.

 

Figure 2 Example of a thin section magnification.

 

 Figure 3 Good example of a carbic podzol profile, a natural occurring soiltype in the Netherlands

 

Applications within archaeology

Apart from habitation and how the landscape in the past must have looked like, soils and sediments also have an impact upon your own body. Yes, your stomach might be affected if you have been trying to distinguish silt from clay by tasting it – and especially when you are trying to determine the texture of an anthroposol (a soil type which has been altered by human interference) that might have been fertilized with human manure. However, I am talking in particular about teeth here. Certain elemental ratios from the soil end up into our diet. In the case of strontium, these elements substitute for calcium in our teeth and can provide a useful tool to archaeology. The strontium ratios depend mostly upon the bedrock, the soil and sediment types, hydrology and rainfall and represent the combination of all of these factors within the area where you grew up. At least, in the past this was the case (nowadays we hardly eat locally produced food). Again, soils and sediments from another good application from the geoarchaeological toolbox!

All in all, this toolbox creates opportunities for the geoarchaeologists to further their knowledge on the context of archaeological sites and material. With these tools, the mud surrounding the archaeological material becomes more clear and can provide the necessary context archaeologists long for. Apart from contextualising archaeological material and sites, it also creates awareness of the area I am surrounded in. I am now aware that every colour, particle size and composition – just to name a few - can be used to recreate a past landscape. The ground below my feet has never been this interesting.

Figure 4 Determining the texture of material from the archaeological site of Tofts Ness, Scotland.

 

 

 

Hi, my name is Adem, I’m a student of Environmental Heritage management studying at the University of Stirling (Scotland). Once hearing about the opportunity to develop my skills in geoarchaeology, while learning about the landscape history of the Netherlands I knew I had to go!

Day 1, getting to know you… an introduction to geoarchaeology, and the landscape of the Netherlands
When arriving for the first time at VU University I was amazed by the size and aesthetics of the campus, by far the most modern looking university I’ve ever seen! Excited to start the course, I found my way to first class where I was introduced to my fellow classmates and teaching staff; Prof Ian Simpson, and Dr Sjoerd Kluiving.
Teaching began firstly with developing an understanding of the geology of the Netherlands, and the processes stemming from 2.4 million years ago which formed the landscape. The landscape has changed many times, influenced by changing climate, sea level rise and glaciation processes. Also, the landscape was influenced by changing river and marine dynamics as seen in figure 1. This first step of contextualising the landscape before examining soils is important, as it influence the parent material and deposition of sediments on which the soils are formed. We then understood the soil forming factors in greater depth: Climate, Organic matter, Parent material, Time, and Relief (CleOPaTRa). In addition to this we discussed the impact of humans on soils, and how plaggen soils are formed based on cultural farming. Then we took part in a mapping exercise, which illustrated how high topography formed by glacial push moraines influence the soil types as well as anthropogenic land uses. We found that areas which were low lying and wet were likely to be peaty mollisols associated with agriculture, and soils at higher altitude on free draining sands were more likely to be podzols.


Figure 1: An illustrated map showing the dynamic river and marine influences on the Netherlands.


Armed with this new knowledge, we put theory into practice and took part in an exercise describing and interpreting soils preserved on lacquer peels! In groups, we described soil colour (using a Munsell colour chart), texture and structure and then interpreted the soils based on these observations. This was a great learning experience, as we were able to work with a variety of soil types in one place under the guidance of expert knowledge. Here in Figure 2 Sjoerd can be seen describing how time influences the formation of a pozol soil with comparison between the far right and centre lacquer peels.

Figure 2: Sjoerd describing the lacquer peels, explaining how and why they differ.

Day 2 Fieldwork Field-fun!
Our field research began at Wekeromse Zand. This location part of the highlands of the Netherlands, an area with sandy soils where erosion and sand dune formation take place. Our objective was to core the soil using auger coring and then describe the soil and interpret how it may have formed. We started by sampling a flat farmed landscape. Here we found a plaggen type A horizon, followed by what appeared to be an eluviated B horizon and then yellow sand thereafter. Using our observations, we interpreted that the soil had once been a podzol leading to an eluviated B horizon. This soil had then been mixed and added too using plaggen agriculture creating a new anthropogenic A horizon. This underlying B horizon is an example of a Relict soil.

 
Figure 3: Site 1, flat farming landscape.