VU Geoplaza

Day 1: Another one bites the dust

Having already participated in the first, more theoretical part of the Archon geoarchaeology course, I was very curious what would await me in the practical part. Definitely more soils and sediments. Upon my late arrival, I was not disappointed: the task was to examine lacquer peels and to infer from their composition of horizons the kind of soil type on the peel sample. For doing so, the first step was really to determine the different horizons based on the visibly different colours and textures of the soil sample. As we all knew, these differences between the horizons were due to soil forming processes influenced by factors such as climate, organisms/vegetation, parent material, time and relief/drainage (CleOPaTRa in short [the ‘Richard Of York Gave Battle In Vain’ of geology]) and were, naturally, individual for each soil type. After doing so, we ‘measured’ the colour via Munsell as well as the fine -/coarseness of the material in each horizon, which proved to be equally a subjective task. Lastly, we assigned each horizon a number and a letter equivalent to the kind of soil horizon, e.g. the ‘O’ horizon stands for the top layer organic material. After having collected all these data, one should be able to determine the soil type now, which, as turned out in the group discussion of our cases, were mostly podzols, podzols with a layer created by anthropogenic interferences, i.e. an anthrosol, on top of it (fig. 1) and other podzol variations (haarpodzol, for instance).

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Fig. 1: The lacquer peel of a podzol with a thick (plaggic) anthrosol layer on top of it analysed by our group.

However, naturally, there are more soil types than just the mere podzol and its variations. Moreover, one has to consider soils formed by human influence as well, especially when dealing with samples from the beginning of the Holocene and onwards. For exemplifying this, this exercise had the creation of landscape profiles of three archaeological sites on the Northern Isles of Scotland (Netherskail Marwick, Old Scatness, Tofts Ness), which were used during different time periods (Late Neolithic, Bronze Age, Iron Age, Late Norse and Medieval times), as objective. Via various websites, such as www.soils-scotland.gov.uk, we identified the solid geology, soil types, agricultural land classification and archaeological sites and landscapes at said locations and fed our profiles with the data. This exercise should help us to think about and understand the formation of anthrosols in regards of the different ways of lives of people during different time periods. As a method used in geoarchaeology, it also showed us its biases and limitations.

Since especially determining the texture of the material has proven to be difficult, the last exercise aimed to sharpen exactly that – our sense for the texture of the material, accurate to the micrometre. We were given samples of different depths of which we ‘munselled’ the colour and measured the texture again (fig. 2). In addition, we also needed to give indication about the structure of the texture, i.e. slightly silty sand and so on. This kind of analysis required more senses than just the vision: much feeling and tasting was involved (yum!).

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Fig. 2: Samples of different depth. Traces of close examination are visible.

Day 2: Encounters of the clay kind

After the preparatory first day, today revolved around testing our skills in the field. First stop was at Wekeromse Zand. There, we took three coring samples in three different locations. The first point was located next to a field, which has been in agricultural use. Overall, the terrain was quite sandy (drift sand area due to Aeolian processes) and via the ArcGIS Collector app we could see that we are dealing with a podzol region with cover sand at the field to which we were standing next to. The first coring samples were taken in four groups within a distance of about 10 m in between each other. Overall, they showed, moving from the edge of the field towards its middle, a thickening and broadening (plaggic) anthrosol horizon above a podzol (“Stop saying that!”) (figs. 3 – 6). These irregularities might be explained by the undulating landscape character of the field.

 

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Fig. 3: Preparations for taking our coring sample. 

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Fig. 4: Professor Ian Simpson teaching us his coring skills

   

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Fig. 5: Our coring sample showing a podzol with a plaggic anthrosol. 

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Fig. 6: Professor Ian Simpson and Dr. Sjoerd Kluiving contemplating our sample.

Afterwards we moved into a forest on the Wekeromse Zand area, right next to the field. The landscape there was quite different from the one encountered at the field, being very hilly (fig. 7). As our coring samples showed, this was due to accumulated drift sand (“…the Aeolian thing again?”) (fig. 8). The reason why it is drift sand and not a Pleistocene formation is that the sand had a rather greyish, ‘dirty’ colour. If it were originated from a Pleistocene formation, it would have a different, ‘clean’ colour, more yellowish and less greyish (thank Munsell). Moreover, further down the cover of drift sand would probably lay a podzol as well, however it was unreachable for us at that time.

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Fig. 7: Hilly landscape of the forest. 

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Fig. 8: Our coring sample consisting mostly of drift sand and a weak humus.

As a last coring spot at Wekeromse Zand, we walked to the open, sand dune area (fig. 10). There, we looked at a sequence of soil horizons, which was nicely visible at one of the wooded slopes (fig. 9). The cover sand situation was clearly observable as well as the podzol underneath it. We also did a coring in the sand dunes, on whose horizons the difference between drift and Pleistocene sands was noticeably to see: here, the sand had a nicely yellowish tone to its colour.

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Fig. 9: Dr. Sjoerd Kluiving explaining the different horizons visible at the slope.               

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Fig. 10: One can see why people prefer this open, sandy landscape.

 Now it was time to leave the Wekeromse Zand and to move on to our second and last stop, the low lands of the Western Netherlands at Amstelveen. A quick look on the ArcGIS collector app showed, we were on a gleysol area. The difference between the high- and lowlands of the Netherlands was nicely visible by the sluice next to which we took our last two coring samples for the day. The first was taken in the lowlands at around -2 m under NAP, whereas the second was even lower, at -4 m NAP. Overall, they both showed rather humid conditions with nice smelling peat layers. In comparison, however, the ‘lower’ sample was ‘less worked’ by human activity than the upper one, the disturbed layer being much thinner, for instance. During the coring of the lower sample we decided to get deeper to the bottom of the soil. This was a fascinating as well as equally dirty endeavour, as it produced nice clay coring samples, which were, at the same time, very wet and liquid. The fascinating thing about these clay samples was now that, the deeper we got, the older they became (we were at around 10000 ago at one point). They were of varying blue/grey colour and consistency too. In some horizons we even found some clams (sometimes smaller clams in bigger clams), which could have been used as in situ data for dating.

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Fig. 11: Dr. Sjoerd Kluiving taking a coring sample at the higher point of the low lands.

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Fig. 12: The clay core samples from the lower spot of the low lands.

Day 3: I know what you did 10000 years ago – hidden stories in thin sections

The morning of the third and last day we spent with what the next step of any geoarchaeological investigation would be: the microscopic examination of the micromorphology on thin sections taken as a sample from an archaeological site, in this case from the three sites of day 1. We examined the samples for different criteria such as microstructure, the composition of the coarse as well as fine minerals, organic material, anthropic inclusions and pedofeatures. The composition of the thin sections is, naturally, directly influenced by the CleOPaTRa factors as well as anthropogenic activities. The impact of the latter component was especially nice visible since the people lived in different ways during the different time periods. On these grounds, it was visible, for instance, how the amount and quality of the pedofeatures changes considerably when comparing the features of the Neolithic site Tofts Ness with the Iron Age site Old Scatness. A considerable rise in the amount of excremental pedofeatures at the latter site is clearly visible, indicating either a cesspit or the use of manure as fertilizer for the fields. A nice addition to the examination process was the scrutiny of the thin sections under polarised light, which showed the coarse and fine material in an eerie, spacey reversed colour scheme. As hypnotising as these light effects might have been, they made it possible to discern different details on the components, entailing criteria such as structure as well as colours.

After this fascinating view into the micro – verse of micromorphology, it was our turn to show what we have learned during these past days and how we would incorporate geoarchaeology in our own research. Each of us chose our own topic, presenting new research themes such as crysols, identity, and geoarchaeology in the setting of a maritime cultural landscape as well as others such as landscape formation processes and land use over time in the context of a reciprocal relationship between landscape and people. The course was concluded with a quick synthesis of the course and a reflection of the newly learned information as well as aspects.

A few words at the end – what did actually stick to my short term memory student brain?

Overall, I found the course quite enjoyable, the kind of knowledge that was communicated not only useful, but also offering new perspectives for future research methods in archaeology. The atmosphere in the group was harmonious and interested too, which created nice working conditions and made working on the group assignments pleasant. Personally, I think learning how to be able to distinguish and explain soil horizons and formations is important for our understanding of how the archaeological record is deposited and preserved within the ground. Apart from that, the geoarchaeological information provides us with empirical data that can give us a clear notion about land use in the past as well as anthropogenic alterations of the landscape and, naturally, how these choices by past humans were influenced by the soil types and formation processes in the past. Especially the clay coring during the second day at Amstelveen had a bit the overtone of time travel: not only were the samples of deeper depths incredibly old, finding actual clams within them really showed how this whole area was once part of the North Sea. Considering the other field exercises, I think they all showed what vital information geoarchaeology has to offer in terms of reconstructing the past landscape people lived in, much of the information being even online available for free. Because of these low costs and the readily accessible information, it should not be too difficult to create preparatory landscape profiles for sites investigated by a project. Based on this, I believe it might be actually of advantage to use some of the geoarchaeological methods more often as a tool in the general archaeology toolbox.

 

When looking at the presentations of my fellow students, I think it is safe to say they equally enjoyed the course. All of them showed how the incorporation of geoarchaeology can contribute and broaden their own research interests and were in one way or another connected to their interests. Also, I have seldom seen a group of people looking at and touching completely mesmerized and fascinated some old as the hills wet clay ´, contemplating about how the texture and colour changes over time. This is passion as far as it gets without becoming obscene and I am glad I was a part of it. 9/10 recommend this Archon course!

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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!

Dig this! A reflection on three days of geoarchaeology 

 

Three days of an intensive goarchaeology course does something to a human being. One is altered in a way that one can never look at the landscape again with a mind that is blank, naïve, oblivious. Landscape, like beauty, is in the eye of the beholder. I feel like a novice hunter that has been taught how to see, and to pick up signals so that the landscape reveals a layer of itself that I have not layed eyes on before (see Ingold, 2000). Whether this change inside me and my fellow students is for the better, I could not tell you.

 

One has to see a sol to know a sol

Everything has a context. In the case of archaeology, the space-time continuum (FitzPatrick, 1983) of soil gives context to what we find, or what we don’t find. Archaeology will always have a soil and sediment record surrounding it which is like a story of what happened in the past. If someone walks the soil, ploughs it, manures it, or digs it: it affects the underlying soils and sediments. Archaeologists try to read this thick book through an extensive set of tools. Describing features like color, texture, structure, organic contents, and the nature of the lower transition from one soil horizont to another, are a prerequisite for a geo-scientific approach to understanding soils and sediments. The landscape can be understood subsequently, but understanding has to be built op by describing before combining soil features to an analytical conclusion.

 

However, before one can describe a soil, one has to see a soil. One can see a soil profile in the form of a lacquer peel, and one can see a soil in real life. Both could be done in this course and both leave different impressions on novice hunters or on, of course, me and my fellow students. On day 1 of this geoarchaeology course we got confronted with an extensive range of laquer peels that didn’t smell or didn’t taste quite as good as, we discovered the next day, real life soils, but anyways could be described for different abovementioned soil features. Me and my partner-in-crime hit checkpot directly because we were describing a so-called ‘Vaaggrond’ (if directly translated to English a ‘vague soil’, which mostly leaves the layman with utter confusion) (Fig. 1). Following is an account of the process of describing the soil and its features (Fig. 2). I will go more deeply into the features that I found particularly interesting and will only mention the others briefly.


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Fig.  1. Our Vaaggrond: you can see the greyish and brownish colors and limited soil formation.


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Fig. 2. The description of the soil features.

  

 

 

Firstly we drew the soil profile and divided it into several ‘layers’ that we could distinguish (or at least we thought so), and ended up with 15 layers which we later refrained to only 4 distinct soil horizonts. We described the color through comparement with the Munsell color chart and discovered that most colors in our profile were shades of greyish brown or brownish grey. Mostly the top layer(s) were browner and darker and the following layers lighter with more grey. These colors can give indications of drainage, leaching of the soil, and organic components and are thus very useful. Next thing to describe is the texture of the soil: how fine or coarse is it ranging from silt to gravel? This gives indications regarding the depositional process, fertility of the soil, and drainage possibilities. I found our profile particularly interesting for this feature because we had a so-called ‘fining upward sequence’. Dr. Sjoerd Kluiving explained to me and my partner that we had an alluvial deposit for which the rivers ‘stroomdraad’ changed over time.  Later, we evaluated the texture which can tell us for example about the presence of clay or silt. Following this, the organic compound of the soil is described. This is of interest because it can give an indiciation of vegetation. Next we described the presence of iron oxide, clay skins, and the nature of the boundary between one horizont and the next.

            Now came the part we highly awaited: the final analysis in which I could finally make conclusions and check my skills in pattern recogniton. With some illuviation of knowledge from prof. Ian Simpson and Dr. Sjoerd Kluiving into the brains of me and my partner, we could conclude that our soil showed evidence of a plowed Anthrosol, an illuviated plowed Anthrosol, followed by an illuviated sol, and finishing it off with a thick layer of parent material. Translating these horizonts we came to our Final Judgement: a Vaaggrond. A Vaaggrond – which has no literal translation in the World Reference Base for Soil Resources but can either be classified as an Arenosol or a Regosol, depended upon texture – is a soil that hasn’t developed clear horizonts, which is mostly due to the young age of the soil.

 

Real life soils going wild!

A fieldtrip of any kind brings joy to the hearts of archaeologists. Even more so if a friendly busdriver makes sure everyone stays safe by giving you a firm hand around your underarm by every disembarkment. Even more so if one is to get dirty. And even more so if one sees fellow students getting dirty while observing in amusement. I would happily write about the social and soily dynamics but I will contain myself as I am not an anthropologist but an archaeologist. Armed with gouges, cores (an ‘Edelmanboor’ in our case), gouge knives, tapelines, paper and pencil, Dr. Sjoerd Kluiving and prof. Ian Simpson showed us the places of interest for the second day of the course. Coring we went through 4 observation points near and on the Wekeromse Zand, culling a Vaaggrond, a Micropodzol, a Podzol, and a Carbic Podzol. Unable to control our soil rage, subsequently we gouged at 2 observation points in Amstelveen. Two Gleysols were slaughtered that afternoon.  

            The Gleysols in particular left most students in amazement because of the endless layers of peat and clay. Especially when we were told that each 1 meter of sediment approximates a 1000 years of sedimentation: how could our young brains ever comprehend this magic? At the second observation point in Amstelveen we already had to physically descend to around 4 to 5 meters below NAP (Normaal Amsterdams Peil, describing the average sea level - originally calibrated to the geoid). We gouged (Fig. 3) out firstly a disturbed layer of around 20 centimeters, whereafter only about 50 centimeters of peat. This was not surprising because the rest of the peat has already been removed to be used as fuel in earlier times (remember our descend to around 4 to 5 meters below NAP?). Subsequently we came into endless layers of clay; blueish clay, sandy clay, greish clay, compact clay, and shelly clay. This went on for about 5 meters before Dr. Sjoerd Kluiving and Prof. Ian Simpson decided this was enough. Dr. Sjoerd must have seen the bewildered faces of me and my fellow students because he explained:

 

            The peat that formed developed in a closed habitat, which is an indication of the closed circumstances of the coast because of shore formations. This peat is lying on top of this very open marine system, where shells could live and people couldn’t. On one point below this there would be a based peat layer, which developed because of   rising ground water tables which in turn were due to rising sea levels. Only later the Netherlands would actually flood because of the sea level rise. Below this based peat layer there would be a layer of Pleistocene substrate. This could have been river deposits or a sandy soil, or there is even the possibility of a podzol having developed   there. This was possible because before the Pleistocene substrate became flooded by the sea, this soil had thousands of years to develop and to form horizonts. Even hunter-gatherers could have lived on this surface.

 
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 Fig. 3. Endless layers of clay in our gouge at the second observation point in Amstelveen. 

Thin sections of rubbish

Looking through a microscope is always fun. Actually it doesn’t really matter what you are looking at because the colors and shapes under different lights are beautiful anyways. However, I have to admit that knowing that the multi-colored slide you are looking at is kitchen-waste makes you think slightly different about rubbish. At the third and last day of our geoarchaeology course we got confronted with thin section micromorphology. In micromorphology it’s possible to take a closer look at the stratigraphy and is an analysis of the undisturbed soil and sediments under the microscope. It gives insight into how the soil and sediments are organised, which gives clues about how the soil is related to each other and thus formed. My first moments behind the microscope made me feel mentally disoriented (not the first time I experienced that mental state in the last couple of days), but prof. Ian Simpson came to our rescue with examples and explanations. We managed (I say ‘we’ and not ‘I’ because prof. Ian Simpson rescued me many times) to partly untangle 1 thin section – from an agricultural layer at Tofts Ness, Sanday – which I will briefly describe in the following alinea.

            In the thin section from Tofts Ness (Fig. 4) we could discover a microstructure of chambers. The related distribution, which explains the relationship between coarse and fine material was porphyric with a coarse/fine ratio of 30/70. Porphyric means that the coarse and fine material is totally mixed with each other. Of the coarse mineral material that was present, quartz was very frequent, sandstone was only present in traces, and clacareous sands only in small amounts. This coarse material was moderately sorted, which means that it was not all of the same size, but also didn’t show big size differences. Regarding the fine mineral material, this thin section dominantly showed organic material, very few rubified material, and a speckled and random B-fabric. Linear patterns of the B-fabric could indicate an agricultural layer, but in this thin section there didn’t seem to be a particular organisation to it. Futhermore, we saw shell fragments, bone fragments, and fungal spores (Fig. 5).

 
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Fig. 5. Micromorphology in the thin section from Tofts Ness. A: a shell fragment under cross polarized light. B: a bone fragment under polarized light. C: the same bone fragment under crossed polarized light. D: fungal spore under polarized light.

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Fig.   4. Thin section from Tofts Ness.

Prof. Ian Simpson explained to us that the thin section of Tofts Ness gave us a look into a kitchen-waste layer that is used to mend with the soil. The soil predominantly existed out of wind-blown calcareous sands which was freely drained. People tried to farm in the area and it was a difficult environment to work with. Mending kitchen-waste with soil gave it the opportunity to be cultivated. This was an interesting insight and made me think about what ‘rubbish’ or ‘waste’ actually means in a world where maybe everything gets a second purpose.

 

Of blank minds and stuffed brains: geoarchaeology ain’t bringing sand to the beach

All in all I have to say that this course changed the way in how I look at landscape. Whether I like to have a blank mind when I look at the landscape surrounding me or one stuffed with questions and theories depends a bit on the day. From experience I can tell you however: one does not simply switch the geoarchaeology switch off! A couple of days have passed and my mind is still not back to normal yet…

            - No longer is this a ‘just whatever augmentation’ in the Dutch landscape. This, before, uninteresting augmentation has changed into a push moraine; a relic from the second last ice age during which big icecaps smoothed along the Dutch landscape, pushing softer sediments like river deposits into hillish features. During the last ice age wind-borne cover sands were deposited on top of this push moraine, for then this part of the landscape was a vast polar desert. After that, finer sands like driftsand could be deposited. Then, during the Middle Ages or later, humans found ingenuitive ways to fertilize this sterile soil. They augmented the push moraine even more through depositing heath sods mingled with dung from livestock. These and later generations plowed the soil and precipitation drained through it to leach minerals and organic matter from the topsoil into earlier deposits, like the cover sand. I have learned that this cover sand lost its clean color when approaching the layer of plaggen; now being a darker …... Down, brain! Down! … Good girl. -

 

            I did learn a lot, and the course also gave me insight in how I could use geoarchaeology for my own research (which mostly revolves around reindeer and circumpolar communities – what about reconstructing migratory patterns of domesticated reindeer through different properties of soil and its stratigraphy?). Knowledge can definitely be a burden, but it does open ones eyes for sure.

 

 

References

 

FitzPatrick, E.A., 1983. Soils. Their formation, classification and distribution. Longman: London.

 

Ingold, T., 2000. The perception of the environment: Essays on livelihood, dwelling, and skill. Routledge: London.

 

 

 

 

 

 

 

 

 

 

 

 

 

                  

 

Sediments, sediments, sediments – what on earth are they and what to do with them? 

For many students of archaeology and the more general public, soils and sediments might just as well be one and the same. After all, most archaeologists go mindlessly through the layers and, at most, note down the changes in colour or texture only after being forced to do so by the supervisor – a dreaded moment for most beginners. Yet, often we do not know why we are recording any of this information and expect a specialist to magically tell us how the landscape looked at that particular point in time and space. Moreover, it is important to know how the artefacts ended up where they were discovered, and knowing the type of deposition is key to this information. In the process to recognising the mode of deposition, the geoarchaeologist is constantly considering a wide variety of possible scenarios based on the deposits’ qualities. For instance, the size of the grains or stones in a layer depends on the energy involved in the deposition, while the roundedness or angularity of the material in the deposit will reveal whether the material was deposited by gravity or water. The geoarchaeologist then uses this information to answer whether or not a certain layer is a soil or a sediment, a knowledge of which makes the world of difference, as discussed in the next section. 

But what then makes a soil and what is considered a sediment? How does a specialist differentiate between the two? Well, the short answer is that a sediment is the material that accumulates on top of the bedrock through various modes of deposition, while soils are formed in the sediment through chemical, physical and biological processes acting upon the earth’s surface. Among the specialists, sediments are commonly known as the parent materials for soils. Soils represent periods of inactivity in the deposition of material, and the length of time that the landscape has remained unaffected by outside forces can be inferred from the various stages of soil formation. For us archaeologists, identifying the formation stage at which the soil formation was interrupted by human activities, such as cultivation, can be a useful indicator of the kind of environment in which certain behaviours, including agriculture, first appeared. Furthermore, it is possible to go into more detail about the way in which the land was managed. For instance, it is possible to differentiate between slash and burn versus annual cultivation, as the more sedentary the agricultural community becomes, the more they have to depend on fertilising the soil as it becomes depleted from nutrients without fertilisation. 

Typical anthrosol, or human induced soil formation.

What about distant past?

In Palaeolithic archaeology, the importance of soils is slightly different from the archaeology dating to the Holocene. Soils still formed during the Palaeolithic, but today they are often either eroded or overlain by new sediments that subsequently formed soils. The soils that are still preserved and below a sedimentary deposit are called palaeosols. These are very important layers in Palaeolithic archaeology, as they represent stable conditions during which sedimentation processes halted, and thus allow us to infer that no vertical movement of artefacts have occurred. In addition, palaeosols are very good chronological markers. However, because palaeosols may have taken several thousand years to form, any artefact assemblage within a palaeosol is formed during that time period. What this then means is that in palaeosols, the differentiation between occupations is not possible, as the artefacts were simply dropped on the surface, resulting in large accumulations without any layering in between the various visits. In contrast, due to the continuous nature of sedimentation processes, if an artefact assemblage of ten artefacts with a vertical distance of ten centimetres from each other is found in, say, one metre deep sedimentary deposit, each of those individual artefacts may represent individual instances of deposition and therefore represent ten visits to the site. However, these ten artefacts might also represent either a single episode within a reworked deposit, or a secondary deposition of the artefacts by water or colluvium, depending on the mode of sedimentation. These hypotheses would have to be confirmed through micromorphological or fabric analysis. It is therefore easy to understand that recognising the presence of palaeosols and sediments in Palaeolithic sites is of importance, as the interpretation of whether the site was visited, or if the artefacts derive from somewhere else is highly dependent on the identification of sediments. 

 

Cave sedimentation

First, it is important to realise that there are two types of caves: exogene and endogene caves. Exogene caves are commonly known as rock shelters, and they are formed in a different manner than endogene caves, which are caves that have passages and/or chambers. Both types of caves act as natural depositional traps, in which the deposits are mostly protected from subaerial weathering and erosion. Because of this quality, caves represent longer time sequences than open air locations, they preserve human and faunal activities better, and they hold a higher quality climatic record. Studying several well dated cave sedimentary records may reveal changes in regional climate, while changes in local environments are discernible in practically all records. This allows us to reconstruct entire landscapes with or without human presence during the Palaeolithic. 

There are three main types of material contributing to cave sediments: clastic detritus, organic detritus, and precipitated carbonates. The term clastic detritus refers to all rock rubble, cave earth, and water-lain material within a sediment, while organic detritus refers to all organic matter within the sediment. Precipitated carbonates are essentially speleothems, or flow- and dripstones, which may cover entire walls and floors, protecting the artefacts from re-deposition. The proportions in which these three materials are represented in the cave sediment is related to the rock type, size of fissure, groundwater regime, as well as topographical, geological and geographical context. All of these materials can be analysed to reconstruct very fine detail palaeoenvironments and record climatic changes. Their origin is often exogenous, but faunal and human remains may also originate from the individuals who once occupied the cave, whilst the speleothems are always local formations. Organic deposits rarely make up the most of a sedimentary layer, although bone and artefact beds do occur. 

1. Breccias formation under a pitfall trap 2. and 3.Waterlain silts;  4. Den accumulation of bones;  5. Accumulation of bat remains beneath roosting area in the cave roof and accumulation of small mammals beneath owl roosting/nesting area in the cave roof; 6. Water transported mud from further inside the cave;  7. Speleothems; 8. Roof fall; Accumulation of bones of cave bear, died during hibernation in the deeper regions of the cave; 9. Former lower chamber of the cave that acted as a natural trap/ accumulation room of amalgamated debris flows. - See more at: http://historyofgeology.fieldofscience.com/2010/10/if-you-gaze-long-into-abyss-abyss-will.html#sthash.Baj7tbmO.dpuf

1. Breccias formation under a pitfall trap
2. and 3.Waterlain silts; 
4. Den accumulation of bones; 
5. Accumulation of bat remains beneath roosting area in the cave roof and accumulation of small mammals beneath owl roosting/nesting area in the cave roof;
6. Water transported mud from further inside the cave; 
7. Speleothems;
8. Roof fall; Accumulation of bones of cave bear, died during hibernation in the deeper regions of the cave;
9. Former lower chamber of the cave that acted as a natural trap/ accumulation room of amalgamated debris flows.
Taken from: History of Geology Blog - Taphonomy of Cave Environments

 

My research

In my research, I look at the differences between interglacial and glacial deposits. My research asks how do sedimentation processes vary according to the environment in south-western France? Are there any discernible differences between interglacial and glacial deposits? If so, what are they? In trying to answer these questions, my focus is not solely on micromorphological differences, but also macroscopic differences. This knowledge can then be used to determine whether taphonomic factors affect the interpretations of archaeological remains. Moreover, this information may reveal settlement patterns across the landscape if several sites with similar sedimentation processes and timeframes are noted. 

 

Further reading

Farrand, W.R., 2001. Sediments and Stratigraphy in Rockshelters and Caves: A Personal Perspective on Principles and Pragmatics. Geoarchaeology, 16(5), 537-557.

Karkanas, P., and Goldberg, P., 2013. Micromorphology of Cave Sediments. In: John F. Shroder (Editor-in-chief), Frumkin, A. (Volume Editor). Treatise on Geomorphology, Vol 6, Karst Geomorphology. San Diego: Academic Press, 286-297.

Lowe, J., and Walker, M., 2015. Reconstructing Quaternary Environments. 3rd ed. London: Routledge.

History of Geology Blog - Taphonomy of Cave Environments

White, W. B., 2007. Cave sediments and paleoclimate. Journal of Cave and Karst Studies, 69(1), 76-93.

 

Interdisciplinary Archaeology: The underestimated possibilities of geological practices 


 

It is well known that the importance of geological methods and theories within archaeological research is of upmost importance to understand the context of our findings. However, the further role geology could play within archaeological research is often underestimated. As archaeology is a rather young scientific discipline, and is formed by its interdisciplinary approaches, it is important to continue exploring the possibilities other disciplines might offer archaeology as a field of research. Every now and then, we (archaeologists) would do well to be reminded of this, and to re-explore other disciplines that may hold innovative and revealing approaches, methods and techniques that would benefit our own research.

The entanglement of archaeology with geology is deep, and though we might think we have learned all there is of geology and what it has to offer to archaeology, I think every self-respecting archaeologist should be open and willing to refresh, update, or even upgrade  its geological knowledge every once in a while. Therefore I have chosen to do a Geoarchaeological workshop at the VU (Amsterdam), provided by the ARCHON research school of archaeology. This three-day workshop has been refresehing and eye-opening to me, and has allowed me to reconsider and broaden my own thesis research. Don’t believe me? Let me explain to you why:  

The first day was all about re-excavating our geological knowledge as we kicked off with some very basic information about the origins of the dutch landscape. The influences of the Saalian glaciation, river and sea deposits, eolian (a.k.a. wind) deposits and peat formations have formed the landscape as we know it today. Apart from these sedimentary processes, soil formation processes provide us with information that sedimentary formations cannot: presence of well-developed soils for instance, indicate hiatuses (stable periods of no erosion/accumulation), different soil types may indicate different human activity as the kind of soil that is formed is dependent on its parent material, climatic factors, organisms, time and relief/drainage. Human activity found in relation to certain soils may thus help us understand why certain areas were preferred, as the soils are a proxy to reconstruct and understand the former landscapes. In addition, we got our hands dirty by examining actuals soils and determining their traits in order to understand their origin and formation processes.

To practice what we preached, the second day was devoted to a field-trip to two distinct types of areas that mark the dutch landscape: The Pleistocene formed hilly outskirts of the Wekeromse Zand and the flat landscape of Amstelveen. Here, we did some serious coring into the dwellings of these different areas. learning us to recognize, for instance, the naturally formed podzols (both completely and partly formed) and understand the locations of these soil types in relation to the relief, as was the case at the Wekeromse Zand, and to recognize the younger thickly accumulated sediments of the Holocene deposits at Amstelveen.

The third and final day has been the most eye-opening to me in terms of underestimated and not-often-enough-used methods: for this day kicked off with my first ever introduction to micromorphology. Of course, I knew of the existence of this technique, yet I never really realized how this exactly works and what this technique could actually offer archaeologists. Which is, actually, quite a lot. Thin sections of in-situ sediment samples were placed under the microscope, allowing the examination of traits within the composition of sediments and soils otherwise hardly visible to the naked eye. In addition, human influences or biologically created disturbances, such as worm-activity, could be recognized that otherwise may gone unnoticed. Micromorphology could also be really useful to understand the integrity of stratigraphy and allows the distinction between seemingly heterogeneous layers.    

But how has this workshop helped me with my own thesis research as I previously mentioned? My research focuses on the integrity of a techno-cultural assemblage, the so called Châtelperronian,  of which the authorship is unknown (Neanderthals or Anatomically Modern Humans) due to the possible high occurrence of post-depositional processes that may have resulted from the highly fluctuating climate during the times theses assemblages were deposited. I mainly try to reconstruct the possible post-depositional processes that have occurred by focusing on the artefacts themselves: their distribution within the site as well as the orientation of all elongated artefacts. certain patterns within these may be indicative of certain processes. However, the precise distinction between such processes are hard to observe. The geoarchaeological workshop has made me realize that it will we worth advising some geomorphological maps and micromorphological analyses to help me distinguish different types of post-depositional processes.

As this has convinced me that geoarchaeological implementations on archaeological research are very beneficial, I can imagine you may still not be fully convinced. And therefore I would like to tell you the following. Within the workshop, all the archaeologists, having different backgrounds and different specializations, were able to implement new methods, concepts, or approaches to a great variety of archaeological research.                     

Why is dirt fun?

It was my first year as an archaeology student. I invited both old friends from school and new ones from university to my birthday party. Amazed by the extensive chit-chat about sediments, soils and excavating -and clearly also fairly bored- a non-archaeologist friend asked me: “Why do you guys like dirt so much?” Here, I will briefly show why dirt is fun -both for the layman and the obsessed archaeologist– with the explanation of the geo-toolkit, applied on a Javanese, Pleistocene site, containing important fossils in the study of human evolution.

Video field report - Why dirt is fun

Equipment in the geo-toolkit

Archaeology exploits methods and data from a variety of disciplines, such as anthropology, biology and history. Fundamental applications come from geology, since archaeology explores material remains in the ground. By taking the geological toolkit with into the field ‑both actual tools and mental tools— an accurate context of site formation, dating and (post)depositional processes can be provided. In other words, it helps us, archaeologists, to understand how and when finds ended up where we found them. The toolkit contains an infinite number of instruments, of which many are yet to be developed. A few of those tools in the geo-box include studying old and new geographical maps, geomorphological studies through coring, micromorphology, which investigates contents of sediments and soils, and geochemical isotope analysis, which uses patterned variation in elements on earth in order to reconstruct ecology in the past. 

A Javanese site in need of the toolkit

Eugène Dubois was the first researcher to discover and recognise Homo erectus fossils, which were found in 1984 at the site Trinil on the island of Java, Indonesia. Homo erectus can be considered an essential species in studying the emergence of the modern human body, brain and behaviour. The Dubois collection – which is curated at Naturalis (click for collection history (Dutch) and for an extensive description of the collection) contains a great variety of faunal fossils from the context and the whole region, thus providing the archaeological and ecological context of Homo erectus. However, since geology and archaeology were not yet well-developed, documentation quality and quantity lacks significantly. New excavations might improve our understanding of past and future finds at Trinil.

Sundaland, the biogeographical region that contains Java, is a biodiversity hotspot, caused by tectonic activity and climate dynamics throughout the Pleistocene. With warmer and colder periods, level rising and dropping hid or exposed shelves of the marine continent, which served as (resp.) barrier or bridges and corridors (dis)connecting mainland to islands. See for descriptions and reconstructions Semah et al. 2010 and Bird et al. 2005

The Trinil shells

An environmental reconstruction of Trinil, based on aquatic fauna from the Dubois collection indicated that Homo erectus lived in a coastal and riverine environment. In addition, an abundance of large bivalves at the main palaeoanthropological layer suggested hominin activities for gathering, dexterously opening and consuming molluscs. Moreover, on shell showed to be a retouched tool and a second shell contained a geometric patterns of groove zigzags on its exterior. All three finds are important in the discussion of developments human behaviour, including fish consumption – related to big brains and an associated required high-quality diet, aquatic resource use as raw material - and interesting addition to the debate on the Movius Line, and possibly even symbolic behaviour in species other than Homo sapiens.

Applying the toolkit

Historical documentation and modern maps

Re-evaluation of old documentation by Eugène Dubois and a comparison with modern data can allow for a general image of what to expect if new fieldwork will occur. Dubois’ original drawings were simplistic and of brief description. Modern accessible maps, such as ONEGEOLOGY, often relate to larger geographical areas in lower resolution. However, by cafefull combining the data, pointing out lacking information and detail in the geological knowledge of the site, might actually be useful and provide precise recommenations for future fieldwork. 

 

Dirty shells and their significance

The assemblage of bivalves that included the perforated molluscs’ exterior and the modified shells, included some left-over sediments, which were subjected to micromorphological analyses. Other sedimantary remains within the Dubois collection, a hominin skull and a Stegodon skull, allowed for comparisons of the residues. These indicated that the contents of these sediments, matrices and micro-concretions, are very similar in all three types of fossils. In addition, volcanic materials in the sediments allowed for the first direct dates of the site, pushing the original estimations back with 500.000 years, to a date of 0.45-0.54 ka. Finally, observations of thin sections provided for more information on the depositional character of the layer that contained these fossils. Absence of soil formation and bioturbation (disturbance by animals or plants) indicated a quick infill of the shells, thus a quick covering of the fossils, sealing it well-preserved.

Conclusions

Careful studying of dirt -either as described on maps, fresh from cores, or tiny bits on long-excavated fossils- can teach us where we come from and how human cognition evolved. Dirt provides context of archaeological sites, possibilties for accurate age determination of the first occurance of human traits, landscape formation details trought time and, most importantly, a pandora's box of possibilities to develop new tools to understand remains of our distance past.

Day 1

On my way to the Archon course ‘Geoarchaeology – Theories and Practice 2015-2016’ in Amsterdam, I am starring out the window of a fully packed train. The sun is starting to rise over the by-passing landscape which makes for a pretty view. Still partially unknown to the heaps of information buried under the surface, I wonder what this course will bring. Led by dr. Sjoerd Kluiving (VU Amsterdam) and Prof. Ian A. Simpson (University of Stirling), we start the day with an introduction on the formation of the Quaternary geology in the Netherlands, and the associated processes. Next, the landscape and soil of the Netherlands and north-west Europe is discussed. Some important basic geological distinctions, like pedogenesis-geogenesis, alluviation-illuviation and sediment-soil, were highlighted and the process of podsolization was explained. 

The second part of the day was devoted to part of the geoarchaeological toolkit. Using a topographical map of Amersfoort, we looked at the different ways in which the geological characteristics given in the legend of the map, could be used to study archaeologically relevant questions, such as ‘What is the influence of the different types of soil/sediment on the way in which past societies arranged their agricultural allotments?’. Next, we went down under ground and examined the different structures of soil through several lacquers peels.

Dr. Kluiving holding our carbic podzol lacquer peelOur description of the lacquer peel

As can be seen, our carbic podzol contained enough food for the geoarchaeological brain. We ended our first day with what must be the favorite activity of every geo(archaeo)logist; seeing, feeling and perhaps even tasting actual soil samples. On the basis of the pocket version of the characteristics of soil, i.e. the ‘Munsell soil color charts’ and the ‘soil texture triangle’, we were able to distinguish between different types of soil. Seeing as I was still a geological newbie at this point, many questions arose regarding the connection between the toolkit and archaeological research. Luckily, dr. Kluiving and Prof. Simpson did not shy away for these, and the many more questions that were fired at them. 

Day 2

The day starts with a bumpy ride to the first location of our coring field trip, the Wekeromse Zand, since our tour bus gets stuck inside the muddy surface (pointed out by dr. Kluiving in the picture). This could however not stop us and we continued our path on foot.

Three cleverly chosen coring locations made sure that we would get a very good view on the difference in soil formations which can be present in one area, and the way in which these differences have been shaped over the decades. Since we started this day in one of the higher parts of the Netherlands (+ 25 NAP), the sandy soils introduced our muscles to the intensive part of the geoarchaeological toolkit. The hard part of the coring process was however still to come. 

Our first coring locationOur second coring locationOur third coring location

After waiting for one hour on a bus driver who was nowhere to be found, which gave us the time to discuss and evaluate on our past activities and future assignments, we traveled about 75 kilometers west-north-west and sunk 26 meters, ending up in the wet soils of Amstelveen which lie 1 meter below sea level. The is where the hardcor(e)(ing) started. Due to the fact that we ran behind on schedule, dr. Kluiving decided to bravely take upon himself the task of coring and showing us as much of the soil in the amount of time we had. It soon became clear why the Edelman auger, which we had used in Wekeromse Zand, was not suited for these wet and clayey soils. We therefor had switched to the gouge auger. The end score of the day was an impressive 7,10 meters deep (- 8.10 NAP), which was reached by dr. Kluiving and a courageous participant of the course. This meant that they were able to reach the Dutch basal peat layer (visible on the picture at the end of the drill core) and we had traveled back at least 5500 years in time. 

Day 3

The final day of the course started off with a practical lecture, given by Prof. Simpson, on thin section micromorphology. He showed us the many ways in which a small square of soil could reveal so much on the area from which it originates. Take for instance the three pictures below. Fltr: bone, manure, fungi spores. These indicators can be used to study the diet of past societies, the way they fertilized their agricultural soils and the grazing locations of their cattle, respectively.

Eager as we were, many questions were asked and Prof. Simpson did not hesitate to explain and discuss until everything was clear. 

The afternoon was devoted to a mini geoarchaeological conference in which each of the participants gave a 15 min presentation on the subject of their final paper for this course. Even though we had only had 2 days to think on this, dr. Kluiving and Prof. Simpson had been able to teach us enough to all come up with highly relevant geoarchaeological research questions. This was also noted by both teachers who applauded us for our broadmindedness. 

Coming up with a subject was not easy. I had started this course with a lack of knowledge on geoarchaeology and found it difficult to incorporate it into my own research. During my Research Master, I have specialized in (ethno)archaeobotany and had recently conducted research on the effects of carbonization on barley grain kernels. As my knowledge on geoarchaeology grew during the course, my mind was also opened up to the possibilities of incorporating geoarchaeology in archaeobotanical research, specifically into my previously conducted research. I have gotten curious to the effects of different types of soil and sediment on archaeobotanical macro-remains and the ways in which this information can be used to optimize sampling strategies. This is what I will be studying in my final paper. 

After the successful mini conference, we end this informative and pleasant course with an evaluation while enjoying a drink at a café nearby. Even though this is the first time this course is given in this format, it has taught me a lot on geoarchaeology and the possibilities of incorporating it in my future research. Satisfied, I travel back to Groningen, staring at a landscape from which I now know holds many secrets to be uncovered.