Thoughts on stratigraphy and sampling

I came across a paper by Tipper (1998) which reminded me of the importance of looking at stratigraphy in multiple dimensions. In the paper he discusses stratigraphic completeness and the notion of ‘‘spatio-temporal masking’’: the effect when primarily spatial variations mask primarily temporal variations. He then tries to estimate the optimum sizes of the sampling area in order to best estimate the stratigraphic completeness in the field. Admittedly, I did not follow Tipper’s calculations at some parts but two things became clear to me: the problems that this paper discusses are very relevant to specifically micromorphology and micromorphological sampling, and that it is very important to have micromorphology samples of at least two orientations when studying a site. 

Unfortunately, at Umhlatuzana it was only possible to sample the west profile. To solve the problem of having only N-S oriented samples, I ended up cutting some of the thicker samples vertically after impregnation. So, even if they were originally sampled at the west profile, they ended up having an E-W orientation.

The term spatio-temporal masking discussed by Tipper reminded me of the Law of Facies (aka Walther’s Law), a stratigraphic term explaining how depositional environments that are laterally related can become superimposed and result in trans-transgressive sedimentary formations (see more at Karkanans and Goldberg 2018, 163). The Law of Facies is for me one of the most complicated stratigraphic principles to fully comprehend but something you always have to take into account when studying a stratigraphic sequence.

Karkanas, P., & Goldberg, P. (2018). Reconstructing archaeological sites: Understanding the geoarchaeological matrix. Hoboken, NJ: John Wiley & Sons.

Tipper, J.C. (1998). The influence of field sampling area on estimates of stratigraphic completeness. Journal of Geology, 106(6), 727-738.

Recap of 2019

2019 has been relatively productive for my PhD research. Here I am going to overview some of the activities undertaken and their various ups and downs! 

Conferences attended

With participation in three international conferences (happening within a small time period), I would say that 2019 was rather conference heavy! 

In June I attended the Developing International Geoarchaeology conference in Vancouver, Canada. There I presented a poster and got to meet many interesting researchers in geoarchaeology, including the conference organizer Francesco Berna and his team. Link for poster.

In July I attended the Association of South African Professional Archaeologists conference in Kimberley, South Africa. It was a very nice experience that gave me the opportunity to meet many archaeologists that work or study in South Africa. Link for poster.

Lastly, in September I attended the European Society of Human Evolution conference in Liege, Belgium. I got the opportunity to meet a lot of old colleagues and friends and to attend talks on the latest evolutionary findings. Link for poster

Ups: networking, research exposure, conferences had different research focus, traveling

Downs: conferences too close to each other timewise, too many posters- next time presentation


Various analyses were undertaken from samples of both the 2018 and 2019 expeditions in Umhlatuzana. All of the sediment analysis (granulometry, XRF, pH, LOI) is concluded and under preparation for publication. A total of 9 micromorphology thin sections were produced of the 2018 samples and are ready for analysis. Hopefully, the rest of the thin sections will have been prepared during the first half of 2020. 

Ups: interesting results, micromorphology samples not destroyed during shipping (!)

Downs: micromorphology thin section analysis delayed



To begin with, I attended the Site Formation Processes field school in Athens, Greece organised by Takis Karkanas and Paul Goldberg. 

In July and August I participated in the Umhlatuzana excavation and took additional samples for micromorphology and other sediment analyses. In addition, a small fieldwork expedition was undertaken in Lesotho where I visited a Later Stone Age rock shelter, studied the stratigraphy and took some micromorphology samples.

Ups: balanced amount of time spend during fieldwork, lots of sampling

Downs: Needed one more week to reach bedrock in all the squares in Umhlatuzana!

reading 2020
Entering 2020 with no surprises since my fate was already foreseen!

South Africa Fieldwork 2019

Fieldwork is one of the best things when working in archaeology. Visiting new places, excavating exciting sites, meeting new people.

This year, our South Africa field season included all of the above! 

ASAPA 2019 poster presentation

The first stop was the ASAPA archaeological conference that was held in Kimberley, Northern Cape. There, we presented a poster on first results of the stratigraphic assessment of Umhlatuzana rock shelter. We also got the chance to visit fascinating rock art sites in the area.



Engraved rock art at WildebeestKuil and Nooitgedacht, Northern Cape, South Africa


Our excavation started shortly after. The team consisted of 7 people and we were regularly assisted by volunteers of the local archaeological society.

Umhlatuzana rock shelter


This year we decided to undertake intensive sediment sampling in the excavated profile. The aim is to locate changes in geochemistry and mineralogy throughout the section in order to identify possible occupation signals and better assess the taphonomy of the site. We have so far conducted XRF, pH, and Magnetic Susceptibility analyses.

Grid sampling
XRF analysis undertaken at the University of Witwatersrand


Looking forward to an academic year analyzing all the data from this year’s fieldwork! 


Site Formation Processes Field School

I recently had the chance to attend a field school in Site Formation Processes of the Athenian Agora in Athens, Greece. It was organized by Takis Karkanas and Paul Goldberg through the Americal School of Classical Studies and the Wiener Lab

It was an amazing experience and gave the participants the chance to deepen our knowledge in aspects of geoarchaeology concerning formation processes of an urban archaeological site. Different scales of the site were discussed: the regional scale, the site scale, as well as the microstratigraphic scale.


Looking at the broader picture: Geological section of fluvial deposits and palaeosoils in Boeotia, Greece


The field school combines both field (geomorphology, stratigraphy, sampling strategies) and laboratory (micromorphology, FTIR) training.


Discussing the profiles within the Athenian Agora

In addition to the skillset acquired, the field school was a lot of fun and gave the opportunity to meet people interested in the same research field. It is organized annually (applications due ~April) and I would highly recommend it!

Sedimentology Lab visit

The Leiden GeoArch group organised a visit to the sedimentology laboratory at Leiden University College, Den Haag. The lab is led by physical geographer Peter Houben and fluvial geomorphologist Paul Hudson. There, they conduct various sedimentological analyses like grain-size analysis and pH measurements.


Our visit started with an introductory session where Paul and Peter presented their work and research. We then moved on to the sedimentology lab where they showed us their facilities and talked about future plans for expanding the lab.


Finally, we discussed the potential for collaboration in research and teaching.


We hope that our visit will provide foundations for the development of a geoarchaeological connection between the Faculty of Archaeology (Leiden University) and Leiden University College.

Soil geochemistry on an early Swahili daub house, Zanzibar

I came across an interesting paper by Frederica Sulas and others (2019) who conducted a geoarchaeological study on an early Swahili (medieval) daub house at Unguja Ukuu, Zanzibaar (7th-14th c. AD). The study integrated geochemical, artefact distribution, and phytolith analyses. For the geochemical study pH, Loss on Ignition, and multi-element (ICP-MS) analyses were conducted on bulk sediment samples. The samples were derived from both the archaeological site (indoor and outdoor of the daub house structure) and the surrounding landscape. The main objective of the research was to investigate spatial organisation and activities within the house and test high-resolution systematic sampling strategies in this type of contexts.


View of the excavation trench and the 50 cm interval sampling grid (Sulas et al. 2019)


The use of multi-proxy geoarchaeological techniques helps to further explore the microarchaeological record that would otherwise not be visible with the naked eye. Various anthropogenic everyday activities leave microscopic and elemental traces that can be present even in seemingly homogeneous archaeological deposits. For example, this paper considers the use of Rare Earth Elements (REEs) as indicators of human remains (e.g. nails, skin, hair), seaweed, shell, sand, and animal manures (as ref. by Sulas et al. 2019, 34).


Distribution of Sm, V, Na, and K chemical concentrations (Sulas et al. 2019)


The REEs in this study reveal significant concentration patterning, and when combined with the other results can provide insight into the way people lived on the site, their subsistence strategies, and their spatial organisation. All in all, this paper showcases another example of how integrating various geoarchaeological techniques can develop a deeper understanding of various aspects of archaeological sites. 



Sulas, Kristiansen, and Wynne-Jones. “Soil Geochemistry, Phytoliths and Artefacts from an Early Swahili Daub House, Unguja Ukuu, Zanzibar.” Journal of Archaeological Science 103 (2019): 32-45.

Leiden GeoArch: New geoarchaeology group

Exciting news for the Faculty of Archaeology, Universiteit Leiden: a newly founded group, Leiden GeoArch, that plans to promote and discuss matters concerning geoarchaeology!

The first event will have the format of a lunch-lecture where Victor Klinkenberg will present his work on micromorphology of Mycenaean chamber tombs (March 4th/ 12h/ Van Steenis, Leiden).

What a wonderful opportunity to get inspired by various applications of geoarchaeological techniques to answer archaeological questions!

Leiden GeoArch: Micromorphology of Mycenean Chamber Tombs poster

Various lectures and activities are on the schedule for the near future including my talk “Micromorphology for dummies” coming up May 6!

Spring agenda 2019 for the LeidenGeoarch group: Faculty of Archaeology, Universiteit Leiden


Stay tuned!